Population Inversion X-Ray Laser Oscillator
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An Application of the Theory of Laser to Nitrogen Laser Pumped Dye Laser
SD9900039 AN APPLICATION OF THE THEORY OF LASER TO NITROGEN LASER PUMPED DYE LASER FATIMA AHMED OSMAN A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Physics. UNIVERSITY OF KHARTOUM FACULTY OF SCIENCE DEPARTMENT OF PHYSICS MARCH 1998 \ 3 0-44 In this thesis we gave a general discussion on lasers, reviewing some of are properties, types and applications. We also conducted an experiment where we obtained a dye laser pumped by nitrogen laser with a wave length of 337.1 nm and a power of 5 Mw. It was noticed that the produced radiation possesses ^ characteristic^ different from those of other types of laser. This' characteristics determine^ the tunability i.e. the possibility of choosing the appropriately required wave-length of radiation for various applications. DEDICATION TO MY BELOVED PARENTS AND MY SISTER NADI A ACKNOWLEDGEMENTS I would like to express my deep gratitude to my supervisor Dr. AH El Tahir Sharaf El-Din, for his continuous support and guidance. I am also grateful to Dr. Maui Hammed Shaded, for encouragement, and advice in using the computer. Thanks also go to Ustaz Akram Yousif Ibrahim for helping me while conducting the experimental part of the thesis, and to Ustaz Abaker Ali Abdalla, for advising me in several respects. I also thank my teachers in the Physics Department, of the Faculty of Science, University of Khartoum and my colleagues and co- workers at laser laboratory whose support and encouragement me created the right atmosphere of research for me. Finally I would like to thank my brother Salah Ahmed Osman, Mr. -
Ultrafast Fiber Lasers Enabled by Highly Nonlinear Pulse Evolutions
ULTRAFAST FIBER LASERS ENABLED BY HIGHLY NONLINEAR PULSE EVOLUTIONS A Dissertation Presented to the Faculty of the Graduate School of Cornell University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by Walter Pupin Fu August 2019 c 2019 Walter Pupin Fu ALL RIGHTS RESERVED ULTRAFAST FIBER LASERS ENABLED BY HIGHLY NONLINEAR PULSE EVOLUTIONS Walter Pupin Fu, Ph.D. Cornell University 2019 Ultrafast lasers have had tremendous impact on both science and applications, far beyond what their inventors could have imagined. Commercially-available solid-state lasers can readily generate coherent pulses lasting only a few tens of femtoseconds. The availability of such short pulses, and the huge peak in- tensities they enable, has allowed scientists and engineers to probe and manip- ulate materials to an unprecedented degree. Nevertheless, the scope of these advances has been curtailed by the complexity, size, and unreliability of such devices. For all the progress that laser science has made, most ultrafast lasers remain bulky, solid-state systems prone to misalignments during heavy use. The advent of fiber lasers with capabilities approaching that of traditional, solid-state lasers offers one means of solving these problems. Fiber systems can be fully integrated to be alignment-free, while their waveguide structure en- sures nearly perfect beam quality. However, these advantages come at a cost: the tight confinement and long interaction lengths make both linear and non- linear effects significant in shaping pulses. Much research over the past few decades has been devoted to harnessing and managing these effects in the pur- suit of fiber lasers with higher powers, stronger intensities, and shorter pulse durations. -
Rate Equations
Ultrafast Optical Physics II (SoSe 2019) Lecture 4, May 3, 2019 (1) Laser rate equations (2) Laser CW operation: stability and relaxation oscillation (3) Q-switching: active and passive 1 Possible laser cavity configurations The laser (oscillator) concept explained using a circuit model. 2 Self-consistent in steady state V.A. Lopota and H. Weber, fundamentals of the semiclassical laser theory 3 Laser rate equations Interaction cross section: [Unit: cm2] !") ") Spontaneous = −*") = − !$ τ21 emission § Interaction cross section is the probability that an interaction will occur between EM !" field and the atomic system. # = −'" ( !