Mie谐振耦合的亚波长金属孔宽带高透射传输

表面等离激元共振激发的亚波长金属孔透射较Bethe理论有大幅度的提高,然而,由于共振对频率的敏感性以及金属在光频的高损耗特性,表面等离激元共振难以实现亚波长金属孔的宽带高透射传输.本文采用放置在金属孔两边的硅纳米颗粒的Mie谐振耦合取代表面等离激元共振,实现亚波长金属孔的宽带高透射传输.全波仿真结果表明,采用Mie谐振耦合的亚波长金属孔(r/λ=0.1)光传输,透射系数超过90%的带宽达到65 nm,与表面等离激元共振诱导的透射增强相比,峰值增高了1.5倍,3 dB带宽拓宽了17倍.根据耦合模理论,建立了Mie谐振耦合亚波长金属孔透射的等效电路模型,并在临界耦合状态下反演出电路模型中的元件参数值.进一步研究发现,仅通过改变等效电路模型中的耦合系数,就可全面揭示Mie谐振耦合亚波长金属孔透射的传输规律,并得到与全波电磁仿真完全一致的结果,从而找到光与放置硅纳米颗粒的亚波长金属孔相互作用的数学表达,也给予人们在光学领域按照电路设计方法构建相应功能模块的启示.

Broadband and high transmission of Mie-resonance-coupled subwavelength metal aperture

Transmission of the subwavelength metal aperture excited by the surface plasmon resonance is much higher than that from the Bethe theory.However,due to the sensitivity of resonant frequency and the loss of metal in optical band,it is difficult to achieve broadband and high transmission of the subwavelength metal aperture through surface plasmon resonance.In this article,the broadband and high transmission of the subwavelength metal aperture is realized when Mie-resonant-coupled silicon nanoparticles placed on both sides of the metal aperture are used to replace the surface plasmon resonance.The full wave simulation results show that bandwidth of the transmission coefficient more than 90% of the sub wavelength aperture(r/λ=0.1) reaches65 nm by using Mie-resonance-coupled silicon nanoparticles.Compared with the transmission induced by surface plasmon resonance,the peak value is improved by 1.5 times and the 3 dB bandwidth is widened by 17 times.According to the coupled mode theory,the equivalent circuit model of transmission of the subwavelength metal aperture added with Mie-resonance-coupled silicon nanoparticles is established,and the element parameters in the circuit model are inversed under the critical coupling state.Further research shows that transmission rule of the subwavelength metal aperture added with Mie-resonance coupled silicon nanoparticles can be accurately revealed by changing the coupling coefficient in the equivalent circuit model,and the results are consistent with the full wave electromagnetic simulation results.The mathematical expression of the interaction between light and Mie-resonance-coupled subwavelength metal aperture is found,therefore it can inspire us to construct certain functional modules in optical field according to circuit design method.