DOCSLIB.ORG

Group 3 Physical Acoustics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Group 3 Physical Acoustics Group 3 Physical Acoustics PGP – General Physical Acoustics • phoxonics (simultaneous photonic and phononic Phenomena and theory of physical acoustics. crystals and structures) • Novel experimental methods and theory • Brillouin light scattering • New computational methods and visualizations • Interaction of photons and phonons • Picosecond acoustics and laser ultrasound PAT – Acoustic Tweezers and Particle Manipulation • Generation of sound by light (electrostriction, photo- Understanding and exploiting acoustic radiation force on acoustics) objects. • Optical interferometry for ultrasound metrology • Forces on particles, fluids and suspensions • Interactions of ultrasound with electromagnetic waves • Analytical and numerical force calculations • Experimental field and force measurements PMI – Modelling and Inversion • Acoustic streaming Numerical methods to simulate propagation of acoustic and • Devices exploiting the acoustic radiation force, elastic waves in heterogeneous media and structures, or to including: resonant devices, surface acoustic wave perform imaging and inversion on measured wave fields. devices, and acoustic beam and array tweezers • Model tailoring • Particle manipulation (sorting, trapping, patterning, • Coupled acoustic effects filtering, manufacturing and tissue engineering) • Parameter extraction • Acoustic levitation and manipulation in air • Compact modelling • Acousto-fluidics / acoustic microfluidics for lab-on-a- • Model validation chip applications • Imaging • Inverse problems PNL – Nonlinear Acoustics Nonlinear effects related to acoustic waves (bulk or guided) PPN – Phononics in the ultrasonics frequency regime, as well as applications Harnessing elastic and acoustic waves by engineering the of such effects or countermeasures to reduce them. structure of propagation media. • Nonlinear generation effects like harmonic or sub- • Phononic crystals, sonic crystals, and generally wave harmonic generation, intermodulations, etc. propagation in periodic media and structures • Nonlinear effects in oscillators / resonators, non- • Acoustic metamaterials, elastic metasolids, and destructive evaluation, acousto-fluidics, biological metasurfaces tissue, etc. • Micro- and nanoresonators • Acoustic imaging of nonlinear effects (e.g. nonlinear • Bulk, surface, and guided waves in the above media or bubble dynamics) structures • Nonlinear reflection / transmission, contact • Topological phononic insulators, non-reciprocal nonlinearities devices, acoustic diodes • Nonlinear material properties with relation to • Applications of phononics to waveguides, filters, ultrasound, and their physical origin (classical or non- resonators, imaging, acoustic or vibration insulation, classical nonlinearities) energy harvesting, and other functions • Nonlinear coupling of ultrasound to other degrees of • Theory and numerical methods for phononics freedom • Nonlinear waves (shock waves, solitons, etc.) PTF – Thin Films • Experimental techniques and theoretical methods for • Deposition techniques for piezoelectric, dielectric, and investigating and modelling nonlinear effects metallic films • Measurement of extrinsic (thickness, roughness, strain) PTE – High Power and Temperature effects and intrinsic properties (material parameters) Acoustic effects in materials and devices at high excitation • Novel materials in thin film form levels and/or at different temperatures or temperature • Fabricating acoustic devices in thin film form profiles, and the interaction of thermal and acoustic effects. • Analysis of heat dissipation PUM – Ultrasonic Motors & Actuators • Thermo-elastic interaction • Novel ultrasonic motors and actuation mechanisms • Effects of high excitation levels • Performance test and measurement • Design for high power operation • Analysis of mechanism • Thermal modelling and measurements • Modelling for simulation • Temperature dependence of material parameters • Characterization • Applications POA – Opto-Acoustics • Design methodology Physical studies regarding the interaction of sound with electromagnetic waves (e.g. light). PNR – Non-Reciprocal Acoustics • Acousto-optics (diffraction of light by sound) • … • Optomechanics .
