NONLINEAR ABSORPTION AND REFRACTIVE-INDEX OF A BRILLOUIN-SCATTERED MODE IN MAGNETOACTIVE CENTROSYMMETRIC SEMICONDUCTOR PLASMAS

An analytical investigation has been made for the nonlinear refractive index and absorption coefficient of the Brillouin-scattered Stoke's m ode resulting from the nonlinear interaction of an intense pumping lig ht beam with acoustic perturbations internally generated due to the el ectrostrictive property of the doped semiconductor plasma. The origin of this nonlinear interaction lies in the third-order optical suscepti bility arising from the nonlinear current density and electrostriction of the medium. The magnitude of third-order optical susceptibility de termined from our analysis is found to agree with the theoretically an d experimentally quoted values. The total refractive index and absorpt ion coefficient are determined through the effective susceptibility de rived with the help of the coupled-mode theory of plasmas. The magneti c field and the obliquity of the pump are found to augment the refract ive index. The absorption coefficient decreases with increasing scatte ring angle and achieves a minimum value for the backscattered mode. Th e analysis reveals that the large refractive index and small absorptio n coefficient can easily be obtained in a magnetized centrosymmetric s emiconducting crystal, and establishes their potentials as candidate m aterials for fabrication of cubic nonlinear devices.