Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Box 603-146, Beijing 100190, China.
ACS Nano. 2012 Sep 25;6(9):8128-35. doi: 10.1021/nn302755a. Epub 2012 Aug 17.
Seeking better plasmonic waveguides is of critical importance for minimizing photonic circuits into the nanometer scale. We have made a theoretical study of the properties of surface plasmon polaritons in a metallic nanowire over substrate (NWOS) configuration. The dielectric substrate breaks the symmetry of the system and mediates the coupling of different primary wire plasmons. The lowest order hybridized mode can be used for subwavelength plasmonic waveguiding for NWOS with thin wire, for a low-permittivity substrate, and in the shorter wavelength region. For NWOS with a high-permittivity substrate, leaky radiation into the substrate raises the propagation losses so that the propagation distance is shorter in the longer wavelength region. By simply adding a high-permittivity layer onto the low-permittivity substrate, we show that leaky radiation can be blocked and high-performance plasmonic waveguiding can be extended to the near-infrared region. Importantly, the NWOS configuration is compatible with current silicon technologies and can be designed into various deep subwavelength active devices such as electro-optical or all-optical modulators.
寻求更好的等离子体导波结构对于将光子电路缩小到纳米尺度至关重要。我们对金属纳米线置于介质衬底之上（NWOS）的结构中的表面等离激元极化激元的性质进行了理论研究。介电衬底打破了系统的对称性，并介导了不同基本线等离子体的耦合。最低阶杂化模式可用于亚波长等离子体导波，适用于细线、低介电常数衬底和较短的波长区域。对于高介电常数衬底的 NWOS，漏入衬底的辐射会增加传播损耗，从而使较长波长区域的传播距离更短。通过简单地在低介电常数衬底上添加高介电常数层，我们表明可以阻止漏辐射，并将高性能等离子体导波扩展到近红外区域。重要的是，NWOS 结构与当前的硅技术兼容，并且可以设计成各种深亚波长有源器件，如电光或全光调制器。
