CHARACTERIZATION OF STIMULATED BRILLOUIN SCATTERING IN DIFFERENT MATERIALS
Submitted by
FAISAL KHAN I Reg No: 95713002
A dissertion presented in partial fulfilment of the academic requirements for the award of the degree of
MASTER OF TECHNOLOGY In OPTOELECTRONICS AND LASER TECHNOLOGY
INTERNATIONAL SCHOOL OF PHOTONICS COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY COCHIN - 682022
Under the guidance of DR.V P N NAMPOORI EMERITUS PROFESSOR INTERNATIONAL SCHOOL OF PHOTONICS
JUNE -2015 ACKNOWLEDGEMENT
I Thank ALLAH
With deep sense of gratitude, I express my heartfelt thanks to Dr.V P N Nampoori, Emeritus Professor, International school of photonics, CUSAT for the guidance, motivation, support and encouragement given throughout my project work.
I am thanking Dr M. Kailasnath, Director, International School of Photonics, CUSAT for giving all facilities that helped me to complete this mission.
I extend my sincere thanks to Dr P. Radhakrishnan, Professor, International School of Photonics, CUSAT for his motivation and support during my work
I am thankful to the research scholar of ISP Mr. Mathew S for his support and help.
I am thankful to my friends Mr. Sreejith S L, Mr. George P Mathew, Ms. smrithi V and Ms. Divya narayanan for their support and help.
I extend my sincere thanks to the teaching and non- teaching staff of ISP for all the help and assistance.
I would like to express our gratitude and appreciation to all those who gave me the possibility to complete this report.
I am extremely grateful to my family who were a constant source of encouragement.
FAISAL KHAN I ABSTARCT
Stimulated Brillouin scattering has been well investigated in a varety of materials. Stimulated Brillouin scattering, this originates from the χ3 nonlinearity of the medium especially related to acoustic phonon interaction. Now days studies are going on the field of stimulated Brillouin scattering for many applications. In my work I have analysed the properties of stimulated Brillouin scattering in different materials such as Acetone, Xylene, methanol, methyl acetate and demineralised water. Threshold laser power for stimulated Brillouin scattering emission is different for all the above materials. The samples prepared by adding dyes such as methylene blue, Rhodamine 6G and Rhodamine B to the above materials having threshold power greater than the pure material. The threshold power in some dyes in the above materials and for all the concentration have the same threshold power for some dyes in the above materials the threshold power is decreasing as the concentration decreases. For methanol and acetone there have change in wavelength of scattered wave with different dyes at different concentrations and for methyl acetate and demineralised water the wavelength is remains constant for all the concentrations of the dyes. For all the materials with all the dyes at all the concentrations `the amplitude scattered wave is increasing with the laser power. This is due to the increased phonon generation at the higher power due to the reduced radiative effect. In some dyes in the above materials as the concentration increases the amplitude of the scattered wave decreases due to the increased molecular interaction. In some dyes at some particular points of concentration the amplitude increases with concentration. There has no stimulated Brillouin scattering is observed from xylene since it is not optically polarisable. From the work methyl acetate is found to be the good medium to have stimulated Brillouin scattering with all the dyes at all the concentrations. We can use this methyl acetate for the study of phase conjugation and its properties Optical phase conjugation has got variety of application in now days. Optical phase conjugation can be created by forward mixing and stimulated scattering. If the phase conjugation is created by the stimulated scattering the properties of phase conjugation can be controlled by the medium properties since it is active process and it has got an energy transfer between medium and the photon. The work can be extended to study symmetry of a solid system by analysing the photon – phonon interaction in solids because the photon - phonon interaction is depend on the symmetry of the system. CONTENTS
1. Introduction………………………………………………………………………..1 1.1 Electromagnetic scattering...... 3 1.2 Elastic scattering……………………………………………………………….5 1.3 In eleastic scattering…………………………………………………………...7 1.4 Stimulated brilluin scattering………………………………………………….9 1.5 Application of stimulated brillouin scattering ………………………………..13 2. Experiment setup………………………………………………………………….17 2.1 laser …………………………………………………………………………...18 2.2 lens…………………………………………………………………………….18 2.3 cell……………………………………………………………………………..19 2.4 Ocean optics HR 4000………………………………………………………...19 2.5 Ocean optics software – spectrasuit…………………………………………..23 2.6 Filters……………………………………………………………………...…..23 3. Research materials………………………………………………………………...24 3.1 Acetone………………………………………………………………………..24 3.2 Methanol……………………...………………………………………………28 3.3 Methyl acetate………………………………………………………………....32 3.4 Demineralised water…………………………………………………………..33 3.5 Xylene…………………………………………………………………………34 3.6 Rhodamine 6G………………………………………………………………...36 3.7 Rhodamine B………………………………………………………………….37 3.8 Methylene blue………………………………………………………………..38 4. Experiment and observations……………………………………………………..41 4.1 Acetone……………………………………………………………………...... 41 4.2 Methanol……………………………………………………………………....54 4.3 Methyl acetate…………………………………………………………………64 4.4 Demineralised water…………………………………………………………..71 4.5 Xylene…………………………………………………………………………78
5. Result and analysis………………………………………………………………..79 5.1 Power versus amplitude graph at various concentrations in acetone………...79 5.2 Concentration versus amplitude graph at various power levels in acetone…..81 5.3 Power versus amplitude graph at various concentrations in methanol……….83 5.4 Concentration versus amplitude graph at various power levels in methanol…85 5.5 Power versus amplitude graph at various concentrations in methyl acetate….87 5.6 Concentration versus amplitude graph at various power levels in methanol…88 5.7 Power versus amplitude graph at various concentrations in methyl acetate….89 5.8 Concentration versus amplitude graph at various power levels in methanol…90 6. Conclusion and future work……………………………………………………….92 Characterisation of stimulated Brillouin scattering for different materials
1. INTRODUCTION – SCATTERING
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections that undergo scattering are often called diffuse reflections and unscattered reflections are called specular (mirror-like) reflections.
Scattering may also refer to particle-particle collisions between molecules, atoms, electrons, photons and other particles. Examples are: cosmic rays scattering by the Earth's upper atmosphere; particle collisions inside particle accelerators; electron scattering by gas atoms in fluorescent lamps; and neutron scattering inside nuclear reactors.
The types of non-uniformities which can cause scattering, sometimes known as scatterers or scattering centers, are too numerous to list, but a small sample includes particles, bubbles, droplets, density fluctuations in fluids, crystallites in polycrystalline solids, defects in monocrystalline solids, surface roughness, cells in organisms, and textile fibers in clothing. The effects of such features on the path of almost any type of propagating wave or moving particle can be described in the framework of scattering theory.
Some areas where scattering and scattering theory are significant include radar sensing, medical ultrasound, semiconductor wafer inspection, polymerization process monitoring, acoustic tiling, free-space communications and computer-generated imagery. Particle-particle scattering theory is important in areas such as particle physics, atomic, molecular, and optical physics, nuclear physics and astrophysics.
Single and multiple scattering
When radiation is only scattered by one localized scattering center, this is called single scattering, It is very common that scattering centers are grouped together, and in
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Characterisation of stimulated Brillouin scattering for different materials those cases the radiation may scatter many times, which is known as multiple scattering. The main difference between the effects of single and multiple scattering is that single scattering can usually be treated as a random phenomenon and multiple scattering is usually more stochastic. Because the location of a single scattering center is not usually well known relative to the path of the radiation, the outcome, which tends to depend strongly on the exact incoming trajectory, appears random to an observer. This type of scattering would be exemplified by an electron being fired at an atomic nucleus. In that case, the atom's exact position relative to the path of the electron is unknown and would be immeasurable, so the exact direction of the electron after the collision is unknown, plus the quantum-mechanical nature of this particular interaction also makes the interaction random. Single scattering is therefore often described by probability distributions.
With multiple scattering, the randomness of the interaction tends to be averaged out by the large number of scattering events, so that the final path of the radiation appears to be a deterministic distribution of intensity. This is exemplified by a light beam passing through thickfog. Multiple scattering is highly analogous to diffusion, and the terms multiple scattering and diffusion are interchangeable in many contexts. Optical elements designed to produce multiple scattering are thus known as diffusers. Coherent backscattering, an enhancement of backscattering that occurs when coherent radiation is multiply scattered by a random medium, is usually attributed to weak localization.
Not all single scattering is random, however. A well-controlled laser beam can be exactly positioned to scatter off a microscopic particle with a deterministic outcome, for instance. Such situations are encountered in radar scattering as well, where the targets tend to be macroscopic objects such as people or aircraft.
Similarly, multiple scattering can sometimes have somewhat random outcomes, particularly with coherent radiation. The random fluctuations in the multiply scattered intensity of coherent radiation are called speckles. Speckle also occurs if multiple parts of a coherent wave scatter from different centers. In certain rare circumstances, multiple scattering may only involve a small number of interactions such that the randomness is not completely averaged out. These systems are considered to be some of the most difficult to model accurately.
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Characterisation of stimulated Brillouin scattering for different materials
1.1 Electromagnetic scattering Electromagnetic waves are one of the best known and most commonly encountered forms of radiation that undergo scattering. Scattering of light and radio waves (especially in radar) is particularly important. Several different aspects of electromagnetic scattering are distinct enough to have conventional names. Major forms of elastic light scattering (involving negligible energy transfer) are Rayleigh scattering and Mie scattering. Inelastic scattering includes Brillouin scattering, Raman scattering, inelastic X-ray scattering and Compton scattering.
Light scattering is one of the two major physical processes that contribute to the visible appearance of most objects, the other being absorption. Surfaces described as white owe their appearance to multiple scattering of light by internal or surface inhomogeneities in the object, for example by the boundaries of transparent microscopic crystals that make up a stone or by the microscopic fibers in a sheet of paper. More generally, the gloss (or lustre or sheen) of the surface is determined by scattering. Highly scattering surfaces are described as being dull or having a matte finish, while the absence of surface scattering leads to a glossy appearance, as with polished metal or stone.
Spectral absorption, the selective absorption of certain colours, determines the colour of most objects with some modification by elastic scattering. The apparent blue colour of veins in skin is a common example where both spectral absorption and scattering play important and complex roles in the coloration. Light scattering can also create colour without absorption, often shades of blue, as with the sky (Rayleigh scattering), the human blue iris, and the feathers of some birds. However, resonant light scattering in nanoparticles can produce many different highly saturated and vibrant hues, especially when surface Plasmon resonance is involved
Models of light scattering can be divided into three domains based on a dimensionless size parameter, α which is defined as:
Where πDp is the circumference of a particle and λ is the wavelength of incident radiation. Based on the value of α, these domains are:
α ≪ 1: Rayleigh scattering (small particle compared to wavelength of light); α ≈ 1: Mie scattering (particle about the same size as wavelength of light, valid only for spheres);
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Characterisation of stimulated Brillouin scattering for different materials
α ≫ 1: geometric scattering (particle much larger than wavelength of light).
Rayleigh scattering is a process in which electromagnetic radiation (including light) is scattered by a small spherical volume of variant refractive index, such as a particle, bubble, droplet, or even a density fluctuation. This effect was first modelled successfully by Lord Rayleigh, from whom it gets its name. In order for Rayleigh's model to apply, the sphere must be much smaller in diameter than the wavelength (λ) of the scattered wave; typically the upper limit is taken to be about 1/10 the wavelength. In this size regime, the exact shape of the scattering center is usually not very significant and can often be treated as a sphere of equivalent volume. The inherent scattering that radiation undergoes passing through a pure gas is due to microscopic density fluctuations as the gas molecules move around, which are normally small enough in scale for Rayleigh's model to apply. This scattering mechanism is the primary cause of the blue colour of the Earth's sky on a clear day, as the shorter blue wavelengths of sunlight passing overhead are more strongly scattered than the longer red wavelengths according to Rayleigh's famous 1/λ4 relation. Along with absorption, such scattering is a major cause of the attenuation of radiation by the atmosphere. The degree of scattering varies as a function of the ratio of the particle diameter to the wavelength of the radiation, along with many other factors including polarization, angle, and coherence.
For larger diameters, the problem of electromagnetic scattering by spheres was first solved by Gustav Mie, and scattering by spheres larger than the Rayleigh range is therefore usually known as Mie scattering. In the Mie regime, the shape of the scattering center becomes much more significant and the theory only applies well to spheres and, with some modification, spheroids and ellipsoids. Closed-form solutions for scattering by certain other simple shapes exist, but no general closed-form solution is known for arbitrary shapes.
Both Mie and Rayleigh scattering are considered elastic scattering processes, in which the energy (and thus wavelength and frequency) of the light is not substantially changed. However, electromagnetic radiation scattered by moving scattering centers does undergo a Doppler shift, which can be detected and used to measure the velocity of the scattering centers in forms of techniques such as lidar and radar. This shift involves a slight change in energy.
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Characterisation of stimulated Brillouin scattering for different materials
Fig1: Rayleigh scattering and Mie scattering
At values of the ratio of particle diameter to wavelength more than about 10, the laws of geometric optics are mostly sufficient to describe the interaction of light with the particle, and at this point the interaction is not usually described as scattering.
For modeling of scattering in cases where the Rayleigh and Mie models do not apply such as irregularly shaped particles, there are many numerical methods that can be used. The most common are finite-element methods which solve Maxwell's equations to find the distribution of the scattered electromagnetic field. Sophisticated software packages exist which allows the user to specify the refractive index or indices of the scattering feature in space, creating a 2- or sometimes 3-dimensional model of the structure. For relatively large and complex structures, these models usually require substantial execution times on a computer.
