Showing papers on "Brillouin scattering published in 1970"
TL;DR: The elastic constants of SbSI in the neighbourhood of the ferroelectric transition have been determined from high resolution backscattering measurements using a double-passed, fully stabilised, scanning Fabry-Perot interferometer as mentioned in this paper.
120 citations
TL;DR: In this article, a generator-amplifier system with singlemode giant laser pulses was used to measure the amplitude of stimulated thermal Brillouin scattering in a generator and amplifier system.
Abstract: Stimulated Brillouin scattering was studied both theoretically and experimentally. The evolution in time of the scattering process, its dependence on frequency, and the influence of optical absorption were analyzed. For quantitative investigations, the individual shapes of the laser and signal pulses were taken into account. Strong transient effects predicted by theory were confirmed experimentally. The amplification of Brillouin light was measured in a generator-amplifier system using single-mode giant laser pulses. Several liquids, glasses, and quartz were investigated. The experimental results allow the determination of phonon lifetimes $\ensuremath{\tau}$ and of elasto-optic constants. In our amplifier system, accurate values of $\ensuremath{\tau}$ are obtained for $\ensuremath{\tau}l3$ nsec, i.e., for liquids and some solids. The limitation of the method is discussed. In absorbing media, stimulated thermal Brillouin scattering was observed in quantitative agreement with theory.
109 citations
50 citations
45 citations
33 citations
TL;DR: In this article, the authors measured the velocity and attenuation of high frequency first sound in liquid helium under its saturated vapor pressure between 1.4 and 1.5°K.
21 citations
TL;DR: The sound velocity in xenon on the critical isochore was determined in Brillouin scattering measurements at scattering angles of 40\ifmmode^\circ\else\text degree\fi{} and 90
Abstract: The sound velocity in xenon on the critical isochore was determined in Brillouin scattering measurements at scattering angles of 40\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{}. The sound dispersion calculated from our data, ultrasonic data, and other Brillouin data agrees with the Kawasaki theory for a particular choice of parameters, but the dispersion in the Brillouin velocities is 2 to 3 times smaller than the theory predicts when values obtained for the parameters from other experiments are used.
20 citations
TL;DR: In this paper, Brillouin scattering methods of the frequency spectrum for growing acousto-electric domains in CdS support the importance of parametric subharmonic frequency conversion effects.
18 citations
TL;DR: In this paper, a Fabry-Perot etalon and digital scanning was used to measure the Brillouin scattering at 90 degrees from thermally excited first sound in superfluid 4.
Abstract: Brillouin scattering at 90 degrees from thermally excited first sound in superfluid 4He has been measured with a Fabry-Perot etalon and digital scanning. The line shifts confirm that there is no dispersion compared with low frequency orthodox measurements over the range of temperature 1.25 K to 2.15 K.
15 citations
14 citations
TL;DR: In this paper, a theory of resonanceenhanced Brillouin scattering that is analogous to that of resonance-enhanced Raman scattering was presented in terms of the scattering of polaritons by acoustic phonons via the exciton and continuum electron-hole pair excitation parts of the polariton.
Abstract: The Brillouin scattering intensity exhibits resonance enhancement as the frequency of the incident radiation approaches exciton absorption bands and the interband absorption edge. A theory of resonance‐enhanced Brillouin scattering that is analogous to that of resonance‐enhanced Raman scattering [E. Burstein, D. L. Mills, A. Pinczuk, and S. Ushioda, Phys. Rev. Lett. 22, 348 (1969)] is presented in terms of the scattering of polaritons by acoustic phonons via the exciton and continuum electron‐hole pair excitation parts of the polaritons. The theory also provides a basis for the enhancement of the electro‐optic and elasto‐optic coefficients, which is observed in II–VI compounds near the absorption edge. Two mechanisms are taken into account, that of the deformation potential coupling arising from the strain field, which gives rises to the piezo‐optic effect and, in the case of piezoelectric crystals, that of the Frolich interaction arising from the macroscopic electric field, which gives rise to the electr...
Patent•
10 Dec 1970
TL;DR: In this article, an apparatus to produce Brillouin scattering by means of two oppositely directed colinear optical beams, frequency-translated and of varying power level, in a time sequence suitable for processing doppler-shifted radar target echoes was presented.
Abstract: An apparatus to produce Brillouin scattering by means of two oppositely directed colinear optical beams, frequency-translated and of varying power level, in a time sequence suitable for processing doppler-shifted radar target echoes by means of a simplified optical heterodyne detection system.
TL;DR: In this paper, the authors derived an integral equation fitting the experimental situation and numerically solved it for first-order processes, which indicated higher phonon frequencies than previously obtained by optical Brillouin scattering on different samples and expected from Hutson and White [3] gain and McFee and Bateman [9] losses.
Abstract: Evaluation of phonon distributions from satellites of X-ray Bragg reflections is complicated by convolutions with spectral and angular distributions of the primary beam. Assuming only first-order processes an integral equation fitting the experimental situation is derived and numerically solved. First results indicate higher phonon frequencies than previously obtained by optical Brillouin scattering on different samples and expected from Hutson and White [3] gain and McFee and Bateman [9] losses.
TL;DR: In this article, a study of the hypersonic velocity and absorption in liquid benzene as a function of frequency and temperature, using Brillouin scattering of laser light, was performed.