$ # § Interaction cross section only depends Absorption on the dipole matrix element and the linewidth of the transition !" ) Stimulated = −'")( !$ emission 4 How to achieve population inversion? relaxation relaxation rate relaxation Induced transitions Pumping rate relaxation Pumping by rate absorption relaxation relaxation rate Four-level gain medium 5 Laser rate equations for three-level laser medium If the relaxation rate is much faster than and the number of possible stimulated emission events that can occur , we can set N1 = 0 and obtain only a rate equation for the upper laser level: This equation is identical to the equation for the inversion of the two-level system: upper level lifetime equilibrium upper due to radiative and level population w/o non-radiative photons present processes 6 More on laser rate equations Laser gain material V:= Aeff L Mode volume fL: laser frequency I: Intensity vg: group velocity -
A Laser (From the Acronym Light Amplification by Stimulated Emission of Radiation) Is an Optical Source That Emits Photons in a Coherent Beam
LASER A laser (from the acronym Light Amplification by Stimulated Emission of Radiation) is an optical source that emits photons in a coherent beam. The verb to lase means "to produce coherent light" or possibly "to cut or otherwise treat with coherent light", and is a back- formation of the term laser. Laser light is typically near-monochromatic, i.e. consisting of a single wavelength or color, and emitted in a narrow beam. This is in contrast to common light sources, such as the incandescent light bulb, which emit incoherent photons in almost all directions, usually over a wide spectrum of wavelengths. Laser action is explained by the theories of quantum mechanics and thermodynamics. Many materials have been found to have the required characteristics to form the laser gain medium needed to power a laser, and these have led to the invention of many types of lasers with different characteristics suitable for different applications. The laser was proposed as a variation of the maser principle in the late 1950's, and the first laser was demonstrated in 1960. Since that time, laser manufacturing has become a multi- billion dollar industry, and the laser has found applications in fields including science, industry, medicine, and consumer electronics. Contents [hide] 1 Physics 2 History 2.1 Recent innovations 3 Uses 3.1 Popular misconceptions 3.2 "LASER" 3.3 Scientific misconceptions 4 Laser safety 5 Categories 5.1 By type 5.2 By output power 6 See also 7 Further reading 7.1 Books 7.2 Periodicals 8 References 9 External links [edit] Physics See also: Laser science Principal components: 1. -
The Science and Applications of Ultrafast, Ultraintense Lasers
THE SCIENCE AND APPLICATIONS OF ULTRAFAST, ULTRAINTENSE LASERS: Opportunities in science and technology using the brightest light known to man A report on the SAUUL workshop held, June 17-19, 2002 THE SCIENCE AND APPLICATIONS OF ULTRAFAST, ULTRAINTENSE LASERS (SAUUL) A report on the SAUUL workshop, held in Washington DC, June 17-19, 2002 Workshop steering committee: Philip Bucksbaum (University of Michigan) Todd Ditmire (University of Texas) Louis DiMauro (Brookhaven National Laboratory) Joseph Eberly (University of Rochester) Richard Freeman (University of California, Davis) Michael Key (Lawrence Livermore National Laboratory) Wim Leemans (Lawrence Berkeley National Laboratory) David Meyerhofer (LLE, University of Rochester) Gerard Mourou (CUOS, University of Michigan) Martin Richardson (CREOL, University of Central Florida) 2 Table of Contents Table of Contents . 3 Executive Summary . 5 1. Introduction . 7 1.1 Overview . 7 1.2 Summary . 8 1.3 Scientific Impact Areas . 9 1.4 The Technology of UULs and its impact. .13 1.5 Grand Challenges. .15 2. Scientific Opportunities Presented by Research with Ultrafast, Ultraintense Lasers . .17 2.1 Basic High-Field Science . .18 2.2 Ultrafast X-ray Generation and Applications . .23 2.3 High Energy Density Science and Lab Astrophysics . .29 2.4 Fusion Energy and Fast Ignition. .34 2.5 Advanced Particle Acceleration and Ultrafast Nuclear Science . .40 3. Advanced UUL Technology . .47 3.1 Overview . .47 3.2 Important Research Areas in UUL Development. .48 3.3 New Architectures for Short Pulse Laser Amplification . .51 4. Present State of UUL Research Worldwide . .53 5. Conclusions and Findings . .61 Appendix A: A Plan for Organizing the UUL Community in the United States . -
