论文部分内容阅读
用多模倾斜光纤光栅(Tilted fiber Bragg grating,TFBG)实现多模光纤中简并模式群(Degenerated modegroup,DMG)的分别探测。多模倾斜光纤光栅将光纤中的导模耦合到辐射光线,用透镜将辐射光线聚焦在焦平面上,使非简并模式群对应的辐射光线的像在焦平面上分离。在焦平面上用空间滤波器使简并模式群选择透过并进行分别探测。用芯径为62.5μm的标准通信多模光纤进行了简并模式群分别探测实验,用单模光纤激励多模光纤,测量简并模式群功率随激励光纤的横向对准偏差的变化关系。低阶简并模式群的测量结果与仿真计算结果基本一致,高阶简并模式群的测量结果与仿真结果有一些不同。用倾斜光纤光栅进行单简并模式群激励,在单简并模式群条件下测量简并模式群耦合效率的想法还需进一步实验验证。
The detection of degenerated mode groups (DMGs) in multimode fiber is achieved by using Tilted fiber Bragg grating (TFBG). The multi-mode tilted fiber grating couples the guided mode in the optical fiber to the radiated light, and focuses the radiated light on the focal plane with a lens to separate the image of the radiated light corresponding to the non-degenerate mode group on the focal plane. A spatial filter is used on the focal plane to allow the degenerate mode group to be selected for transmission and to detect separately. A degenerate mode group detection experiment was conducted with a standard communication multimode fiber with a core diameter of 62.5μm. Single mode fiber was used to excite the multimode fiber to measure the variation of degenerated mode group power with respect to the lateral misalignment of the excitation fiber. The results of the low-order degenerate model group are basically consistent with those of the simulation results. The measurement results of the high-order degenerate model group are somewhat different from the simulation results. The idea of measuring the coupling efficiency of degenerate mode groups with a single degenerate mode group excitation using a tilted fiber grating needs further experimental verification.