Stimulated Brillouin scattering of laser radiation inn-GaAs

Abstract

In this paper we have investigated the three-wave parametric decay of a high-power laser radiation into an ion acoustic wave and a scattered laser radiation, that is, the stimulated Brillouin scattering in an $n$-type GaAs sample. The dc electric bias is applied to assist the laser beam in transferring electrons from the lower conduction valley to upper satellite valleys in $n$-GaAs. For a laser beam of power density \ensuremath{\sim}12 MW/${\mathrm{cm}}^{2}$ and for the typical plasma parameters: ${n}_{0}^{0}={10}^{9}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, ${\ensuremath{\nu}}_{0}=5\ifmmode\times\else\texttimes\fi{}{10}^{12}$ rad ${\mathrm{sec}}^{\ensuremath{-}1}$, ${\ensuremath{\epsilon}}_{L}\ensuremath{\cong}13.5$ (at 300 K), ${\ensuremath{\omega}}_{0}=1.778\ifmmode\times\else\texttimes\fi{}{10}^{14}$ rad ${\mathrm{sec}}^{\ensuremath{-}1}$ (corresponding to a C${\mathrm{O}}_{2}$ laser), ${E}_{d}\ensuremath{\cong}5$ esu and $\ensuremath{\theta}=60\ifmmode^\circ\else\textdegree\fi{}$, the growth rate of the ion acoustic mode is \ensuremath{\sim}${10}^{9}$ rad ${\mathrm{sec}}^{\ensuremath{-}1}$. It is seen that the negative differential resistivity region in $n$-GaAs has a great influence on the growth of the ion acoustic wave.