Stimulated Raman scattering and Raman instability of an intense helicon wave in longitudinally magnetized n-type piezoelectric semiconducting plasma

A detailed analytical investigation is made of the Raman instability of the Stokes component of the scattered helicon wave in longitudinally magnetized n-type nondegenerate cubic piezoelectric semiconductor crystal belonging to the class 4-bar3m. The general dispersion relation is obtained by using coupled mode theory and considering that the scattering is due to both the molecular vibrations produced due to the pump wave at a frequency equal to that of the transverse optical phonons and the electron plasma wave. The dispersion relation is solved for both the cases of scattered helicon waves (i.e. in the cases of left-hand and right-hand circularly polarized waves). The threshold value of the pump amplitude necessary for the onset of instability and the growth rate well above the threshold are obtained analytically for both the modes. The analysis is applied to a specific semiconductor, n-InSb at 77 K duly irradiated by a high-power helicon wave for numerical estimations. The laser wave intensities used are in the range of 109 to 1012 Wm-2 which is assumed to be less than the damage threshold of the InSb crystal. The order of wave amplitude is feasible presently. (author)