Stimulated Brillouin scattering of laser radiation in a piezoelectric semiconductor

A high-power laser beam propagating through a piezoelectric semiconductor decays efficiently into an acoustic wave (mainly a lattice mode) and a scattered laser wave. This phenomenon is known as stimulated Brillouin scattering (SBS). The coupling of waves for SBS is provided by the nonlinear response of free electrons and the resonance conditions are easily satisfied over a wide range of scattering angles and semiconductor parameters. The threshold laser power is quite low; of the order of ${10}^6$ W/${\mathrm{cm}}^2$ for a C${\mathrm{O}}_2$ laser and ${10}^8$ W/${\mathrm{cm}}^2$ for a glass: Nd laser. Above the threshold, the growth rate of decay waves is considerably large (∼${10}^7$ ${\sec }^{-1\mathrm{}}$).