InGaAsP–InP Heterojunction Phototransistors and Light Amplifiers

A very high optical gain (~900) was obtained near the 1.1-µm wavelength by the InGaAsP-InP heterojunction phototransitor. The light amplifier, which is an integral device of a heterojunction phototransistor and a double-heterojunction laser (or light-emitting diode with confining layers), is presented. The optical bias method is described for the amplification of a weak incident light.