Showing papers on "Brillouin scattering published in 1971"
TL;DR: In this article, it was shown that the transfer of intensity from a pump beam simultaneously to forward and backward stimulated scattered beams in an infinite medium can lead to pulsations similar to relaxation oscillations in the scattered intensities.
Abstract: The equations describing the transfer of intensity from a pump beam simultaneously to forward and backward stimulated scattered beams in an infinite medium are shown to lead to pulsations similar to relaxation oscillations in the scattered intensities. The period of the pulsations is simply related to the gain length for the forward-scattered beam, and may be much longer than the ordinary transient time (related to the damping of material excitations) usually associated with stimulated scattering. Similar oscillations occur for backward scattering alone (stimulated Brillouin scattering) if the scattering medium is finite. In this case the period equals the photon round-trip time in the medium if the latter exceeds the backward gain length. Both phenomena should be observable in scattering from gases such as ${\mathrm{N}}_{2}$ and ${\mathrm{H}}_{2}$ at high pressure, and may also play a role in determining the temporal structure of light scattered from the region of a self-focus in liquids.
80 citations
TL;DR: In this paper, a simple molecular I2 vapor filter is described which can attenuate the unshifted scattered light in Brillouin and Raman scattering by greater than 108 with a background attenuation of less than 10.
Abstract: A simple molecular I2 vapor filter is described which can attenuate the unshifted scattered light in Brillouin and Raman scattering by greater than 108 with a background attenuation of less than 10, i.e., a discrimination ratio of > 107 : 1.
80 citations
TL;DR: In this paper, the Brillouin spectra of liquid CCl4 (at 20.0°C) have been investigated 20 scattering angles, from 40° to 145°.
Abstract: Brillouin spectra of liquid CCl4 (at 20.0°C) have been investigated 20 scattering angles, from 40° to 145°. The spectra were excited by 6328‐A radiation from a He‐Ne laser and analyzed with a pressure‐scanned Fabry‐Perot spectrometer. The measured frequency shifts and linewidths of the Brillouin component were used to determine velocities and attenuations of thermal waves in the frequency range 1.6–4.7 Gc/sec. A large dispersion (>10%) and corresponding change in attenuation were found, characteristic of a thermal relaxation process in this region. A broad new component in the spectrum of isotropic scattering was observed, which is also characteristic of a relaxation process. Analyses of these data were carried out in two ways: one is based on a simple extension of acoustic equations to light scattering, and the other, on Mountain's theory of light scattering in the region of a thermal relaxation. It is shown that the observed spectra and derived data agree with Mountain's theory in all respects. Also, fr...
32 citations
TL;DR: In this paper, two methods for generating sound at microwave frequencies with a Q-switched ruby laser were presented, based on the modulation of the laser due to its mode structure and on the nonlinear properties of the solid.
Abstract: Two methods are presented for generating sound at microwave frequencies with a Q‐switched ruby laser. They are based on the modulation of the laser due to its mode structure and on the nonlinear properties of the solid. Sound is created at the laser modulation frequency. (1) Electrostrictive mixing in a LiNbO3 crystal, using a forward Brillouin scattering geometry, produces sound pulses at 800 MHz inside the crystal. Acoustic power densities were around 0.1 mW/mm2. (2) We then used surface heating of a metal film deposited on the surface of a dielectric crystal. At microwave frequencies, good efficiencies can be achieved; at 840 MHz, we generated in a gold film nearly 10 mW/mm2 of sound in 30‐nsec pulses.
31 citations
TL;DR: In this article, the authors used stimulated Brillouin scattering (SBS) to measure hypersonic absorption and velocity in quartz glass at 24 GHz with a mean free path of 2 mm below 3.5°K.
Abstract: By making use of stimulated Brillouin scattering, hypersonic absorption and velocity measurements in quartz glass were carried out at 24 GHz. Absorption data for longitudinal sound waves are presented below 8°K and velocity data between 4° and 300°K. The hypersonic absorption is observed to decrease strongly on cooling corresponding to a mean free path of the hypersonic phonons larger than 2 mm below 3.5°K. This value exceeds the mean free path calculated from heat conductivity data at 1.5°K for thermal phonons of similar energy by three orders of magnitude. The absorption data are discussed in connection with previous lower‐frequency measurements.
