This paper reports that the designed optical polarization mode dispersion compensator shows a good performance under the real-time variation of differential group delay,state of polarization and principal state of polarization in a (40×43)-Gb/s dense-wavelength-multiplexing,1200-km enhanced return-to-zero differential-quadrature-phase-shift-keying (RZ-DQPSK) system.The polarization mode dispersion tolerance of the system is improved by 26 ps using the optical polarization mode dispersion compensator.The short and long time stabilities are tested with the bit error ratio recorded. This paper reports that the designed optical polarization mode dispersion compensator shows a good performance under the real-time variation of differential group delay, state of polarization and principal state of polarization in a (40 × 43) -Gb / s dense-wavelength-multiplexing 1200-km enhanced return-to-zero differential-quadrature-phase-shift-keying (RZ-DQPSK) system. The polarization mode dispersion of the system is improved by 26 ps using the optical polarization mode dispersion compensator. long time stabilities are tested with the bit error ratio recorded.