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Study on Non-coherent Detection of DP-QPSK Signal Based on Delay-Line-Interferometer

Dual-polarization quadrate phase shift keying (DP-QPSK) is one of the mainstream modulation formats in the current 100Gbps backbone optical network. Study on DP-QPSK demodulation in published literature are more about digital coherent detection. However, in the context of noncooperative communication, the carrier frequency is unable to know which leads to residual frequency offset with coherent detection. This paper studies the method of DP-QPSK noncoherent detection based on delay line interferometer (DLI), avoiding the problems caused by the unknown carrier frequency. An algorithm is proposed to restore the raw data from transmitting end and the simulation results demonstrate that the algorithm is effective.