Showing papers on "Brillouin scattering published in 1982"
01 Jan 1982
278 citations
TL;DR: Stimulated Brillouin scattering (SBS) in low-loss single-mode silica fiber is observed at 1.32 μm using a continuous-wave single-frequency Nd:YAG laser as discussed by the authors.
Abstract: Stimulated Brillouin scattering (SBS) in low-loss single-mode silica fibre is observed at 1.32 μm using a continuous-wave single-frequency Nd:YAG laser. The threshold for SBS is 5 mW and the transmitted power reaches a saturated maximum for launch powers exceeding about 10 mW. A conversion efficiency of 65% is observed. The Stokes frequency shift is 12.7±0.2 GHz.
154 citations
TL;DR: In this article, the authors survey the developments in Brillouin scattering during the past fifteen years and describe classical effects, including stimulated and resonance effects, on the frequency interval of acoustic excitations in the hypersonic regime.
Abstract: Surveys the developments in Brillouin scattering during the past fifteen years. Mainly classical effects are described, therefore excluding stimulated and resonance Brillouin scattering. The study is limited so that the frequency interval of the acoustic excitations lies in the hypersonic regime.
145 citations
TL;DR: In this paper, a quantitative comparison of experiment to the theoretical descriptions of two mechanisms for the optical generation of tunable ultrasonic waves is presented, where crossed picosecond excitation pulses drive the acoustic response either by stimulated Brillouin scattering or absorptive heating.
86 citations
TL;DR: In this paper, the authors used Brillouin spectroscopy to provide information about the hypersonic velocity and absorption of thermal waves in a glass-forming 60% KNO3-40% Ca(NO3)2 mixture (mol %) in a temperature range of 90-380°C for gigahertzian frequencies.
Abstract: Brillouin spectroscopy has been used to provide information about the hypersonic velocity and absorption of thermal waves in a glass‐forming 60% KNO3–40% Ca(NO3)2 mixture (mol %) in a temperature range of 90–380°C for gigahertzian frequencies. A relaxation process was revealed in both the longitudinal velocity and attenuation. The data are consistent with ultrasonic results for the limiting low‐frequency velocity. The limiting high‐frequency velocity is considerably larger than that reported from ultrasonic studies and the position of the maximum of the amplitude absorption coefficient is shifted to higher temperatures. The variation of the relaxation time with temperature was found to be Arrhenius with a temperature‐independent activation energy in excellent accordance with the model proposed by Weiler, Bose, and Macedo. At low temperatures, a transverse mode due to shear waves was observed close to the Rayleigh line.
70 citations
TL;DR: In this article, a method for transmitting narrowband laser radiation over long lengths of monomode fiber at high power levels without suffering nonlinear attenuation due to stimulated Brillouin scattering is described.
Abstract: A method is described for transmitting narrowband laser radiation over long lengths of monomode fibre at high power levels without suffering nonlinear attenuation due to stimulated Brillouin scattering. The technique could be applied to long-distance coherent optical data transmission.
63 citations
TL;DR: In this paper, the authors analyzed the transient stimulated scattering produced when the laser is modulated, and concluded that the limitations due to SBS could be circumvented by using particular modulation techniques.
Abstract: Recent experiments show that stimulated Brillouin scattering (SBS) in low-loss fibres could place a severe limitation on optical power levels for coherent optical transmission. The letter analyses the transient stimulated scattering produced when the laser is modulated, and it is concluded that the limitations due to SBS could be circumvented by using particular modulation techniques.
57 citations
TL;DR: In this article, the theory of stimulated Brillouin scattering is applied to the experimental situation of crossed mode-locked laser pulses, centered at the same frequency, in isotropic and anisotropic materials.
Abstract: The theory of stimulated Brillouin scattering is applied to the experimental situation of crossed mode‐locked laser pulses, centered at the same frequency, in isotropic and anisotropic materials. It is shown that generation of pure transverse (shear) ultrasonic waves should be possible with reasonable efficiency. In general, any acoustic phonon mode that the material can support— pure shear, quasishear, quasilongitudinal, and pure longitudinal—can be populated coherently. The results permit straightforward determination of the experimental configuration that most effectively couples laser energy to the desired mode. The acoustic frequency can be tuned conveniently from about 3 MHz to 30 GHz in most materials.
49 citations
TL;DR: These glasses show promise for waveguide fibers for the 3-4-microm region if ultrahigh purity specimens can be prepared.
