Enhanced performance of polarization-independent four-wave mixing in polarization-sensitive semiconductor optical amplifiers

A detailed analysis of polarization-insensitive and frequency conversion interval-independent four-wave mixing (FWM) is undertaken in an optical loop configuration, which employs a single semiconductor optical amplifier (SOA) and two pump waves. It is shown that by appropriately aligning the polarization states of the pump waves at the input ports of the scheme, the utilization of a polarization sensitive SOA not only supports polarization-independent FWM, but can also significantly enhance the output conjugate power. Methods for obtaining the optimum polarization directions of the pump waves are reported. Investigations have also shown that SOAs with polarization dependent optical gains do not affect the residual FWM polarization sensitivity of the optical loop.