Load more

Recommended publications
  • Using the Partial Wave Method for Wave Structure Calculation and the Conceptual Interpretation of Elastodynamic Guided Waves
    applied sciences Article Using the Partial Wave Method for Wave Structure Calculation and the Conceptual Interpretation of Elastodynamic Guided Waves Christopher Hakoda and Cliff J. Lissenden * Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, USA; [email protected] * Correspondence: [email protected] Received: 8 May 2018; Accepted: 8 June 2018; Published: 12 June 2018 Featured Application: Shortcut to wave-structure calculation for elastodynamic guided waves and prediction of acoustic leakage behavior. Abstract: The partial-wave method takes advantage of the Christoffel equation’s generality to represent waves within a waveguide. More specifically, the partial-wave method is well known for its usefulness when calculating dispersion curves for multilayered and/or anisotropic plates. That is, it is a vital component of the transfer-matrix method and the global-matrix method, which are used for dispersion curve calculation. The literature suggests that the method is also exceptionally useful for conceptual interpretation, but gives very few examples or instruction on how this can be done. In this paper, we expand on this topic of conceptual interpretation by addressing Rayleigh waves, Stoneley waves, shear horizontal waves, and Lamb waves. We demonstrate that all of these guided waves can be described using the partial-wave method, which establishes a common foundation on which many elastodynamic guided waves can be compared, translated, and interpreted. For Lamb waves specifically, we identify the characteristics of guided wave modes that have not been formally discussed in the literature. Additionally, we use what is demonstrated in the body of the paper to investigate the leaky characteristics of Lamb waves, which eventually leads to finding a correlation between oblique bulk wave propagation in the waveguide and the transmission amplitude ratios found in the literature.
    [Show full text]
  • The Physics of Sound 1
    The Physics of Sound 1 The Physics of Sound Sound lies at the very center of speech communication. A sound wave is both the end product of the speech production mechanism and the primary source of raw material used by the listener to recover the speaker's message. Because of the central role played by sound in speech communication, it is important to have a good understanding of how sound is produced, modified, and measured. The purpose of this chapter will be to review some basic principles underlying the physics of sound, with a particular focus on two ideas that play an especially important role in both speech and hearing: the concept of the spectrum and acoustic filtering. The speech production mechanism is a kind of assembly line that operates by generating some relatively simple sounds consisting of various combinations of buzzes, hisses, and pops, and then filtering those sounds by making a number of fine adjustments to the tongue, lips, jaw, soft palate, and other articulators. We will also see that a crucial step at the receiving end occurs when the ear breaks this complex sound into its individual frequency components in much the same way that a prism breaks white light into components of different optical frequencies. Before getting into these ideas it is first necessary to cover the basic principles of vibration and sound propagation. Sound and Vibration A sound wave is an air pressure disturbance that results from vibration. The vibration can come from a tuning fork, a guitar string, the column of air in an organ pipe, the head (or rim) of a snare drum, steam escaping from a radiator, the reed on a clarinet, the diaphragm of a loudspeaker, the vocal cords, or virtually anything that vibrates in a frequency range that is audible to a listener (roughly 20 to 20,000 cycles per second for humans).
    [Show full text]
  • Directivity Patterns of Laser-Generated Sound in Solids: Effects of Optical and Thermal Parameters
    Directivity patterns of laser-generated sound in solids: Effects of optical and thermal parameters Victor V. Krylov Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK Abstract In the present paper, directivity patterns of laser-generated sound in solids are investigated theoretically. Two main approaches to the calculation of directivity patterns of laser- generated sound are discussed for the most important case of thermo-optical regime of generation. The first approach, which is widely used in practice, is based on the simple modelling of the equivalent thermo-optical source as a mechanical dipole comprising two horizontal forces applied to the surface in opposite directions. The second approach is based on the rigorous theory that takes into account all acoustical, optical and thermal parameters of a solid material and all geometrical and physical parameters of a laser beam. Directivity patterns of laser-generated bulk longitudinal and shear elastic waves, as well as the amplitudes of generated Rayleigh surface waves, are calculated for different values of physical and geometrical parameters and compared with the directivity patterns calculated in case of dipole-source representation. It is demonstrated that the simple approach using a dipole-source representation of laser-generated sound is rather limited, especially for description of generated longitudinal acoustic waves. A practical criterion is established to define the conditions under which the dipole-source representation gives predictions with acceptable errors. It is shown that, for radiation in the normal direction to the surface, the amplitudes of longitudinal waves are especially sensitive to the values of thermal parameters and of the acoustic reflection coefficient from a free solid surface.
