Dynamic adaptive PMD compensation in a 40Gb/s OTDM system

An experiment of two-stages four degrees high-order polarization mode dispersion (PMD) compensation in 40 Gb/s optical communication system with a large PMD is reported. The former stage adopts polarization controller and fixed time-delayed line of polarization-maintaining fiber (PMF). The second stage consists of a polarization rotator and a tunable differential group delay (DGD) line that is based on magneto optical crystal. The second stage is used to compensate remnant first-order PMD. The PMD monitoring technique adopted degree of polarization (DOP) as error signal. A novel practical adaptive optimization algorithm was introduced in dynamic adaptive PMD compensation. Some experimental results show that large PMD is compensated by this compensator in a 40 Gbits/s non-return-to-zero (NRZ) OTDM transmission systems. A significant improvement of system performance can be achieved in the eye pattern of a received signal. Most first-order compensating ability of the compensator is 35 ps. Second-order compensating ability of the compensator is 200 ps
²
. The optimum compensating time is within several milliseconds