Boost up of four wave mixing signal in semiconductor optical amplifier for 40 Gb/s optical frequency conversion

The 40 Gb/s optical frequency converter for non-return to zero differential phase shift keying (NRZ-DPSK) signal by using four wave mixing in semiconductor optical amplifier (SOA) have achieved sucessfully. The optimized signal-to-pump ratio for NRZ-DPSK by using optimized SOA structure with enhanced FWM effect is also evaluated. The optimum signal-to-pump ratio is 12 dB and 10 dB with Q factor penalty of 0.685 dB and 0.663 dB. The dependence of four wave mixing efficiency and converted signal power on signal input power is studied and it is evaluated that four wave mixing efficiency decreases with increase in the input power. The impact of pump power, signal-to-pump ratio, and SOA parameters with Q factor penalty for 40 Gb/s has been illustrated. It has shown that converted signal power increases up to the saturation power of semiconductor optical amplifier, then decreases. It is observed that for the optimum pump power, OSNR of converted signal varies little with signal input power.