1.2 Elastic Scattering Elastic scattering is a form of particle scattering in scattering theory, nuclear physics and particle physics. In this process, the kinetic energy of a particle is conserved in the centre-of-mass frame, but its direction of propagation is modified (by interaction with other particles and/or potentials). Furthermore, while the particle's kinetic energy in the centre-of-mass frame is constant, its energy in the lab frame is not. Generally, elastic scattering describes a process where the total kinetic energy of the system is conserved. During elastic scattering of high-energy subatomic particles, linear energy transfer (LET) takes place until the incident particle's energy and speed has been reduced to the same as its surroundings, at which point the particle is "stopped."
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Characterisation of stimulated Brillouin scattering for different materials
1.2.1 Optical elastic scattering
1. Thomson scattering Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is just the low-energy limit of Compton scattering: the particle kinetic energy and photon frequency are the same before and after the scattering. This limit is valid as long as the photon energy is much less than the mass energy of the particle
In the low-energy limit, the electric field of the incident wave (photon) accelerates the charged particle, causing it, in turn, to emit radiation at the same frequency as the incident wave, and thus the wave is scattered. Thomson scattering is an important phenomenon in plasma physics and was first explained by the physicist J. J. Thomson. As long as the motion of the particle is non-relativistic (i.e. its speed is much less than the speed of light), the main cause of the acceleration of the particle will be due to the electric field component of the incident wave, and the magnetic field can be neglected. The particle will move in the direction of the oscillating electric field, resulting in electromagnetic dipole radiation. The moving particle radiates most strongly in a direction perpendicular to its acceleration and that radiation will be polarized along the direction of its motion. Therefore, depending on where an observer is located, the light scattered from a small volume element may appear to be more or less polarized.
2. Rayleigh scattering Rayleigh scattering, named after the British physicist Lord Rayleigh, is the (dominantly) scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. The Rayleigh scattering does not change the state of material hence it is a parametric process. The particles may be individual atoms or molecules. It can occur when light travels through transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering results from the electric polarizability of the particles. The oscillating electric field of a light wave acts on the charges within a particle, causing them to move at the same frequency. The particle therefore becomes a small radiating dipole whose radiation we see as scattered light.
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Characterisation of stimulated Brillouin scattering for different materials
Rayleigh scattering of sunlight in the atmosphere causes diffuse sky radiation, which is the reason for the blue colour of the sky and the yellow tone of the sun itself.
For historical reasons, Rayleigh scattering of molecular nitrogen and oxygen in the atmosphere includes elastic scattering as well as the inelastic contribution from rotational Raman scattering in air, since the changes in wave number of the scattered photon are typically smaller than 50 cm−1.[2] This can lead to changes in the rotational state of the molecules. Furthermore, the inelastic contribution has the same wavelengths dependency as the elastic part.
1.3 Inelastic scattering In chemistry, nuclear physics, and particle physics, inelastic scattering is a fundamental scattering process in which the kinetic energy of an incident particle is not conserved (in contrast to elastic scattering). In an inelastic scattering process, some of the energy of the incident particle is lost or increased. Although the term is historically related to the concept of inelastic collision in dynamics, the two concepts are quite distinct; the latter refers to processes in which the total kinetic energy is not conserved. In general, scattering due to inelastic collisions will be inelastic, but, since elastic collisions often transfer kinetic energy between particles, scattering due to elastic collisions can also be inelastic
1.3.1 Raman scattering When photons are scattered from an atom or molecule, most photons are elastically scattered (Rayleigh scattering), such that the scattered photons have the same energy (frequency and wavelength) as the incident photons. A small fraction of the scattered photons (approximately 1 in 10 million) are scattered by an excitation, with the scattered photons having a frequency different from, and usually lower than, that of the incident photons. In a gas, Raman scattering can occur with a change in energy of a molecule due to a transition. Typically, in Raman spectroscopy high intensity laser radiation with wavelengths in either the visible or near-infrared regions of the spectrum is passed through a sample. Photons from the laser beam produce an oscillating polarization in the molecules, exciting them to a virtual energy state. The oscillating polarization of the molecule can couple with other possible polarizations of the molecule, including vibrational and electronic excitations. If the polarization in the molecule does not couple to these other possible polarization, then it will
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Characterisation of stimulated Brillouin scattering for different materials not change the vibrational state that the molecule started in and the scattered photon will have the same energy as the original photon. This type of scattering is known as Rayleigh scattering. When the polarization in the molecules couples to a vibrational state that is higher in energy than the state they started in, then the original photon and the scattered photon differ in energy by the amount required to vibrationally excite the molecule. In perturbation theory, the Raman Effect corresponds to the absorption and subsequent emission of a photon via an intermediate quantum state of a material. The intermediate state can be either a "real", i.e., stationary state or a virtual state. The Raman interaction leads to two possible outcomes: 1) the material absorbs energy and the emitted photon has a lower energy than the absorbed photon. This outcome is labelled Stokes Raman scattering. 2) The material loses energy and the emitted photon has a higher energy than the absorbed photon. This outcome is labelled anti-Stokes Raman scattering. The energy difference between the absorbed and emitted photon corresponds to the energy difference between two resonant states of the material and is independent of the absolute energy of the photon.
The spectrum of the scattered photons is termed the Raman spectrum. It shows the intensity of the scattered light as a function of its frequency difference Δν to the incident photons. The locations of corresponding Stokes and anti-Stokes peaks form a symmetric pattern around Δν=0. The frequency shifts are symmetric because they correspond to the energy difference between the same upper and lower resonant states. The intensities of the pairs of features will typically differ, though. They depend on the populations of the initial states of the material, which in turn depend on the temperature. In thermodynamic equilibrium, the upper state will be less populated than the lower state. Therefore, the rate of transitions from the lower to the upper state (Stokes transitions) will be higher than in the opposite direction (anti-Stokes transitions). Correspondingly, Stokes scattering peaks are stronger than anti-Stokes scattering peaks. Their ratio depends on the temperature (which can practically be exploited for the measurement of temperature).
1.3.2 Brillouin scattering Brillouin scattering, named after Léon Brillouin, occurs when light, transmitted by a transparent carrier interacts with that carrier's time-&-space-periodic variations in refractive index. As described by optics, the index of refraction of a transparent material changes under deformation (compression-distension or shear-skewing).
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Characterisation of stimulated Brillouin scattering for different materials
The result of the interaction between the light-wave and the carrier-deformation-wave is that a fraction from the passing-through light-wave changes its momentum (thus its frequency and energy) along preferential angles, as if by being diffracted by an oscillating 3- D grating.
If the involved light carrier is a solid crystal, a macromolecular chain condensate or a viscous liquid, then the low frequency atomic-chain-deformation waves in the carrier (represented as a quasiparticle) could be for example: 1. mass oscillation (acoustic) modes (called phonons); 2. charge displacement modes (in dielectrics, called polarons); 3. magnetic spin oscillation modes (in magnetic materials, called magnons).
1.4 Stimulated Brillouin scattering Brillouin scattering is related to the interaction between an incident optical wave and the elastic acoustic wave in a transparent medium. The feature of this effect is that the frequency-shift of the scattering light is dependent on the scattering .ingle and the acoustic velocity in the medium
It is well known that when a collimated monochromatic light beam is incident on a grating, there will be several diffraction (or reflection) maxima along certain directions. Moreover, if the grating is in a moving situation with a given velocity, the frequency of the diffracted (or reflected) light will shift with respect to that of the incident light because of the- Doppler effect. In practice, an ultrasonic cell filled with an appropriate acousto-optical medium can play such a role of moving grating. In this case, the density of the medium will experience a periodical spatial and temporal modulation. When a directional and monochromatic light beam passes through this ultrasonic cell, a frequency-shifted diffraction maximum can be observed in a definite direction. The frequency-shift value and direction of the diffraction maximum are determined by the properties of the ultrasonic field in the medium
Generally, there is always a spontaneous acoustic field in any optical medium, which is generated by the thermal elastic motion of a great number of particles of which the medium is composed. This thermal acoustic field can be visualized as a superposition of various monochromatic and plane acoustic waves. Each of these acoustic wave- may-produced a periodic spatial and temporal modulation of the density of the medium and, therefore, can
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Characterisation of stimulated Brillouin scattering for different materials cause a grating diffraction effect on the incident light beam. In this case the direction and frequency-shift of the diffracted light will depend on the velocity, propagation direction, and frequency of the considered acoustic wave. This is the classical picture of spontaneous Brillouin scattering of light. It is known that the thermal elastic acoustic field in an ordinary medium is very weak; therefore the observation of Brillouin scattering is very difficult if the input light bean is from a conventional light source. The advent of laser technology has opened a new opportunity for the development of Brillouin scattering technique. Using lasers as the intense and coherent monochromatic light sources makes the observation of spontaneous Brillouin scattering much easier than before; and most importantly, if the monochromatic intensity of the input laser beam is high enough, the scattering light exhibits a stimulated feature. This is the so-called stimulated Brillouin scattering effect
The essential difference between the spontaneous and stimulated Brillouin scattering is that the former is caused by a very weak thermal acoustic field, whereas the latter is caused by an intense laser beam-induced electrostrictive acoustic field. -Under the electro-strictiye action of an intense laser field, the induced acoustic. Vibration can be created in the scattering medium, which in turn plays role of an induced density-modulated grating and produces the Brillouin scattering light. If the pump intensity is so strong that the growth of both the induced electrostrictive acoustic wave and the scattered light wave can significant overcome their losses inside the medium, we may observe the simultaneous, stimulated amplification of the both fields. This is a classical description of the, stimulated Brillouin scattering effect
It is different from Raman scattering that the Brillouin scattering is not related to any change of molecular microscopic states, and the energy and momentum exchange only occurs between the optical field and the elastic acoustic field. In this sense, the Brillouin scattering is essentially-a parametric interaction between these two fields, and a certain phase-matching requirement must be fulfilled.
On the other hand, both the optical field and the acoustic field can be quantized. Therefore, we can also use a quantum theoretical model to describe the mechanism of an elementary Brillouin scattering process. In this approach, the elementary Brillouin scattering process can be recognized as a parametric interaction between an input photon, a scattered photon, and a phonon inside the medium. The conservation of energy and momentum can be fulfilled in the P following two possible ways.
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Characterisation of stimulated Brillouin scattering for different materials
(1) Stokes Scattering Generation.
This process can be described as the annihilation of an incident photon and the simultaneous creation of one scatterer photon and one induced phonon. In this case the conservation of energy and momentum requires that
where , , and are the frequencies of the incident photon, scattered photon, and induced phonon, and are the wave vectors of these three quanta respectively. The feature of this scattering process is that the partial energy of the input optical field is transferred to the acoustic field. The Stokes frequency shift of the scattered light is determined by the phase-matching condition as shown in Fig
Fig 2: Phase matching condition of the Stokes Brillouin process for (a) the forward scattering and (b) the backward scattering. Phonon in the scattering medium
(2) Anti-Stokes Scattering Generation
This process can be described as the annihilation of one incident photon and one existing phonon and the simultaneous creation of one scattered photon. The conservation of energy and momentum requires that
Where and are the frequency and wave vector of the anti-Stokes scattering light. The feature of this process is that the partial energy of the acoustic field in the medium is
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Characterisation of stimulated Brillouin scattering for different materials transferred to the scattering light field. In this case the phase-matching condition is shown in Fig
Fig 3: Phase-matching condition of the anti-Stokes Brillouin process for (a) the forward scattering and (b) the backward scattering
1.4.1 Stimulated Brillouin scattering in optical fibers
Brillouin scattering is a nonlinear process that can occur in optical fibers at large intensity. The large intensity produces compression (due to electric field also known as pump field) in core of fiber through the process known as electrostriction. This phenomenon produces density-fluctuations in fiber medium. It increases the material disorder, which in turn modulates the linear refractive index of medium and results in an electrostrictive- nonlinearity. The modulated refractive index behaves as an index grating, which is pump- induced. The scattering of pump light through Bragg diffraction by the pump induced index grating is called as Brillouin scattering. The disorder is time dependent so the scattered light is shifted (Brillouin shift) in frequency by the frequency of sound wave. For pulses shorter than 500 ps, there is no spatial overlap between the pulse and acoustic wave, which results in negligible electrostrictive nonlinearity. Quantum mechanically the Brillouin shift originates from the photon-phonon interaction, and associated Doppler displacement. In this interaction either a phonon is annihilated (Stokes process-positive Brillouin shift) or created (anti-stokes process-negative Brillouin shift).
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Characterisation of stimulated Brillouin scattering for different materials
1.5 Application of stimulated Brillouin scattering
1.5.1 Phase conjugation by SBS
Optical phase conjugation (OPC) is a new laser-based technique developed since 1970s. As this technique is feasible for use in many significant applications, the study of OPC has become one of the most active research subjects in the areas of nonlinear optics and quantum electronics. Before the 1960s and the advent of lasers, it was well known that there were two impossibilities within the regime of conventional optics. The first was that the brightness of any given light beam cannot be increased via any type of optical imaging systems or specially designed devices. The second was that a perfect and reversible optical imaging system was impossible because of the aberration influence from optical elements and propagating media. The first impossibility was removed after the advent of laser oscillators and amplifiers. The second restraint could also be released by utilizing the OPC technique. In general, a pair of optical waves is phase conjugated to each other if their complex amplitude functions are conjugated with respect to their phase factors. Optical phase-conjugate waves can be generated through various nonlinear optical processes (such as four-wave mixing, three-wave mixing, backward stimulated scattering, and others). They can also be generated through one-photon or multiphoton pumped backward stimulated emission processes in a lasing medium. In many cases, however, one can say that the principles of the major methods for generating optical phase-conjugate waves are based on the intense light-induced holographic gratings and subsequent wavefront reconstruction.