26 citations
TL;DR: In this paper, the permanent damage in optical glass is characterized by filamentary tracks of fine fractures, which are a few micrometers in diameter, straight to within 0.7 \ensuremath{mu}m, up to 9 cm long, and collinear with the incident laser beam.
Abstract: The permanent damage in optical glass investigated here is characterized by filamentary tracks of fine fractures. These tracks are a few micrometers in diameter, straight to within 0.7 \ensuremath{\mu}m, up to 9 cm long, and collinear with the incident laser beam. There may also be damage stars (regions of fracture gross compared with the track diameter). These damage stars are usually near the upstream ends of the tracks. Track formation is characterized by a flash of side-scattered white light from the track, laser light side-scattered from the damage stars, a marked increase in the exit divergence angle of the laser beam, and a weak back-scattered pulse of laser light. The back-scattered pulse preserves the polarization of the incident beam, is of shorter duration than the incident laser pulse, and has a frequency shift corresponding to Brillouin scattering from a free compressional sound wave in the glass. Track formation is accompanied by a detectable cylindrical sound wave. The track formation threshold is repeatable at different locations in the glass sample. Both the power threshold and the energy-density threshold are rapidly varying functions of the incident beam radius at focus. The threshold power is as low as 10 kW for a ruby-laser beam sharply focused in dense flint glass, and more than 2 MW for an unfocused beam in fused silica.
24 citations
23 citations
TL;DR: In this article, the inelastic scattering of light by interband electronic transitions (interband electronic Raman scattering) in semiconductors and semimetals is examined, and the form and magnitude of the Raman efficiency associated with interband transitions near the $\ensuremath{Gamma}$ point of the Brillouin zone in materials with the gray-tin band structure in zero magnetic field.
Abstract: In this paper we examine the inelastic scattering of light by interband electronic transitions (interband electronic Raman scattering) in semiconductors and semimetals. A number of general features of the scattering process and the resulting Raman spectrum are examined. We also present detailed calculations of the form and magnitude of the Raman efficiency associated with interband transitions near the $\ensuremath{\Gamma}$ point of the Brillouin zone in materials with the gray-tin band structure in zero magnetic field.
22 citations
TL;DR: In this article, the spectrum of Rayleigh and Brillouin scattering from superfluid mixtures of 3He and 4He has been observed at different temperatures and concentrations, and a preliminary assessment is made of the relative intensities.
Abstract: The full five component spectrum of Rayleigh and Brillouin scattering from superfluid mixtures of 3He and 4He has been observed. Recordings are shown at different temperatures and concentrations, and a preliminary assessment is made of the relative intensities.
21 citations
20 citations
TL;DR: In this paper, the spectrum of piezoelectrically amplified acoustic shear waves in GaAs is obtained in the microscopic limit, where the electron mean free path is much greater than the acoustic wavelength.
Abstract: X‐ray diffraction from piezoelectrically amplified acoustic shear waves in GaAs is reported. The spectrum of amplified acoustic flux is obtained in the microscopic limit, where the electron mean free path is much greater than the acoustic wavelength. The peak acoustic intensity occurs at 50 GHz, which corresponds to the frequency of maximum net gain according to the linear theory. The spectrum of piezoelectrically amplified acoustic waves is observed at frequencies an order of magnitude larger than may be studied by the previously reported Brillouin scattering technique.
TL;DR: In this article, the main features of transient stimulated light scattering, the time delay of the Stokes maximum and the reduction of gain were investigated using Brillouin scattering, even for laser pulses much longer than the phonon relaxation time.
TL;DR: In this paper, a simple spectrometer was developed to detect the Brillouin spectra that are associated with the interaction of light and random surface ripples, and a doublet was predicted and was observed with increasing wave number for the air-water interface.
TL;DR: The theory of Brillouin scattering by superfluid helium is discussed in this paper, and the predicted scattering for helium under pressure is shown to differ significantly from that quoted by Ganguly (Phys. Rev. Lett., vol. 26, 1623, 1971).
