Optical mode division multiplexing for secure Ro-FSO WLANs

Abstract

The widespread deployment of various wireless radio access systems in public areas poses acute issues in frequency assignment. Radio-over-free-space-optics (Ro-FSO) technology enhances spectral efficiency and may pave the way towards a ubiquitous platform for radio and optical domains without optical fiber in local area networks. This paper investigates the performance of simultaneous optical mode division multiplexing of a donut mode, a Laguerre-Gaussian (LG) mode and two Hermite-Gaussian (HG) modes to realize 4x20 Gbps transmission in a Ro-FSO system under clear weather conditions. The power coupling coefficients, received power, signal-to-noise ratios and constellations and are analyzed.