A novel method for chromatic-dispersion monitoring

A novel method for chromatic-dispersion monitoring based on PM–AM conversion is presented. A nonlinear element (NLE) was used as phase-modulator to improve the monitoring performance. The method was investigated numerically and experimentally for 40-Gbit/s signals in NRZ/RZ and CSRZ formats. The monitoring range was enlarged to 1670 ps/nm, and the monitoring sensitivity was improved to 0.012 dB/(ps/nm) for the NRZ signal. The corresponding values for the RZ50 signal were 680 ps/nm and 0.0046 dB/(ps/nm), respectively, and, for the CSRZ signal, 620 ps/nm and 0.0092 dB/(ps/nm), respectively.