    [Show full text]
  • St. Dom's Is Proud to Recognize Our Alumni Who Are Achieving
    Ronald Roy, Ph.D. ‘75 A Journey through Science St. Dom’s is proud to recognize our alumni who are achieving greatness in their personal and professional lives. Our graduates have done many noteworthy things. Among them is Prof. Ronald Roy, a member of the class of 1975. Having recently been named the next Head of the Department of Engineering Science at Oxford University only scratches the surface of his list of accomplishments in the realm of science. Fortifying this honor is the fact that Oxford engineering is ranked #1 in the world, and Ron is the first ever American to be selected to fill this post. In pursuit of a career in science, Ron attended the University of Maine and earned a B.S. in engineering physics in 1981. Having not quenched his thirst for knowledge, Ron went on to earn a Master of Science degree in Physics at the University of Mississippi (1983), a Master of Philosophy degree (1985) and a Ph.D. (1987) at the Yale University School of Engineering and Applied Science. He was also conferred an M.A. degree at the University of Oxford by special resolution in 2006. After a lengthy career as a student of engineering, it seems natural that Ron then began imparting his vast knowledge to young engineers. He served as Professor and Chairman of the Department of Mechanical Engineering at Boston University and as a Senior Physicist at the Applied Physics Laboratory and an Associate Research Professor of Bioengineering, both at the University of Washington. In addition, Ron held a stint on the research staff at the National Center for Physical Acoustics at the University of Mississippi.
    [Show full text]
  • Chapter 12: Physics of Ultrasound
    Chapter 12: Physics of Ultrasound Slide set of 54 slides based on the Chapter authored by J.C. Lacefield of the IAEA publication (ISBN 978-92-0-131010-1): Diagnostic Radiology Physics: A Handbook for Teachers and Students Objective: To familiarize students with Physics or Ultrasound, commonly used in diagnostic imaging modality. Slide set prepared by E.Okuno (S. Paulo, Brazil, Institute of Physics of S. Paulo University) IAEA International Atomic Energy Agency Chapter 12. TABLE OF CONTENTS 12.1. Introduction 12.2. Ultrasonic Plane Waves 12.3. Ultrasonic Properties of Biological Tissue 12.4. Ultrasonic Transduction 12.5. Doppler Physics 12.6. Biological Effects of Ultrasound IAEA Diagnostic Radiology Physics: a Handbook for Teachers and Students – chapter 12,2 12.1. INTRODUCTION • Ultrasound is the most commonly used diagnostic imaging modality, accounting for approximately 25% of all imaging examinations performed worldwide nowadays • Ultrasound is an acoustic wave with frequencies greater than the maximum frequency audible to humans, which is 20 kHz IAEA Diagnostic Radiology Physics: a Handbook for Teachers and Students – chapter 12,3 12.1. INTRODUCTION • Diagnostic imaging is generally performed using ultrasound in the frequency range from 2 to 15 MHz • The choice of frequency is dictated by a trade-off between spatial resolution and penetration depth, since higher frequency waves can be focused more tightly but are attenuated more rapidly by tissue The information in an ultrasonic image is influenced by the physical processes underlying propagation, reflection and attenuation of ultrasound waves in tissue IAEA Diagnostic Radiology Physics: a Handbook for Teachers and Students – chapter 12,4 12.1.
    [Show full text]
  • James Clerk Maxwell and the Physics of Sound
    James Clerk Maxwell and the Physics of Sound Philip L. Marston The 19th century innovator of electromagnetic theory and gas kinetic theory was more involved in acoustics than is often assumed. Postal: Physics and Astronomy Department Washington State University Introduction Pullman, Washington 99164-2814 The International Year of Light in 2015 served in part to commemorate James USA Clerk Maxwell’s mathematical formulation of the electromagnetic wave theory Email: of light published in 1865 (Marston, 2016). Maxwell, however, is also remem- [email protected] bered for a wide range of other contributions to physics and engineering includ- ing, though not limited to, areas such as the kinetic theory of gases, the theory of color perception, thermodynamic relations, Maxwell’s “demon” (associated with the mathematical theory of information), photoelasticity, elastic stress functions and reciprocity theorems, and electrical standards and measurement methods (Flood et al., 2014). Consequently, any involvement of Maxwell in acoustics may appear to be unworthy of consideration. This survey is offered to help overturn that perspective. For the present author, the idea of examining Maxwell’s involvement in acous- tics arose when reading a review concerned with the propagation of sound waves in gases at low pressures (Greenspan, 1965). Writing at a time when he served as an Acoustical Society of America (ASA) officer, Greenspan was well aware of the importance of the fully developed kinetic theory of gases for understanding sound propagation in low-pressure gases; the average time between the collision of gas molecules introduces a timescale relevant to high-frequency propagation. However, Greenspan went out of his way to mention an addendum at the end of an obscure paper communicated by Maxwell (Preston, 1877).
