Polarization mode dispersion compensation experiments in 10 Gb/s and 40 Gb/s optical communication systems

Abstract

Polarization mode dispersion is becoming major system impairment in high speed and long distance optical fiber transmission systems. As the bit rate climbs from 10 to 40 Gb/s per wavelength division multiplexed channel and beyond, optical pulses are increasingly distorted by polarization mode dispersion effect. We report on polarization mode dispersion compensation experiments in 10 Gb/s, 40 Gb/s optical communication systems. The polarization mode dispersion compensator used in the experiments is a compact variable differential group delay element base on concatenation via six magneto-optic polarization rotators (Faraday rotators) of six YVO 4 birefringence crystals whose lengths decrease in a binary power series. Feedback scheme is used to optimize the performance of polarization mode dispersion compensation, using degree of polarization as the feedback signal. In the experiments in 10 Gb/s and 40 Gb/s optical transmission systems, eye-diagrams and bit error rate curves of the code sequences before and after polarization mode dispersion compensation are analyzed. The experimental results demonstrate that the polarization mode dispersion effect induced by the polarization mode dispersion emulator is feasibly mitigated. Separate experiment to reshape the 39 ps pulses distorted by polarization mode dispersion is also carried out. The incident optical pulses with width of 39ps are broadened and distorted by polarization mode dispersion effect and then reshaped by the polarization mode dispersion compensator. The relationship between the feedback signal degree of polarization and differential group delay is also analyzed.