Nonlinear waveguide structures with grating couplers may operate as sensitive and contrasted alloptical switches (with threshold refractive index changes as low as ≈10~(-3)). III-V materials exhibit high nonlinearities around their bandgap edge and are good candidates for optical switching. However, as these material absorption (n") and nonlinear coefficients vary very rapidly near their bandgap edge, it is important to measure them in-situ to define operating conditions and coupler characteristics.In these materials, various nonlinear phenomena can be observed, which depend on the material and device properties and on the time scale under study.
展开▼
