Research on polarization insensitive AOWC system for 40Gbps 16QAM-OFDM based on wide optical comb generation self-pumping structure

Abstract

In this paper, we proposed a 40Gbps 16QAM-OFDM polarization insensitive all-optical wavelength conversion (AOWC) system based on self-pumping structure of wide optical comb. In this scheme, the carrier suppression modulation is carried out by a laser with Mach-Zehnder modulator (MZM) to generate a wide comb with only 3 dB odd sidebands flatness. By changing the frequency selection of the optical comb, the signal light and two pump lights are generated by the system itself. The analytical results show that the frequency selection of the optical comb and comb flatness can affect the performance of the system. The smaller the frequency interval among three lights selected as signal light and two pump lights are, the smoother the comb is, the better the system performance is. We have also numerically demonstrated that the system performance is best when the frequency interval is minimum, and with the increase of flatness, the system performance gradually decreases. The simulation results can be agreed with the theoretical analyses, the constellation of 40 Gb/s 16QAM-OFDM signal can be seen clearly and the bit error rate of the system can up to 1.26×10- 4. In addition, the effects of injection current of SOA and linewidth of continuous wave (CW) on system performance are also discussed. The proposed system can be a candidate to realize polarization insensitive by the parallel pump lights and signal light from this self-pumping structure, it has the characteristic that the amplitude phase noise conversion can be neglected.