星间激光通信发射终端耦合单元的研究

Research of the optical coupling unit for the transmitting terminal of intersatellite optical communication system

针对星间光通信系统的要求,采用一种新型的半导体激光耦合方案,用前后正交的非球面柱面透镜准直半导体激光束,再经渐变折射率(graduated refractive index,GR IN)自聚焦透镜聚焦,把光束耦合入单模光纤。就此耦合单元,对耦合效率随半导体激光器的位置偏离及角度偏移进行了研究,在光纤尾纤处测得了输出功率随驱动电流的变化关系,单模运行的半导体激光二极管经耦合后的出纤功率可以达到80mW。结果表明,耦合效率随位置偏离及角度偏移的变化灵敏度都不高,这可以满足星间光通信的要求。

The laser diode-coupling unit is an important part of an intersatellite optical communication system. In terms of the requirement of the intersatellite optical communication system, a new coupling method was proposed , in which an aspherical cylindrical lens,whose front cylindrical lens is orthonormal to its back cylindrical lens, was used to collimate the laser beam,and then the beam was focused by a GRIN lens and coupled to a single-mode fiber. How the coupling efficiency changing with the fiber position displacement and fiber axial angle variation was studied, and it was found that the coupling efficiency was insensitive to both the above parameters. Furthermore,the optical power versus the driver current at the end of the fiber was tested,and 80mW output power was obtained, which showed the optical unit satisfied the designed request.