Dispersion Monitoring for Advanced Modulation Formats using Nonlinear Detection

In high bit rate transmission systems beyond 10 Gbit/s (such as 100 Gbit/s Ethernet) static dispersion compensation is not sufficient to guarantee reliable links. Dispersion monitoring is necessary for adaptive dispersion compensators. Dispersion estimation by means of nonlinear detection is a promising approach that was studied so far for amplitude modulation formats like NRZ and RZ. In this paper, we show that this technique can also be used for modulation formats like DPSK and DQPSK. The behavior of these modulation schemes in the presence of chromatic dispersion is shown and the output of the nonlinear detector is explained using numerical simulations and analytical calculations.