Femtosecond Investigations of Optical Switching and X(3) in GaAs Waveguides

摘要

A new technique is described for performing femtosecond transient measurements ofnonlinear index and absorption in waveguide devices. Using a time division interferometry technique in conjunction with a tunable femtosecond laser source we have performed the first measurement of the wavelength dependent nonresonant nonlinear index in AlGaAs. Contributions to nonlinear index arise from both virutal as well as real population mediated processes depending on the wavelength from resonance. Complementary pump-probe measurements of transient absorption provide information on excited state population as well as two-photon induced absorption processes. These measurements provide information on the mechanism and dynamics of fundamental nonlinear optical processes below the band edge in semiconductors and are relevant to possible all optical switching applications in waveguide devices.