Polarization decay in ultrafast collinear nondegenerate four-wave mixing in a semiconductor amplifier

The time evolution of the nondegenerate four-wave mixing polarization in a semiconductor optical amplifier (SOA) is investigated theoretically by solution of the semiconductor Bloch equations, including all the relevant scattering processes. The results are in direct agreement with recent experimental measurements, showing that a treatment of coherent and incoherent effects in SOA's on the level of a microscopic theory is highly desirable.