Transistor laser functions as non-linear electronic switch, processor

Scanning electron microscope image of a dual-input heterojunction bipolar transistor laser (HBTL) on a Cu heat sink acting as frequency mixer for up and down conversion. The image shows a cleaved, front to back, segment of the laser crystal with emitter (E), base (B), and collector (C) metallization as shown. The laser output is shown schematically as hV and the electrical output as Vout. Both output signals produce integer multiples (mixing) of the input signals at frequencies mf1 +nf2. Credit: Milton Feng and Nick Holonyak