Rigorous three-dimensional theory of the parametric excitation of space-charge waves in semiconductors

Abstract

We analyze the stability against parametric excitation of space-charge waves of the space-charge field induced in a semiconducting crystal by a traveling light grating. We show that when the grating velocity is low, an important element of the analysis is the allowance for higher Fourier harmonics of the field. By combining analytic and numerical methods we study the stability against an increase in the amplitude of small three-dimensional perturbations of a general type. We find that instability is possible only within a single range of light-pattern velocities and that it leads to selective excitation of one-dimensional perturbations. Finally, we use the results of our analysis to interpret experiments on the generation of spatial subharmonics in sillenite crystals.