In this paper, a coherent 100 Gb/s Wave Division Multiplexing (WDM)/Dual Polarization-Quadrature Phase Shift Keying (DP-QPSK) transceiver is proposed and optimized. The transmission of 40-channels has been achieved over 25×80 km of Standard Single Mode Fiber (SSMF) at 50-GHz channel spacing. A Digital Signal Processing (DSP) module has been implemented at the receiver for further system performance improvement. Simulation results have showed that the Polarization Mode Dispersion (PMD) effect have been efficiently compensated by 45 ps. The system has obtained a high Quality Factor (Q-Factor) for a wide range of input optical power from -10 dBm to 10 dBm with its maximum of 13.8 dB and has just decreased to 10.4 dB at 2000 km. The system has offered a high Degree of Polarization (DOP) of 0.9, indicating that the PMD compensation has been achieved remarkably. Furthermore, the proposed system has attained a spectral efficiency of 1-bits/s/Hz and the eye opening has improved significantly. It has been found out that the constellation diagrams have been distinguishable with very low data transmission errors and the received Radio Frequency (RF) signal has been strong with a very low level of noise.