| Free-Space Optical Communication is a promising technology through transmitting laser signals in the atmosphere channel to realize the communication of voice, image and data between point-to-point, point-to-multipoint and multipoint-to-multipoint. FSO has received a great deal of attenuation lately both in the military and civilian information society due to its huge capacity, rapid deployment, low cost and high security.In this dissertation, we put forward an all-optical free-space link structure based on the previous photon diode coupled structure. This new structure can be well integrated with fiber-optical communication networks with lower cost. The most crucial part of the link design turn out to be the receiver optics and several design solutions were investigated. We do a number of single mode fiber coupling efficiency and multimode fiber coupling efficiency calculations to see which kind of antenna is best suited. An overall discussion on the loss factors of the FSO link is presented including optical spreading loss, misdirected loss and atmosphere turbulence induced loss. Simulation model of the FSO link is constructed and how the atmosphere attenuation, laser output power and communication range influence BER performance is analyzed. Meanwhile we give the experimental description and the result is analyzed. Finally further improvements for the system have been summarized, which is the next step to research. |
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