Performance Analysis of All-optical PPM-mQAM Communication Systems

Abstract

Abstract Increasing the spectral efficiency of transmission has increased interests in hybrid optical communication systems. However, these systems suffer from the nonlinear fiber impairments that produce nonlinear phase noise (NPN). In this paper, we investigate all-optical coding m-ary quadrature amplitude modulation (mQAM) by pulse position modulation (PPM) in a single channel optical communication system to increase the transmission capacity and reduce the NPN. The system performance that optically modulates the data by hybrid PPM-mQAM format is numerically investigated by simulation. The results show that the transmission capacity is duplicated and NPN is significantly moderated when PPM-4QAM and PPM-16QAM are used. At bit error rate (BER) of 10−4, the transmission distances of PPM-4QAM is increased by about 33%, in comparison to 4QAM system. In addition, the required optical signal-to-noise ratios (OSNRs) for achieving BER of 1×10−4 are decreased by 4.7 dB and 7.5 dB for the PPM-4QAM and PPM-16QAM schemes, respectively.