Soliton content in the standard optical OFDM signal

Abstract

Nonlinear Schrödinger equation (NLSE) is often used as a master path-average model for fiber-optic transmission lines. In general, NLSE describes the coexistence of dispersive waves and soliton pulses. Propagation of signal in such a nonlinear channel is conceptually different from linear systems. We demonstrate here that the conventional orthogonal frequency-division multiplexing (OFDM) input optical signal at powers typical for modern communication systems might have soliton components statistically created by the random process corresponding to the information content. Applying Zakharov-Shabat spectral problem to a single OFDM symbol with multiple sub-carriers we quantify the effect of statistical soliton occurrence in such an information-bearing optical signal. Moreover, we observe that at signal powers optimal for transmission OFDM symbol incorporates multiple solitons with high probability. The considered optical communication example is relevant to a more general physical problem of generation of coherent structures from noise.

Evolution of Spatiotemporal Intensity of Partially Coherent Pulsed Beams with Spatial Cosine-Gaussian and Temporal Laguerre–Gaussian Correlations in Still, Pure Water

“…The self-focusing effect comes from the source-induced spatial and temporal interference effects (pulse chirp) and should not be associated with the medium's non-linear effects. In cases when the dispersive medium is nonlinear, the four-wave-mixing [53] and formation of optical solitons must be additionally discussed [54]. We note that there is a report available on propagation of the spatially partially coherent beams with non-Gaussian correlation in oceanic turbulence [55] in which the correlation-induced phenomenon of self-focusing also appears, confirming the validity of our results.…”

Analysis of laser radiation using the Nonlinear Fourier transform

“…The experimental methodology can also be expanded to account for polarisation diversity of the radiation in the study of Manakov-like systems. The demonstrated techniques are not limited to fibre lasers, and can be extended to the study of other lasers 50 , optical signals 67 and partially coherent light sources in general. Utilising NFT jointly with other well-known techniques, like collective coordinates, can help modelling some of these light sources.…”

Neural networks for computing the continuous nonlinear Fourier spectrum in focusing nonlinear Schrodinger equation: NFT-Net

“…In this work, without loss of generality, we analyse the NF decomposition of the signals having the form of wavelength division multiplexing (WDM) format with random modulation and return-to-zero carrier functions, considered in 59,60 . In the time domain, one (normalised) WDM symbol to decompose is given as the sum of independent subcarriers:…”