干旱区生态环境知识资源中心

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 mu m 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 mu m wavelength, it should be possible to overcome many transmission limitations associated with atmospheric conditions such as adverse weather and turbulence.