Nonlinear absorption and refractive index of a Brillouin-scattered mode in magnetoactive centrosymmetric semiconductor plasmas.

Abstract

An analytical investigation has been made for the nonlinear refractive index and absorption coefficient of the Brillouin-scattered Stoke's mode resulting from the nonlinear interaction of an intense pumping light beam with acoustic perturbations internally generated due to the electrostrictive property of the doped semiconductor plasma. The origin of this nonlinear interaction lies in the third-order optical susceptibility arising from the nonlinear current density and electrostriction of the medium. The magnitude of third-order optical susceptibility determined from our analysis is found to agree with the theoretically and experimentally quoted values. The total refractive index and absorption coefficient are determined through the effective susceptibility derived with the help of the coupled-mode theory of plasmas. The magnetic field and the obliquity of the pump are found to augment the refractive index. The absorption coefficient decreases with increasing scattering angle and achieves a minimum value for the backscattered mode. The analysis reveals that the large refractive index and small absorption coefficient can easily be obtained in a magnetized centrosymmetric semiconducting crystal, and establishes their potentials as candidate materials for fabrication of cubic nonlinear devices.