Theoretical investigation of an integrated all-optical controller-modulator device using QCSE in a multiquantum well phototransistor

Theoretical investigation of an all-optical controller-modulator device based on excitonic transitions for the purpose of a general logic implementation are discussed. The device is based on the quantum confined Stark effect of the heavy-hole excitonic transition in a multiquantum well. The device consists of three basic elements: modulator, controller, and load. The controller is a heterojunction phototransistor with multiquantum wells in the base-collector depletion region. This allows an amplified photocurrent-controlled voltage feedback with low light levels, allowing one to change the state of the modulator. A detailed analysis of the sensitivity of this device in various modes of operation (i.e. floating base and contacted base) is presented. Studies on the cascadability of the device as well as its integrating-threshold properties are also presented. Switching of the resistive load and optically active load with less than 10 mu W total power is demonstrated to be feasible.<>