Effect of nonlinear phase noise on performance of DQPSK modulation system

In order to study the effect of nonlinear phase noise on the performance of DQPSK modulation system, based on the analysis of mathematical model of nonlinear phase noise, the property of bit error rate (BER) varying with the change of signal to noise ratio at transmitter was simulated in a 40 Gb/s DQPSK modulation system by keeping the signal to noise ratio at transmitter invariable. Compared with DPSK modulation, DQPSK modulation is much more sensitive to the effect of nonlinear phase noise, and the BER will obviously increase when the nonlinearity is big enough, by which communication quality of the system will be seriously influenced. As a result, the effect of nonlinear phase noise on the system must be taken into consideration when DQPSK modulation is used.