Brillouin scattering

About: Brillouin scattering is a research topic. Over the lifetime, 11426 publications have been published within this topic receiving 178306 citations.

Temperature-strain discrimination in distributed optical fiber sensing using phase-sensitive optical time-domain reflectometry.

Abstract: A method based on coherent Rayleigh scattering distinctly evaluating temperature and strain is proposed and experimentally demonstrated for distributed optical fiber sensing. Combining conventional phase-sensitive optical time-domain domain reflectometry (ϕOTDR) and ϕOTDR-based birefringence measurements, independent distributed temperature and strain profiles are obtained along a polarization-maintaining fiber. A theoretical analysis, supported by experimental data, indicates that the proposed system for temperature-strain discrimination is intrinsically better conditioned than an equivalent existing approach that combines classical Brillouin sensing with Brillouin dynamic gratings. This is due to the higher sensitivity of coherent Rayleigh scatting compared to Brillouin scattering, thus offering better performance and lower temperature-strain uncertainties in the discrimination. Compared to the Brillouin-based approach, the ϕOTDR-based system here proposed requires access to only one fiber-end, and a much simpler experimental layout. Experimental results validate the full discrimination of temperature and strain along a 100 m-long elliptical-core polarization-maintaining fiber with measurement uncertainties of ~40 mK and ~0.5 μe, respectively. These values agree very well with the theoretically expected measurand resolutions.

Multi-wavelength Brillouin fiber laser using Brillouin-Rayleigh scatterings in distributed Raman amplifier

Abstract: An efficient multi-wavelength Brillouin fiber laser (BFL) is demonstrated by using a self feedback mechanism of Brillouin-Rayleigh scatterings with the presence of distributed Raman gain. The balanced of these three scatterings generates a laser comb more than 27 lines with a relatively flat amplitude and constant spacing of 0.09 nm. This is realised using a piece of dispersion compensating fiber as the nonlinear gain medium, an amplified Brillouin pump and a broad-band fiber Bragg grating as a reflector.

In situ Brillouin scattering from surface-anisotropy-dominated Damon-Eshbach modes in ultrathin epitaxial Fe(110) layers

Abstract: Epitaxially grown Fe(110) layers on W(110) with thicknesses between 8 and 150 \AA{} have been investigated in situ by Brillouin scattering. Below 60 \AA{} a so-far-unobserved strong increase of the frequency of the Damon-Eshbach mode by a factor of up to 3 has been found with decreasing layer thickness. This novel behavior is described quantitatively by a model, which takes explicitly into account magnetic surface anisotropies. An additional growth-induced uniaxial magnetic surface anisotropy due to steps in the Fe layer could be identified.

Brillouin Scattering in Simple Liquids: Argon and Neon

Abstract: Recent theoretical work has suggested that at high frequencies, there should be significant departure from classical hydrodynamic behavior in simple fluids. In particular, the frequency dependence of transport coefficients is no longer negligible and may introduce observable effects into the propagation of high-frequency sound. We have measured the sound velocity of high-frequency phonons (1-3 GHz) in liquid argon and liquid neon along their vaporpressure equilibrium curves using the Brillouin scattering technique. The Brillouin spectra were excited with a single-mode argon-ion laser operating at 5145 or 4765 and were analyzed and detected with a Fabry-Perot interferometer and standard photoelectric techniques. Hypersonic (3 GHz) velocities observed in argon decrease linearly from 850 m/sec at 85°K to 742 m/sec at 100°K and uniformly exhibit a small departure from low-frequency (1 MHz) data obtained under the same thermodynamic conditions. This effect is in qualitative agreement with theoretical-model predictions of a negative velocity dispersion at high frequencies. Our measurements of the sound velocity in liquid neon are the first in this material by any technique, and hance cannot be compared with ultrasonic values. The hypersonic velocity in neon decreases not quite linearly from 620 m/sec at 24.9°K to 508 m/sec at 32°K. When compared with results in other noble-gas liquids through corresponding-state arguments, these data suggest the existence of measurable quantum effects in the hypersonic velocity of liquid neon. In addition, an interesting change in slope of the velocity-versus-temperature curve (of 17%) is observed at 28°K. © 1969 The American Physical Society.

Nonlinear evolution of stimulated Raman scattering in homogeneous plasmas

Abstract: A model for stimulated Raman scattering (SRS) in a homogeneous plasma has been designed to account for the presence of stimulated Brillouin scattering (SBS) and the nonlinear coupling between Langmuir and ion waves described by Zakharov equations. The nonlinear evolution of electron plasma waves also includes an effective damping resulting from electron diffusion in localized Langmuir fields produced during simultaneous SRS and SBS evolutions. Numerical results based on this model show two distinct SRS behaviors. Close to ncr/4 the Langmuir collapse dominates nonlinear evolution of the instability. At lower densities low level SRS is observed for a relatively long time after which SRS is terminated as a result of ion fluctuations produced by SBS. In addition, the anomalous absorption of backscattered SRS radiation by ion fluctuations produced by the collapse is proposed as a mechanism that may explain some recent experimental observations showing a gap in the SRS spectrum.