脊形结构LiNbO_3光波导调制器的扩展点匹配法分析

Analysis of Ridge-Type LiNbO_3 Optical Waveguide Modulators with the Extended Point-Matching Method

将点匹配法扩展应用于脊形结构LiNbO3 光波导调制器电极的准静态分析中。将调制器各区域的势函数表示为该区域中满足Laplace方程的一系列基函数的级数 ,匹配边界上有限个点的边界条件以确定出级数项的系数。通过势函数得到脊形结构LiNbO3 光波导调制器结构中电场分布的解析表达式 ,利用求得的电场可以得到调制器特性阻抗及有效折射率。所得的特性阻抗和有效折射率与采用有限元法得到的结果十分吻合。这一分析方法简便快捷 ,精度高 。

The point-matching method is extended to analyze a travelling-wave electrode structure for ridge-type LiNbO 3 optical modulators. The potential function is expended in terms of a Fourier sine series, and the coefficients of the series are obtained by satisfying the boundary conditions in the contact plane at a finite, discrete set of pints. The calculated fields are used to estimate the characteristic impedance and microwave effective index. This method provides a simple and fast approach to the quasi-static analysis of the multi-layered structures with finite electrode thickness. The results agree well with those obtained using the finite-element method. Some significant conclusions are made for design and optimization of modulators.