1.5.2 Pulse compression by SBS
The idea of compressing laser pulses in the course of stimulated backscattering dates from the late 1960s when experiments on pulse compression in travelling-wave Raman amplifiers were conducted by Maier and many others. It was noted that backward Raman scattering could efficiently compress (50 - 70%) a seeded weak Stokes pulse, thus producing an intense short pulse with duration limited by the decay time of the vibrational excitation in the medium (of the order of pico-seconds). This efficiency, combined with powerful excimer lasers (typically KrF at 248 nm), was used in attempts to create high-peak intensity short ultraviolet pulses for laser assisted nuclear fusion experiments. After nearly a decade of development the idea was abandoned due to complications arising from competing nonlinearities (two-photon absorption, optical breakdown, and self-focusing) and most
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Characterisation of stimulated Brillouin scattering for different materials notably the generation of super-fluorescent second Stokes radiation during the compression process. The possibility to compress pulses by means of stimulated backscattering is not restricted to Raman scattering only. It was theoretically predicted for SBS as well, but it was not before 1980 when the first experimental demonstration was reported by Hon. The use of SBS offers several potential advantages over compressor systems based upon stimulated Raman scattering (SRS). Firstly, the production of second Stokes is not a serious problem, because SBS occurs only in backward direction, unlike SRS where the forward gain is usually stronger than backward. Tapered waveguide geometry was used in the first experiments in order to keep the peak intensity of both the pump and Stokes pulses below threshold for second backward Stokes generation. Secondly, the quantum efficiency of the SBS process is almost 100% since the Stokes frequency ωs is approximately equal to the laser frequency ωL. Thirdly, the fact that he SBS is initiated from spontaneous scattering avoids the necessity of injection of weak Stokes pulse as required in SRS based compressors. Fourthly, since the Stokes beam under proper conditions is the phase conjugate of the input beam, compensation for inhomogeneities automatically takes place.
1.5.3 Brillion-enhanced-four-wave mixing
One of the main advantages of phase conjugation by degenerate four-wave mixing (DFWM) over SBS phase conjugation is the possibility of conjugating weak beams; the possibility to produce in principle infinitely large reflectivity. In practice the experimental realizations rarely reach 100. This is because the conditions required to achieve high reflectivities are extremely precise; in experiments involving real Gaussian beams it is not possible to achieve these conditions with sufficient precision. The Brillouin enhanced four- wave mixing (BEFWM) is a form of nearly-degenerate four-wave mixing in which the four beams are coupled by the Brillouin nonlinearity. The incoming signal beam has a Brillouin frequency-shift with respect to one of the pump beams in geometry, so that the interference pattern they produce moves at acoustic velocity and drives an acoustic wave. This scatters the second pump beam to form the conjugate beam. High reflectivity (∼ 106) can experimentally be achieved by BEFWM phase conjugation. This is because the reflectivity results from an instability in which the conjugate intensity grows exponentially in time until pump beam depletion prevents further growth. Providing that the pump beams exceed a certain critical intensity, it is found that whatever the strength of the input signal the conjugate intensity will grow until the pump beams are significantly depleted. It can be shown, that maximum
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Characterisation of stimulated Brillouin scattering for different materials conjugate power is obtained if an anti-Stokes signal creates a Stoke conjugate, while the minimum signal requirement is achieved if a Stokes-shifted signal is used. The first experimental realization of BEFWM using two pumps of the same frequency and a suitable Brillouin-shifted signal beam was reported in 1980 by Bespalov who achieved reflectivity of the order of 20. High reflectivity BEFWM conjugation was reported soon after by Andreev with a value of 7 × 105 measured. BEFWM has got many applications ranging from phase conjugating and amplifying very weak signals (≈ 4×10−17 J) to phase locking of laser beams. The latter is used for vector phase conjugation and beam combination. As discussed above, the phase conjugation by SBS is a scalar phase conjugation, for it does not conjugate the polarization state. In addition, conventional SBS has a random overall phase that can fluctuate in time. It is possible to split a beam into two orthogonal polarizations, conjugate each using scalar phase conjugation, and recombine them such that they emulate vector phase conjugator. This can only be achieved if the phases of both beams are locked together. BEFWM can be successfully used as a phase controlled scalar conjugator, since in this scheme the conjugate signal does not build up from noise, thus retaining a control over its phase via the characteristics of the pump beams.
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Characterisation of stimulated Brillouin scattering for different materials
Reference
1. Stimulated Brillouin Scattering: Fundamentals and Applications By M J Damzen, V Vlad, Anca Mocofanescu, V Babin
2. E. P. Ippen and R. H. Stolen, “Stimulated Brillouin scattering in optical fibers”, Appl. Phys. Lett. 21, 539 (1972)
3. Bohren, Craig F.; Donald R. Huffman (1983). Absorption and Scattering of Light by Small Particles. Wiley. ISBN 0-471-29340-7. 4. Colton, David; Rainer Kress (1998). Inverse Acoustic and Electromagnetic Scattering Theory. Springer. ISBN 3-540-62838-X
5. A. T. Young, "Rayleigh scattering," Appl. Opt. 20, 522–535, 1981 6. Stimulated raman, librational, and Brillouin scattering in water O. Rahn, M. Maier, W. Kaiser 7. Gonis, Antonios; William H. Butler (1999). Multiple Scattering in Solids. Springer. ISBN 0-387-98853-X.
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2.
EXPERIMENT SETUP
Fig 4: Experiment setup
Experiment setup is shown above. To do this experiment we used a1 joule Nd- Yag laser and the light wavelength used is 532 nm. The light from the laser is focused to a cell that contains our sample using a pair of 532 nm mirror and a lens with focal length of 10 cm. The backward stimulated Brillouin scattering wave is passed through the lens and 532 nm mirrors and it is collected using a optical fiber and is given to ocean optics detector. By using ocean optics software we plotted the spectrum of the stimulated Brillouin scattering light.
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Characterisation of stimulated Brillouin scattering for different materials
2.1 Laser
We were used Spectra- Physics Quanta-Ray high-pulse energy Nd: YAG laser with a power of 1 joule for 1064 nano meter at 10 Hz. For 532 nano meter it have energies 500 milli joule, 400 milli joule, 250 milli joule and 120 milli joule for 10Hz,30 Hz, 50Hz, 100Hz respectively. Spectra-Physics Quanta-Ray high-pulse energy Nd:YAG lasers are recognized worldwide for their unsurpassed performance, reliability and quality. They incorporate pioneering technologies such as dual-rod oscillators, gold-coated elliptical pump chambers, internal sealed beam paths, and high-damage-threshold optics from Spectra-Physics advanced coatings lab all combine to create the best beam quality and highest energies in the industry.
The heart of the Quanta-Ray laser is its unique pump chamber. The chamber strikes the perfect balance between efficiency and beam mode quality by employing elliptical gold coated reflectors to couple the lamps into the Nd:YAG rod. The gold surfaces provide high reflectivity at pump wavelengths while attenuating UV wavelengths. Proprietary diffusion techniques ensure uniform illumination of the Nd:YAG rod Quanta-Ray lasers are also the only lasers on the market to feature completely sealed internal beam paths through the use of nitrogen-purged beam tubes. Sealed beam paths greatly extend the longevity of optical coatings by shielding all optical components from harmful contaminants in even the harshest of environments Sol-Gel coated pockels cells coating greatly enhances the lifetime of the cells and improves the performance of the laser system. BBO FHGs give highest energies, best beam quality and highest damage thresholds. 2.2 Lens
A lens is a transmissive optical device that affects the focus of a light beam through refraction. A simple lens consists of a single piece of material, while a compound lens consists of several simple lenses (elements), usually along a common axis. Lenses are made from transparent materials such as glass, ground and polished to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly refract radiation other than visible light are also called lenses, such as microwave lenses or acoustic lenses.
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Characterisation of stimulated Brillouin scattering for different materials
We have used a lens with a focal length of 10 cm. It is helping us to focus the laser beam into the middle of the cell. 2.3 Cell
We have used a cell with 10 centi meter length and 4 cm diameter. The length of the cell makes more interaction length between acetone and laser beam. It is helped us to get better SBS and SRS.
Fig 5: Glass cell 2.4 Ocean optics hr4000
The spectrometer used is the ocean optics HR4000 High-Resolution Miniature Fiber Optic Spectrometer. The HR4000 High-Resolution Miniature Fiber Optic Spectrometer provides optical resolution as good as 0.025 nm (FWHM). The HR4000 is responsive from 200-1100 nm, but the specific range and resolution depends on your grating and entrance slit selections. The HR4000 is perfect for applications where high resolution is necessary, such as absorbance of gases or atomic emission lines (for solution chemistry or for color measurements, the USB4000 is more appropriate). Data programmed into a memory chip on each HR4000 includes wavelength calibration coefficients, linearity coefficients, and the serial number unique to each spectrometer. Our
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Characterisation of stimulated Brillouin scattering for different materials spectrometer operating software simply reads these values from the spectrometer — a feature that enables hot swapping of spectrometers among computers.
Fig 6: Ocean Optics HR4000 High-Resolution Fiber Optic Spectrometer
The HR4000 Spectrometer connects to a notebook or desktop computer via USB port or serial port. When connected to the USB port of a computer, the HR4000 draws power from the host computer, eliminating the need for an external power supply
Fig 7: HR4000 Spectrometer with Components
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Characterisation of stimulated Brillouin scattering for different materials
2.4.1 SMA Connector
Secures the input fiber to the spectrometer. Light from the input fiber enters the optical bench through this connector
2.4.2 Slit A dark piece of material containing a rectangular aperture, which is mounted directly behind the SMA Connector. The size of the aperture regulates the amount of light that enters the optical bench and controls spectral resolution. You can also use the HR4000 without a Slit. In this configuration, the diameter of the fiber connected to the HR4000 determines the size of the entrance aperture. Only Ocean Optics technicians can change the Slit.
2.4.3 Filter
Restricts optical radiation to pre-determined wavelength regions. Light passes through the Filter before entering the optical bench. Both bandpass and longpass filters are available to restrict radiation to certain wavelength regions.
2.4.4 Collimating Mirror
Focuses light entering the optical bench towards the Grating of the spectrometer. Light enters the spectrometer, passes through the SMA Connector, Slit, and Filter, and then reflects off the Collimating Mirror onto the Grating.
2.4.5 Grating Diffracts light from the Collimating Mirror and directs the diffracted light onto the Focusing Mirror. Gratings are available in different groove densities, allowing you to specify wavelength coverage and resolution in the spectrometer.
2.4.6 Focussing Mirror Receives light reflected from the Grating and focuses the light onto the CCD Detector or L2 Detector Collection Lens (depending on the spectrometer configuration).
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Characterisation of stimulated Brillouin scattering for different materials
2.4.7 L2 Detector Collection Lens An optional component that attaches to the CCD Detector. It focuses light from a tall slit onto the shorter CCD Detector elements. The L2 Detector Collection Lens should be used with large diameter slits or in applications with low light levels. It also improves efficiency by reducing the effects of stray light.
2.4.8 CCD Detector (UV or VIS) Collects the light received from the Focusing Mirror and converts the optical signal to a digital signal.
HR4000 Spectrometer Specification Value Dimensions 148.6 mm x 104.8 mm x 45.1 mm
Weight 570 g
Power consumption 450 mA @ 5 VDC
Detector 3648-element linear silicon CCD array
Detector range 200-1100 nm
Gratings 14 gratings available
Specification Value Entrance aperture 5, 10, 25, 50, 100 or 200 μm wide slits
Order-sorting filters Installed longpass and bandpass filters
Focal length f/4, 101 mm
Optical resolution Depends on grating and size of entrance aperture
Stray light <0.05% at 600 nm; <0.10% at 435 nm
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Characterisation of stimulated Brillouin scattering for different materials
2.5 Ocean optics software – spectrasuite
SpectraSuite is the latest generation of operating software for all Ocean Optics spectrometers. It is a completely modular, Java-based spectroscopy software platform that operates on Windows, Macintosh and Linux operating systems. The software can control any Ocean Optics USB spectrometer and device, as well as any other manufacturer’s USB instrumentation using the appropriate drivers. SpectraSuite is a user-customizable, advanced acquisition and display program that provides a real-time interface to a variety of signal-processing functions. With SpectraSuite, you have the ability to perform spectroscopic measurements (such as absorbance, reflectance, and emission), control all system parameters, collect and display data in real time, and perform reference monitoring and time acquisition experiments. 2.6 Filters
1064 nano meter filter has a centre wavelength of 1064 ± 2 nano meter, and full width half max of 10 ± 2 nano meter. It is optimized to block X-ray to 1200 nano meter wavelengths. Laser Line Filters are ideal for transmitting laser light while suppressing ambient light. 532 nano meter filter has a centre wavelength of 532 ± 2 nano meter, and full width half max of 10 ± 2 nano meter. It is optimized to block X-ray to Far IR wavelengths. Laser Line Filters are ideal for transmitting laser light while suppressing ambient light.
Reference
1. HR4000 and HR4000CG-UV-NIR Series Spectrometers Installation and Operation Manual 2. Quanta-Ray® Nd:YAG Laser data sheet
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3. RESEARCH MATERIALS
3.1 Acetone
Acetone (systematically named propanone) is the organic compound with the formula (CH3)2CO. It is a colorless, volatile, flammable liquid, and is the simplest ketone.
