Analytical Calculation of Stimulated Brillouin Scattering in Magnetic Fields Applied to n-InSb

For the study of parametric excitation, we have considered that the origin of Stimulated Brillouin Scattering (SBS) nonlinear interaction lies in the third-order optical susceptibility in a centrosymmetric, doped semiconductor which is subjected to transverse magnetic field. The third-order optical polarization in a SBS system arises due to nonlinear current density and acousto-optical strain of the medium. The displacement of lattice motion and threshold expressions are determined and conditions for the onset of the SBS are obtained. The induced acousto-optical polarization and effective Brillouin polarization are determined using a coupled mode scheme. Using the effective Brillouin polarization so achieved, the transmitted intensity and efficiency of the Brillouin cell have also been calculated. The effect of wave number, electric field, doping and magnetic field on different parameters is also studied and numerical estimations are made for n-InSb at 77 K duly shined by a pulsed 10.6 mm CO2 laser. The lattice displacement is significantly enhanced by wave vector, electric field and transverse magnetostatic field. It is observed that the acousto-optical polarization increases with magnetic field while the nonlinear induced polarization decreases. The effective Brillouin polarization increases with wave number, electric field amplitude and magnetic field which is required to achieve an optical-phase-conjugation process.