Optimization of InP-InGaAs HPT gain: design of an opto-microwave monolithic amplifier

We have designed an opto-microwave monolithic amplifier with emphasis on the definition of the opto-microwave power gain. First, we present physical simulations of an InP-InGaAs heterostructure phototransistor (HPT), which enable the structural analysis of the composition and behavior of the phototransistor. From these simulations and from both electrical and optical measurements, we next established a large-signal model, which adds photoelectric effect to an HBT model. Small-signal opto-microwave S-parameters of the HPT are first defined and then related to the small-signal opto-microwave power gain of the phototransistor. Relations are given to enable optimum loads on the base and collector ports to be found so that the opto-microwave gain can be optimized. An opto-microwave amplifier is then designed, realized, and measured with a setup based on the beating of two lasers.