A high-sensitive numerical measurement of methane based on the combined use of the localized surface plasmon resonance (LSPR) and Fano resonance in a slotted metal-dielectric-metal (MDM) periodic structure is numerically investigated. A groove is etched in an original MDM structure to excite the diploe mode at both sides of the groove, and the coherent coupling of two dipole modes is enhanced to realize a fast response, which is beneficial to gas-sensing. The influence of geometric parameters on the reflection spectra and methane sensitivity are analyzed to obtain optimal geometry. Moreover, an etching ring is introduced on the top metal to further raise the coupling area and coupling strength. The Fano resonance is subtly integrated into the optimized structure with asymmetry to achieve greater gas sensitivity. After the introduction of the Fano resonance, the field enhancement caused by the LSPR effect becomes greater and the methane sensitivity can reach up to 8.421 nm/% in numerical calculations, which increases 56.8% more than that of the original one. The combined use of the LSPR and Fano resonance in an optimized MDM structure provides an effective method for high-sensitive gas detection.

数值研究了基于局部表面等离子体共振 (LSPR) 和 Fano 共振在开槽金属-介电-金属 (MDM) 周期结构中结合使用的甲烷高灵敏度数值测量。在原有的MDM结构中刻蚀凹槽，激发凹槽两侧的偶极模，增强两种偶极模的相干耦合，实现快速响应，有利于气敏传感。分析几何参数对反射光谱和甲烷敏感性的影响，以获得最佳几何形状。此外，在顶部金属上引入了蚀刻环，以进一步提高耦合面积和耦合强度。法诺共振巧妙地融入不对称的优化结构中，以实现更高的气体灵敏度。引入Fano共振后，LSPR效应引起的场增强变大，数值计算甲烷灵敏度可达8.421 nm/%，比原来提高了56.8%。在优化的 MDM 结构中结合使用 LSPR 和 Fano 共振为高灵敏度气体检测提供了一种有效的方法。