Abstract: The theory of Brillouin scattering by superfluid helium is discussed, and the predicted scattering for helium under pressure is shown to differ significantly from that quoted by Ganguly (Phys. Rev. Lett., vol. 26, 1623, 1971).
TL;DR: In this article, the threshold powers for stimulated Raman and Brillouin scattering were studied as a function of temperature in the backward stimulated scattering of nematic liquid crystal MBBA in the isotropic phase.
TL;DR: In this paper, an account of the Brillouin scattering of light from liquids is given and different contributions to the spectrum are discussed and are shown to depend on liquid properties such as sound velocity, viscosity, thermal conductivity, structural relaxation and concentration effects.
Abstract: An account is given of the Brillouin scattering of light from liquids. Different contributions to the Brillouin spectrum are discussed and are shown to depend on liquid properties such as sound velocity, viscosity, thermal conductivity, structural relaxation and concentration effects. The importance of these measurements to liquid-state theory is emphasized. Stimulated Brillouin scattering is briefly explained. Finally, the use of the Fabry-Perot interferometer in these experiments is discussed.
TL;DR: In this article, the effect of nonlinear properties of liquid solvents on the performance of liquid laser and amplifier has been investigated and no connection has been found between stimulated Brillouin scattering and the phenomenon of self-Q -switching.
Abstract: Inorganic liquids, phosphorous, and selenium oxychlorides, used as solvents for Nd, exhibit a number of nonlinear properties, which may reflect in the performance of liquid lasers. Spontaneous and stimulated Raman scattering have been studied. Measured cross sections and gains indicate that up to power levels of a few hundred megawatts per square centimeter the effect on laser and amplifier properties are negligible. No self-focusing has been observed. Under mode-locked conditions substantial conversion to Raman frequencies have been obtained. No connection has been found between stimulated Brillouin scattering and the phenomenon of self- Q -switching.
TL;DR: In this paper, a new optical method for exciting an ultrasonic pulse in opaque materials was proposed, where the velocity of the waves detected by a piezoelectric detector agrees with the compressional sound-wave velocity.
TL;DR: In this article, the temperature dependence of the longitudinal sound velocity in the [100]-direction has been measured in a single crystal of argon in a temperature range from 4.2°K to 77°K by stimulated Brillouin scattering.
TL;DR: Substantial deviations from the statistics of chaotic light have been found in the Brillouin scattered laser light from amplified acoustic flux in ZnO as mentioned in this paper, presumably due to nonlinear amplitude stabilization during the acoustic amplification process.
TL;DR: In this article, the results of a "small signal" theoretical treatment of the transient behavior of the stimulated thermal scattering of light by a small colored liquid sample are given, and the analysis is applicable to an amplifier experimental set-up in which an undepleted pump beam and a small signal beam travel in opposite directions through the sample.
Abstract: The results of a "small signal" theoretical treatment of the transient behavior of the stimulated thermal scattering of light by a small colored liquid sample are given. The analysis is applicable to an amplifier experimental set-up in which an undepleted pump beam and a small signal beam travel in opposite directions through the sample. In addition to reproducing features which have been previously predicted and experimentally confirmed, new features arise from terms which were neglected in previous analyses. For example, oscillatory behavior of the signal-beam gain factor can occur under certain conditions. It is also shown where the controversy of whether the Rayleigh lifetime τR or the Brillouin lifetime τB′ is the characteristic time for achieving steady-state stimulated thermal Brillouin scattering arises and how it is resolved.
TL;DR: The effect of electrostrictively induced stimulated Brillouin scattering on atmospheric depolarization is studied and solutions for steady-state and transient conditions are obtained.
Abstract: The effect of electrostrictively induced stimulated Brillouin scattering on atmospheric depolarization is studied. Solutions for steady-state and transient conditions are obtained.
01 Jan 1971
TL;DR: The effect of Brillouin scattering on the image quality of a Bragg-imaging system is analyzed in this paper, where the authors use a cylindrically convergent illuminating light beam.
