Space Optical Communications, Optical Antenna System Design And Performance Analysis

Recently, much attention has been paid on communication systems at 1550 nm band with the development of Optical Fiber Communications, especially the mature technology of optical amplifiers and WDM. The space optical communication at 1550 nm will become the development trend in the filed of high speed satellite optical communication in future. According to the current technology level, many key technologies should be still further improved. They mainly contains: (1)Precision transmitting and receiving optical antenna technique, (2)High precision alignment technique, (3)Optical amplifier technology with high energy conversion efficiency, (4)The technique of coupling space light to fibers, (5)Space environmental adaptability technique. Based on the first two key technologies mentioned above, the design principle and methods of optical antenna systems have been researched in this paper. An optical antenna system with the central wavelength located in 1550nm has been designed. The system has been realized by manufacture and test.The main contents are as follows:1. The methods of optical systems design have been introduced, meanwhile, the application and optical properties of aspheric optical parts have also been analyzed. According to the comparative analysis of structures and the image quality of the optical antennas, the Cassegrain antenna has been chosen to be applied in the design of this optical antenna system.2. By the analysis of Cassegrain antenna structure and Zemax, the 1°field angle Cassegrain antenna, whose primary and secondary mirrors are aspheric, has been designed. Its properties have been analyzed, such as gain, image quality, collimation characteristic, and transmission efficiency.3. The optical antenna system in transceiver has been designed by means of Zemax. This system includes transmitter channel, receiving channel and experiment channel. The system can realize the functions of transmitter-receiver isolation and multi-light ways using dichroic mirrors and beam splitting prisms. The materials of optical elements have been analyzed and reasonably selected after consulting with the produced unit.4. The wavefront aberration and transmission efficiency of the system have been tested, the RMS is 0.046λand the efficiency is 71.4%. Both of them satisfy the design requirement. The image quality and beam spread loss have been analyzed, meanwhile, the power decline curve has been obtained by means of the detailed analysis of antenna system in partial axis situation.