Abstract

Differential pairs of PnpN optical thyristors are among the most promising devices for digital parallel optical information processing systems. Very recently it has been shown that these AlGaAs based detector-emitter type of devices can be cascaded at 50 MHz with only 7.2 fJ external optical input energy [1], and that this optical input energy scales with device area resulting in a record sensitivity of 15 aJ/μm² [2]. The layer structure of these optical thyristors has been designed such that all free carriers can be extracted from the center p- and n-type layers by applying a small negative anode-to-cathode voltage pulse (complete depletion for a turn-off voltage of - 4V), while switching on the device requires a break-over voltage of 2.7 V. To be of use in practical systems the device has also been engineered to be cascadable. In this way, an optical thyristor operating as a detector is sensitive to the light that an identical element, working as an emitter, generates. Moreover, a differential pair configuration has been adopted to increase the optical input sensitivity [3]. Finally, correct operation of 8*8 monolithic arrays (see Fig la) of these completely depleted, cascadable differential pairs has been demonstrated [4].

© 1995 Optical Society of America