OPTICAL SWITCHING WITH GAIN IN WAVE-GUIDE-MODULATOR STRUCTURES

Optical switching with gain realised with monolithic waveguide-based s mart pixels is reported. In this smart pixel a high-power light beam p ropagating in a waveguide structure is controlled by small surface-nor mal optical input beams incident on a reference diode and a threshold switch. A photoconductive switch, a reference diode and a high-contras t waveguide modulator have been fabricated monolithically from the sam e GaAs/AlGaAS double-hetero-p-i-n structure grown on a semi-insulating GaAs substrate. Even with this first nonoptimised structure an optica l gain larger than 150 has been achieved. The contrast ratio of the ou tput signal was greater than 17dB. The switching energy is 2pJ, corres ponding to 5fJ/mu m(2).