DENSITY-MATRIX MODEL FOR HIGHLY NONDEGENERATE 4-WAVE-MIXING IN SEMICONDUCTOR-LASER DEVICES

A model for highly nondegenerate four-wave mixing in semiconductor las ers has been implemented, with possible application to amplifiers oper ating under multifrequency optical fields and to oscillators used for frequency conversion. Fast phenomena, such as spectral hole burning an d hot carrier effects, are accounted for in a unified approach through the density matrix formalism. Hence, the model is suitable for evalua ting frequency mixing effects over a very wide range of beat frequency , starting from zero up to thousands of gigahertz. Interest in these p henomena has increased in recent years, both for the analysis of basic material characteristics and for application to devices for multichan nel coherent optical communication systems. As an example, the model h as been used to compute intermodulation effects in a travelling-wave a mplifier, under multicarrier operation. The numerical simulation resul ts are in satisfactory agreement with experimental measurements recent ly reported in the literature.