2018 Volume 15 Issue 12 Pages 20180453
In this paper, we present a general cross-phase modulation (XPM) model based on the Volterra series transfer function (VSTF) method in hybrid coherent QPSK/OOK wavelength division multiplexed (WDM) systems. The general model can entirely describe XPM effects in dispersion management (DM) fiber links. Normalized square deviation (NSD) is employed to test the precision of our model. The results show that we can achieve NSD less than 10−3 as launched peak power below 4 dBm/ch in DM fiber links. The accuracy of our model is sufficient for current hybrid coherent QPSK/OOK WDM systems. Based on our XPM model, the statistical properties of XPM effects can be predicted at the end of DM fiber links, the launched optical power can be optimized to achieve the optimum system performance, and the analytical expression of bit error rate (BER) can be obtained to predict the performance of QPSK channel coherent receiver. We present comprehensive analysis regarding the applications of our model through both theoretical analysis and Monte Carlo (MC) simulation. The good consistence between MC simulation and analytical result validates our theoretical derivation. Our results will be very useful for the design of hybrid coherent QPSK/OOK WDM systems without resorting to time-consuming numerical simulation.