Abstract

We have demonstrated nonlinear grating coupling into InSb planar waveguides at room temperature using a CO₂ laser. This is a thermal, positive nonlinearity causing changes in the index of refraction and thus in the Bragg coupling condition. The nonlinearity manifests itself in a shift in the angle for maximum coupling as well as a change in line shape of the coupled power-vsangle curve. The resulting asymmetry, which agrees qualitatively with the theory of Carter and Chen, leads to switching from low to high coupled intensity as the input intensity is varied.

© 1986 Optical Society of America