An optoelectronic semiconductor device using stimulated emissionand absorption to achieve the functions of detection, modulation,generation and/or amplification of light. In one embodiment, thedevice includes a waveguide heterojunction bipolar transistor (HBT)biased in the active mode where the minority carrier concentrationin the base is designed with bandgap engineering to optimizeoptical gain in this region. This HBT configuration allows opticalmodulation at considerably higher frequencies and/or with improvedefficiency compared to the prior art, and is particularly suited tothe fabrication of direct or external modulated wideband fiberoptic links.
High injection bipolar transistor
Enquist, P. (1998). IPC No. U.S. High injection bipolar transistor. (Patent No. 5780880).