Quadratic nonlinear response to 1.56 \mu m continuous wave laser in semi insulat

The nonlinear photoresponse to a 1.56-\mu m infrared continuous wave laser in semi-insulating (SI) galliumarsenide (GaAs) is examined. The double-frequency absorption (DFA) is responsible for the nonlinear photoresponse based on the quadratic dependence of the photocurrent separately on the coupled