Security Threats for Free Space Optics due to Fog Scattering Phenomena

The paper deals with analyzing possible security risks for Free Space Optics (FSO) communication systems caused by a non-line of sight (NLOS) scattering channel. The higher concentration of scattering particles in the atmosphere leads to increasing scattered optical power, potentially detectable by an eavesdropper. The optical power model of the NLOS FSO channel based on lidar equation is presented. At the end of the paper, the parameters of the eavesdropper's receiver are estimated.