Coherent light detection in solid-state photodiodes

Abstract
The operation of solid-state photodiodes as mixers of coherent light is discussed. Particular attention is given to the parameters that influence 1) frequency response, 2) quantum efficiency and 3) sensitivity. The highest mixed frequency that can be detected is determined by carrier transport considerations as well as RC circuit parameters. Output mixed frequencies to 100 kMc can be obtained in appropriately designed structures. Experimental results verifying the existence of photomixing in Si, Ge, GaAs and InAs photodiodes are presented.