    [Show full text]
  • Hot Topics in Physical Acoustics THEUNIVERSITY of MISSISSIPPI
    Hot Topics in Physical Acoustics THE UNIVERSITY OFMISSISSIPPI UNIVERSITY THE J.R. (Josh) Gladden Dept. of Physics and Astronomy University of Mississippi ASA Fall Meeting The University of Mississippi November 12, 2008 Institute for Advanced Education in Geospatial Science J.R. Gladden Outline . Sound waves in the early universe OFMISSISSIPPI UNIVERSITY THE . Nature of sound in a hot plasma . Acoustic imprint in the microwave background . Connections to dark energy and matter . Acoustics and slip-stick friction . A table top model fault zone . The role of transient elastic waves . Connections to earthquake triggering . Acoustic Metamaterials . Generalized wave phenomenon . Coherent scattering effects: negative index of refraction, band gaps . Applications: acoustic lenses, filters, cloaking The University of Mississippi Institute for Advanced Education in Geospatial Science J.R. Gladden Sound waves in the early universe THE UNIVERSITY OFMISSISSIPPI UNIVERSITY THE . After Inflation phase (0 – 380k yrs) . Baryonic (n,p) matter was fully ionized . Acoustic waves driven by radiation pressure . Momentum transfer between photons and free electrons . Source: small, early (quantum?) fluctuations in photon density ⇉ radiation pressure gradients ⇉ propagating sound waves. Courtesy of NASA/WMAP Science Team The University of Mississippi Reference: Eisenstein and Bennett, Physics InstituteToday for Advanced, p. 44-50,April 2008 Education in Geospatial Science J.R. Gladden Radiation Pressure THE UNIVERSITY OFMISSISSIPPI UNIVERSITY THE . Compton scattering h p = . Analogous to molecular collisions, BUT inertia is much lower . Speed of sound restoring potential 1 v= = c The University of inertial property Mississippi 3 Institute for Advanced Education in Geospatial Science J.R. Gladden The end of the acoustic era . At Recombination (~380k years), free electrons OFMISSISSIPPI UNIVERSITY THE dropped by 104 .
    [Show full text]
  • Mean-Acoustic Fields Exerted on a Subwavelength Axisymmetric Particle
    Mean-acoustic fields exerted on a subwavelength axisymmetric particle Everton B. Lima1 and Glauber T. Silva1, a Physical Acoustics Group, Instituto de F´ısica, Universidade Federal de Alagoas, Macei´o,AL 57072- 970, Brazil (Dated: 29 June 2021) The acoustic radiation force produced by ultrasonic waves is the \workhorse" of particle manipulation in acoustofluidics. Nonspherical particles are also subjected to a mean torque known as the acoustic radiation torque. Together they constitute the mean-acoustic fields exerted on the particle. Analytical methods alone cannot calculate these fields on arbitrar- ily shaped particles in actual fluids and no longer fit for purpose. Here, a semi-analytical approach is introduced for handling subwavelength axisymmetric particles immersed in an isotropic Newtonian fluid. The obtained mean-acoustic fields depend on the scattering co- efficients that reflect the monopole and dipole modes. These coefficients are determined by numerically solving the scattering problem. Our method is benchmarked by comparison with the exact result for a subwavelength rigid sphere in water. Besides, a more realistic case of a red blood cell immersed in blood plasma under a standing ultrasonic wave is investigated with our methodology. ©2021 Acoustical Society of America. [https://doi.org(DOI number)] [XYZ] Pages:1{11 I. INTRODUCTION acoustic fields have to be re-calculated at each time step in the interval of interest. As a consequence, particle Acoustofluidics is extensively based on the acoustic 1 dynamics analysis in acoustofluidics might be a very in- radiation force produced by ultrasonic waves to control tense computational task. We emphasize that such anal- and pattern micro/nanoparticles (cells, microorganisms, ysis is of fundamental importance for understanding and and viruses) in a liquid medium.
