Research On Array Receiving Techniques Of Wireless Optical Communication Based On LCSLM

Wireless optical communication, which is a kind of fiber-free communication technology, is also called free space optical communication. Free space optical communication is becoming a new direction of optical communication because of its advantages of high bit rate, high security, broad bandwidth and good performance on anti-jamming. Specially, optical wireless access system is a better method to solve the"last mile"problem between the LAN and fiber backbone. With computer Wide Band developing, we pay attention to wireless optical communication again.However, because of the channel of the wireless optical communication is the atmosphere channel, the optical signal is inevitably influenced by the effect of the absorbing and the scattering. What is more, the atmospheric turbulence could also induce scintilla, excursion of the facula during the transmission, which badly affect the stability and reliability of the wireless optical communication system. The bad effects of the diffusing and attenuation of the laser during the transmission are both the difficulty that the technology of the wireless optical communication need to overcome.In order to reduce the impact of the influence stated as above, this paper proposed a method of receiving in array to improve the performance of the communication system. With optical receiver system of synthetic aperture principle, a more in-depth analysis of sub-aperture set to receive the signal characteristics. On this basis, in order to overcome the attenuation caused by atmospheric turbulence, a use of liquid crystal spatial light modulator(LCSLM) by changing the way of the beam phase to achieve the signal enhancement purposes. This paper introduces the atmospheric laser communications system and its features, analysis the domestic and foreign research institutions in the atmosphere laser communications research. Then, it discussed the wireless optical communication channel characteristics of the atmosphere and analysis the effects of turbulence and the attenuation of the atmospheric to the beam. In order to overcome such effects, the diversity conception in the wireless communication is used for reference to discuss the variety of the features and power gain influence by the different modes of the diversity. Then the paper introduced the theory of optical synthetic aperture, analyzed the ways of different numbers of the apertures and gave an experimental verification to some extent.In the aspect of beam control, the paper introduced the basic concept of the adaptive optics(AO), proposed the array signal processing program which bases on the liquid crystal spatial light modulator(LCSLM), and analyze in detail the theoretical model of the liquid crystal as for the spatial light modulator(SLM). Finaly, based on the use of the liquid crystal spatial light modulator(LCSLM), an experiment programme of processing the array signals was envisioned.