Bian Yusheng, Gong Qihuang
State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing, China.
Appl Opt. 2013 Aug 10;52(23):5733-41. doi: 10.1364/AO.52.005733.
The optical characteristics of a metal-coated dielectric wedge structure are investigated at a wavelength of 1550 nm. The effects of the metal/gap layers' thicknesses, as well as the dimension of the dielectric wedge on the guided modes' properties, are systematically analyzed. It is revealed that the characteristics of the fundamental quasi-TE and quasi-TM plasmonic modes supported by the configuration demonstrate similar trends against the variation of the metal layer thickness while exhibiting quite different behaviors with the change of the wedge size. By choosing appropriate physical dimensions, both modes could simultaneously achieve low modal loss and subwavelength field confinement, along with reasonable mode power inside the low-index gap region. Investigations on the directional coupling between adjacent identical waveguides indicate that ultralow crosstalk can be enabled by the quasi-TE mode, with the coupling length more than two orders of magnitude larger than that achieved by the plasmonic mode in conventional hybrid counterparts. The presented metal-coated dielectric wedge structures can be employed as important building blocks for a number of integrated nanophotonic components, and could also enable numerous applications at the subwavelength scale.
在1550纳米波长下研究了金属包覆介质楔形结构的光学特性。系统分析了金属/间隙层厚度以及介质楔形尺寸对导模特性的影响。结果表明，该结构所支持的基本准TE和准TM等离子体模的特性在金属层厚度变化时呈现出相似的趋势，而在楔形尺寸变化时表现出截然不同的行为。通过选择合适的物理尺寸，两种模式都可以同时实现低模式损耗和亚波长场限制，以及低折射率间隙区域内合理的模式功率。对相邻相同波导之间的定向耦合的研究表明，准TE模式可以实现超低串扰，其耦合长度比传统混合结构中等离子体模式实现的耦合长度大两个数量级以上。所提出的金属包覆介质楔形结构可作为许多集成纳米光子元件的重要构建块，也可实现亚波长尺度的众多应用。
