| In free space optical communications, laser beam propagating in the atmosphere, the received optical signal quality is degraded by the turbulence, which will seriously affect the stability and reliability of the communication systems. In this paper, a binary optical array antenna is designed based on analyzing the characteristics of light transmitting in the turbulent atmosphere. Its various sub-apertures receive optical signals and coupled to the fibers, respectively. In the light path, optical components such as phase shifters and couplers are used to process and merge the signal to improve the output signal quality.This article analyze and optimize the structure of binary optical lens using the angular spectrum theory in the space frequency domain, and obtain the binary optical structural parameters, which have the maximum coupling efficiency to couple with optical fiber. Through simulation, when the lens and fiber at different locations, and the incident light wavelengths are different, the coupling efficiency is analyzed, and discussed the binary optical lens's field of view.The article gets the strengthening interference condition and the optimal coupling coefficient from the 2×2 coupler's field equation, and designs a N×N coupler structure. The antenna array receivers can be effective against the atmospheric turbulence, and improve the system's signal to noise ratio and enlarge its'field of view. The simulation shows that, the array antenna's performance will be obvious when the fluctuation of optical signal received by sub-lenses increase or the relevance of the signal decrease. When the array lenses grow in number, the insertion loss is increased by the times of coupling, so the detector circuit noise becomes obvious, and will reduce the array antenna's effect. In the experiment, an array antenna is designed with its various sub-lenses optical axises are set with a certain angle, and the structure further increases the system's field of view. |
PDF Full Text Request