PMD Monitoring by Tracking the Chromatic-Dispersion-Insensitive RF Power of the Vestigial Sideband

We demonstrate a simple technique for polarization-mode-dispersion (PMD) monitoring that is insensitive to chromatic dispersion (CD). By monitoring the extracted radio-frequency clock power from the vestigial sideband, a CD-insensitive PMD feedback signal is realized. For a 10-Gb/s return-to-zero (RZ) system, experimental results show that the fluctuation of the feedback clock power due to CD is reduced from /spl sim/20 to /spl sim/3 dB. In the presence of all-order PMD, the distribution of the clock power is essentially unchanged as the inline CD varies. Simulation results for a 40-Gb/s RZ system are also presented.