Autoencoder assisted subcarrier optimization for nonlinear frequency division multiplexing.

Nonlinear frequency division multiplexing (NFDM) is a novel optical communication technique that can achieve nonlinear free transmission. However, current design of NFDM is analogous to orthogonal frequency division multiplexing (OFDM), where sinc function is utilized as subcarriers, which may not be optimal for nonlinear spectrums. In this paper, we propose an auto-encoder (AE) assisted subcarrier optimization scheme for dual-polarized (DP) NFDM systems.

Joint nonlinear optical signal-to-noise ratio estimation and modulation format identification based on constellation-points trajectory information and multitask 1DCNN for WDM systems.

We propose a joint monitoring scheme of nonlinear optical signal-to-noise ratio ( ) estimation and modulation format identification (MFI) in wavelength division multiplexing (WDM) systems. Based on the abundant information of both nonlinear noise (NLN) and modulation format (MF) in received signals, this scheme first counts the trajectory information of all adjacent constellation points, and then quantifies them into the adjacent matrix. Subsequently, the eigenvectors corresponding to the largest eigenvalues are extracted via eigen-decomposition of the adjacent matrix, which characterize the information of NLN and MF effectively.

Offset double sideband carrier assisted differential detection with field recovery at low carrier-to-signal power ratio.

Four system frameworks based on carrier assisted differential detection (CADD) receivers for offset double sideband (DSB) signal transmission, including offset DSB asymmetric CADD (offset DSB A-CADD), offset DSB symmetric CADD (offset DSB S-CADD), offset DSB parallel double delay asymmetric CADD (offset DSB PDD-A-CADD), and offset DSB parallel double delay symmetric CADD (offset DSB PDD-S-CADD) are proposed to reduce the requirement for carrier-to-signal power ratio (CSPR) and improve the spectral efficiency (SE) of the self-coherent detection. These frameworks accommodate signal-signal beat interference (SSBI) and efficiently solve the noise enhancement by placing a frequency gap as wide as the signal bandwidth in the middle of the left and right sideband signal. Massive theoretical derivation and simulation verification illustrated that compared with previous interleaved A-CADD, our system achieve field recovery under the condition of 0 dB CSPR with the improvement of SE by 5%, and the OSNR sensitivity is improved by 4.

Blind modulation format identification based on improved PSO clustering in a 2D Stokes plane.

Blind modulation format identification (MFI) is indispensable for correct signal demodulation and optical performance monitoring in future elastic optical networks (EON). Existing MFI schemes based on a clustering algorithm in Stokes space have gained good performance, while only limited types of modulation formats could be correctly identified, and the complexities are relatively high. In this work, we have proposed an MFI scheme with a low computational complexity, which combines an improved particle swarm optimization (I-PSO) clustering algorithm with a 2D Stokes plane.