Chai Yuwei, Kang Guoguo
Appl Opt. 2022 Oct 10;61(29):8819-8825. doi: 10.1364/AO.468390.
Subwavelength dielectric gratings based on guided mode resonances (GMRs) provide a compact, low-cost, and readily fabricable platform for narrowband spectral filters applied in numerous fields, such as sensors, spectrometers, and hyperspectral imaging. We numerically designed two long-wave infrared transmission bandpass filters based on Ge-ZnS-Ge thin film stacks and 2D zero-contrast gratings. The first filter is attributed to double GMR mode coupling, exhibiting a broadband high reflectance between 8 and 12 µm and a narrow transmission peak with a spectral linewidth of 53 nm and transmittance efficiency of 98% at the resonance. The other filter adopts a low-refractive-index material as the substrate, which displays a lower-transmittance sideband from 8.6 to 9.4 µm, and a higher transmission efficiency up to 100% at the resonance. The physical mechanisms of two spectral responses are all relevant to guided mode coupling and Fabry-Perot resonance.
基于导模共振（GMR）的亚波长介质光栅为应用于众多领域（如传感器、光谱仪和高光谱成像）的窄带光谱滤波器提供了一个紧凑、低成本且易于制造的平台。我们基于Ge-ZnS-Ge薄膜堆栈和二维零对比度光栅，通过数值方法设计了两种长波红外透射带通滤波器。第一种滤波器归因于双GMR模式耦合，在8至12微米之间表现出宽带高反射率，以及一个窄透射峰，其光谱线宽为53纳米，在共振时的透射效率为98%。另一种滤波器采用低折射率材料作为基底，在8.6至9.4微米处呈现较低透射率的边带，在共振时具有高达100%的更高传输效率。两种光谱响应的物理机制均与导模耦合和法布里-珀罗共振相关。