Abstract: The effect of Brillouin scattering on the image quality of a Bragg-imaging system is analyzed in this chapter. The particular Bragg-imaging system considered here uses a cylindrically convergent illuminating light beam. The signal-to-noise ratio for an image element (that is, a resolution cell) is shown to vary with the image-plane location when the image sensor is broadband in temporal frequency. It is also shown that quantum noise due to light scattered from thermal phonons (Brillouin scattering) is the dominant limiting source of noise for a Bragg-imaging system operating in the ultrasonic band at room temperature when the best available TV camera tube is used for detecting the image. Competing noise sources which are evaluated include quantum noise due to signal photons and image sensor noise. The effects of dust particles and other inhomogeneities on scattered light are not considered.
TL;DR: In this article, it was shown that the intensity of emission from a laser based on the stimulated Brillouin scattering effect can be increased by raising the pumping level, the pumping energy density, and the duration of the pumping pulses above their threshold values.
Abstract: It is shown that the intensity of emission from a laser based on the stimulated Brillouin scattering effect can be increased by raising the pumping level, the pumping energy density, and the duration of the pumping pulses above their threshold values. An experimental investigation was made of a CS2 Brillouin laser whose emission intensity was raised in this way, and an ether Brillouin laser whose emission intensity was not increased. The CS2 laser was pumped with ruby laser pulses which satisfied the conditions necessary for an increase in the emission intensity. The CS2 laser was found to have the following parameters: energy efficiency 2%, divergence of the output radiation 3 10–4 rad, enhancement of the emission intensity by a factor of nine. The efficiency of the ether laser was 20%.
TL;DR: In this article, the Brillouin scattering studies of acoustoelectric interactions CdS and ZnO are reviewed and the important characteristics of amplified acoustic shear-wave noise as determined by Brillour scattering is summarized.
Abstract: Brillouin‐scattering studies of acoustoelectric interactions CdS and ZnO are reviewed. The important characteristics of amplified acoustic shear‐wave noise as determined by Brillouin scattering is summarized. Data on acoustic parametric amplification is also given.
TL;DR: In this article, the Brillouin scattering from SF6 near its critical point for two scattering angles, 166° and 45°, was observed and the sound velocities were deduced from these measurements at T−Tc=0.5°C.
Abstract: Using techniques described by Ford, Langley, and Puglielli, we have observed Brillouin scattering from SF6 near its critical point for two scattering angles, 166° and 45°. Sound velocities deduced from these measurements at T−Tc=0.5°C are Cs=112±1 m/sec for a sound frequency of 370 MHz and Cs=95±2 m/sec for a frequency of 130 MHz. The dispersion in the sound velocity of about 15% at T−Tc=0.5°C decreases as the temperature is increased to about 1% at T−Tc=40°C, where the sound velocity has increased to 160 m/sec. These data are compared with existing ultrasonic data and discussed in the light of a dynamical model considered by Mountain.
TL;DR: In this article, the authors used Brillouin scattering to study very small changes produced in the distribution of thermal phonons by the acoustoelectric interaction and observed perturbation in the thermal acoustic flux with carrier drift velocity less than the sound velocity.
Abstract: Brillouin scattering is used to study very small changes produced in the distribution of thermal phonons by the acoustoelectric interaction. Perturbation in the thermal acoustic flux has been observed with carrier drift velocity less than the sound velocity.
TL;DR: The Rayleigh-Brillouin spectrum of light scattered from H2, D2, and HD has been measured at densities ranging from 1/2 to 104 amagat, all at room temperature as mentioned in this paper.
Abstract: The Rayleigh–Brillouin spectrum of light scattered from H2, D2, and HD has been measured at densities ranging from 1/2 to 104 amagat, all at room temperature. The apparatus consisted of a 20 mW He–Ne laser, a high pressure cell for 90° scattering, a pressure scanned Fabry–Perot interferometer, and photon counting electronics. A discrepancy is noted between the observed spectra and various theoretical spectra. It is suggested that the discrepancy arises from an omission in the theories of coupling between relaxation of the rotational states and thermal conduction.
TL;DR: In this article, a preliminary lowest order calculation of Brillouin scattering in molecular crystals indicates that the long wavelength dependence corresponds to that generally given for Rayleigh scattering, namely, lambda -4.
Abstract: A preliminary lowest order calculation of Brillouin scattering in molecular crystals indicates that in contrast to a formula already in the literature, the long wavelength dependence corresponds to that generally given for Rayleigh scattering, namely, lambda -4.