Efficient and reliable digital sub-band multiplexed nonlinear frequency division multiplexing system

Nonlinear frequency division multiplexing (NFDM) is a promising optical transmission system that avoids fiber nonlinear effects, but suffering from unsatisfied spectral efficiency due to the guard interval (GI) devoting to combat the cumulative chromatic dispersion (CD), whose contribution to efficiency declination is quadratic to the bandwidth. In this paper, we propose what we believe to be a novel digital sub-band multiplexed (DSBM) NFDM system that can diminish the minimal required guard interval and therefore realize considerable information rate without reliability degradation. Through numerical simulation, we show that root raised cosine (RRC) shaped subcarriers are more suitable than the commonly used orthogonal frequency division multiplexing (OFDM) shaped ones in our DSBM-NFDM system. By multiplexing 15 sub-bands, we achieve a 129.7% improvement in effective information rate (EIR) compared to the single channel (SC) NFDM system with the same effective bandwidth. Meanwhile, we achieve a net information rate of 531.0 Gbps NFDM transmission over 960 km with SE of 3.86 bit/s/Hz, which is below the hard decision forward error correction (HD-FEC) threshold. This work is the first to introduce the DSBM technique into NFDM system, and it can be considered as a novel subcarrier shaping scheme for NFDM that has potential to advance its practical implementation.