Abstract: The optical transparency and refractive index were measured over a wide wavelength range from the UV into the infrared for five glasses of potential use for long-wavelength optical fibers. The glasses contain 30–50 mole % GeO2 with the addition of Bi2O3, Tl2O, PbO, and Sb2O3. Indices were measured with a computerized refractometer to an accuracy of ±3 × 10−5 and were fitted within this accuracy to a three-term Sellmeier formula. This formula was then used to obtain interpolated index values, the dispersion, Abbe number, wavelength for zero material dispersion λ0, and slope of material dispersion vs wavelength (dM/dλ) at λ0. The temperature coefficients of the refractive index were also measured over a wide wavelength range, and the glasses were characterized by density, thermal expansion, glass transition, and crystallization temperatures. Raman and Brillouin spectra were also recorded on one of these glasses and the latter used to determine the elastic constants. The refractive indices ranged from nD = 1.93948 to nD = 2.28553, with Abbe numbers between 22.7 and 10.5. Values of λ0 were in the range from 2.08 to 2.81 μm combined with −dM/dλ values from 54.8 to 85.0 psec/nm ⋅ km ⋅ μm, significantly lower than that of fused silica (101 psec/nm ⋅ km ⋅ μm). These glasses show promise for waveguide fibers for the 3−4-μm region if ultrahigh purity specimens can be prepared.
48 citations
TL;DR: In this paper, a measurement of surface Brillouin scattering from a 2250-AA{} film of silica grown on (001) silicon is presented, and the spectrum shows many structures related to Rayleigh, Sezawa, and Lamb waves.
Abstract: A measurement of surface Brillouin scattering from a 2250-\AA{} film of silica grown on (001) silicon is presented. The spectrum shows many structures related to Rayleigh, Sezawa, and Lamb waves. We calculate the Brillouin cross section taking the ripple and the elasto-optic coupling mechanisms into account in the two media. Both the mechanisms are found to be important and there is evidence of strong interference effects between the ripple and the elasto-optic contributions to the scattering amplitude.
47 citations
TL;DR: Optic observation of phase conjugation by stimulated Brillouin scattering using KrF-laser radiation (248 nm) is reported.
Abstract: We report observation of phase conjugation by stimulated Brillouin scattering using KrF-laser radiation (248 nm). The backscattered signal consists of both phase-conjugate and non-phase-conjugate components, which have different temporal behavior. This phase-conjugate Brillouin mirror has been used in a double-pass KrF laser-amplifier system, and as an element in a KrF-laser resonator, to compensate for aberrations and to produce a diffraction-limited output beam.
TL;DR: In this article, a large asymmetry is found in the intensity between Stokes peaks and the equivalent anti-Stokes peaks in scattering from magnons in very thin ferromagnetic films.
Abstract: A large asymmetry is found in the intensity between Stokes peaks and the equivalent anti-Stokes peaks in scattering from magnons in very thin ferromagnetic films. It is shown that this asymmetry is due to the contribution of the off-diagonal spin-spin correlation function $〈{S}_{x}{S}_{y}〉$ to the light scattering intensity. This contribution is only seen when the wave vector of the light in the ferromagnet is complex, the case for absorptive materials. The asymmetry is studied both theoretically and experimentally, and good agreement is found.
TL;DR: The use of phase-conjugate stimulated Brillouin scattering mirrors to produce high-quality, short-pulse KrF laser beams from angular multiplexed and regenerative amplifiers is demonstrated.
Abstract: We have demonstrated the use of phase-conjugate stimulated Brillouin scattering mirrors to produce high-quality, short-pulse KrF laser beams from angular multiplexed and regenerative amplifiers. The mirror was also shown to isolate systems optically from amplifier spontaneous emission. Automatic alignment of targets using this mirror as a retroreflector was also demonstrated.
TL;DR: In this article, Brillouin scattering from spin waves has been applied to thin ferromagnetic films and the Damon Eshbach (DE) surface wave has been observed at a mode crossing in Fe films under variation of the thickness.
Abstract: The new technique of Brillouin scattering from spin waves has been applied to thin ferromagnetic films Scattering from standing spin waves and the Damon Eshbach (DE) surface wave is observed The interaction of both types of waves at a mode crossing in Fe films under variation of the thickness d is investigated The results suggest the absence of surface anisotropy and pinning For d≲20 nm scattering from standing modes becomes too weak to be observed In contrast to this, for the DE mode there is a strong increase in the scattering intensity when the films have been evaporated onto the proper substrates It is shown that this is due to both an increase in the thermal DE mode amplitudes and multiple interference effects in the lightscattering process Very strong scattering is obtained from films with d≊5 nm There is also a remarkable Stokes‐Antistokes asymmetry, which persists down to d≲3 nm It comes from the elliptical spin‐precession characteristic for such small values of d and the strong metallic
TL;DR: HAL as discussed by the authors is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not, which may come from teaching and research institutions in France or abroad, or from public or private research centers.
