FREQUENCY-CONVERSION IN TRAVELING-WAVE SEMICONDUCTOR-LASER AMPLIFIERSWITH BULK AND QUANTUM-WELL STRUCTURES

A microscopic model of four-wave mixing in semiconductor materials is applied to the analysis of bulk and multiple quantum well travelling w ave amplifiers. The nonlinear optical response includes, in the framew ork of the density matrix formalism, the main four-wave mixing process es for frequency detuning of the input optical fields up to the THz re gion. A typical pump and probe configuration is considered, where a st rong pump at angular frequency omega(pump) with a weaker probe omega(p robe) is injected at the input; at the output a new signal appears wit h omega(signal) = 2 omega(probe) - omega(probe). Particular emphasis i s given to the comparison and the optimisation of frequency conversion in bulk and quantum well amplifiers. In optimised devices, the numeri cal results show good conversion performances in the two kinds of stru ctures, even if quantum well amplifiers give higher conversion gains.