Nondegenerate four-wave mixing in Mid-IR quantum cascade semiconductor optical amplifier

We present a structure for nondegenerate four-wave mixing (FWM) generation between two short optical pulses in mid-infrared quantum cascade semiconductor optical amplifier (QCSOA) and analyze by using finite-difference beam propagation method (FD-BPM) for the first time. We use the simple nonlinear propagation equation taking into account gain saturation, short carrier relaxation time, ultrafast nonlinear refraction, and gain dispersion. To analyze FWM in a QCSOA, the evolution in time and spectral domain of optical pulses with different frequencies during propagation is calculated. Simulation results reveal that these parameters are important in characteristics of output optical pulses in the time and frequency domains.