    [Show full text]
  • Picosecond Ultrasonic Study of Surface Acoustic Waves on Periodically 2 Patterned Layered Nanostructures
    1 Picosecond ultrasonic study of surface acoustic waves on periodically 2 patterned layered nanostructures 3 Michael Colletta,a Wanjiru Gachuhi,a Samuel A. Gartenstein,a Molly M. James,a Erik A. Szwed,a 4 Brian C. Daly,a† Weili Cui,b George A. Antonelli,c 5 a: Vassar College, 124 Raymond Ave, Poughkeepsie, NY, USA 12604 6 b: SUNY Maritime College, Throggs Neck, NY, USA 10465 7 c: Antonelli Research and Technology, 3227 SE Lambert St, Portland, OR,USA 97202 8 †: corresponding author’s email: [email protected] 9 Abstract: 10 We have used the ultrafast pump-probe technique known as picosecond ultrasonics to generate 11 and detect surface acoustic waves on a structure consisting of nanoscale Al lines on SiO2 on Si. 12 We report results from ten samples with varying pitch (1000 nm to 140 nm) and SiO2 film 13 thickness (112 nm or 60 nm), and compare our results to an isotropic elastic calculation and a 14 coarse-grained molecular dynamics simulation. In all cases we are able to detect and identify a 15 Rayleigh-like surface acoustic wave with wavelength equal to the pitch of the lines and 16 frequency in the range of 5 GHz – 24 GHz. In some samples, we are able to detect additional, 17 higher frequency surface acoustic waves or independent modes of the Al lines with frequencies 18 close to 50 GHz. We also describe the effects of probe beam polarization on the measurement’s 19 sensitivity to the different surface modes. 20 Keywords: ultrafast optics; picosecond ultrasonics; laser ultrasonics; surface acoustic waves 21 Introduction 22 The highest frequency surface acoustic waves (SAWs) have to date been generated and detected 23 by ultrafast optical pump-probe techniques.1,2,3,4 The most common method is to use lithography 24 to fabricate a nanoscale pattern of metallic lines on a substrate and excite those lines by means of 25 an ultrafast laser pulse.
    [Show full text]
  • Picosecond Ultrasonics with a Free-Running Dual-Comb Laser
    Picosecond ultrasonics with a free-running dual-comb laser JUSTINAS PUPEIKIS,1,* BENJAMIN WILLENBERG,1 FRANCOIS BRUNO,2 MIKE HETTICH,3 ALEXANDER NUSSBAUM-LAPPING,1 MATTHIAS GOLLING,1 CAROLIN P. BAUER,1 SANDRO L. CAMENZIND,1 ABDELMJID BENAYAD,4 PATRICE CAMY,4 BERTRAND AUDOIN,2 CHRISTOPHER R. PHILLIPS,1 AND URSULA KELLER1 1Department of Physics, Institute for Quantum Electronics, ETH Zurich, Switzerland 2Univ. Bordeaux, CNRS, I2M, UMR 5295, F-33400 Talence, France 3Research Center for Non-Destructive Testing GmbH, 4040 Linz, Austria 4Centre de Recherche sur Les Ions, Les Matériaux et La Photonique (CIMAP), UMR 6252 CEA-CNRS- ENSICAEN, Université de Caen Normandie, 6 Boulevard Du Maréchal Juin, 14050, Caen Cedex 4, France *[email protected] Abstract: We present a free-running 80-MHz dual-comb polarization-multiplexed solid-state laser which delivers 1.8 W of average power with 110-fs pulse duration per comb. With a high- sensitivity pump-probe setup, we apply this free-running dual-comb laser to picosecond ultrasonic measurements. The ultrasonic signatures in a semiconductor multi-quantum-well structure originating from the quantum wells and superlattice regions are revealed and discussed. We further demonstrate ultrasonic measurements on a thin-film metalized sample and compare these measurements to ones obtained with a pair of locked femtosecond lasers. Our data show that a free-running dual-comb laser is well-suited for picosecond ultrasonic measurements and thus it offers a significant reduction in complexity and cost for this widely adopted non-destructive testing technique. © 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 1.
