星地光通信发展状况与趋势

星地之间日益增长的高数据率和大通信容量的通信需求，必须用光通信来实现。否则卫星光网与光纤光网之间将形成传输“瓶颈”，限制通信的发展。美国的激光通信演示系统、光通信演示和高速率链路设备、空间技术研究卫星2实验、同步轨道轻量技术实验、火星激光通信演示系统，日本的激光通信实验装置等均对星地光通信进行了有成效的探索。中国也在跟瞄（APT）、光相控阵和新型星地通信等研究方面不断探索。如何提高跟瞄系统的性能，如何克服空同大气影响，如何将数据传输率提高到每桫吉比特并实现低误码率，如何使卫星与地面光纤网相连将是未来星地光通信的发展趋势。

Status and Trends of Satellite-to-earth Optical Communications

The increasing demand for high-speed, large capacity data transmission between the earth and satellites may be solved by optical communications today. Otherwise, the satellite-to-earth communication will be constrained by the transmission bottleneck. Relevant researches have been done and resultfull achievements have been obtained, such as the Optical Communication Demonstration System, Optical Demonstration and High-speed Link Devices, STRV-2 Experiment, Geosynchronous Lightweight Technology Experiment (GeoLITE), and Mars Laser Communication Demonstration System (MLCD) developed by the US, as well as the laser communication experimental devices developed by Japan. Researches have also been conducted in China in the areas of Acquisition, Pointing and Tacking (APT), optical phased array and new types of satellite-to-earth communications. There are many problems that are expected to be solved in the future, such as how to improve APT performance, how to overcome the effect of space atmosphere, how to raise the data rate to Gigabit per second with low bit error rate, and how to link the satellite and earth optical networks.