Effects of photoexcited carriers on dynamic response of quantum-well optical modulators

The dynamic response of quantum-well optical modulators in the intrinsic domain is discussed on the basis of a proposed simple model, characterised by the following two processes: excitonic response and photoexcited-carrier relaxation. The response is found to be enhanced in a certain region of modulation frequency and optical power density (quasiresonance phenomena). Comparison between the two most promising quantum-well materials (InGaAs-InP and InGaAs-InAlAs) indicates that the former is more liable to be affected by the photoexcited carriers than the latter.