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

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