Research On Free Space Optical Communication System

Free space optical communication (FSO) or wireless optical communication as other called, a combination of optical fiber communication and wireless communication, is a dual direction communication technology using laser as media to transmit audio, data and video through the space. FSO technology has the same ability as optical fiber in transport, capable of communicating in the speed of up to the order of thousand MHz. It is also called"visual optical fiber communication", because it have similar mechanism with optical fiber communication, each of which consists of transmitter and receiver.At present, most of big cites in China have implemented Fiber To The Curb (FTTC ) and Fiber To The Zone (FTTZ.), But the"last mile"from curb, zone to terminal users still remains narrow band connection, which becomes the choke point to the services of wide band. FSO technology is wildly used to address this problem.The dissertation first introduces the history of the FSO, its advantages and current development, discusses the main factors which affects its communication performance, and presents an applicable scheme for the FSO system. Afterwards, the dissertation analyzes the functions of transmitter and receiver of the FSO system, especially the VCSEL transmitter circuit, APD receiver circuit, APD bias circuit and PECL interface circuit. At last, the dissertation introduces experiments with FSO sample product, with associated parameters are evaluated and some advices on how to enhance the performance of the FSO system.