Topic
Brillouin scattering
About: Brillouin scattering is a research topic. Over the lifetime, 11426 publications have been published within this topic receiving 178306 citations.
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TL;DR: The first observation of backward stimulated Brillouin scattering in fully cladded Si-N waveguides is reported, and the intrinsic BrillouIn gain at 25 GHz and the photoelastic constant are estimated to be 4 × 10−13 m/W and |p| = 0.047 ± 0.004 respectively.
Abstract: Silicon nitride (Si_{3}N_{4}) has emerged as a promising material for integrated nonlinear photonics and has been used for broadband soliton microcombs and low-pulse-energy supercontinuum generation. Therefore, understanding all nonlinear optical properties of Si_{3}N_{4} is important. So far, only stimulated Brillouin scattering (SBS) has not yet been reported. Here we observe, for the first time, backward SBS in fully cladded Si_{3}N_{4} waveguides. The Brillouin gain spectrum exhibits an unusual multipeak structure resulting from hybridization with high-overtone bulk acoustic resonances of the silica cladding. The reported intrinsic Si_{3}N_{4} Brillouin gain at 25 GHz is estimated as 4×10^{-13} m/W. Moreover, the magnitude of the Si_{3}N_{4} photoelastic constant is estimated as |p_{12}|=0.047±0.004, which is nearly 6 times smaller than for silica. Since SBS imposes an optical power limitation for waveguides, our results explain the capability of Si_{3}N_{4} to handle high optical power, central for integrated nonlinear photonics.
69 citations
TL;DR: In this article, the authors measured the Brillouin scattering from the liquid under hydrostatic pressure up to 30 GPa, and derived Elastic moduli derived from the frequency shifts with bulk modulus values obtained from compressibility data.
Abstract: Brillouin scattering from ${\mathrm{H}}_{2}$O under hydrostatic pressures up to 30 GPa is reported. Sound velocities in the liquid region agree with previous ultrasonic measurements and discontinuities are observed at the liquid---ice VI and ice VI---ice VII phase transitions. Elastic moduli derived from the frequency shifts are compared with bulk modulus values obtained from compressibility data.
69 citations
TL;DR: In this article, a solution to the linearized hydrodynamic equations is developed to model the dynamics of the thermal grating, including the effects of finite-rate energy deposition, damping by viscosity and thermal conduction, mass diffusion of the excited-state grating and electrostrictive compression.
Abstract: The nature of optical scattering from laser-induced thermal gratings created in the gas phase is investigated. Thermal gratings are produced with the illumination geometry used to perform degenerate four-wave mixing (DFWM) measurements. Such scattering from thermal gratings can act as a phase-matched interference signal. A solution to the linearized hydrodynamic equations is developed to model the dynamics of the thermal grating. Predictions of this model that uses realistic gas properties are shown to compare favorably with laboratory measurements. The model includes the effects of finite-rate energy deposition, damping by viscosity and thermal conduction, mass diffusion of the excited-state grating, and electrostrictive compression.
69 citations
TL;DR: This work has developed a technique for studying the elasticity of single crystals of solid hydrogen and related materials at very high pressures and used the method to determine the second-order elastic moduli of single-crystal n-type hydrogen to 24 GPa at 295 K.
Abstract: We have developed a technique for studying the elasticity of single crystals of solid hydrogen and related materials at very high pressures and used the method to determine the second-order elastic moduli of single-crystal n-type hydrogen to 24 GPa at 295 K. The method involves the measurement of acoustic velocities as a function of crystallographic direction by Brillouin scattering in a diamond anvil cell with the orientation of the single crystals determined by synchrotron x-ray diffraction. Between 6 and 24 GPa, the adiabatic bulk modulus of ${\mathrm{H}}_{2}$ increases by more than a factor of 3 and the shear modulus increases by more than a factor of 4. The acoustic anisotropy of hydrogen decreases from 11% to 6% for compressional waves and from 23% to 14% for shear waves. The data are also used to calculate thermodynamic properties of hydrogen at high pressures. By including the observed velocity anisotropy, the equation of state of ${\mathrm{H}}_{2}$ derived from Brillouin data is in agreement with previous results derived solely from x-ray diffraction.
69 citations
TL;DR: In this article, the backward optical wave stimulated by a multimode, monochromatic, incident optical wave in a waveguide filled with a transparent nonlinear medium was considered, and conditions on guide length, area, mode number, and Stokes shift were derived in order that a given high percentage of the power in the backscattered field be the phase conjugate of the incident field.
Abstract: We consider the backward optical wave stimulated by a multimode, monochromatic, incident optical wave in a waveguide filled with a transparent nonlinear medium, when the incident wave is negligibly perturbed by the nonlinear processes We derive the conditions on guide length, area, mode number, and Stokes shift in order that a given high percentage of the power in the backscattered field be the “phase conjugate” of the incident field, ie, be proportional to its complex conjugate in the entrance plane of the waveguide
69 citations