Brillouin scattering

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

Design and operation of a 150 W near diffraction-limited laser amplifier with SBS wavefront correction

Abstract: The design and operation of a Nd:glass regenerative amplifier using a stimulated Brillouin scattering (SBS) phase conjugate mirror is presented. The system can be operated at 25-30 J per pulse with a pulse width of 14 ns and a pulse repetition frequency (PRF) of 6 Hz. This results in an average output power of >150 W with a peak power of 2 GW. The experimentally measured divergence of the amplifier output is 1.25/spl times/ the diffraction limit and it can be frequency doubled with >80% efficiency. The detailed considerations required for this specific amplifier design are discussed as well as how these considerations apply to the design of high average power, high beam quality laser systems in general. >

Brillouin scattering in systems of biological significance

Abstract: Brillouin scattering spectra, with a single mode argon-ion laser and triple-pass Fabry-Perot interferometer, have been measured for natural biological fibres and for films of synthetic polypeptides. For wet unstretched rat tail collagen, with the scattering vector parallel and perpendicular to the fibre axis, single Brillouin shifts of ± 7.9 GHz and ± 6.3 GHz respectively were observed. With the scattering vector at 45° to the fibre axis, two peaks ( ± 6.35 GHz and ± 7.7 GHz) were found. For horse hair keratin the shifts for the scattering vector parallel and perpendicular to the fibre axis were ± 8.7 GHz and ± 7.7 GHz respectively. A single peak only was found with the vector at 40° to the fibre axis. Two synthetic polypeptides poly(DL-caprylic acid) and poly(Y-ethyl-L-glutamate), known to have the a-helix conformation, gave shifts of ± 6.36 and ± 6.1 GHz. The results are discussed.

A theoretical study of transient stimulated Brillouin scattering in optical fibers seeded with phase-modulated light

Abstract: Beam combining of phase-modulated kilowatt fiber amplifiers has generated considerable interest recently. We describe in the time domain how stimulated Brillouin scattering (SBS) is generated in an optical fiber under phase-modulated laser conditions, and we analyze different phase modulation techniques. The temporal and spatial evolutions of the acoustic phonon, laser, and Stokes fields are determined by solving the coupled three-wave interaction system. Numerical accuracy is verified through agreement with the analytical solution for the un-modulated case and through the standard photon conservation relation for counter-propagating optical fields. As a test for a modulated laser, a sinusoidal phase modulation is examined for a broad range of modulation amplitudes and frequencies. We show that, at high modulation frequencies, our simulations agree with the analytical results obtained from decomposing the optical power into its frequency components. At low modulation frequencies, there is a significant departure due to the appreciable cross talk among the laser and Stokes sidebands. We also examine SBS suppression for a white noise source and show significant departures for short fibers from analytically derived formulas. Finally, SBS suppression through the application of pseudo-random bit sequence modulation is examined for various patterns. It is shown that for a fiber length of 9 m the patterns at or near n=7 provide the best mitigation of SBS with suppression factors approaching 17 dB at a modulation frequency of 5 GHz.

Broadband true time delay for microwave signal processing, using slow light based on stimulated Brillouin scattering in optical fibers.

Abstract: We experimentally demonstrate a novel technique to process broadband microwave signals, using all-optically tunable true time delay in optical fibers. The configuration to achieve true time delay basically consists of two main stages: photonic RF phase shifter and slow light, based on stimulated Brillouin scattering in fibers. Dispersion properties of fibers are controlled, separately at optical carrier frequency and in the vicinity of microwave signal bandwidth. This way time delay induced within the signal bandwidth can be manipulated to correctly act as true time delay with a proper phase compensation introduced to the optical carrier. We completely analyzed the generated true time delay as a promising solution to feed phased array antenna for radar systems and to develop dynamically reconfigurable microwave photonic filters.

Resonant Brillouin Scattering of Excitonic Polaritons in Gallium Arsenide

Abstract: We report the first experimental observation of resonant Brillouin scattering of excitonic polaritons in a semiconductor The usual symmetric Brillouin doublet becomes an asymmetric multiplet when the incident light energy is scanned through the $n=1$ exciton resonance and allows a direct measurement of the polariton dispersion curve In GaAs we determine a longitudinal-transverse splitting of 008 \ifmmode\pm\else\textpm\fi{} 002 meV and a translational mass ${M}_{\mathrm{ex}}=(06\ifmmode\pm\else\textpm\fi{}01){m}_{0}$ for the [100] heavy exciton The excitions couple preferentially to LA phonons