MOVING SPACE-CHARGE FIELD EFFECTS IN PHOTOCONDUCTIVE SEMICONDUCTORS WITH INTERBAND OPTICAL-EXCITATION OF FREE CHARGE-CARRIERS

An internal space-charge electric field is established when two mutual ly coherent optical fields interfere inside an intrinsic photoconducti ve semiconductor containing deep-level recombination centers with band -gap energy smaller than the incident photon energy. Dc photocurrents are generated when the two optical fields have unequal center frequenc ies. A mathematical characterization of the behavior of the do photocu rrent, which can be used to characterize the host photoconductive mate rial, is presented and verified experimentally for a Si sample. (C) 19 97 Optical Society of America.