| Since the birth of the optical communication technology,space optical communication has promoted the development of all human beings from the previous industrialized society to the current high-speed information society.The birth of free space optical communication has brought about more secure and private,lower power consumption,stronger anti-electromagnetic interference ability,larger transmission capacity,smaller equipment volume,and more convenient technology for erection.Optical antennas for transmitting and receiving beams and optical fibers for beam transmission are very important components in optical transmission systems.In order to improve the transmission efficiency,the center occlusion of the optical antenna is a problem that researchers have been exploring continuously.This paper uses the dark hollow characteristic of Bessel Gaussian beam to analyze and study this problem.At the same time,this paper also studied the coupling efficiency of Bessel Gaussian light and optical fiber.The main research contents of the thesis are as follows:(1)Proposed to use the hollow characteristic of Bessel Gaussian beam to try to solve the occlusion problem of the antenna secondary mirror,and at the same time analyzed and calculated the transmission efficiency at this time.The Bessel Gaussian beam can significantly improve the transmission efficiency in the Cassegrain antenna.(2)The optical field distribution,phase distribution and far field of the Bessel Gaussian beam transmitted by the Cassegrain optical transmitting antenna are studied and analyzed,as well as the wavelength change and the defocusing of the antenna main mirror due to various factors.Influence on optical field distribution,phase distribution and transmission efficiency.When the defocus of the antenna main mirror is positive,the transmission efficiency will increase,but when there is defocus,the intensity distribution and phase distribution of the Bessel Gauss transmitted by the double-throw Cassegrain optical antenna will change in the observation plane.The quality of the transmitted beam is greatly reduced,so it is not feasible to increase the transmission efficiency by defocusing the Cassegrain antenna system.(3)A comparative analysis of the efficiency of Bessel Gaussian light and other vortex lights that have the same hollow characteristics as the optical field and the distribution of the far-field in the antenna are carried out.Generally speaking,the Bessel Gaussian beam is in the Casseger.The transmission performance of Len optical antenna is better than that of Laguerre Gaussian beam.(4)The coupling efficiency of the Bessel Gaussian beam and the single-mode fiber is analyzed,including the transmission efficiency of the coupling between the Bessel-Gaussian beam and the single-mode fiber in the case of horizontal and vertical deviation and random jitter.(5)A combined lens is designed to improve the transmission efficiency of the Bessel Gaussian beam when it is coupled with it.The coupling efficiency is greatly improved when the reciprocal of the numerical aperture of the coupling lens is different. |
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