Abstract: HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Elastic properties of GaS under high pressure by Brillouin scattering Alain Polian, M. Besson, M. Grimsditch, H. Vogt
TL;DR: Efficient, diffraction-limited, phase conjugation of an XeF (3511-A) laser beam using stimulated Brillouin scattering is reported, and approximately 70% of the 1-GHz bandwidth-locked portion of an injection-lockedXeF laser output is phase conjugal by focusing the laser beam at 5 GW/cm (2) into hexane or isopropanol.
Abstract: We report efficient, diffraction-limited, phase conjugation of an XeF (3511-A) laser beam using stimulated Brillouin scattering. Approximately 70% of the 1-GHz bandwidth-locked portion of an injection-locked XeF laser output is phase conjugated by focusing the laser beam at 5 GW/cm2 into hexane or isopropanol.
TL;DR: Brillouin scattering from hypersonic waves in the eye lenses of many animals has been observed with a multipass Fabry Perot interferometer and high-frequency elastic moduli may be derived from the spectroscopic and density measurements.
Abstract: Brillouin scattering from hypersonic waves in the eye lenses of many animals has been observed with a multipass Fabry Perot interferometer. The measured values of speed and attenuation range widely among the different species and in different parts of any one lens. These variations correlate broadly with the observed stiffness and the densities that have been measured with a graded column. From the spectroscopic and density measurements high-frequency elastic moduli may be derived. The results are also evaluated at a macromolecular level in terms of scattering of hypersonic waves from spherical entities composed of the crystallins and their aggregates. Reasonable agreement is obtained for the hypersonic speed for lower protein concentration; the hypersonic attenuation and variation with scattering vector are consistent with the presence of large aggregates (of order 100 nm radius) in certain of the materials.
17 Dec 1982
TL;DR: In this article, a 20 mJ pulse from a Nd:YAG laser is compressed from 20 nsec to 3 nec in a fiber 7 feet long by stimulated Brillouin scattering in a tapered glass fiber.
Abstract: Laser pulse compression by the process of stimulated Brillouin scattering in a tapered glass fiber is discussed. A 20 mJ pulse from a Nd:YAG laser is compressed from 20 nsec to 3 nec in a fiber 7 feet long.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the Brillouin scattering from spinwaves in thin thin films was used to determine the magnetic parameters of thin films of Fe, Ni and Ni 0.8 Fe 0.2 (permalloy).
01 Jan 1982
TL;DR: In this article, a forward Raman gain of 2.9 dB was measured in a 1.1 km low-loss fiber using an LED at 1.118 μm as a signal source and a CW Nd: YAG laser as a pump.
Abstract: A forward Raman gain of 2.9 dB has been measured in a 1.1 km low-loss fibre using an LED at 1.118 μm as a signal source and a CW Nd: YAG laser as a pump. Backward Brillouin scattering, which depletes the pump power towards the end of the fibre, is found to enhance the Raman gain at the front end.
TL;DR: In this article, the growth of ion waves at a wave number of 2k/sub pump/ has been studied in a CO/sub 2/-laser-plasma interaction, by use of Thomson scattering.
Abstract: The growth of ion waves at a wave number of 2k/sub pump/ has been studied in a CO/sub 2/-laser--plasma interaction, by use of Thomson scattering. Time- and wave-number--resolved spectra have been obtained. Harmonic generation has been observed in the ion-wave spectrum. Saturation of the reflectivity is also observed. These results are consistent with nonlinearities in the ion wave affecting both the damping and the interaction length.
TL;DR: The elastic constants and Pockels coefficients of CH4 and CD4 single crystals near their triple points have been determined using high-resolution Brillouin spectroscopy.
