A transfer matrix approach based on local normal modes for coupled waveguides with periodic perturbations
A transfer matrix approach based on local normal modes for coupled waveguides with periodic perturbations
复制标题
基于局域简正模的耦合波导周期性扰动传输矩阵方法
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
J. Hong
中科院分区：
文献类型：
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作者：
Wei;J. Hong
本文用一种简单的传输矩阵法分析了折射率周期性扰动的光波导结构中的功率耦合和散射。传递矩阵是由模式匹配技术的结构的本地正常模式。这种方法考虑了场模式沿着波导轴的变化，比基于理想模式的耦合模理论更严格。该方法的显著优点是：（1）可适用于由大光栅高度和/或大折射率差引起的折射率扰动较强的结构;（2）可适当处理横向电场垂直于折射率界面的TM模;（3）可估算沿波导轴沿着折射率不连续处散射引起的辐射损耗。推导了光栅辅助同向耦合器中功率耦合的解析表达式，并给出了几种典型结构的数值计算结果。>
A simple transfer matrix method is used to analyze power coupling and scattering in optical waveguide structures with periodic index perturbations. The transfer matrix is determined by a mode-matching technique for the local normal modes of the structures. This approach accounts for the change in the field patterns along the waveguide axis and is more rigorous than coupled-mode theory based on ideal modes. The distinct advantages of the method are that (1) it can be applied to structures with relatively strong index perturbations caused by large grating height and/or large index difference; (2) the TM modes whose transverse electric field is perpendicular to the index interface can be properly treated; and (3) the radiation loss due to scattering at the index discontinuities along the waveguide axis can be estimated. Analytical expressions for the power coupling in a grating-assisted codirectional coupler are derived, and numerical results are shown for some typical structures. >