Impact of cross-phase and self-phase modulation on the performance of a multispan WDM system

An analytical approach to incorporate the cross-phase modulation (XPM) and self-phase modulation (SPM) to the calculation of system bit-error rate (BER) in a multispan intensity-modulation direct-detection (IM-DD) WDM system is presented in this paper. The effects of three important link parameters such as pump and probe power and span length, on the system performance have been investigated in terms of BER. An increase in pump power is found to deteriorate the system performance. Increasing probe power is reported to enhance SNR at the receiver end while, aiding the absolute power transfer due to XPM and SPM as well. Conversely, decreasing the probe power allows the fixed noises at the receiver, effectively, the thermal noise, gain ascendancy over the signal power increasing BER. So, restraining the transmission power between an optimum limit is found to be appropriate in maintaining a standard system performance. Increasing span length is also noted to be deleterious in terms of BER imposing a constraint on maximum allowable span length. In all the cases of above mentioned phenomena, a short-period dispersion managed fiber (SPDMF) is found to be very effective as a compensating measure.