Balanced Versus Single-Ended Detection of DPSK: Degraded Advantage Due to Fiber Nonlinearities

We study the effect of nonlinear transmission on the receiver sensitivity advantage of differential-phase-shift-keying systems using balanced detection. We show how the accumulation of nonlinear phase noise owing to the Gordon-Mollenauer effect reduces the advantage of balanced detection, until it is completely eliminated in highly nonlinear scenarios. The results of our analysis are consistent with existing experimental observations