级联槽型腔表面等离子体滤波器

Study on Surface Plasmonic Filter with Cascaded Slot Cavities

摘要:

提出一种中心波长随槽型腔腔长线性变化、透射率随耦合距离可调的级联腔表面等离子体滤波器。该滤波器由输入波导、两个级联的介质槽型腔和输出波导组成。通过级联两个相同的槽型腔，共振模被分离从而实现窄带的双通道滤波器；进一步调节输出波导的位置，能够将双通道分离，实现单通道的滤波。通过时域有限差分法和耦合模理论对模型进行仿真分析，结果表明，该滤波器的最小半高宽低至20nm。同基于单槽型腔的滤波器相比，半高宽显著减小。

Abstract:

A novel and compact narrow band-pass plasmonic filter with tunable wavelength and transmittivity based on cascaded slot cavities is proposed. The structure consists of incident waveguide, two metal-insulator-metal slot cavities and output waveguide. Consequently, a dual-channel filter can be achieved by cascading two identical cavities due to the near-field interaction in metamaterials. By choosing the proper position of the output waveguide, the two channels can be separated from each other without interferences. The structure is numerically investigated by utilizing Finite-Difference Time-Domain (FDTD) simulations and the coupled mode theory (CMT). Results show that the minimum full-width at half-maximum ( FWHM ) is about 20 nm, which is obviously narrower than that of the filters based on single slot.