Multiple quantum well bistable optical devices with gain

Optical devices utilising the quantum confined Stark effect in thin semiconductor layers are promising candidates for incorporation in fast, low energy switching arrays. The absorption edge in the smaller (direct) band gap material (the quantum well) in such a system is generally dominated by a strong exciton absorption at room temperature. The same multiple quantum well (MQW) device also functions as a high quantum efficiency detector. Simple external circuits can be made to cause positive optoelectronic feedback and bistability in this so-called self-electro-optic-effect device (SEED). One example is a current source consisting of a reverse bias voltage source in series with a photodiode. The authors describe two different modifications to the SEED in which gain is incorporated through phototransistor action giving lower switching power and other possible advantages