Silicon Photonic Integrated Circuits for Soliton Based Long Haul Optical Communication

We demonstrate a silicon photonic transmitter for soliton-based communications enabling the interleaving of QPSK and APSK modulated soliton pulses overlapping in both the time and frequency domains. The nonlinear Fourier transform is used to both determine adequate soliton launch conditions and facilitate nonlinear equalization at the receiver. A spectral efficiency of 0.5 b/s/Hz per polarization is reached over a 5400 km transmission distance and constitutes, to the best of our knowledge, a record for soliton transmission over such long distances. Linear and nonlinear minimum mean square error and artificial neural network-based equalizers are also experimentally benchmarked, with artificial neural networks resulting in particularly effective equalization in this system.