Robust architecture for autonomous coherent optical receivers

We propose a new architecture for coherent intradyne optical receivers that autonomously identifies and decodes OOK, BPSK, QPSK, and 16-QAM modulation formats. The architecture robustly determines the total accumulated chromatic dispersion, the symbol rate that is not tightly constrained, the number of distinct modulated polarizations, and the modulation format using higherorder statistics of the sampled signal. Thus, unknown signals from noncooperating transmitters, including legacy transmitters, can be optimally demodulated yielding minimum BER. Experimental single-channel signals transmitted through 1056 km of large-area fiber are demodulated with the new autonomous receiver with essentially identical performance compared to receivers with prior knowledge of the modulation format.