激光与光电子学进展, 2017, 54 (6): 060602, 网络出版: 2017-06-08
基于光栅螺旋扫描和SPGD算法的单模光纤耦合方法 下载: 645次
Single-Mode Fiber Coupling Based on Raster Spiral Scanning and SPGD Algorithm
光通信 光纤耦合 光栅螺旋扫描 随机并行梯度下降算法 对准误差 optical communications fiber coupling raster spiral scanning stochastic parallel gradient descent algorithm alignment error
摘要
自由空间光通信系统需要将空间光高效耦合到单模光纤中,但聚焦光斑与单模光纤间的初始对准误差和随机横向偏移会导致极大的耦合损耗。对空间光到单模光纤耦合的理论模型进行了阐述,并分析了横向偏移及随机抖动对耦合效率的影响。在此基础上,为了提高光纤耦合效率,提出了一种基于光栅螺旋扫描算法和随机并行梯度下降(SPGD)算法的耦合方案,并仿真分析了误差校正过程及其对耦合效率的改善情况。仿真结果表明:通过设定最佳扫描步长,光栅螺旋扫描算法能够有效地校正初始对准误差,校正成功概率高于99%;校正后的残余初始对准误差集中在0.5~6.5 μm范围内,耦合效率得到初步改善;开启SPGD控制算法后,聚焦光斑与单模光纤间的随机横向偏移得到校正,耦合效率能够有效提升至0.81,接近无湍流情况下的理论极限。校正后,耦合效率得到显著提高。
Abstract
For free-space optical communication systems, spatial light must be efficiently coupled into the single-mode fiber first. However, the initial alignment error and the random lateral deviation existed between focused spot and single-mode fiber lead to a dramatic coupling loss. A theoretical model of coupling the spatial light into single-mode fiber is expounded, and the effects of the lateral deviation and the random jitter on coupling efficiency are analyzed. On this basis, in order to improve the fiber coupling efficiency, a coupling scheme based on raster spiral scanning algorithm and stochastic parallel gradient descent (SPGD) algorithm is proposed. Simulations on the process of error correction and the improvement of coupling efficiency after error correction are carried out. The results show that, by setting the optimal scanning step, the initial alignment error can be efficiently corrected by raster spiral scanning algorithm, the success probability of initial alignment error correction can be higher than 99%. The residual initial alignment error focuses in 0.5-0.6 μm, and the coupling efficiency has been improved perliminarily. By adopting the SPGD algorithm, the random lateral deviation between focused spot and single-mode fiber can be corrected, and the coupling efficiency also rises to 0.81, which approaches the theoretical limit without turbulence. After the correction, the coupling efficiency is significantly improved.
吴子开, 陈莫, 刘超, 鲜浩. 基于光栅螺旋扫描和SPGD算法的单模光纤耦合方法[J]. 激光与光电子学进展, 2017, 54(6): 060602. Wu Zikai, Chen Mo, Liu Chao, Xian Hao. Single-Mode Fiber Coupling Based on Raster Spiral Scanning and SPGD Algorithm[J]. Laser & Optoelectronics Progress, 2017, 54(6): 060602.