金属纳米光栅表面等离子体共振光学传播特性

Abstract

本文分析了几种典型沟槽形状的金属纳米光栅(MNG)的光波传播特性。利用多重多级子程序法(MMP)计算了光栅形状和入射光波长对反射率和透射率的影响。结果显示，金属纳米光栅存在表面等离子体共振(SPR)和局域化表面等离子体共振(LSPR)两种共振模式。LSPR共振波长强烈依赖于光栅的沟槽形状、槽深、槽宽等结构参数，呈现宽带光谱响应机制，而SPR更多的依赖于光栅周期大小，呈现窄带光谱响应机制。两种共振模式的不同特性拓展了我们对金属纳米光栅的光学传播特性的认识，这对根据需要合理设计金属纳米光栅有重要的指导意义。 Optical propagation properties of metallic nano-gratings (MNG) with several classic groove shapes are analyzed. Influences of grating shape parameters and incident wavelength on reflectivity and transmission are calculated by means of multiple multipole program (MMP). Our results demonstrate that there are two resonant modes on the surface of MNG, surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR), respectively. LSPR presents a kind of broad band spectral response machanism, whose resonant wavelength strongly depends on groove shapes, groove depth and groove width parameters. SPR presents a kind of narrow band spectral response machanism, and its resonant wavelength is more dependent on grating period parameters. The different characteristics of the two resonant modes increase our knowledge about optical propagation properties of MNG. This investigation can be used as a guideline in designing metallic nano-gratings for certain applications.