Stimulated Brillouin scattering in a centrosymmetric semiconductor plasma

Abstract

Based upon the electromagnetic treatment, stimulated Brillouin scattering (SBS) in a centrosymmetric, doped semiconductor which is subjected to a transverse magnetic field is investigated analytically. The origin of this non-linear interaction is considered to be found in the third order optical susceptibility arising due to non-linear current density and acousto-optic polarization of the medium. The threshold condition is obtained for the onset of the SBS. The effective Brillouin susceptibility and the resulting gain is determined using the coupled mode scheme. Using the effective third order polarization so achieved, authors have also calculated the transmitted intensity and Brillouin cell efficiency. The effect of magnetic field and doping on threshold field and Brillouin gain is also studied. Numerical estimations are made for n-InSb at 77K duly shined by a pulsed 10.6 μm CO2 laser. The gain constant is significantly enhanced under high power pulsed excitation below the damage threshold and under the influence of a transverse magnetostatic field when the cyclotron frequency is less than the acoustic wave frequency. The required threshold electric field for the onset of the SBS process is also reduced significatly in the presence of a magnetostatic field. The minimum cell length required to achieve optical phase conjugation is found to be 0.45 μm.