Orbital-angular-momentum mode-group multiplexed transmission over a graded-index ring-core fiber based on receive diversity and maximal ratio combining

TL;DR

This paper demonstrates a novel OAM mode-group multiplexing scheme over a graded-index ring-core fiber that uses receive diversity and maximal ratio combining to improve signal quality without complex MIMO processing.

Contribution

The paper introduces a simple, effective OAM-MGM transmission scheme utilizing receive diversity and MRC, avoiding complex MIMO equalization in fiber-optic communications.

Findings

Successful transmission of 100-Gb/s over 1 km fiber

Successful transmission of 40-Gb/s over 18 km fiber

Effective noise mitigation using receive diversity and MRC

Abstract

An orbital-angular-momentum (OAM) mode-group multiplexing (MGM) scheme based on a graded-index ring-core fiber (GIRCF) is proposed, in which a single-input two-output (or receive diversity) architecture is designed for each MG channel and simple digital signal processing (DSP) is utilized to adaptively resist the mode partition noise resulting from random intra-group mode crosstalk. There is no need of complex multiple-input multiple-output (MIMO) equalization in this scheme. Furthermore, the signal-to-noise ratio (SNR) of the received signals can be improved if a simple maximal ratio combining (MRC) technique is employed on the receiver side to efficiently take advantage of the diversity gain of receiver. Intensity-modulated direct-detection (IM-DD) systems transmitting three OAM mode groups with total 100-Gb/s discrete multi-tone (DMT) signals over a 1-km GIRCF and two OAM mode groups with total 40-Gb/s DMT signals over an 18-km GIRCF are experimentally demonstrated, respectively, to confirm the feasibility of our proposed OAM-MGM scheme.