Ultrafast all-optical switching in Al _0.18 Ga _0.82 As directional coupler in 1.55 μm spectral region

Abstract

The observation of all-optical switching in a nonlinear AlGaAs directional coupler using the nonresonant contribution to the intensity dependent refractive index, below half the bandgap, is reported. These results represent the first demonstration of an ultrafast device using semiconductor waveguides, where the throughput is not limited by absorption processes.