基于耦合模理论, 数值仿真了两种耦合结构(FW和WF)下的耦合损耗随锥形光波导芯层尺寸的变换规律; 进一步分析了两种耦合结构下锥形光波导端面粗糙度对其模式耦合损耗特性的影响, 表明不同模式其端面散射损耗不同; 实验结果表明, 锥形光波导的输入端芯层尺寸、输出端芯层尺寸及光波导长度, 对FW结构下的耦合损耗影响较小, 对WF结构下的耦合损耗影响较大。

Based on coupled-mode theory, the variations of the coupling loss of both fiber-waveguide (FW) and waveguide-fiber (WF) structures with the size of tapered optical waveguide were simulated. Further, the mode loss characteristics for the two kinds of coupling structures induced by the end-face roughness were analyzed, and it indicated that there are different scattering loss for different modes. Experimental results prove that the size of input waveguide core, the size of output waveguide core and the length of the tapered optical waveguide have less impact on the coupling loss of FW structure, but have a great influence on that of WF structure.