TL;DR: The frequency shifts associated with the 180° stimulated Brillouin scattering (SBS) from N2, CH4, CO2, and SF6 at moderate pressures were determined with an error of ±00004 cm−1.
Abstract: The frequency shifts associated with the 180° stimulated Brillouin scattering (SBS) from N2, CH4, CO2, and SF6 at moderate pressures were determined with an error of ±00004 cm−1 The apparatus and the ruby-laser system designed for this experiment are described The theory of SBS is reviewed with special consideration of the frequency shift associated with the stimulated process Experimental and theoretical reasons for the differences observed between the SBS hypersonic speeds and ultrasonic speeds are discussed Available spontaneous Brillouin-scattering results are compared Especially at lower pressures, the SBS measurements may yield hypersonic speeds that are lower than those at ultrasonic frequencies
TL;DR: In this paper, the pressure dependence of the longitudinal sound velocity was measured in a single crystal of argon for a particular direction by stimulated Brillouin scattering, and the Gruneisen constant of this mode was determined to be 2.72 ± 0.12 at 77°K and at a frequency of 5.2 GHz.
TL;DR: In this article, the Brillouin scattering of laser light with optical heterodyne detection has been used to investigate the acoustic strain in a cadmium sulphide electro-acoustic oscillator.
Abstract: The technique of Brillouin scattering of laser light with optical heterodyne detection has been used to investigate the acoustic strain in a cadmium sulphide electro-acoustic oscillator. Measurements are described of both the amplitude and spatial distribution of strain under various conditions showing the high spatial and frequency resolution obtainable. A maximum strain of approximately 10−4 was observed.
TL;DR: Inelastic coherent neutron scattering and stimulated Brillouin scattering of light are discussed in this article in the framework of first-order self-consistent theory of quantum crystals, applied to solid argon over the temperature range 4°-77°K and over a range of pressures from 0 to 200 atm.
Abstract: Inelastic coherent neutron scattering and stimulated Brillouin scattering of light are discussed in the framework of first‐order self‐consistent theory of quantum crystals. The theory is applied to solid argon over the temperature range 4°–77°K and over a range of pressures from 0 to 200 atm. We show that anharmonic effects are substantial. Thermal expansion effects are identified and discussed separately. Our work is based on a (6–12) Lennard‐Jones potential with parameters fixed to the sublimation energy and lattice constant of Ar at 0°K.
TL;DR: In this paper, the terms responsible for Brillouin scattering in molecular crystals were derived in dipole approximation by a canonical transformation and certain divergent series originating in the rigid infinite lattice assumption were rendered convergent once this assumption was relaxed.
Abstract: Terms responsible for Brillouin scattering in molecular crystals are derived in dipole approximation by a canonical transformation Certain divergent series originating in the rigid infinite lattice assumption are rendered convergent once this assumption is relaxed
TL;DR: The elastic constants for KBr at the (10-20) kMc region were measured by the Brillouin scattering technique as mentioned in this paper, and the constants were found to have smaller values than in the ultrasonic region, and the anisotropy was increased.
TL;DR: In this paper, a discontinuity in the threshold power for backward stimulated Brillouin scattering in cholesteryl 2-(2 ethoxy ethoxy) ethyl carbonate around the liquid crystal to isotropic phase transition was observed.
TL;DR: In this paper, a review of the theory of Brillouin and Rayleigh scattering from an ordinary simple pure liquid is given, and a brief review is given of the special situation that obtains in the neighbourhood of the &point.
Abstract: A review is given of the scattering of light by superfluid helium. A brief discussion is given first of the theory of Brillouin and Rayleigh scattering from an ordinary simple pure liquid. It is shown how this discussion must be modified in the case of the superfluid phase of purc 4He, and experimental observations of Brillouin scattering from first sound in liquid helium are described. The discussion is extended to the case of a superfluid mixture of 3He and 4He, and a recent observation of Brillouin scattering from second sound in such a mixture is described. Recent work on Raman scattering from superfluid helium (two roton production) is then discussed, and in a final section a brief review is given of the special situation that obtains in the neighbourhood of the &point.
TL;DR: In this paper, the dispersion of the velocity of sound for C6H6 and C6D6 has been measured using Brillouin scattering techniques and it was shown that the observed dispersions can be accounted for by considering relaxation processes involving the entire vibrational specific heats.
TL;DR: In this paper, the frequency spectrum of acoustic waves amplified from the thermal background by acoustoelectric effect was studied and it was shown that some frequencies show an oscillating behaviour of intensity as a function of flux propagation along the sample.
TL;DR: In this paper, the authors measured the longitudinal sound velocity in fused quartz at 50 GHz by using the stimulated Brillouin scattering of the second harmonic of a ruby laser and found no dispersion of the sound velocity exceeding the experimental uncertainty of ± 0.3% in the temperature range between 4° and 300°K.
TL;DR: In this paper, the phase velocities of D2O16 and H2O18 were measured at 4.2 and 0.9 GHz, respectively, using spontaneous Brillouin scattering and an injected phonon technique.
Abstract: Measurements of the phase velocity and the attenuation of sound in H2O16, D2O16, and H2O18 at 4.2 and 0.9 GHz, respectively, are reported. Spontaneous Brillouin scattering techniques and an injected phonon technique were employed. The phase velocities of D2O16 and H2O18 are very similar; classical theories cannot explain the experimental results. The values of α/f2, the attenuation α divided by the frequency squared, are higher for H2O18 and D2O than for H2O16.