耦合内嵌银条圆盘腔的金属-介质-金属弯曲波导滤波特性

Filtering Characteristics of Metal-Insulator-Metal Curved Waveguide Coupled with Embedded-Silver-Bar Disk Cavity

基于表面等离子激元的传输及耦合特性,设计了一种耦合内嵌银条圆盘腔的金属-介质-金属弯曲波导滤波器结构。并应用有限元法对该结构的光谱特性及滤波特性进行了分析。结果表明,内嵌的银条打破了结构的对称性,实现了双模式共振效应,且该结构由于具有双边耦合效应,获得了比单边耦合更高的耦合效率,透射谱中出现了两个明显的阻带,获得了很好的双频窄带滤波功能,相比已报道的同类滤波器得到了更高的品质因子;改变圆盘谐振腔半径或腔内介质折射率,可实现滤波波长的近似线性调节。

This study presents the design of a metal-insulator-metal curved waveguide filter coupled with an embedded-silver-bar disk cavity, which is based on the transmission and coupling characteristics of surface plasmon polaritons. Herein, the spectral and filtering characteristics of the proposed structure are analyzed via the finite element method. The results indicate that the dual-mode resonance effect is achieved because the silver bars embedded into the disk cavity destroy the structural symmetry. In addition, the structure possesses the bilateral coupling effect, which makes the coupling efficiency higher than that for single-sided coupling. There exist two distinct forbidden bands in the transmission spectrum and the good dual-band narrowband filtering function is obtained. Furthermore, a quality factor higher than those of the previously reported filters is achieved. The wavelength of such a filter can be approximately linearly adjusted by varying the radius of disk cavity or the refractive index of the medium in the cavity.