Demonstration of a 630-GHz photomixer used as a local oscillator

We report the first successful demonstration of a photomixer local oscillator (LO) integrated with a superconducting heterodyne detector. The photomixer LO generated the difference frequency of two diode lasers by optical heterodyne conversion in low temperature-grown GaAs. The measured receiver noise temperature, 331 K at 630 GHz, compares favorably with that achieved using a varactor multiplier LO. We also report the design of a high power distributed photomixer structure.