聚合物脊形光波导的变分有效折射率法分析

Variational Effective Index Analysis of Polymer Rib Optical Waveguide

聚合物脊形光波导是聚合物集成光电子器件的重要构成单元。利用有效折射率法计算聚合物脊形光波导的横向折射率分布及有效折射率,将各区域中的光场分布近似用分段函数表达。基于导模满足的标量波动方程,利用变分法确定变分参量,以求得准确的横向光场分布。对聚合物脊形多模光波导基模和高阶模的色散特性与横向场分布进行分析,研究了波导结构参数对色散特性的影响,计算出TM基模和高阶模的光场分布,得出了聚合物脊形光波导的单模传输条件。研究表明,该方法计算量小、精度高,对聚合物光电子器件中脊形光波导的理论分析与设计优化提供了简单高效的方法。

Polymer rib optical waveguide is an important component in polymeric integrated optoelectronic devices such as electro-optic modulators. By using effective index method （EIM） to calculate the transverse refractive index distribution and effective index of polymer rib waveguide, the optical field distribution in each region is expressed as piecewise functions approximately. Based on the scalar wave equation that governs the guided modes, the variational parameter is determined by variational method （VM） for obtaining accurate transverse optical field distribution. The dispersion characteristics and transverse field distribution of the fundamental and higher-order modes are analyzed for polymer rib multimode waveguide. An algorithm is implemented to study the effect of the structural parameters and dimensions on the dispersion characteristics, and the optical field distribution of the fundamental and higher-order modes for TM modes is calculated. The single-mode transmission condition for polymer rib optical waveguide is obtained. The approach has advantages of high precision, small calculation complexity and high efficiency, which will provide theoretical reference and optimization method for the fabrication of polymeric electro-optic devices.