等离激元银金属膜耦合氮化硅纳米空腔在可见光-近红外区间的多谱带完美吸收和传感性质的仿真研究

Simulative Study of Multiband Perfect Absorption and Sensing Properties of Plasmonic Silver Film Coupled Si_(3)N_(4) Nanocavities in Visible-NIR Region

具有多谱带完美吸收效应的超构材料在光学滤波和折射率传感等多种应用中是理想的材料。提出了一种由银金属上的氮化硅介电纳米空腔阵列组成的多谱带窄带完美吸收超构材料。有限元仿真给出了四个最高可达99.9%的吸收峰,以及最小达到0.74 nm的吸收峰宽。这些吸收谱带来自于表面晶格模式和三个表面等离激元极化子模式。此外,这些模式的谱峰对超构材料几何外形和环境介质光学参数的变化敏感,从而在可见光-近红外范围内可以被调控。用于折射率传感时,其具有347 nm每折射率单位的灵敏度,Figure of Merit达到469。这些特性令这一材料适用于光学滤波器和折射率传感器等用途。

Metamaterials with multiband optical perfect absorption effect are highly desired in applications like optical filtering and refractive index sensing.This paper proposes a multi-narrowband perfect metamaterial absorber composed of a Si_(3)N_(4) dielectric nanocavity array on a silver film.Simulation by finite element method gives four absorption bands with peak absorptances up to 99.9%and narrow bandwidth down to 0.74 nm.These absorption bands come from surface lattice resonance mode and three surface plasmon polariton modes.Besides,these modes are highly susceptible to changes in geometrical and optical parameters,which means absorption peaks can be tuned in the visible-near infrared range.The refractive index sensing capability of the structure was also investigated,giving 347 nm per refractive index unit sensitivity and 469 figure of merit.These features make the proposed structure suitable for applications such as refractive index sensors and optical filters.