A modulation format identification method based on information entropy analysis of received optical communication signal

Modulation format identification is an important part of optical performance monitoring in elastic optical networks. We propose a modulation format identification scheme based on the information entropy analysis of received optical communication signal. In our method, the information entropy is calculated based on the amplitude distribution of the received signal and employed to identify four commonly used modulation formats, including QPSK, 16QAM, 32QAM, and 64QAM. The results demonstrate that the modulation format can be identified with the required OSNR not higher than the FEC threshold. The influence of the residual chromatic dispersion on the proposed scheme is also discussed. It is insensitive to phase noise caused by laser linewidth and frequency offset, and can tolerate a range of fiber nonlinearity, which is also an advantage of our method. Compared to other blind modulation formats identification methods, the proposed method needs no additional hardware or training samples, is more simple and cost-effective.