Optical millimeter wave mode division multiplexing of LG and HG modes for OFDM Ro-FSO system

The scarcity of RF spectrum at lower frequencies has recently been addressed by millimeter wave transmission in fiber-wireless and radio-over-free-space optics networks for more flexible frequency spectrum allocation. This work focuses on parallel transmission of four independent radio OFDM based channels, each carrying 20Gbps data, by optical millimeter mode division multiplexing of spiral-phased Laguerre-Gaussian modes and Hermite-Gaussian modes using a spatial light modulator to realize 80 Gbps-160 GHz data over 50 km free-space link. The performance of proposed system is evaluated under the influence varying levels of fog.