20-Gb/s and higher bit rate optical wavelength conversion for RZ-DPSK signal based on four-wave mixing in semiconductor optical amplifier

摘要

We investigate 20Gb/s wavelength conversion for return-to-zero differntial phase-shift keying (RZ-DPSK) signal using four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). We show that the 10-Gb/s RZ-DPSK signal-to-pumb ratio increases up to -0.286 dB with Q factor improvement of 1.663 dB for increasing the cascadeability of optical networks. The effect of variation in bandwidth for an ideal dual-arm Mach-Zehnder interferometer (MZI) is illustrated. For different bit rates, the converted power signal is invesitigated with increase in signal input power. We show that the quality of converted singal is best before the saturation of SOA. The signal input power is also studied, and it is found that FWM effiiciency decreased with increase in singal input power. The impact of signal-to-pump powe ratio, unsaturated amplifer gain, and pump power is further optimized with minimum Q factor penalty for 10-Gb/s and 20Gb/s bit rate. We show that converted signal power increase up to power satuation level and then starts decreasing . We also show that with higher bit rate, we have a wide range of choices for pumping power signal. We further investigte the quality of converted signal at 10Gb/s, which shows an improvement over signal input power. Finally, the increase in transmission distance after wavelength conversion is investigated.