Abstract: The elastic constants and Pockels coefficients of CH4 and CD4 single crystals near their triple points have been determined using high-resolution Brillouin spectroscopy. For CH4 at 90.4 K, the elastic constants are C11 = 19.57 ± 0.30, C12 = 14.46 ± 0.20, C44 = 9.20 ± 0.15 kbar, and the ratios of the Pockels coefficients are p12/p11 = 1.031 ± 0.035 and p44/p11 = 0.069 ± 0.010. For CD4 at 89.2 K, C12 = 20.04 ± 0.30, C12 = 15.00 ± 0.25, C44 = 9.15 ± 0.15 kbar, and p12/p11 = 1.027 ± 0.020, P44/p11 = 0.138 ± 0.010. The velocities of the low-frequency transverse modes in CH4 and CD4 are anomalously slow in the direction, indicative of rotational–translational coupling of molecules. Isotopic differences are also evident: the Pockels coefficient p44 in CD4 is double that in CH4; and the velocities of both transverse modes in the principle directions , , and are in the ratio V(CH4)/V(CD4) = 1.130 instead of 1.118 as expected from the isotopic mass ratio.
TL;DR: In this paper, wavefront reversal via stimulated Brillouin scattering (SBS) is shown to possess the capability to compensate for phase aberrations in laser media and also to temporally compress long laser pulses.
Abstract: Wavefront reversal (WFR) via stimulated Brillouin scattering (SBS) is shown to possess the capability to compensate for phase aberrations in laser media and also to temporally compress long laser pulses. Such techniques, which involve passive and lightweight conjugator elements, are believed to be simple and practical.
TL;DR: In this article, the elastic stiffness constants have been determined at room temperature using Brillouin spectroscopy, and the spectral width of the corresponding spectral width has been shown to show important variations around the transition temperature (Ti = -143°C) between prototypic and incommensurate phases.
Abstract: All elastic stiffness constants have been determined at room temperature using Brillouin spectroscopy. Some of them and the spectral width of the corresponding Brillouin peaks show important variations around the transition temperature (Ti = -143°C) between prototypic and incommensurate phases. Below Ti, the anomalies associated with the acoustic phonons propagating in the (001) direction are explained assuming a linear coupling between deformations and an overdamped mode. This mode is equivalent to a Debye relaxation process characterized by a relaxation time τ0 = 2.6 10-12 s.K.
TL;DR: The elastic instability in the ferroelastic phase transition of BiVO 4 was investigated by the observation of the Brillouin scattering spectra as a function of temperature around the transition temperature.
Abstract: The elastic instability in the ferroelastic phase transition of BiVO 4 was investigated by the observation of the Brillouin scattering spectra as a function of temperature around the transition temperature. From the temperature dependence of the observed spectra in two different scattering geometries it turns out clear that the softening of elastic stifiness constant c 11 - c 12 , not of c 66 , causes the ferroelastic transition. The elastic softening is discussed in connection with the domain structure.
TL;DR: In this article, a laser is described utilizing neodymium phosphate glass, an unstable resonator, and Q switching by stimulated Brillouin scattering, which occurs when the resonator changes over from an unstable to a stable configuration.
Abstract: A laser is described utilizing neodymium phosphate glass, an unstable resonator, and Q switching by stimulated Brillouin scattering. It was found that Q switching occurred when the resonator changed over from an unstable to a stable configuration. Wavefront reversal then caused lasing to take place in the lowest-order mode, the radiation having the diffraction-limited divergence and completely filling the 6.3 mm diameter of the active element.
TL;DR: The first Brillouin-scattering measurements of single-crystal Mg2SiO4 have been made at 1 atm and pressures up to 40 kbar in a diamond anvil cell at room temperature as mentioned in this paper.
Abstract: The first Brillouin‐scattering measurements of single‐crystal Mg2SiO4 have been made at 1 atm and pressures up to 40 kbar in a diamond‐anvil cell at room temperature. The elastic moduli C11,C22,C33,C44,C55, and C66, and their pressure derivatives were obtained. These results were compared with those obtained by ultrasonic measurements up to 10 kbar. The observation of low dCij/dP slopes for the transverse moduli. C44, C55, and C66, and the evidence for negative second derivatives as well, support Poirier’s proposed mechanism for the olivine→spinel transition due to gliding of close‐packed oxygen layers. Moreover, the numerical relationships among photoelastic constants were determined by studying the intensity ratio of LA to TA modes.
TL;DR: In this paper, a two branch polariton model was used to estimate the translational exciton mass of 2.3 m 0 and the effective dielectric constant of 10.4 m 0.
Abstract: Resonant Brillouin scattering spectra are measured on a layer semiconductor 2H–PbI 2 . The observed exciton polariton dispersion in the direction parallel to the c -axis is interpreted by a two branch polariton model yielding the translational exciton mass of 2.3 m 0 and the effective dielectric constant of 10. The anisotropy of the effective mass is estimated to be m // / m ⊥ =3.4 for exciton and 4.4 for conduction electron, respectively.