Modeling of semiconductor optical amplifier-delayed interferometer wavelength converter

A model of the semiconductor optical amplifier-delayed interferometer (SOA-DI) wavelength converter is developed and analyzed. Simulations of the device were conducted at 10 Gb/s with Return-to-Zero (RZ) input pulses. It was determined that the performance of the device was heavily dependent on the phase recovery time of the SOA. Slow phase recovery time caused pattern effects and degradation in the Q-factor. The Q-factor and the extinction ratio of the output signal were improved when the phase recovery time was decreased. It was also observed that the parameters that most strongly affect the performance of the device include the phase shifter and the time delay of the interferometer. For each input operating condition, the value of the phase shifter can be selected to maximize the Q-factor, the output extinction ratio, or the contrast ratio. Furthermore, it was determined that the output signal quality is improved with a short delay in the interferometer but at the expense of conversion efficiency. For wavelength conversion, it was determined that the gain of the input CW signal should be greater than the gain of the input RZ signal along the gain spectrum to ensure a high Q-factor at the output. Simulations of the device were also conducted to examine the regenerative properties of the SOA-DI. Inputs with poor extinction ratio, dispersion-broadened pulses, and poor Q-factor were tested and it was observed that the device improved both the extinction ratio and the Q-factor of the input signal. Whereas, for dispersed input signals (large input pulsewidth), the device performed poorly as low Q-factor and output extinction ratio were observed at the output.