Abstract

All-optical switching has been demonstrated for the first time in a single-mode GaAs/AIGaAs strip-loaded nonlinear directional coupler (NLDC). The sample is grown by molecular beam epitaxy (MBE), and the guiding layer consists of sixty periods of GaAs/AIGaAs multiple quantum wells with 100-Å thickness for both the wells and barriers. The channels are formed by reactive ion etching of the top AIGaAs layer with a photoresist mask. The cleaved ends of the NLDC allow light to be end-fire coupled into the guides. A microscope objective with a numerical aperture of 0.65 is used to focus the light into the waveguides, and the output intensity profiles are monitored on an oscilloscope screen by means of a line scan. Linear cross coupling is observed at low input intensities, ~870-nm wavelength, and most light can be switched back into the input channel with a contrast ratio >3. Using picosecond pulses, the effect of carrier diffusion is negligible.

© 1988 Optical Society of America