Acetone is miscible with water and serves as an important solvent in its own right, typically for cleaning purposes in the laboratory. About 6.7 million tonnes were produced worldwide in 2010, mainly for use as a solvent and production of methyl methacrylate andbisphenol A. It is a common building block in organic chemistry. Familiar household uses of acetone are as the active ingredient in nail polish remover and as paint thinner.
Acetone is produced and disposed of in the human body through normal metabolic processes. It is normally present in blood and urine. People with diabetes produce it in larger amounts. Reproductive toxicity tests show that it has low potential to cause reproductive problems. Pregnant women, nursing mothers and children have higher levels of acetone. Ketogenic diets that increase acetone in the body are used to counter epileptic attacks in infants and children who suffer from recalcitrant refractory epilepsy.
Acetone was first produced by alchemists during the late middle ages via the dry distillation of metal acetates (e.g., lead acetate, which produced "spirit of Saturn" (since the alchemical symbol for lead was also the astrological symbol for the planet Saturn)). In 1832, French chemist Jean Baptiste Dumas and German chemist Justus von Liebig determined the empirical formula for acetone. In 1833, the French chemist Antoine Bussy named acetone by adding the suffix -one to the stem of the corresponding acid (viz, acetic acid). By 1852, English chemist Alexander William Williamson realized that acetone was methyl acetyl; the following year, the French chemist Charles Frédéric Gerhardt concurred. In 1865, the German chemist August Kekulé published the modern structural formula for acetone.
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Characterisation of stimulated Brillouin scattering for different materials
Fig 8: structure of acetone
3.1.1 Biosynthesis
Small amounts of acetone are produced in the body by the decarboxylation of ketone bodies. Certain dietary patterns, including prolonged fasting and high-fat low-carbohydrate dieting, can produce ketosis, in which acetone is formed in body tissue. Certain health conditions, such as alcoholism and diabetes, can produce ketoacidosis, uncontrollable ketosis that leads to a sharp, and potentially fatal, increase in the acidity of the blood. Since it is a by- product of fermentation, acetone is a by-product of the distillery industry.
3.1.2 Production
Acetone is produced directly or indirectly from propylene. Approximately 83% of acetone is produced via the cumene process; as a result, acetone production is tied to phenol production. In the cumene process, benzene is alkylated with propylene to produce cumene, which is oxidized by air to produce phenol and acetone
Fig 9: production of acetone
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Characterisation of stimulated Brillouin scattering for different materials
Previously, acetone was produced by the dry distillation of acetates, for example calcium acetate in ketonic decarboxylation.
Ca(CH3COO)2 → CaO(s) + CO2(g) + (CH3)2CO (v)
Before that, during World War I acetone was produced using acetone-butanol-ethanol fermentation with Clostridium acetobutylicumbacteria, which was developed by Chaim Weizmann (later the first president of Israel) in order to help the British war effort in the preparation of Cordite. This acetone-butanol-ethanol fermentation was eventually abandoned when newer methods with better yields were found. 3.1.3 Uses
Solvent
Acetone is a good solvent for many plastics and some synthetic fibers. It is used for thinning polyester resin, cleaning tools used with it, and dissolving two- part epoxies and superglue before they harden. It is used as one of the volatile components of some paints and varnishes. As a heavy-duty degreaser, it is useful in the preparation of metal prior to painting. It is also useful for high reliability soldering applications to remove rosin flux after soldering is complete; this helps to prevent the rusty bolt effect.
Acetone is used as a solvent by the pharmaceutical industry and as a denaturant in denatured alcohol. Acetone is also present as an excipient in some pharmaceutical drugs.
Although itself flammable, acetone is used extensively as a solvent for the safe transportation and storage of acetylene, which cannot be safely pressurized as a pure compound. Vessels containing a porous material are first filled with acetone followed by acetylene, which dissolves into the acetone. One liter of acetone can dissolve around 250 liters of acetylene.
Chemical intermediate
Acetone is used to synthesize methyl methacrylate. It begins with the initial conversion of acetone to acetone cyanohydrin:
(CH3)2CO + HCN → (CH3)2C(OH)CN
In a subsequent step, the nitrile is hydrolyzed to the unsaturated amide, which is esterified:
(CH3)2C(OH)CN + CH3OH → CH2=(CH3)CCO2CH3 + NH3
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Characterisation of stimulated Brillouin scattering for different materials
The third major use of acetone (about 20%) is synthesizing bisphenol A. Bisphenol A is a component of many polymers such aspolycarbonates, polyurethanes, and epoxy resins. The synthesis involves the condensation of acetone with phenol:
(CH3)2CO + 2 C6H5OH → (CH3)2C(C6H4OH)2 + H2O
Many millions of kilograms of acetone are consumed in the production of the solvents methyl isobutyl alcohol and methyl isobutyl ketone. These products arise via an initial aldol condensation to give diacetone alcohol.
2 (CH3)2CO → (CH3)2C(OH)CH2C(O)CH3
Laboratory In the laboratory, acetone is used as a polar, aprotic solvent in a variety of organic reactions, such as SN2 reactions. The use of acetone solvent is critical for the Jones oxidation. It does not form an azeotrope with water. It is a common solvent for rinsing laboratory glassware because of its low cost and volatility. Despite its common use as a supposed drying agent, it is not effective except by bulk displacement and dilution. Acetone can be cooled with dry ice to −78 °C without freezing; acetone/dry ice baths are commonly used to conduct reactions at low temperatures. Acetone is fluorescent under ultraviolet light, and its vapor may be used as a fluorescent tracer in fluid flow experiments. Medical and cosmetic uses Acetone is used in a variety of general medical and cosmetic applications and is also listed as a component in food additives and food packaging. Dermatologists use acetone with alcohol for acne treatments to peel dry skin.
Acetone is commonly used in chemical peeling. Common agents used today for chemical peels are salicylic acid, glycolic acid, 30% salicylic acid in ethanol, and trichloroacetic acid (TCA). Prior to chemexfoliation, the skin is cleaned and excess fat removed in a process called defatting. Acetone, Septisol, or a combination of these agents is commonly used in this process
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Characterisation of stimulated Brillouin scattering for different materials
3.2 Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH(often abbreviated MeOH). Methanol acquired the name "wood alcohol" because it was once produced chiefly as a byproduct of thedestructive distillation of wood. Modern-day methanol production occurs in a catalytic industrial process directly from carbon monoxide, carbon dioxide, and hydrogen.
Methanol is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to that ofethanol (drinking alcohol). However, unlike ethanol, methanol is highly toxic and unfit for consumption. At room temperature, it is apolar liquid, and is used as an antifreeze, solvent, fuel, and as a denaturant for ethanol. It is also used for producing biodiesel viatransesterification reaction.
Methanol is produced naturally in the anaerobic metabolism of many varieties of bacteria, and is commonly present in small amounts in the environment. As a result, there is a small fraction of methanol vapor in the atmosphere. Over the course of several days, atmospheric methanol is oxidized with the help of sunlight to carbon dioxide and water.
Methanol also forms in abundant quantities in star forming regions of space, and is used in astronomy as a marker for such regions. It is detected through its spectral emission lines.[10]
Methanol burns in oxygen, including open air, forming carbon dioxide and water:
2 CH3OH + 3 O2 → 2 CO2 + 4 H2O
Methanol ingested in large quantities is metabolized to formic acid[11] or formate salts, which is poisonous to the central nervous system, and may cause blindness, coma, and death. Because of these toxic properties, methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses. This addition of methanol exempts industrial ethanol (commonly known as "denatured alcohol" or "methylated spirit") from liquor excise taxation in the US and some other countries.
Fig 10: structure of methanol
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3.2.1 Production From synthesis gas
Carbon monoxide and hydrogen react over a catalyst to produce methanol. Today, the most widely used catalyst is a mixture of copper, zinc oxide, and alumina first used by ICIin 1966. At 5–10 MPa (50–100 atm) and 250 °C (482 °F), it can catalyze the production of methanol from carbon monoxide and hydrogen with high selectivity (>99.8%):
CO + 2 H2 → CH3OH
It is worth noting that the production of synthesis gas from methane produces three moles of hydrogen gas for every mole of carbon monoxide, while the methanol synthesis consumes only two moles of hydrogen gas per mole of carbon monoxide. One way of dealing with the excess hydrogen is to inject carbon dioxide into the methanol synthesis reactor, where it, too, reacts to form methanol according to the equation:
CO2 + 3 H2 → CH3OH + H2O
Some chemists believe that the certain catalysts synthesize methanol using CO2 as an intermediary, and consuming CO only indirectly.
CO2 + 3 H2 → CH3OH + H2O where the H2O byproduct is recycled via the water-gas shift reaction
CO + H2O → CO2 + H2,
This gives an overall reaction, which is the same as listed above.
CO + 2 H2 → CH3OH
From methane
The direct catalytic conversion of methane to methanol using Cu-zeolites or other catalysts is an alternative process for the efficient production of methanol. This is currently an active field of research, however there are challenges including lifetime of the catalysts and use of affordable reactants to oxidise the methane.
From carbon dioxide
Methanol has been generated directly from carbon dioxide in solution using copper oxide (CuO) nanorods coated by cuprous oxide (Cu2O) and energy from (simulated) sunlight. The process operated with 95% electrochemical efficiency and is claimed to be scalable to industrial size.
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3.2.2 Applications Feedstock
The largest use of methanol by far is in making other chemicals. About 40% of methanol is converted to formaldehyde, and from there into products as diverse as plastics, plywood, paints, explosives, and permanent press textiles.
Also in the early 1970s, a methanol to gasoline process was developed by Mobil for producing gasoline ready for use in vehicles. One such industrial facility was built at Motunuiin New Zealand in the 1980s. In the 1990s, large amounts of methanol were used in the United States to produce the gasoline additive methyl tert-butyl ether (MTBE). While MTBE is no longer marketed in the U.S., it is still widely used in other parts of the world. In addition to direct use as a fuel, methanol (or less commonly, ethanol) is used as a component in the transesterification of triglycerides to yield a form of biodiesel.
Other chemical derivatives of methanol include dimethyl ether, which has replaced chlorofluorocarbons as an aerosol spray propellant, and acetic acid. Dimethyl ether (DME) also can be blended with liquified petroleum gas (LPG) for home heating and cooking, and can be used as a diesel replacement for transportation fuel.
Methanol-to-Olefins/Methanol-to-Propylene (MTO/MTP), among others processes such as: Metathesis, Propane Dehydrogenation (PDH), High Severity FCC, and Olefins Cracking, is a new and novel lower-cost chemical process for on- purpose propylene production technology of high interest to the petrochemical marketplace, to supply the tight market for propylene.
The market became tight because of the ethane prices falling in the USA, due to the exploration of shale gas reserves. The low price ethylene produced from this raw material has given chemical producers in North America a feedstock advantage. Such change has put naphtha-fed steam crackers at a disadvantageous position, with many of them shutting down or revamping to use ethane as feedstock. Nevertheless, the propylene output rates from ethane-fed crackers are negligible.
Fuel for vehicles
Methanol is used on a limited basis to fuel internal combustion engines. Pure methanol is required by rule to be used in Champcars, Monster Trucks, USAC sprint cars (as well as midgets, modifieds, etc.), and other dirt track series, such as World of Outlaws, and Motorcycle Speedway. Methanol is also used, as the primary fuel ingredient since the late 1940s, in the powerplants for radio control, control line and free flight airplanes (as
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Characterisation of stimulated Brillouin scattering for different materials methanol is required in the engines that primarily power them), cars and trucks, from such an engine's use of a platinum filament glow plug being able to ignite the methanol vapor through a catalytic reaction. Drag racers and mud racers, as well as heavily modified tractor pullers, also use methanol as their primary fuel source. Methanol is required with a supercharged engine in a Top Alcohol Dragster and, until the end of the 2006 season, all vehicles in the Indianapolis 500 had to run methanol. Mud racers have mixed methanol with gasoline with nitrous oxide to produce more power than mixing gasoline and nitrous oxide alone.
One of the potential drawbacks of using high concentrations of methanol (and other alcohols, such as ethanol) in fuel is the corrosivity to some metals of methanol, particularly to aluminium. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminum from corrosion:
6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O
The resulting methoxide salts are soluble in methanol, resulting in a clean aluminium surface, which is readily oxidized by dissolved oxygen. Also, the methanol can act as an oxidizer:
6 CH3OH + 2 Al → 2 Al(OCH3)3 + 3 H2
This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH3OH is negligible. Concerns with methanol's corrosivity have been addressed by using methanol-compatible materials, and fuel additives that serve as corrosion inhibitors.
When produced from wood or other organic materials, the resulting organic methanol (bioalcohol) has been suggested as renewable alternative to petroleum-based hydrocarbons. Low levels of methanol can be used in existing vehicles, with the use of proper co solvents and corrosion inhibitors.
Methanol fuel has been proposed for ground transportation. The chief advantage of a methanol economy is that it could be adapted to present internal combustion engines with a minimum of modification in both engines and infrastructure to store and deliver liquid fuel.
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Characterisation of stimulated Brillouin scattering for different materials
3.3 Methyl acetate
Methyl acetate, also known as MeOAc, acetic acid methyl ester or methyl ethanoate, is a carboxylate ester with the formula CH3COOCH3. It is a flammable liquid with a characteristically pleasant smell reminiscent of some glues and nail polish removers. Methyl acetate is occasionally used as a solvent, being weakly polar and lipophilic, but its close relative ethyl acetate is a more common solvent being less toxic and less soluble in water. Methyl acetate has a solubility of 25% in water at room temperature. At elevated temperature its solubility in water is much higher. Methyl acetate is not stable in the presence of strong aqueous bases or aqueous acids. Methyl acetate is not considered as a VOC
Fig 11: structure of methyl acetate
3.3.1 Preparation
Methyl acetate is produced industrially via the carbonylation of methanol as a byproduct of the production of acetic acid. Methyl acetate also arises by esterification of acetic acid with methanol in the presence of strong acids such as sulfuric acid, this production process is famous because of Eastman Kodak's intensified process using a reactive distillation.
