No abstract

The wet oxidation kinetics of AlAs layers of interest in vertical cavity surface emitting laser (VCSEL) fabrication are investigated in detail. The process is modeled as a diffusion-reaction process. For oxidation over a long time interval, variation of the oxidation rate with the variation of the radius of the etched mesa of the VCSEL is observed. A theory has been developed to obtain the rate equation of the oxidation process and the dependence of the oxidation rate on the size of the VCSEL is explained.

Room-temperature all-optical switching has been achieved in single-mode strip-loaded nonlinear directional couplers with a GaAs/AlGaAs multiple quantum well guiding layer. For low input intensities nearly complete (1:3–1:5) cross coupling occurs, while at high input intensities switching occurs so that most (>3:1) of the light stays in the input guide. The effects of carrier diffusion are minimized by the use of picosecond pulses. The response time and the recovery time of the nonlinear directional couplers are measured with pump-probe experiments, and the origin of the nonlinearity is attributed to fast electronic effects.