2014 The Brillouin shift and width for poly(vinyl alcohol) hydrogels of two different crosslink densities have been obtained as a function of gel network volume fraction using a five-pass Fabry-Pérot interferometer. The results are discussed in the light of a theory for Brillouin lightscattering from gels proposed recently by J. A. Marqusee and J. M. Deutch. J. Physique Lett. 46 (1985) L-887 L-...

Brillouin scattering allows the determination of acoustic velocities and adiabatic elastic moduli in matter. These data are crucial in many areas of science, such as fundamental physics, geosciences and technology, especially when measured as a function of the density (pressure). In this paper, we present a review of the work performed on Brillouin scattering under high pressure in diamond anvi...

Propagation of a Brillouin precursor in a Lorentz dispersive medium is considered. The precursor is excited by a sine modulated initial signal, with its envelope described by a hyperbolic tangent function. The purpose of the paper is to show how the rate of growth of the initial signal affects the form of the Brillouin precursor. Uniform asymptotic approach, pertinent to coalescing saddle point...

We analyze how thermal fluctuations near a finite temperature nematic phase transition affect the spectral function A(k,ω) for single-electron excitations in a two-dimensional metal. Perturbation theory yields a splitting of the quasiparticle peak with a d-wave form factor, reminiscent of a pseudogap. We present a resummation of contributions to all orders in the Gaussian fluctuation regime. In...

Rayleigh-Brillouin spectra for heated nitrogen gas were measured by imaging the output of a Fabry-Perot interferometer onto a CCD array. The spectra were compared with the theoretical 6-moment model of Rayleigh-Brillouin scattering convolved with the Fabry-Perot instrument function. Estimates of the temperature and a dimensionless parameter proportional to the number density of the gas as funct...

Brillouin scattering in perfluorinated graded-index (PFGI-) polymer optical fibers (POFs) has been extensively studied for structural health monitoring, including seismic diagnosis. Here, we measure the propagation loss of PFGI-POFs at telecom wavelengths as a function of large applied strain (up to 100%) at three optical powers and as a function of strain rate at a constant optical power. The ...

Long range simultaneous distributed strain and temperature sensors have many applications for measurements in the power and oil industries and also for structural monitoring. We present an efficient technique to measure both the intensity and frequency shift at every point along the sensing fibre with a low loss filtering device utilising two in-fibre Mach-Zehnder interferometers. From these tw...

A new technique for Brillouin scattering-based, distributed fiber-optic measurements of temperature and strain is proposed, analyzed, simulated, and demonstrated. Broadband Brillouin pump and signal waves are drawn from the filtered amplified spontaneous emission of an erbium-doped fiber amplifier, providing high spatial resolution. The reconstruction of the position-dependent Brillouin gain sp...

Brillouin spectroscopy is an emerging technique in the biomedical field. It probes the mechanical properties of a sample through the interaction of visible light with thermally induced acoustic waves or phonons propagating at a speed of a few km/sec. Information on the elasticity and structure of the material is obtained in a nondestructive contactless manner, hence opening the way to in vivo a...

We experimentally demonstrate optical delay in the second-order Brillouin gain spectrum by incorporating a double Brillouin-frequency shifter into the system. By coinciding the seed signal with the second-order Brillouin gain spectrum, it was found that the seed signal experienced significantly larger delay as compared to the Brillouin slow light generated from the first-order Brillouin spectru...