Parametric instability of acoustic waves in transversely magnetised piezoelectric semiconductors

The effect of spatial nonuniformity of a large amplitude high frequency oscillatory electric field and a large transverse magnetostatic field on parametric excitation of acoustic waves is investigated for the case of a piezoelectric semiconductor. The analysis is based on the hydrodynamic model of a plasma in the collision dominated regime for kl much less than 1. In a magnetoplasma (ωsub(c) approximately ωsub(p)) the condition of instability gets modified and is obtained at a much lower value of the high frequency oscillatory electric field. The threshold value of the pump electric field is further reduced by the finite pump wave number k0. Numeric estimates are made for n-InSb at 77 K when the crystal is irradiated with a 1.06 μm Nd:YAG laser. (author)