2-D Digital Frequency Offset Loading Technique for Discrete Spectrum Modulated Nonlinear Frequency Division Multiplexing System

In this paper, we propose a two-dimensional digital frequency offset loading (2D-DFOL) technique for discrete spectrum modulated nonlinear frequency division multiplexing (DS-NFDM) system. It makes full use of two degrees of encoding freedom, the real part and the imaginary part of eigenvalues, to load digital frequency offsets (DFOs), with purpose of improving the transmission capacity and mitigating amplified spontaneous emission (ASE) noise of DS-NFDM system. 1 GBaud DS-NFDM simulation results reveal that after 960 km optical fiber transmission, the 2D-DFOL scheme reduces optical signal-to-noise ratio (OSNR) penalty by about 7.1 dB compared to b-coefficient 32 quadrature amplitude modulation (QAM) scheme. Moreover, the proposed scheme achieves a maximum linewidth tolerance of about 1.5 MHz.