    [Show full text]
  • Recommendation for Promotion and Tenure
    785-864-1753 [email protected] July, 2013 Xinmai Yang Assistant Professor Department of Mechanical Engineering The University of Kansas I. Education Ph. D. Mechanical Engineering, Boston University, Boston, MA, May 2003 M. E. Solid Mechanics, Xi’an Jiaotong University, Xi’an, PR China, June 2000 B. E. Engineering Mechanics, Xi’an Jiaotong University, Xi’an, PR China, June 1997 II. Employment history 8/2008-present Assistant Professor, Mechanical Engineering, University of Kansas 3/2006-8/2008 Postdoctoral Research Associate, Biomedical Engineering, Washington University in St. Louis 6/2003-2/2006 Postdoctoral Research Associate, National Center for Physical Acoustics, University of Mississippi 1/2000-5/2003 Graduate Research Assistant, Mechanical Engineering, Boston University III. Research interests Photoacoustic/ultrasound imaging Therapeutic ultrasound Combination of ultrasound and laser for diagnosis and therapy I. Research record A. Research Publications Peer-reviewed journal publications 28. Huizhong Cui, Ti Zhang, and Xinmai Yang, “Laser-enhanced cavitation during high intensity focused ultrasound: An in vivo study,” Applied Physics Letters, 102 (13), 133702-133702-4 (2013). 27. Ti Zhang, Huizhong Cui, Chia-Yi Fang, Long-Jyun Su, Shenqiang Ren, Huan-Cheng Chang, Xinmai Yang, and M. Laird Forrest, “photoacoustic contrast imaging of biological tissues with nanodiamonds fabricated for high near-infrared absorbance,” Journal of Biomedical Optics, Vol. 18, 026018 (2013). Page 1 785-864-1753 [email protected] July, 2013 26. Huizhong Cui and Xinmai Yang, “Laser enhanced high-intensity focused ultrasound thrombolysis: an in vitro study,” Journal of the Acoustical Society of America, Vol. 133(2), EL123 (2013). 25. Janggun Jo, Hongyu Zhang, Paul D. Cheney, and Xinmai Yang, “Photoacoustic detection of functional responses in the motor cortex of awake behaving monkey during forelimb movement,” Journal of Biomedical Optics, Vol.
    [Show full text]
  • Extremely Low Loss Phonon-Trapping Cryogenic Acoustic Cavities for Future Physical Experiments
    Extremely Low Loss Phonon-Trapping Cryogenic Acoustic Cavities for Future Physical Experiments Serge Galliou,1 Maxim Goryachev,2 Roger Bourquin,1 Philippe Abb´e,1 Jean Pierre Aubry,3 and Michael E. Tobar2, a) 1)Department of Time and Frequency, FEMTO-ST Institute, ENSMM, 26 Chemin de l'Epitaphe,´ 25000, Besan¸con,France 2)ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia 3)Oscilloquartz SA, Br´evards 16, 2002 Neuch^atel,Switzerland, now self-employed consultant ([email protected]) (Dated: 29 September 2018) Low loss Bulk Acoustic Wave devices are considered from the point of view of the solid state approach as phonon-confining cavities. We demonstrate effective design of such acoustic cavities with phonon-trapping techniques exhibiting extremely high quality factors for trapped longitudinally-polarized phonons of various wavelengths. Quality factors of observed modes exceed 1 billion, with a maximum Q-factor of 8 billion and Q × f product of 1:6 · 1018 at liquid helium temperatures. Such high sensitivities allow analysis of intrinsic material losses in resonant phonon systems. Various mechanisms of phonon losses are discussed and estimated. arXiv:1309.4832v1 [cond-mat.mes-hall] 19 Sep 2013 a)Electronic mail: [email protected] 1 INTRODUCTION A Fabry-P´erotinterferometer is an optical resonant system that typically consists of two parallel highly reflecting mirrors. Due to their high quality factors, a Fabry-P´erotcavity is often used to store photons for almost milliseconds while they bounce between the mirrors. Low loss is necessary in order to increase interaction between light and matter or other physical substances under study.
    [Show full text]