Wideband optical heterodyne performance of extrinsic photoconductive infrared radiation detectors.

Heterodyne detection of infrared radiation by cryogenically cooled extrinsic photoconductors is reviewed. Operational characteristics of a highly compensated Ge : Hg detector are calculated from experimentally determined material parameters. In many cases wideband, quantum noise limited performance can be obtained only if substantial refrigeration capacity is available at detector operating temperature.