Study Of Coupling System Of A Novel Optical Antenna

Free space optical communication has the advantages of both fiber communication and microwave communication, and now it is a new broadband communication which arouses great interests of people. Developed countries have carried out comprehensive studies on various systems such as inter-orbital, space-to-ground, ground-to-space, and terrestrial free space optical communication systems, and some have already brought forward commercial products. With the progress of free space optical communication technologies, researchers prefer systems making use of mature commercial fiber communication techniques based on 1550nm that increases capacity and decreases the cost. Just in this research background, this paper presents an optical wireless communication system based on a novel optical antenna, and analyzes the part of optical coupling in this system.The optical coupling system in this paper is divided into two parts: first, the Gauss beam coupled to multi-mode fiber through optical elements; second, multi-optical signal coupled to one fiber.For the first part, this paper finishes simulation of the Gaussian beam coupled to multimode fiber through optical elements based on the theory of Gauss beam transmission, and discusses the effect to coupling efficiency when coupling spot offset from the location of the fiber core diameter. Coupling efficiency can be maximized by optimizing the relative aperture of coupling lens. Theoretical analysis indicates that coupling efficiency reaches a maximum of 81.45% for 1310nm laser beams, when the relative aperture of coupling lens is 0.3100, and the coupling efficiency reaches a maximum of 82.54% for 1550nm laser beams, when the relative aperture of coupling lens is 0.3700.For the second part, this paper establishes the theoretical model of N×1 fiber coupler based on the waveguide theory, and discusses the propagation characteristic of optical power in the coupling area and also analyzes optical coupling loss of system.Finally, this paper estimates the coupling efficiency of 58% of optical wireless communication system, which meets the design requirements of the system.