Abstract
Free-space optics (FSO) holds the potential for high bandwidth communication, but atmospheric conditions can
significantly affect the capability of this type of communication system to transfer information consistently and operate
effectively. The effects of atmosphere on FSO communication and consequent optimal wavelength range for
transmission are investigated through MODTRAN-based modeling of 1.55 μm transmission for multiple elevation
angles in atmospheric weather conditions including clear maritime, desert extinction, and various levels of rain and fog,
to simulate surface-to-surface and surface-to-air FSO communication networks. Furthermore, atmospheric, free-space,
and scintillation losses are analyzed for optical path lengths of 2 km to determine minimum transmit power required for
successful data reception. In addition, FSO transmitter and receiver circuits were designed to optically relay analog
video signals and their operation verified at path distances of up to 130 m. Using advanced laser sources to provide
illumination at infrared wavelengths, particularly around the eye-safe 1.55 μm wavelength, it should be possible to
overcome many transmission limitations associated with atmospheric conditions such as adverse weather and turbulence.
