Nonlinear Guided Wave Grating Phenomena

The periodicity associated with gratings can be used to wavevector match various interactions between guided waves, and between guided waves and radiation fields. We have investigated such interactions in nonlinear waveguides containing gratings for coupling radiation into and out of waveguides, and distributed feedback gratings for retro-reflecting guided waves. Because the waveguides consist of materials with an in­ tensity-dependent refractive index, the wavevector matching becomes in­ tensity-dependent leading to all-optical functions such as bistability and switching. The geometries studied are all contained in Fig. 1. The waveguides were MBE grown lnSb on GaAs substrates, and exhibited a thermo-optic nonlinearity at CO
₂
laser wavelengths.