共面蝴蝶结混合表面等离子体波导模式特征研究

Mode properties of coplanar bow-tie hybrid plasmonic waveguide

基于传统纵向蝴蝶结混合表面等离子体波导(BTHPW),提出一种共水平面BTHPW集成光波导结构,是由半导体硅肋和金属Ag肋两种波导对放在一个SiO_2基底面上构成,采用有限元法对其混合模式特征进行数值模拟,分析该波导传播长度、归一化有效模场面积和品质因子等特性随波导几何尺寸的变化规律。结果表明,该波导模式具有传播损耗较小同时又较强光限制能力的特点,最长传播距离可达108μm,最小有效模面积可达λ~2/3000左右。该波导结构制作工艺简单,并可应用于高灵敏度折射率传感器和微纳米光子集成器件等领域。

Compared to the traditional vertical bow-tie hybrid plasmonic waveguide (BTHPW), a novel coplanar BTHPW comprising a horizontally paralleled Si and Ag ridge above a SiO2 substrate is proposed By using the finite-element method, the hybrid plasmonic mode properties such as the propagation length, the mode confinement and the figure of merit depending on the geometric structure of the coplanar BTHPW are analyzed theoretically. Simulation results reveal that this coplanar BTHPW maintains low propagation loss with long propagation length up to 108μm, high field confinement with small normalized mode area about λ2/3000. The fabrication of such structure is simple, and the coplanar BTHPW has potential applications in high sensitivity refractive index sensor as well as in realizing high density photonic circuits.