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3.4 Demineralised water
Demineralised water is water completely free (or almost) of dissolved minerals as a result of one of the following processes:
distillation
deionization
membrane filtration (reverse osmosis or nanofiltration)
electrodyalisis
or other technologies.
Demineralized water also known as Deionized water, water that has had its mineral ions removed. Mineral ions such as cations of sodium, calcium, iron, copper, etc and anions such as chloride, sulphate, nitrate, etc are common ions present in water. Deionization is a physical process which uses specially-manufactured ion exchange resins which provides ion exchange site for the replacement of the mineral salts in water with water forming H+ and OH- ions. Because the majority of water impurities are dissolved salts, deionization produces a high purity water that is generally similar to distilled water, and this process is quick and without scalebuildup. De-mineralization technology is the proven process for treatment of water. A DM Water System produces mineral free water by operating on the principles of ion exchange, Degasification, and polishing. Demineralized Water System finds wide application in the field of steam, power, process, and cooling.
3.4.1 Production
Principle
Raw water is passed via two small polystyrene bead filled (ion exchange resins) beds. While the cations get exchanged with hydrogen ions in first bed, the anions are exchanged with hydroxyl ions, in the second one.
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3.4.2 Major Applications
• Boilers feed water, Textiles, Pharmaceuticals, Chemicals, Breweries, Swimming pools, Potable Water, Hospitals, Automobile, and Battery, Fertilizers. • Ion Exchange Plants - Softener - Industrial DM Plant - Two Stage & Multi Stage DM Plants - Mix Bed Demineraliser - De-Gasifiers - Cation Polisher - Manual/Automatic Plants - Pharmaceutical Industry - Power Plant - Oil & Gas sector - Chemical Industries - Textile Industries
3.5 Xylene
Xylene (from Greek ξύλο, xylo, "wood"), xylol or dimethylbenzene is an hydrocarbon mixture consisting of a benzene ring with two methyl groups at various substituted positions.
The three isomers of xylene have the molecular formula C8H10, also represented by the semi- structural formulaC6H4(CH3)2. Xylene is a major petrochemical produced by catalytic reforming and also by coal carbonisation in the manufacture of coke fuel. It represents about 0.5–1% of crude oil (depending on the source), and is found in small quantities in gasoline and aircraft fuels. Xylenes are mainly produced as part of the BTX aromatics (benzene, toluene and xylenes) extracted from the product of catalytic reforming known as "reformate". The mixture is a slightly greasy, colourless liquid commonly encountered as a solvent. Xylene was named in 1851, having been discovered as a constituent of wood. Several million tons are produced annually.[1] In 2011, a global consortium began construction of one of the world’s largest xylene plants in Singapore.
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Fig 12: structure of xylene
3.5.1 Production
Xylenes are produced by the methylation of toluene and benzene. Commercial or laboratory grade xylene produced usually contains about 40-65% of m-xylene and up to 20% each of o-xylene, p-xylene and ethylbenzene. The ratio of isomers can be shifted to favor the highly valued p-xylene via the patented UOP-Isomar process or bytransalkylation of xylene with itself or trimethylbenzene. These conversions are catalyzed by zeolites
3.5.2 Applications
Terephthalic acid and related derivatives
p-Xylene is the principal precursor to terephthalic acid and dimethyl terephthalate, both monomers used in the production of polyethylene terephthalate (PET) plastic bottles and polyester clothing. 98% of p-xylene production, and half of all xylenes produced is consumed in this manner. o-Xylene is an important precursor to phthalic anhydride. The demand for isophthalic acid is relatively modest so m-xylene is rarely sought (and hence the utility of its conversion to the o- and p-isomers).
Solvent applications
Xylene is used as a solvent. In this application, mixture of isomers is often referred to as xylenes or xylol. Solvent xylene often contains a small percentage of ethylbenzene. Like the individual isomers, the mixture is colorless, sweet-smelling, and highly flammable. Areas
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Characterisation of stimulated Brillouin scattering for different materials of application include the printing, rubber, and leather industries. It is a common component of ink, rubber, and adhesives. In thinning paints and varnishes, it can be substituted for toluene where slower drying is desired, and thus is used by conservators of art objects in solubility testing. Similarly it is a cleaning agent, e.g., for steel, silicon wafers, and integrated circuits. In dentistry, xylene can be used to dissolve gutta percha, a material used for endodontics (root canal treatments). In the petroleum industry, xylene is also a frequent component of paraffin solvents, used when the tubing becomes clogged with paraffin wax. For similar reasons, it is often the active ingredient in commercial products for ear wax (cerumen) removal.
Laboratory use
Xylene is used in the laboratory to make baths with dry ice to cool reaction vessels, and as a solvent to remove synthetic immersion oil from the microscope objective in light microscopy. In histology, xylene is the most widely used clearing agent. Xylene is used to remove paraffin from dried microscope slides prior to staining. After staining, microscope slides are put in xylene prior to mounting with a coverslip.
Precursor to other compounds
Although conversion to terephthalic acid is the dominant chemical conversion, xylenes are precursors to other chemical compounds. For instance chlorination of both methyl groups gives the corresponding xylene dichlorides (bis(chloromethyl)benzenes) whilst mono-bromination yields xylyl bromide, a tear gas agent used in World War I.
3.6 Rhodamine 6G
Rhodamine 6G is a highly fluorescent rhodamine family dye. It is often used as a tracer dye within water to determine the rate and direction of flow and transport. Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with instruments called fluorometers. Rhodamine dyes are used extensively in biotechnology applications such as fluorescence microscopy, fluorescence correlation
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Characterisation of stimulated Brillouin scattering for different materials spectroscopy and ELISA. Rhodamine 6G is also used as a laser dye, or gain medium, in dye lasers, and is pumped by the 2nd (532 nm) harmonic from an Nd:YAG laser or nitrogen laser. The dye has a remarkably high photostability, high fluorescence quantum yield (0.95), low cost, and its lasing range has close proximity to its absorption maximum (approximately 530 nm). The lasing range of the dye is 555 to 585 nm with a maximum at 566 nm.
Fig 13: structure of Rhodamine 6G
Rhodamine 6G usually comes in three different forms. Rhodamine 6G chloride is a bronze/red powder with the chemical formula C27H29ClN2O3. Although highly soluble, this formulation is very corrosive to all metals except stainless steel. Other formulations are less soluble, but also less corrosive. Rhodamine 6G perchlorate (C27H29ClN2O7) comes in the form of red crystals, while rhodamine 6G tetrafluoroborate (C27H29BF4N2O3) appears as maroon crystals 3.7 Rhodamine B
Rhodamine B is a chemical compound and a dye. It is often used as a tracer dye within water to determine the rate and direction of flow and transport. Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with instruments called fluorometers. Rhodamine dyes are used extensively in biotechnology applications such as fluorescencemicroscopy, flowcytometry, fluorescencecorrelation spectroscopy and ELISA.
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Characterisation of stimulated Brillouin scattering for different materials
Rhodamine B is used in biology as a staining fluorescent dye, sometimes in combination with auramine O, as the auramine-rhodamine stain to demonstrate acid-fast organisms, notably Mycobacterium.
Rhodamine B is tunable around 610 nm when used as a laser dye.[2] Its luminescence quantum yield is 0.65 in basic ethanol, 0.49 in ethanol, 1.0, and 0.68 in 94% ethanol. The fluorescence yield is temperature dependent.
Fig 14: structure of Rhodamine B
Rhodamine B is being tested for use as a biomarker in oral rabies vaccines for wildlife, such as raccoons, to identify animals that have eaten a vaccine bait. The rhodamine is incorporated into the animal's whiskers and teeth.
It is also often mixed with herbicides to show where they have been used.
Rhodamine B (BV10) is mixed with Quinacridone Magenta (PR122) to make the bright pink watercolor known as Opera Rose 3.8 Methylene Blue
Methylene blue (CI 52015) is a heterocyclic aromatic chemical compound with the molecular formula C16H18N3SCl. It has many uses in a range of different fields, such as biology and chemistry. At room temperature it appears as a solid, odorless, dark green
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Characterisation of stimulated Brillouin scattering for different materials powder, that yields a blue solution when dissolved in water. The hydrated form has 3 molecules of water per molecule of methylene blue. Methylene blue should not be confused with methyl blue, another histology stain, new methylene blue, nor with the methyl violets often used as pH indicators.
As an experimental pharmaceutical drug, the International Nonproprietary Name (INN) of methylene blue is methylthioninium chloride.
Methylene blue was first prepared in 1876 by German chemist Heinrich Caro (1834-1910). It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system
3.8.1 Applications
Methylene blue is a component of a frequently prescribed urinary analgesic/anti- infective/anti-spasmodic known as "Prosed", a combination of drugs which also contains phenyl salicylate, benzoic acid, hyoscyamine sulfate, and methenamine (aka hexamethylenetetramine and not to be confused with 'methanamine').
Methylene blue combined with light has been used to treat resistant plaque psoriasis, AIDS- related Kaposi's sarcoma, West Nile virus, and to inactivate staphylococcus aureus, HIV- 1, Duck hepatitis B, adenovirus vectors, and hepatitis C. Phenothiazine dyes and light have been known to have virucidal properties for over 70 years. In some circumstances, the combination can cause DNA damage that may lead to cancer
Since its reduction potential is similar to that of oxygen and can be reduced by components of the electron transport chain, large doses of methylene blue are sometimes used as an antidote to potassium cyanide poisoning, a method first successfully tested in 1933 by Dr. Matilda Moldenhauer Brooks in San Francisco, although first demonstrated by Bo Sahlin of Lund University, in 1926.
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Characterisation of stimulated Brillouin scattering for different materials
References
1. "Methanol". The PubChemProject. USA: National Center for Biotechnology Information
2. Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5. 3. "Acetone". NIST Chemistry WebBook. USA: National Institute of Standards and Technology.
4. "Acetone". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH). 5. Fabri, Jörg; Graeser, Ulrich, and Simo, Thomas A., Xylenes, Ullmann's Encyclopedia of Industrial Chemistry, 2000, Wiley-VCH, Weinheim. Accessed 2015-2- 8doi:10.1002/14356007.a28_433 6. Martindale, David C. and Kuchar, Paul J., Production of xylenes from light aliphatic hydrocarbons via dehydrocyclodimerization and methylation, United States Patent No. 5,043,502, 1991-8-27. Accessed 2012-4-28 7. F. N. Kemmer; The Nalco water handbook; 2. Edition; 1988 8. Degremont; Water treatment handbook; sixth edition; 1991 9. Hosea Cheung, Robin S. Tanke, G. Paul Torrence “Acetic Acid” in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_045 10. http://www.methylene-blue.com/substance.php 11. "Fluorescence quantum yields of some rhodamine dyes". Journal of Luminescence 27 (4): 455–462.doi:10.1016/0022-2313(82)90045-X 12. Casey, Kelly G.; Quitevis, Edward L. (1988). "Effect of solvent polarity on nonradiative processes in xanthene dyes: Rhodamine B in normal alcohols". The Journal of Physical Chemistry 92 (23): 6590–6594
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Characterisation of stimulated Brillouin scattering for different materials
4. EXPERIMENT AND OBSERVATIONS
4.1 Acetone
4.1.1 Pure acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 25 531.36 969 2 32 531.36 1118.5 3 68 531.36 1792.33 4 112 531.36 4465.33 5 195 531.36 16333
The above table shows the readings for pure acetone. We can observe that 25 milli watt is the threshold for the stimulated Brillouin scattering in pure acetone. At threshold the mean amplitude is 969. Above the threshold power as the power increases the mean amplitude is also increases. The wavelength of the scattered wave is also remains constant at 531.36 nm.
From the graph shown below we can clearly identify the power versus amplitude response of the pure acetone
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Characterisation of stimulated Brillouin scattering for different materials
Fig15: Power versus amplitude graph for pure acetone
4.1.2 10-5 mol/litre of Methlyne Blue in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 112 531.1 1443
2 195 531.1 7516.25
3 419 531.1 22560.5
4 658 531.1 37640
5 890 531.1 37887.5
6 1000 531.1 39220
The above table shows the readings for 10-5 mol/litre of Methlyne Blue in acetone. We can observe that 112 milli watt is the threshold for the stimulated Brillouin scattering in 10-5 mol/litre of Methlyne Blue in acetone. At threshold the mean amplitude is 1443. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is also remains constant at 531.1 nm.
