Spectrally stitched nonlinear frequency division multiplexed transmission systems using photonic integrated circuits

We present the implementation of a PIC-based nonlinear frequency division multiplexed transmission system in which spectrally overlapping channels are stitched together without frequency guard bands to obtain a seamless spectrum. To coherently combine the channels with partial overlaps, the channels are generated using a comb source whose pulse repetition rate is synchronized with the clock used to generate the electronic signals. After that, all channels are linearly multiplexed using a PIC in which the delay and phase of all the optical paths are balanced and dynamically corrected. The proposed solution can fill large optical bandwidths while keeping the computational complexity to that of independently processing multiple low bandwidth channels.