Research On The Communication Performance Of Partially Coherent Light Based On Fiber Array

Free space optical communications(FSO) has become one of the best way to the future mobile communication because of its advantages of high bandwidth, security and anti-interference. However, FSO is greatly influenced by atmospheric turbulence, w hich seriously affects the performance of FSO links. Studies have show n that the influence of atmospheric turbulence on partially coherent light is smaller than that on fully coherent light, which can effectively suppress the influence of atmospheric turbulence on FSO link. So partially coherent optical communication becomes a hot topic in the field of communications in recent years. However, traditional ways of producing partially coherent light have disadvantages of low rate, uncontrollable, not suitable for a tmospheric laser communication system. Thus, conducting research of high power and coherence controllable partially coherent light has important academic significance and practical value.This paper systematically analyzes the influence of atmospheric tur bulence effects on atmospheric laser transmission. Utilizing the basic theory of free space optical communication system under the conditions of atmospheric turbulence, this paper analyzes the average signal noise ratio(SNR) and bit error rate(BER) and proposes a new approach of generating partially coherent light based on fiber array. From the light of temporal coherence and spatial coherence, this paper analyzes the basic theory of partially coherent light and builds two kinds of arrays distribution models: a uniformly linear array distribution models and circle array of distribution models. This paper analyzes array beam intensity distribution and transmission characteristics of space in far field, simulates different array beam models, studys the effects of different array model synthesis effects, the impact of different arrays of intensity correlation coefficient model, and the number of different picket effect on the intensity correlation coefficient. Simulation results show that compared with the uniformly linear array, circular array synthesis effect profile is better. The intensity correlation coefficient increases with the number of array elements within a certain range. When the number of array element reaches to a certain value, the growth rate of intensity correlation coefficient gets slow and ultimately tends to the theoretical value of 2. Finally, based on the optical fiber array of partially coherent light experimental system and compared with uniformly linear array,this paper designs circ ular array model and researchs synthesis results. On this basis, this paper increases the voltage range of phase modulator to increase the phase modulation range. The results show that using phase-modulated beam path after seven fiber array synthesis, partially coherent light can be produced whose intensity correlation coefficient is between 1~1.8.Finally, Utilizing the partially coherent Gaussian Schell-Model(GSM), this paper analyzes the intensity flashing index and BER of partially coherent GSM under t he condition of weak atmospheric turbulence. Using the circle fiber array, utilizing the non-Kolmogorov spectrum model under weak atmospheric turbulence, this paper deduces the intensity flashing index of circle fiber array and analyzes the BER of partiall y coherent light based on fiber array utilizing the model of Lognormal.