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Characterisation of stimulated Brillouin scattering for different materials
Fig 16: Power versus amplitude graph for 10-5 mol/litre of Methlyne Blue in acetone
4.1.3 10-6 mol/litre of Methlyne Blue in Acetone
Mean Amplitude Sl . No Power (mj) Wavelength (nm) (arb.unit)
1 112 531.1 1478.5
2 195 531.1 5025.25
3 419 531.1 49447.5
4 658 531.1 89562.5
5 890 531.1 131740.4873
6 1000 531.1 150737.9
The above table shows the readings for 10-6 mol/litre of Methlyne Blue in acetone. We can observe that 112 milli watt is the threshold for the stimulated Brillouin scattering in 10-6 mol/litre of Methlyne Blue in acetone. At threshold the mean amplitude is 1478.5. Above the
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Characterisation of stimulated Brillouin scattering for different materials threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is also remains constant at 531.1 nm
Fig 17: Power versus amplitude graph for 10-6 mol/litre of Methlyne Blue in acetone
4.1.4 10-7 mol/litre of Methlyne Blue in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 112 531.1 1657
2 195 531.1 13280.5
3 419 531.1 69465
4 658 531.1 128712.6
5 890 531.1 153821
6 1000 531.1 167964.4
The above table shows the readings for 10-7 mol/litre of Methlyne Blue in acetone. We can observe that 112 milli watt is the threshold for the stimulated Brillouin scattering in 10-7 mol/litre of Methlyne Blue in acetone. At threshold the mean amplitude is 1657. Above the
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Characterisation of stimulated Brillouin scattering for different materials threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is also remains constant at 531.1 nm
Fig 18: Power versus amplitude graph for 10-7 mol/litre of Methlyne Blue in acetone
4.1.5 10-5 mol/litre of Rhodamine B in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 419 530.84 1027 2 658 530.84 2521.5 3 890 530.84 4873 4 1000 530.84 5658.25
The above table shows the readings for 10-5 mol/litre of Rhodamine b in acetone. We can observe that 419 milli watt is the threshold for the stimulated Brillouin scattering in 10-5 mol/litre of Rhodamine b in acetone. At threshold the mean amplitude is 1027. Above the threshold power as the power increases the mean amplitude is also increases.. The wavelength of the scattered wave is also remains constant at 530.84 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 19: Power versus amplitude graph for 10-5 mol/litre of Rhodamine b in acetone
4.1.6 10-6 mol/litre of Rhodamine B in Acetone
Sl . No Power (milli watt) Wavelength (nm) Mean Amplitude (arb.unit)
1 68 530.84 1589.75 2 195 530.84 194050 3 419 530.84 318875 4 658 530.84 374625 5 890 530.84 389125 6 1000 530.84 384250
The above table shows the readings for 10-6 mol/litre of Rhodamine B in Acetone. We can observe that 68 milli watt is the threshold for the stimulated Brillouin scattering in 10-6 mol/litre of Rhodamine B in acetone. At threshold the mean amplitude is 1589.75. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is also remains constant at 530.84 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 20: Power versus amplitude graph for 10-6 mol/litre of Rhodamine b in acetone
4.1.7 10-7 mol/litre of Rhodamine B in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 68 530.84 2053 2 195 530.84 227325 3 419 530.84 321925 4 658 530.84 345650 5 890 530.84 40885 6 1000 530.84 403375
The above table shows the readings for 10-7 mol/litre of Rhodamine B in Acetone. We can observe that 68 milli watt is the threshold for the stimulated Brillouin scattering in 10-7 mol/litre of Rhodamine B in acetone. At threshold the mean amplitude is 2053. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is also remains constant at 530.84 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 21: Power versus amplitude graph for 10-7 mol/litre of Rhodamine b in acetone
4.1.8 10-6 mol/litre of Rhodamine 6G in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 195 531.36 1062.33 2 419 531.36 4528.5 3 658 531.36 10563.33 4 890 531.36 9894.33
The above table shows the readings for 10-6 mol/litre of Rhodamine 6G in Acetone. We can observe that 195 milli watt is the threshold for the stimulated Brillouin scattering in 10-6 mol/litre of Rhodamine 6G acetone. At threshold the mean amplitude is 1062.33. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is also remains constant at 531.36 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 22: Power versus amplitude graph for 10-6 mol/litre of Rhodamine 6G in Acetone
4.1.9 0.5*10-5 mol/litre of Rhodamine 6G in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 68 531.1 10101.35 2 195 531.1 56393.3 3 419 531.1 111796.95 4 658 531.1 209466 5 890 531.1 205466 6 1000 531.1 220000
The above table shows the readings for 0.5*10-5 mol/litre of Rhodamine 6G in Acetone. We can observe that 68 milli watt is the threshold for the stimulated Brillouin scattering in 0.5*10-5 mol/litre of Rhodamine 6G in acetone. At threshold the mean amplitude is 10101.35. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value The wavelength of the scattered wave is also remains constant at 531.1 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 23: Power versus amplitude graph for 0.5*10-5 mol/litre of Rhodamine 6G in Acetone
4.1.10 0.5*10-6 mol/litre of Rhodamine 6G in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 47 531.1 3801 2 68 531.1 6761 3 195 531.1 24307.63 4 419 531.1 53742.5 5 658 531.1 124736.04 6 890 531.1 162339.44 7 1000 531.1 188625.23
The above table shows the readings for 0.5*10-6 mol/litre of Rhodamine 6G in Acetone. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in 0.5*10-6 mol/litre of Rhodamine 6G in acetone. At threshold the mean amplitude is 3801. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value the wavelength of the scattered wave is also remains constant at 531.1 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 24: Power versus amplitude graph for 0.5*10-6 mol/litre of Rhodamine 6G in Acetone
4.1.11 0.5*10-7 mol/litre of Rhodamine 6G in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 68 531.1 2323.67 2 195 531.1 78210 3 419 531.1 190295.1178 4 658 531.1 280266 5 890 531.1 294900 6 1000 531.1 305733
The above table shows the readings for 0.5*10-7 mol/litre of Rhodamine 6G in Acetone. We can observe that 68 milli watt is the threshold for the stimulated Brillouin scattering in 0.5*10-7 mol/litre of Rhodamine 6G in acetone. At threshold the mean amplitude is 2323.67. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value The wavelength of the scattered wave is also remains constant at 531.1 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 25: Power versus amplitude graph for 0.5*10-7 mol/litre of Rhodamine 6G in Acetone
4.1.12 0.5*10-8 mol/litre of Rhodamine 6G in Acetone
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 68 531.1 6029.5 2 195 531.1 96680 3 419 531.1 274625 4 658 531.1 316650 5 890 531.1 397775 6 1000 531.1 387450
The above table shows the readings for 0.5*10-8 mol/litre of Rhodamine 6G in Acetone. We can observe that 68 milli watt is the threshold for the stimulated Brillouin scattering in 0.5*10-8 mol/litre of Rhodamine 6G in acetone. At threshold the mean amplitude is 6029.5. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is also remains constant at 531.1 nm
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Characterisation of stimulated Brillouin scattering for different materials
Fig 26: Power versus amplitude graph for 0.5*10-8 mol/litre of Rhodamine 6G in Acetone
Observations
From the readings for acetone we can observe that pure Acetone has the lowest threshold power of 25 mw and 10-5 mol/litre solution of Rhodamine B in acetone have the highest threshold power and it is 419 milli watts. For all the concentration of methylene blue in acetone the threshold power is constant and it is 112 miili watts. In the case of 0.5*10-6 mol/litre solution of Rhodamine 6G in Acetone the threshold power is less than 0.5*10-5 mol/litre solution of Rhodamine 6G in Acetone. For pure acetone the scattered wave has a wavelength of 531.36 nm and for all the concentration of methlyne blue in acetone the wavelength for the scattered wave is 531.1 nm. for all the concentration of Rhodamine B in acetone the wavelength is 530.84 nm, in the case of Rhodamine 6G in Acetone the wavelength is 531nm and 531.36 nm.
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Characterisation of stimulated Brillouin scattering for different materials
4.2 Methanol
4.2.1 Pure methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 47 531.1 8256.7 2 68 531.1 41302.5 3 195 531.1 300867 4 419 531.1 723725 5 658 531.1 1205934.5 6 890 531.1 1403418.8 7 1000 531.1 1576790.7
The above table shows the readings for pure methanol. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 8256.7. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is also remains constant at 531.1 nm
Fig 27: Power versus amplitude graph for pure methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.2 10-5 mol/litre of methlyne blue in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 68 531.1, 530.84 1124.25 2 112 531.1 1741.5 3 195 531.1 2431 4 419 531.1 13652 5 658 531.1 40340 6 890 531.1 49785 7 1000 531.1 57790
The above table shows the readings for 10-5 mol/litre of methlyne blue in methanol. We can observe that 68 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 1124.25. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is 531.1 nm and 530.84 nm
Fig 28: Power versus amplitude graph for 10-5 mol/litre of methlyne blue in methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.3 10-6 mol/litre of methlyne blue in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 32 530.84,530.58 1600
2 68 530.84 5036
3 195 530.84 13079.5
4 419 530.84 25055
5 658 530.84 27842.5
6 890 530.84 28730
7 1000 530.84,530.58 31395
The above table shows the readings for 10-6 mol/litre of methlyne blue in methanol. We can observe that 32 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 1600. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is 530.58 nm and 530.84 nm.
Fig 29: Power versus amplitude graph for 10-6 mol/litre of methlyne blue in methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.4 10-7 mol/litre of methlyne blue in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 32 530.58 2745.5 2 68 530.58 35742.5 3 195 530.58 119285 4 419 530.58, 530.84 174431.23 5 658 530.58, 530.84 185728.47 6 890 530.58 196662 7 1000 530.58 198338
The above table shows the readings for 10-7 mol/litre of methlyne blue in methanol. We can observe that 32 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 2745.5. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is 530.58 nm and 530.84 nm
Fig 30: Power versus amplitude graph for 10-7 mol/litre of methlyne blue in methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.5 10-6 mol/litre of Rhodamine 6G in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 47 531.1 11333
2 68 531.1 54344
3 195 531.1 626875
4 419 531.1 1581455
5 658 531.1 1846216.255
6 890 531.1 1980376.38
7 1000 531.1 2147660.873
The above table shows the readings for 10-6 mol/litre of rhodamine 6G in methanol. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 11333. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remain constant at 531.1
Fig 31: Power versus amplitude graph for 10-6 mol/litre of rhodamine 6G in methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.6 10-7 mol/litre of Rhodamine 6G in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 47 531.1 9186.466
2 68 531.1 120870
3 195 531.1 895430.54
4 419 531.1 1585439.5
5 658 531.1 2311624.97
6 890 531.1 2476948.846 7 1000 531.1 2441531.33
The above table shows the readings for 10-7 mol/litre of rhodamine 6G in methanol. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 9186.466. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is remain constant at 531.1
Fig 32: Power versus amplitude graph for 10-7 mol/litre of rhodamine 6G in methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.7 10-8 mol/litre of Rhodamine 6G in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 47 531.1 1531.6
2 68 531.1 118825.74
3 195 531.1 646283
4 419 531.1 1362498.953
5 658 531.1 1601250.9
6 890 531.1 1994954.4
7 1000 531.1 2307830.236
The above table shows the readings for 10-8 mol/litre of rhodamine 6G in methanol. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 1531.6. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remain constant at 531.1
Fig 33: Power versus amplitude graph for 10-8 mol/litre of rhodamine 6G in methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.8 10-6mol/litre of rhodamine b in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 32 530.84 4830.5
2 68 530.84 56412.5
3 195 530.84 313300
4 419 530.84 523675
5 658 530.84 523975
6 890 530.84 506175
7 1000 530.84 508600
The above table shows the readings for 10-6 mol/litre of rhodamine b in methanol. We can observe that 32 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 4830.5. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remain constant at 530.84
Fig 34: Power versus amplitude graph for 10-6 mol/litre of rhodamine b in methanol
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Characterisation of stimulated Brillouin scattering for different materials
4.2.9 10-7mol/litre of rhodamine b in methanol
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 47 530.84 1755.5 2 68 530.84 35480 3 195 530.84 299775 4 419 530.84 348150 5 658 530.84 401450 6 890 530.84 419100 7 1000 530.84 407450
The above table shows the readings for 10-7 mol/litre of rhodamine b in methanol. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 1755.5. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is remain constant at 530.84.
Fig 35: Power versus amplitude graph for 10-7 mol/litre of rhodamine b in methanol
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Characterisation of stimulated Brillouin scattering for different materials
Observations
In the case of methanol the pure methanol have a threshold power of 47 milli watt. The lowest threshold power is for 10-6 mol/litre of rhodamine b and 10-6 mol/litre of methlyne blue in methanol. Highest threshold is for 10-5 mol/litre of rhodamine b in methanol. In the case of methlyne blue the wavelength of the scattered wave is varying drastically. The wavelength of the scattered wave for methlyne blue is 531.1, 530.84, and 530.58. in the case of rodamine 6G the threshold power is remain constant for all the concentrations and it is 47 milli watt. In rodamine 6G the wavelength is also remains constant at 531.1. in the case of rhodamine b the wavelength is 530.84 and is remains constant.
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Characterisation of stimulated Brillouin scattering for different materials
4.3 Methyl acetate
4.3.1 Pure methyl acetate
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 18 530.84 2075.75 2 32 530.84 31477.5 3 68 530.84 148225 4 195 530.84 355975 5 419 530.84 450950 6 658 530.84 461600 7 890 530.84 527250 8 1000 530.84 531175
The above table shows the readings for pure methyl acetate. We can observe that 18 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 2075.75. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remain constant at 530.84nm.
Fig 36: Power versus amplitude graph for pure methyl acetate
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Characterisation of stimulated Brillouin scattering for different materials
4.3.2 10-5 mol/litre of rhodamine 6G in methyl acetate
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 32 530.84 2061.5
2 68 530.84 25245 3 195 530.84 74235 4 419 530.84 202200 5 658 530.84 236525 6 890 530.84 266375 7 1000 530.84 289275
The above table shows the readings for 10-5 mol/litre of rhodamine 6G in methyl acetate. We can observe that 32 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 2061.5. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remain constant at 530.84nm.
