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提出亚波长介质光栅-金属膜-石英玻璃衬底结构,根据等效介质理论该结构可等效为由金属-光栅-包覆层构成的单面金属包覆波导,在入射波长和入射角满足一定条件时,发生导模共振(GMR)从而产生光波全吸收现象。根据严格耦合波分析(RCWA)理论进行数值分析发现,等效波导中的TM1 GMR峰尖锐,并且对光栅包覆层的折射率变化非常敏感,角度灵敏度为127.87°/RIU(RIU为折射率单位),波长灵敏度为409.35 nm/RIU,在很大的折射率范围内线性度良好。与全介质GMR传感器和光栅型表面等离子体共振(SPR)传感器相比,该结构通过GMR实现较高灵敏度的同时,其较窄的共振峰使得检测精度更高。
A subwavelength dielectric grating-metal film-quartz glass substrate structure is proposed. According to the equivalent medium theory, the structure can be equivalent to a single-sided metal-clad waveguide composed of a metal-grating-cladding layer. When the incident wavelength and the incident angle satisfy Under certain conditions, the guided-mode resonance (GMR) occurs and the entire wave absorption occurs. Numerical analysis based on the RCWA theory found that the TM1 GMR peak in the equivalent waveguide is sharp and very sensitive to the refractive index change of the grating cladding with an angular sensitivity of 127.87 ° / RIU (RIU is the refractive index unit ) With wavelength sensitivity of 409.35 nm / RIU and good linearity over a wide range of refractive indices. Compared with all-dielectric GMR sensors and grating-type surface plasmon resonance (SPR) sensors, this structure achieves higher sensitivity through GMR with narrower formants resulting in higher detection accuracy.