Transmission of high data rate optical signals in fog and snow conditions

A well known disadvantage of free space optics (FSO) or optical wireless communication is its sensitivity on local weather conditions-primarily to fog and precipitation, resulting in substantial loss of optical signal power over the communication path. Results of a propagation study on a terrestrial free space optics (FSO) link at 950 nm and 850 nm on 79.8 m long path are presented. Given these wavelengths, for shorter links fog is the primary concern. For longer links, heavy rain, snow, scintillation and clouds frequently become critical issues. We address here the effects of fog and snow both theoretically and experimentally and present some useful comparisons in terms of the optical signal attenuations.