Terahertz Sources
Terahertz sources Pavel Shumyatsky Robert R. Alfano Downloaded from SPIE Digital Library on 22 Mar 2011 to 128.59.62.83. Terms of Use: http://spiedl.org/terms Journal of Biomedical Optics 16(3), 033001 (March 2011) Terahertz sources Pavel Shumyatsky and Robert R. Alfano City College of New York, Institute for Ultrafast Spectroscopy and Lasers, Physics Department, MR419, 160 Convent Avenue, New York, New York 10031 Abstract. We present an overview and history of terahertz (THz) sources for readers of the biomedical and optical community for applications in physics, biology, chemistry, medicine, imaging, and spectroscopy. THz low-frequency vibrational modes are involved in many biological, chemical, and solid state physical processes. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3554742] Keywords: terahertz sources; time domain terahertz spectroscopy; pumps; probes. Paper 10449VRR received Aug. 10, 2010; revised manuscript received Jan. 19, 2011; accepted for publication Jan. 25, 2011; published online Mar. 22, 2011. 1 Introduction Yajima et al.4 first reported on tunable far-infrared radiation by One of the most exciting areas today to explore scientific and optical difference-frequency mixing in nonlinear crystals. These engineering phenomena lies in the terahertz (THz) spectral re- works have laid the foundation and were used for a decade and gion. THz radiation are electromagnetic waves situated between initiated the difference-frequency generation (DFG), parametric the infrared and microwave regions of the spectrum. The THz amplification, and optical rectification methods. frequency range is defined as the region from 0.1 to 30 THz. The The THz region became more attractive for investigation active investigations of the terahertz spectral region did not start owing to the appearance of new methods for generating T-rays until two decades ago with the advent of ultrafast femtosecond based on picosecond and femtosecond laser pulses. -
A Fundamental Approach to Phase Noise Reduction in Hybrid Si/III-V Lasers
A fundamental approach to phase noise reduction in hybrid Si/III-V lasers Thesis by Scott Tiedeman Steger In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 2014 (Defended May 14, 2014) ii © 2014 Scott Tiedeman Steger All Rights Reserved iii Contents Acknowledgements ix Abstract xi 1 Introduction1 1.1 Narrow-linewidth laser sources in coherent communication......1 1.2 Low phase noise Si/III-V lasers.....................4 2 Phase noise in laser fields7 2.1 Optical cavities..............................8 2.1.1 Loss................................8 2.1.2 Gain................................9 2.1.3 Quality factor........................... 10 2.1.4 Threshold condition....................... 11 2.2 Interaction of carriers with cavity modes................ 11 2.2.1 Spontaneous transitions into the lasing mode.......... 12 2.2.2 Spontaneous transitions into all modes............. 17 2.2.3 The spontaneous emission coupling factor........... 19 2.2.4 Stimulated transitions...................... 19 2.3 A phenomenological calculation of spontaneous emission into a lasing mode above threshold........................... 21 2.3.1 Number of carriers........................ 21 2.3.2 Total spontaneous emission rate................. 21 2.4 Phasor description of phase noise in a laser............... 23 iv 2.4.1 Spontaneous photon generation................. 25 2.4.2 Photon storage.......................... 27 2.4.3 Spectral linewidth of the optical field.............. 29 2.4.4 Phase noise power spectral density............... 30 2.4.5 Linewidth enhancement factor.................. 32 2.4.6 Total linewidth.......................... 34 3 Phase noise in hybrid Si/III-V lasers 35 3.1 The advantages of hybrid Si/III-V................... -
Arxiv:1410.6667V2 [Physics.Optics]
