本文利用严格数值仿真研究了550~700 nm波段的可见光通过金属光栅耦合方式激发的表面等离激元(SPP)波在金属表面的光栅衍射行为与现象。研究结果表明: SPP波在金属表面的衍射行为与自由空间光相比有极大不同, 由于SPP波的近场属性, 经金属光栅衍射后在近场可表现出明显的光栅分光现象, 但经过一段传输距离后则分光现象消失而表现为不同级次的光合为同一束光; 在近场衍射情况下, 其情况与自由空间光衍射行为类似, 对SPP亚波长金属光栅来说同样只有零级透射光; 而当金属光栅周期大于SPP波长时, 高级衍射级次则开始出现。研究结果对下一步在金属表面上实现微米级片光谱仪器具有重要借鉴意义。

In this paper, a rigorous numerical simulation method(FDTD) is employed to study the grating diffractive behavior of surface plasmon polariton(SPP) waves on meta-surface excited by the incident visible light through metallic grating coupler in 550-700 nm waveband. The simulation results indicate that the diffraction of SPP waves on meta-surface is quite different from that of free space light. Due to the near-field characteristics, the SPP wave shows obvious diffractive effect in near field when it interacts with a metallic grating. However, the different diffracted orders will merge into one after propagating some distances. Nevertheless, the diffractive behavior in near-field is similar to that in free space. In near field, only the 0th order light is transmitted when metallic gratings have a sub-wavelength period and higher diffraction orders appear when the period of metallic gratings is larger than the wavelength of SPP waves. The research results of this paper are of great significance for designing spectroscopic devices or systems on meta-surface with a micronscale.