Fig 37: Power versus amplitude graph for 10-5 mol/litre of rhodamine 6G in methyl acetate
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Characterisation of stimulated Brillouin scattering for different materials
4.3.3 10-6 mol/litre of rhodamine 6G in methyl acetate
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 18 530.84 3076.25 2 32 530.84 53742.9 3 68 530.84 119423.41 4 195 530.84 275616.21 5 419 530.84 432675 6 658 530.84 455575 7 890 530.84 444775 8 1000 530.84 442050
The above table shows the readings for 10-6 mol/litre of rhodamine 6G in methyl acetate. We can observe that 18 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 3076.25. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is remain constant at 530.84nm.
Fig 38: Power versus amplitude graph for 10-6 mol/litre of rhodamine 6G in methyl acetate
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Characterisation of stimulated Brillouin scattering for different materials
4.3.4 10-5 mol/litre of rhodamine b in methyl acetate
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 32 530.84 4479 2 68 530.84 757776 3 195 530.84 215319.48 4 419 530.84 453950 5 658 530.84 483450 6 890 530.84 540125 7 1000 530.84 541875
The above table shows the readings for 10-5 mol/litre of rhodamine b in methyl acetate. We can observe that 32 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 4479. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remain constant at 530.84nm.
Fig 39: Power versus amplitude graph for 10-5 mol/litre of rhodamine b in methyl acetate
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Characterisation of stimulated Brillouin scattering for different materials
4.3.5 10-6 mol/litre of rhodamine b in methyl acetate
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 32 530.84 3207.25
2 68 530.84 128127.56
3 195 530.84 320046.21
4 419 530.84 480450
5 658 530.84 555600
6 890 530.84 591475 7 1000 530.84 580250
The above table shows the readings for 10-6 mol/litre of rhodamine b in methyl acetate. We can observe that 32 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 3207.25. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is remain constant at 530.84nm
Fig 40: Power versus amplitude graph for 10-6 mol/litre of rhodamine b in methyl acetate
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Characterisation of stimulated Brillouin scattering for different materials
4.3.6 10-7 mol/litre of rhodamine b in methyl acetate Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 18 530.84 2554 2 32 530.84 46357.5 3 68 530.84 220315.88 4 195 530.84 419950 5 419 530.84 502950 6 658 530.84 651900 7 890 530.84 726925 8 1000 530.84 718425
The above table shows the readings for 10-7 mol/litre of rhodamine b in methyl acetate. We can observe that 18 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 2554. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is remain constant at 530.84nm.
Fig 41: Power versus amplitude graph for 10-7 mol/litre of rhodamine b in methyl acetate
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Characterisation of stimulated Brillouin scattering for different materials
Observation
For pure methylacetate threshold power is 18 milli watts. Maximum threshold power is for 10-5 molar rhodamine 6G , 10-5 and 10-6 molar rhodamine b and it is 32 mw. The wavelength is remain constant for all the dyes and at all the concentrations and it is 530.84
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Characterisation of stimulated Brillouin scattering for different materials
4.4 Demineralised water
4.4.1 Pure demineralised water
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 47 530.84 2521 2 68 530.84 44469.5 3 195 530.84 162975.88 4 419 530.84 313326.37 5 658 530.84 484425 6 890 530.84 504750 7 1000 530.84 532350
The above table shows the readings for pure Demineralised water . We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 2521. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remain constant at 530.84nm.
Fig 42: Power versus amplitude graph for pure Demineralised water
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Characterisation of stimulated Brillouin scattering for different materials
4.4.2 10-5 mol/litre of rhodamine 6G in Demineralised water
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 148 530.84 1843.25 2 195 530.84 5360.75 3 419 530.84 80393 4 658 530.84 122712.18 5 890 530.84 129060.45 6 1000 530.84 140950.621
The above table shows the readings for 10-5 mol/litre of rhodamine 6G in Demineralised water. We can observe that 148 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 1843.25. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remaining constant at 530.84nm.
Fig 42: Power versus amplitude graph for10 -5 mol/litre of rhodamine 6G in Demineralised water
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Characterisation of stimulated Brillouin scattering for different materials
4.4.3 10-6 mol/litre of rhodamine 6G in Demineralised water
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 148 530.84 3543.25 2 195 530.84 232957 3 419 530.84 517800 4 658 530.84 662825 5 890 530.84 713300 6 1000 530.84 739350
The above table shows the readings for 10-6 mol/litre of rhodamine 6G in Demineralised water. We can observe that 148 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 3543.25. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remaining constant at 530.84nm.
Fig 43: Power versus amplitude graph for10 -6 mol/litre of rhodamine 6G in Demineralised water
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Characterisation of stimulated Brillouin scattering for different materials
4.4.4 10-7 mol/litre of rhodamine 6G in Demineralised water
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit)
1 47 530.84 1652 2 68 530.84 54011.7 3 195 530.84 230277 4 419 530.84 477725 5 658 530.84 484600 6 890 530.84 542325 7 1000 530.84 556725
The above table shows the readings for 10-7 mol/litre of rhodamine 6G in Demineralised water. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 1652. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remaining constant at 530.84nm.
Fig 44: Power versus amplitude graph for10 -7 mol/litre of rhodamine 6G in Demineralised water
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Characterisation of stimulated Brillouin scattering for different materials
4.4.5 10-5 mol/litre of Methlyne Blue in Demineralised water
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 95 530.84 3181.5
2 195 530.84 37077 3 419 530.84 99619.65 4 658 530.84 134238.68 5 890 530.84 142674.06 6 1000 530.84 136278.35
The above table shows the readings for 10-5 mol/litre of Methlyne Blue in Demineralised water. We can observe that 95 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 3181.5. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is remaining constant at 530.84nm.
Fig 45: Power versus amplitude graph for10-5 mol/litre of Methlyne Blue in Demineralised water
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Characterisation of stimulated Brillouin scattering for different materials
4.4.6 10-6 mol/litre of Methlyne Blue in Demineralised water
Mean Amplitude Sl . No Power (milli watt) Wavelength (nm) (arb.unit) 1 32 530.84 4127 2 68 530.84 54920.85 3 195 530.84 227644.46 4 419 530.84 976195.11 5 658 530.84 1144665.45 6 890 530.84 1392667 7 1000 530.84 1350292.561
The above table shows the readings for 10-6 mol/litre of Methlyne Blue in Demineralised water. We can observe that 32 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 4127. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. At the maximum power the mean amplitude of the scattered wave is going to a lower value. The wavelength of the scattered wave is remaining constant at 530.84nm.
Fig 46: Power versus amplitude graph for10-6 mol/litre of Methlyne Blue in Demineralised water
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Characterisation of stimulated Brillouin scattering for different materials
4.4.7 10-7 mol/litre of Methlyne Blue in Demineralised water
Mean Amplitude Sl . No Power (mj) Wavelength (nm) (arb.unit)
1 47 530.84 1261.67
2 68 530.84 5877
3 195 530.84 226023.79
4 419 530.84 751436.22
5 658 530.84 916586.17
6 890 530.84 1105848.5
7 1000 530.84 1269733.53
The above table shows the readings for 10-7 mol/litre of Methlyne Blue in Demineralised water. We can observe that 47 milli watt is the threshold for the stimulated Brillouin scattering in pure methanol. At threshold the mean amplitude is 1261.67. Above the threshold power as the power increases the mean amplitude is also increases. At the lower power levels the amplitude is increasing steeply but at the higher power levels the increase is less steep and the amplitude is tending to be a constant value. The wavelength of the scattered wave is remaining constant at 530.84nm.
Fig 47: Power versus amplitude graph for10-7 mol/litre of Methlyne Blue in Demineralised water
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Characterisation of stimulated Brillouin scattering for different materials
Observations
For pure demineralised water the threshold power is 47 milli watts. Maximum threshold power is for 10-5 and 10-6 molar rhodamine 6G and it is 148 milli watts. The minimum threshold power is for 10-6 molar methylene blue and it is 32 milli watts. The wavelength is remaining constant for all the concentrations and for all the dyes and it is 530.84 nm 4.5 Xylene
There is no stimulated Brillouin scattering is observed from xylene. Because xylene is not optically polarisable. We can observe stimulated Brilllouin scattering only from optically polarisable materials. References
1. Multipass Amplification Using Optical Phase Conjugation by Stimulated Brillouin Scattering V. Brueckner & M. Kramer
2. Stimulated Brillouin Scattering: Fundamentals and Applications By M J Damzen, V Vlad, Anca Mocofanescu, V Babin
3. Some features of stimulated Brillouin scattering in light-absorbing media S. F. Grigor'ev, 0. P. Zaskal'ko, and V. V. Kuz'min 4. Stimulated Brillouin Scattering in Nonfocusing Liquids J. Walder and C. L. Tang Phys. Rev. 155, 318 5. Generation and suppression of stimulated Brillouin scattering in single liquid droplets Jian-Zhi Zhang and Richard K. Chang 6. Stimulated raman, librational, and Brillouin scattering in water O. Rahn, M. Maier, W. Kaiser 7. Theoretical investigation on the pumping effect of stimulated Brillouin scattering on stimulated Raman scattering in water. Shi, J.; Chen, X.; Ouyang, M.; Gong, W.; Su, Y.; Liu, D. 8. Remote Sensing of Ocean Waters with Raman and Brillouin Scattering Joyanto Mukerjee 9. J. Hansryd et al., “Increase of the SBS threshold in a short highly nonlinear fiber by applying a temperature distribution”, J. Lightwave Technol.
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Characterisation of stimulated Brillouin scattering for different materials
5.
RESULT AND ANALYSIS
5.1 Power versus amplitude graph at various concentrations in acetone
Fig 48: Power versus Amplitude graph for Rhodamine 6G at various concentrations
Fig 49: Power versus Amplitude graph for Methylene Blue at various concentrations
Fig 50: Power versus Amplitude graph for rhodamine b at various concentrations
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Characterisation of stimulated Brillouin scattering for different materials
The graph at 0.5*10-5 and 0.5*10-8 molar concentration of rhodamine 6G in acetone have two regions of constant amplitude and two different slopes for increasing region. It means that for 0.5*10-5 and 0.5*10-8 molar concentration of rhodamine 6G in acetone at different power levels the laser induced accoustic waves are generated with different amplitude, power and wavelength. For 0.5*10-6 molar concentration of rhodamine 6G in acetone the amplitude is linealy increasing with power, it is because of the fact that as the power increases the radiative process is reduced and more phonons are generated. 0.5*10-6 molar concentration of rhodamine 6G in acetone have less amplitude for SBS than 0.5*10-5 molar concentration of rhodamine 6G in acetone it is due to the fact that at 0.5*10-6 the light absorption and particle interaction is maximum, whenever the light absorption and particle interaction is maximum the amplitude of the SBS got reduces. for 0.5*10-8 molar concentration of rhodamine 6G in acetone at higher power level the amplitude of the SBS is getting reduced, it is due to the fact that at higher power levels stimulated flouresence emmision increases.
The graph at 10-5 molar concentration of Methylene Blue in acetone a linear increase after the threshold power and as the power increases the amplitude is getting stabilised, the reason behind this behaviour is that as the power increases the phonon generation and radiative process in the medium is getting saturated. For 10-6 and 10-7 molar concentration of Methylene Blue in acetone the amplitude is linearly increasing this due to the incresing of phonon generation and the reduction of radiative process in the medium.
The graph at 10-5 molar concentration of rhodamine B in acetone have very small amplitude compared to the 10-6 and 10-7 molar concentration of rhodamine B in acetone. It is due to the absorption of light by the dye molecule and the increse in the rate of collission between the molecule at higher concentration. At this concentration the radiative process is also getting in to the account. At 10-6 molar concentration of rhodamine B in acetone the amplitude is increasing linearly after the threshold laser power and at higher laser power the amplitude is getting stabilised and at maximum power it is going to a lower value. Creation of stimulated flouresence emission is reducing the amplitude at the higher power level. For 10-7 molar concentration of rhodamine B in acetone have two regions of constant amplitude and two different slopes for increasing region. It means that at different power levels the accoustic wave is generating with different amplitude, power and wavelength and the radiative process is also changing with power. Creation of stimulated flouresence emission is reducing the amplitude at the higher power level at this concentration.
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Characterisation of stimulated Brillouin scattering for different materials
5.2 Concentration versus amplitude graph at various power levels in Acetone
Fig 51: Concentration versus amplitude graph for Rhodamine 6G at various power levels
Fig 52: Concentration versus amplitude graph for Methylene Blue at various power levels
Fig 53: Concentration versus amplitude graph for Rhodamine B at various power levels
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Characterisation of stimulated Brillouin scattering for different materials
As the concentration of Rhodamine 6G increases in acetone the amplitude of the stimulated Brillouin scattering wave decreases till 0.5*10-6 and then slightly increases for 0.5*10-5. As the concentration increases the radiative process and the interaction between the molecules is very high then the phonon generation decreases as a result the amplitude of the scattered wave decreases. It is clear from the graph that as the power increases the amplitude of the scattered wave is increases. For 68 milli watts the amplitude of the scattered wave is minimum and it is increasing as the power increases. Slight increase at 0.5*10-5 is due to the simultaneous increase of acoustic wave generation and optical absorption.
The amplitude of the stimulated Brillouin scattering wave decreases as the concentration of Methylene blue increases in acetone. As the concentration increases the radiative process and the interaction between the molecules is very high then the phonon generation decreases as a result the amplitude of the scattered wave decreases. From the graph we can infer that as the power increases the amplitude of the scattered wave is increases; this is due to the increase in the creation of phonon due to the reduced radiative process and the molecular interaction.
