文章介绍了40 Gbit/s DP-QPSK(双极化四相相移键控)模块的调制技术、相干接收技术和总体方案设计以及在模块中需要解决的关键问题。利用DP-QPSK调制技术和相干接收技术，实现了40 Gbit/s光系统的长距离传输。40 Gbit/s DP-QPSK具有很高的光谱效率以及较大的色散和偏振模色散容限，可以更好地提高线路利用率，提高密集波分复用系统的光谱效率。

This paper introduces the modulation technology, coherent reception technology,the overall design and other key issues for 40 Gbit/s Dual-Polarization Quadrature Phase Shift Keying (DP-QPSK) modules. Using these technologies, it realizes the long-range transmissions of 40 Gbit/s optical systems. As they feature in high spectrum efficiency and large dispersion and PMD tolerances, it can improve the line efficiency, and maximize the spectral efficiency of the DWDM systems.