Experimental and theoretical study of ultrafast optical switching using guided mode excitation in silicon on sapphire

A silicon film sandwiched between a sapphire substrate and a silver layer is used as nonlinear optical waveguide. Light is coupled in the guide by a grating coupler which has been optimized. This device presents fast switchings under a nonlinear regime. A theoretical analysis taking into account both electronic and thermal refractive index variations in silicon well describes the experimental results.