Theoretical study of a nonlinear fast silicon photoconductive switch

Silicon-On-Insulator waveguide can be used as photoconductor, the light bei ng coupled in the silicon film by a diffraction grating. Nonlinear effects are induced by the photogeneration of electron-hole pairs. This leads to ph otocurrent variations which are much faster than in linear regime and also much steeper than the incident light pulse. A model is presented which take s into account the refractive index variations arising from both the excess carrier density and the temperature rise induced by carrier recombination and Joule effect. The photocurrent is calculated for various values of the incident light power, incidence angle and pulse duration.