As the concentration of Rhodamine B increases in acetone the amplitude of the stimulated Brillouin scattering wave decreases. As the concentration increases the radiative process and the interaction between the molecules is very high then the phonon generation decreases as a result the amplitude of the scattered wave decreases. It is clear from the graph that as the power increases the amplitude of the scattered wave is increases.
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Characterisation of stimulated Brillouin scattering for different materials
5.3 Power versus amplitude graph at various concentrations in methanol
Fig 54: Power versus amplitude graph for methylene blue at various concentrations
Fig 55: Power versus amplitude graph for rhodamine 6G at various concentrations
Fig 56: Power versus amplitude graph for rhodamine b at various concentrations
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Characterisation of stimulated Brillouin scattering for different materials
The graph at 10-5 molar concentration of Methylene blue in methanol have very small amplitude compared to the 10-6 and 10-7 molar concentration of Methylene blue in methanol. It is due to the absorption of light by the dye molecule and the increse in the rate of collission between the molecule at higher concentration. At this concentration the radiative process is also getting in to the account. At higher power levels the amplitude of 10-5 molar concentration is increasing above 10-6 molar. This is due to the increase in radiative process in 10-6 molar solution. In 10-7 , 10-6 , 10-5 molar concentration of methylene blue in methanol the amplitude is increasing linearly after the threshold laser power and at higher laser power the amplitude is getting stabilised. This due to the fact that at higher power levels the phonon generation is getting stabilised and radiative process and collission between the molecules is remains constant.
In the case of Rhodamine 6G in methanol 10-7 molar concentration has the maximum amplitude and its response have a linear increasing region after threshold. At the higher power the higher power the amplitude get a constant value and at the maximum power the amplitude is decreasing, it is because of the fact that as the power increases the radiative process is reduced and more phonons are generated and at the maximum power the stimulated flouresence emission enhances. For 10-6 molar concentration the amplitude increasing lineraly after the threshold and at maximum power also it is increasing but the slop of the line got reduced at the maximum amplitude. From this we can infer that as the power increses the radiative process as well as the molecular intercion got reduced and phonon generation increased. For 10-8 molar cocentration the amplitude is less than 10-7 and it is nearly equal to 10-6. The one reason behind this is that at 10-8 molar cocentration the stimulated flourescence emission got enhanced.
For Rhodamine B in methanol the amplitude of 10-6 molar concentration is always greater than 10-7 molar concentration; the reason is mainly because of the increase in the fluorescence emission at 10-7 molar concentration. 10-6 and 10-7 molar concentration have a linear increasing region after threshold. At the higher power the higher power the amplitude get a constant value. it is because of the fact that as the power increases the radiative process is reduced and more phonons are generated.
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Characterisation of stimulated Brillouin scattering for different materials
5.4 Concentration versus amplitude graph at various power levels in methanol
Fig 57: Concentration versus amplitude graph for Methylene Blue at various power levels
Fig 58: Concentration versus amplitude graph for Rhodamine B at various power level
Fig 59: Concentration versus amplitude graph for Rhodamine 6G at various power level
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Characterisation of stimulated Brillouin scattering for different materials
The amplitude of the stimulated Brillouin scattering wave decreases as the concentration of Methylene blue increases in methanol. As the concentration increases the radiative process and the interaction between the molecules is very high then the phonon generation decreases as a result the amplitude of the scattered wave decreases. From the graph we can infer that as the power increases the amplitude of the scattered wave is increases; this is due to the increase in the creation of phonon due to the reduced radiative process and the molecular interaction. At 658 milli watts, 890 milli watts, 1000 milli watts the amplitude for 10-5 molar concentration is greater than 10-6 molar concentration. This is because of the increased molecular interaction and the increased rate of stimulated flouresence generation.
For Rhodamine B in methanol the amplitude for 10-6 molar concentration is greater than 10-7 molar concentration. This is because of the increased molecular interaction and the increased rate of stimulated flouresence generation.
For rhodamine 6G in methnol the amplitude of 10-7 molar concentration is greater than 10-8 molar concentration for all the power levels. This is because of the increased molecular interaction and the increased rate of stimulated flouresence generation. But for 10-6 molar concentration the amplitude is getting reduced. This is due to the increased inter molecular interaction. Slight increase in the amplitude at the 10-7 molar concentration is due to the simultaneous increase in the acoustic Wave and optical absorption.
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Characterisation of stimulated Brillouin scattering for different materials
5.5 Power versus amplitude graph at various concentrations in methyl acetate
Fig 60: Power versus amplitude graph for rhodamine b at various concentrations
Fig 61: Power versus amplitude graph for rhodamine 6G at various concentrations
From the above graph we can understand that as the concentration increases the amplitude of scattered wave is decreasing; the reason behind this is that the interaction between the molecules increases as the concentration increases. For 10-5, 10-6 and 10-7 molar concentration after the threshold the amplitude is increasing linearly and at the higher power the amplitude got stabilised. The reason for this behaviour is the stabilised phonon generation at the higher power levels. But for 10-6 and 10-7 molar concentration the amplitude at the maximum power level is decreasing; this is due to the increases stimulated flouresence generation at the higher power level.
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Characterisation of stimulated Brillouin scattering for different materials
For rhodamine 6G in Methyl acetate as the concentration increases the amplitude of scattered wave is decreasing; the reason behind this is that the interaction between the molecules increases as the concentration increases. For 10-5 and 10-6 molar concentration after the threshold the amplitude is increasing linearly and at the higher power the amplitude got stabilised. The reason for this behaviour is the stabilised phonon generation at the higher power levels. But for 10-6 molar concentration the amplitude at the maximum power level is decreasing; this is due to the increases stimulated fluorescence generation at the higher power level.
5.6 Concentration versus amplitude graph at various power levels in Methyl acetate
Fig 62: Concentration versus amplitude graph for Rhodamine B at various power levels
Fig 63: Concentration versus amplitude graph for Rhodamine 6G at various power level
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Characterisation of stimulated Brillouin scattering for different materials
The amplitude of the stimulated Brillouin scattering wave decreases as the concentration of Rhodamine B increases in methyl acetate. As the concentration increases the radiative process and the interaction between the molecules is very high then the phonon generation decreases as a result the amplitude of the scattered wave decreases. From the graph we can infer that as the power increases the amplitude of the scattered wave is increases; this is due to the increase in the creation of phonon due to the reduced radiative process and the molecular interaction
The amplitude of the stimulated Brillouin scattering wave decreases as the concentration of Rhodamine 6G increases in methyl acetate. As the concentration increases the radiative process and the interaction between the molecules is very high then the phonon generation decreases as a result the amplitude of the scattered wave decreases.
5.7 Power versus amplitude graph at various concentrations in Demineralised water
Fig 64: Power versus amplitude graph for methylene blue at various concentrations
Fig 65: Power versus amplitude graph for rhodamine 6G at various concentrations
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Characterisation of stimulated Brillouin scattering for different materials
The amplitude for 10-7 molar concentration is lesser than 10-6 molar concentration of methylene blue in Demineralised water. This is due to the increase in flouresence emission at 10-7 molar concentration. For 10-6 molar concentration there has two levels of constant amplitude and it is due to the creation of lase induced acoustic wave with different amplitude and wavelength at different power levels. At the maximum power level is decreasing; this is due to the increases stimulated fluorescence generation at the higher power level.
For methylene blue in Demineralised water the amplitude for 10-7 molar concentration is lesser than 10-6 molar concentration. This is due to the increase in flouresence emission at 10-7 molar concentration. For 10-6 and 10-7 molar concentration after the threshold the amplitude is increasing linearly and at the higher power the amplitude got stabilised. The reason for this behaviour is the stabilised phonon generation at the higher power levels.
5.8 Concentration versus amplitude graph at various power levels in Demineralised water
Fig 66: Concentration versus amplitude graph for Methylene Blue at various power levels
Fig 67: Concentration versus amplitude graph for rhodamine 6G at various power levels
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Characterisation of stimulated Brillouin scattering for different materials
As the power increases the amplitude of the scattered wave increases. This is due to the increase in phonon generation with power increase. For Methylene blue in Demineralised water the amplitude of 10-6 molar concentration is greater than 10-7 molar concentration for all the power levels. This is because of the increased molecular interaction and the increased rate of stimulated flouresence generation. But for 10-5 molar concentration the amplitude is getting reduced. This is due to the increased inter molecular interaction.
For Rhodamine 6G in Demineralised water the amplitude of 10-6 molar concentration is greater than 10-7 molar concentration for all the power levels except at 68 milli watts. This is because of the increased molecular interaction and the increased rate of stimulated flouresence generation. But for 10-5 molar concentration the amplitude is getting reduced. This is due to the increased inter molecular interaction. For all the concentration as the power increases the amplitude of the scattered wave increases. This is due to the increase in phonon generation with power increase.
For both the dyes at 10-6 molar concentration there has slight increase in the amplitude it is due to the simultaneous amplification of acoustic wave and optical absorption. References
1. R. Loudon, The Quantum Theory of Light, 3rd ed.
2. Rendell, D. (1987). Fluorescence and Phosphorescence. Crown
3. Valeur, B.; Berberan-Santos, M. R. N. (2011). "A Brief History of Fluorescence and Phosphorescence before the Emergence of Quantum Theory". Journal of Chemical Education 88 (6): 731.
4. Stimulated raman, librational, and Brillouin scattering in water O. Rahn, M. Maier, W. Kaiser 5. Stimulated Brillouin Scattering: Fundamentals and Applications By M J Damzen, V Vlad, Anca Mocofanescu, V Babin
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Characterisation of stimulated Brillouin scattering for different materials
6.
CONCLUSION AND FUTURE WORK
The stimulated Brillouin scattering characteristics of different materials is studied. We have chosen acetone, methanol, methyl acetate, demineralised water and xylene as the materials for study. Characteristics of all these materials at its pure state are found out and their threshold power is calculated. Then we added dyes at various concentrations to all these materials and studied the stimulated Brillouin scattering properties. The dyes chosen are methylene blue, Rhodamine 6G and Rhodamine B. in all the materials in its pure state and with the dyes in various concentrations the amplitude of the scattered wave is increasing with the increase in laser power. This is due to the increase in the creation of phonon with reduction in radiative process as the power increases. In some samples such as acetone with 0.5*10-8 molar concentration of Rhodamine 6G and with 10-7 molar concentration of Rhodamine B, methanol with 10-7 molar concentration of Rhodamine 6G and Rhodamine B, methyl acetate with 10-6 ,10-7 molar concentration of Rhodamine B and 10-6 molar concentration of Rhodamine 6G and Demineralised water with 10-6 molar concentration of methylene blue, the amplitude at the maximum power level is going to a lower value due to fluorescence emission. In all the materials after the threshold power the amplitude of the scattered wave is increasing linearly up to a particular laser power, after that in most of the samples the amplitude is getting stabilised. This is due to the increase in the creation of phonon with reduction in radiative process as the power increases and at the high laser powers the phonon creation is getting stabilized. For all the materials threshold power is different and after adding the dye threshold power is increasing. In acetone for all the concentrations of methylene blue and Rhodamine 6G the threshold power is remaining constant but for rhodamine B the threshold power is decreasing as the concentration decreases. In methanol the threshold power remains constant for all the concentrations of Rhodamine 6G but for methylene blue the threshold power is decreasing as the concentration decreases. In methyl acetate the the threshold power decreases for both the rhodamine 6G and Rhodamine B as the concentration decreases. In the case of demineralised water threshold
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Characterisation of stimulated Brillouin scattering for different materials power is decreasing for rhodamine 6G as the concentration decreases. For rhodamine B in methanol and methylene blue in Demineralised water the threshold power varies in a non linear way. The wavelength of the scattered wave is different for different materials and with the dyes also the wavelength is changing. In pure acetone the wavelength of the scattered wave is 531.36 nm; with methylene blue, rhodamine b and rhodamine 6G the wavelengths are 531.1 nm, 530.84 nm and 531.1 nm respectively. For pure methnol the wavelength of the scattered wave is 531.1 nm. With methylene blue the wavelength is changing randomly with the following values 531.1 nm, 530.84 nm, and 530.58 nm. For rhodamine 6G and rhodamine B in methanol the wavelength is 531.1 nm and 530.84 nm respectively. For methyl acetate and Demineralised water the wavelength remains constant for all the dyes at all the concentration and the value is 530.84 nm.
Among the tested materials methyl acetate shows the good result with reduction in amplitude as the concentration increases and increase in amplitude with power. It also has a constant wavelength with all the dyes and at all the concentrations. It has got a stble output during the experiment also. Acetone is also a good material for obtaining stimulated Brillouin scattering. Stimulated Brillouin scattering is very hard to obtain from methanol. There is no stimulated Brillouin scattering is observed from xylene. Because xylene is not optically polarisable. We can observe stimulated Brilllouin scattering only from optically polarisable materials.
We can extend this study to get phase conjugation. After finding a good medium to obtain stimulated Brillouin scattering we can perform phase conjugation and we can also study the properties of phase conjugation and the effect of the phase conjugation on the laser beam. Here we can use methyl acetate as a medium since it has got good stimulate Brillouin scattering properties. Optical phase conjugation has got variety of application in now days. Optical phase conjugation can be created by forward mixing and stimulated scattering. If the phase conjugation is created by the stimulated scattering the properties of phase conjugation can be controlled by the medium properties since it is active process and it has got an energy transfer between medium and the photon. We can also extend this work to study the photon – phonon interaction in solids. In a solid the photon – phonon interaction is affected by the symmetry of the solid system. By studying the properties of the photon – phonon interactions in a solid system we can make a clear idea about the symmetry of the solid system. It will be very help full to analyse the chemical changes.
International school of photonics Page 93