Self-starting stable coherent mode-locking in a two-section laser R. M. Arkhipova, M. V. Arkhipovb, I. Babushkinc,d a ITMO University, Kronverkskiy prospekt, 49, 197101 St. Petersburg, Russia, b Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504, Russia c Institute of Quantum Optics, Leibniz University Hannover, Welfengarten 1 30167, Hannover, Germany d Max Born Institute, Max Born Str. 2a, 12489 Berlin, Germany Coherent mode-locking (CML) uses self-induced transparency (SIT) soliton formation to achieve, in contrast to conventional schemes based on absorption saturation, the pulse durations below the limit allowed by the gain line width. Despite of the great promise it is difficult to realize it experimentally because a complicated setup is required. In all previous theoretical considerations CML is believed to be non-self-starting. In this article we show that if the cavity length is selected properly, a very stable (CML) regime can be realized in an elementary two-section ring-cavity geometry, and this regime is self-developing from the non-lasing state. The stability of the pulsed regime is the result of a dynamical stabilization mechanism arising due to finite-cavity-size effects. I. INTRODUCTION Development of ultrashort laser pulse sources with high repetition rates and peak power is an area of principal in- terest in optics. Such lasers have applications in a high- bit-rate optical communications, real time-monitoring of ultrafast processes in matter etc. A well-known method for generating high power ultrashort optical pulses is a passive mode-locking (PML) [1–6]. In order to achieve PML, a nonlinear saturable absorbing medium is placed into the laser cavity. -
Chapter 6. Laser: Theory and Applications
Chapter 6. Laser: Theory and Applications Reading: Sigman, Chapter 6, 7, and 26 Bransden & Joachain, Chapter 15 Laser Basics Light Amplification by Stimulated Emission of Radiation hν = E − E E1 1 0 Stimulated emission hν E0 Population inversion (N1 > N0) ⇒ laser, maser 2 2 4π ⎛ e ⎞ I(ω ) 2 Transition rate W = ⎜ ⎟ 01 M (ω ) ∝ I(ω ) for stimulated emission 01 2 ⎜ ⎟ 2 01 01 01 m c ⎝ 4πε0 ⎠ ω01 Incident light intensity Pumping (optical, electrical, etc.) for population inversion Gain medium High reflector Out coupler Optical cavity Longitudinal Modes in an Optical Cavity EM wave in a cavity Boundary condition: λ cτ πc L = m = m = m m = 1, 2, 3, … 2 2 ω 2L c π c ⇒ λ = ,ν = m, ω = m m 2L L 2L Round-trip time of flight: T = = mτ c Typical laser cavity: L = 1.5 m, λ = 0.75 µm 2L 3 m : T = = =10−8 sec =10 nsec : c 3×108 m / sec 1 ⇒ ν = =108 Hz =100 MHz R T 2L 3 m L m = = = 4×106 = 4 milion !! λ 0.75×10−6 m Single mode 2 2 I(t) = cosω0t = cost Spectrum Intensity 1 Frequency Intensity -100 -50 0 50 100 Time Cavity Quality Factors, Qc End mirror L Out coupler R ≈ 1 T = 1 ~ 5 % Energy loss by reflection, transmission, etc. ∞ −δct /T −iω0t E(ω) = E0e e dt ∫0 E e−δct /T e−iω0t 0 E = 0 i(ω −ω0 ) +δc /T t E(ω) 2 Lorentzian Emission spectrum 2 2 E δ c ω E(ω) = 0 ~ = 2 2 2 T Q (ω −ω ) +δ /T c 0 c ω ω0 Energy of circulating EM wave, Icirc(t) ⎡ t ⎤ 2L T = Icirc (t) = Icirc (0)×exp⎢−δ c ⎥, : round-trip time of flight ⎣ T ⎦ c Number of round trips in t ⎡ ω ⎤ ⇒ Icirc (t) = Icirc (0)×exp⎢− t⎥ ⎣ Qc ⎦ Q-factor of a RLC circuit ωT 4π L 1 ω ωL Q = = Q = = where -
Chirped-Pulse Amplification Ultrahigh Peak Power Production from Compact Short-Pulse Laser Systems
TUTORIAL Chirped-Pulse Amplification Ultrahigh peak power production from compact short-pulse laser systems Introduction of chirped-pulse ampli- It turns out that the hint to a solution THE AUTHOR fication (CPA) enabled the latest revolu- of this problem can be found as early as tion in production of high peak powers the time of the demonstration of the first from lasers through amplification of very laser, but the idea has been initially pro- IGOR JOVANOVIC posed to overcome a different issue – the short (femtosecond) laser pulses to pulse Igor Jovanovic is an power limitations of radars [1]. In 1985 it energies previously available only from Associate Professor of was realized by the group at the University long-pulse lasers. CPA has rapidly bridged Nuclear Engineering at of Rochester led by Gérard Mourou that the gap from its initial modest demon- Penn