High Speed Precompensated Nonlinear Frequency-Division Multiplexed Transmissions

Nonlinear frequency division multiplexing (NFDM) with the modulation of the nonlinear Fourier spectrum (both discrete and/or continuous parts) have been recently considered as a potential transmission method to combat the fiber nonlinearity impairments. However, due to many challenges in design, digital signal processing (DSP), numerical algorithms, and hardware implementation, reported data rates of NFDM systems have been so far limited to 50 Gb/s. In this paper, we experimentally demonstrate a practical approach for increasing the data rate of NFDM transmission systems by increasing the number of modulated nonlinear subcarriers together with the application of a precompensation technique for the channel-induced phase-shift in the nonlinear Fourier domain. As a result, a record-high data rate of 125 Gb/s and spectral efficiency over 2 bits/s/Hz in burst-mode, single-polarization NFDM transmissions were achieved over 976 km of standard single mode fiber with EDFA-only amplification by transmitting and processing 222 32 QAM-modulated nonlinear subcarriers simultaneously.