为了提高自由空间光通信的接收端耦合效率, 将锥形光纤应用于光耦合, 依据BPM算法的仿真结果使用熔融拉锥法制备了满足低损传输条件的锥形光纤。在实验上研究了锥形光纤和双锥形光纤模场传输特性。通过静态空间光-光纤耦合实验, 对比了多/单模熔接光纤和锥形光纤光耦合效率和传输效率的差异, 并研究了以上两种光纤结构耦合效率的横向偏移量容差。结果表明, 锥形光纤的传输效率约为70%, 具有低损传输特性、用于匹配后端单模光电子器件的良好滤波特性以及相比普通光纤更高的横向偏移量容差特性, 因此可以广泛应用于自由空间光通信接收端光耦合、模式转换器等方面。

Free-space optical communication has many advantages over traditional communication. Improving the coupling efficiency of free-space optical communication (FSOC) receivers is of great significance for the quality of communication. We used tapered fibers in optical coupling. Based on the simulation results using the BPM algorithm, tapered fibers with low loss transmission were prepared using a fusion taper method. First, the mode field transmission characteristics of the tapered fibers and double tapered fibers were studied. Second, the difference in coupling efficiency and transmission efficiency between multi/single mode fused fibers and tapered fibers was studied using a static spatial light-fiber coupling experiment. The lateral offset tolerances of the coupling efficiency of these two fiber structures were also studied. The results show that the tapered fibers have good filtering characteristics for matching single-mode optoelectronic devices in the back end. They also have higher lateral offset tolerance characteristics than common fibers and a high transmission efficiency of around 70% that demonstrates low-loss transmission characteristics. Therefore, tapered fibers can be widely applied in the optical coupling of FSOC receivers and mode converters.