State University. this technique, termed chirped-pulse am- strations to multi-terawatt and petawatt- He received his undergraduate degree plification (CPA) [2], can also be applied in scale systems in research facilities and from the University of Zagreb in 1997 the optical domain, with revolutionary con- universities, as well as numerous lower- and his Ph.D. from the University of sequences for laser science and technology California, Berkeley in 2001. He is one of power scientific and industrial applica- and its applications. The idea of CPA is in- the pioneers of the technique of optical tions. deed simple and beautiful: given the limita- parametric chirped-pulse amplification. tions encountered by ultrashort laser pulses After receiving his Ph.D. -
EXPERIMENT on SUPPRESSION of SPONTANEOUS UNDULATOR RADIATION at ATF* Vladimir N
MOPC82 Proceedings of FEL2009, Liverpool, UK EXPERIMENT ON SUPPRESSION OF SPONTANEOUS UNDULATOR * RADIATION AT ATF Vladimir N. Litvinenko† and Vitaly Yakimenko, Brookhaven National Laboratory, Upton, USA Center for Accelerator Science and Education, Stony Brook University, and BNL Abstract We propose undertaking a demonstration experiment on SHOT-NOISE SUPPRESSOR suppressing spontaneous undulator radiation from an Fig. 1 is a schematic of the proof-of-principle for a electron beam at BNL’s Accelerator Test Facility (ATF). laser-based suppressor of shot-noise and spontaneous We describe the method, the proposed layout, and a radiation for a relativistic electron beam. The shot-noise possible schedule. (spontaneous radiation) suppressor system comprises of two short wigglers tuned at the wavelength of a INTRODUCTION broadband laser-amplifier, a transport system for the There are several advantages in strongly suppressing electron beam around the laser, and the buncher. shot noise in the electron beam, and the corresponding The suppressor works as follows: The electron beam spontaneous radiation. passes through the first wiggler where it spontaneously The self-amplified spontaneous (SASE) emission emits radiation proportional to the local values of shot originating from shot noise in the electron beam is the noise. Then, this radiation traverses a high-gain, main source of noise in high-gain FEL amplifiers. It may broadband laser amplifier. In the second wiggler, an negatively affect several HG FEL applications ranging electron interacts with the amplified radiation induced by from single- to multi-stage HGHG FELs [1]. SASE the neighboring electrons, and accordingly, its energy is saturation also imposes a fundamental hard limit on the changed. -
Basic Laser Physics
n Laser Science and Safety tio d a e on ic at on ti t lif l si a h p u is di ig m tim m a L A by S E of R Visible or Intense The physical principle of a laser Invisible Lee Collins, Westmead Hospital, Sydney The word “LASER” is an acronym, divided into three parts, NZ GP CME meeting, Rotorua, June 2010 describing : the nature of the beam, its extreme brightness, and the reason why a laser works. June 2010 With thanks to Penny Smalley for the use of some material 1 2 Understanding of the operation of a laser and tissue effects is CRUCIAL to safe and effective laser use. Basic Laser Physics 3 4 Theodore Maiman Invents the First Laser - 1960 • Ruby Crystal – 694nm Albert Einstein proposed • First Used in Ophthalmology and the theory behind lasers in Dermatology 1916, but it wasn’t made reality until 1960! 5 6 Laser safety course - Lee Collins July 2009 1 Ruby Laser in Use, 1971 (IEEE Virtual Museum) Spontaneous Emission An external energy source raises the atoms to a higher energy state. When the atom drops to the ground state, energy is emitted as a PHOTON 7 8 Stimulated Emission Of Radiation Spontaneous Emission Photons of all wavelengths, emit randomly from all energy levels of atoms, A photon bombards a single energy level in an excited atom, resulting in white light. resulting in release of two identical photons, having identical 9 properties. 10 What is Wavelength? Electromagnetic Spectrum • The wavelength (λ) of light is measured in nanometres or Medical lasers operate between far infrared microns (10,600nm) and far ultraviolet (193nm).