X形谐振腔的共振及其差动传感特性研究

Research on Resonance and Differential Sensing Characteristics of X-shaped Resonator

亚波长金属结构中的共振在纳米传感器领域是很重要的。本文研究了金属结构中纳米腔的共振特性及传感应用。构建了相关的倾斜腔、V形腔和X形腔,其中V形腔由两个倾斜腔构成,X形腔由两个V形腔构成。利用时域有限差分方法模拟了三种腔与波导的耦合作用,并应用耦合模理论对透射谱进行拟合验证。应用驻波理论分析了三种腔内共振的物理机制,发现在倾斜腔和V形腔内皆有1条共振回路,X形腔内有2条共振路径。相对于倾斜腔,V形腔中存在连接模;在X形腔中同时出现了对称和反对称的连接模。当破缺X形腔结构的对称性,其共振模式发生分裂。考虑三种谐振腔结构的差动传感特性,得到倾斜腔、V形腔和X形腔构成的气体折射率传感器的平均测量误差分别为0.00391、0.00185和0.00037,X形腔传感最精确。X形腔中多共振回路形成多个共振模式,有效地消除了多个环境因素的变化对传感的干扰,从而得到更高的传感测量精度,这为差动传感器的应用提供有价值的理论参考。

Resonance in subwavelength metal structures is very important in the field of nanosensors.This paper studies the resonance characteristics and sensing applications of nanocavities in metal structures.The related inclined cavity,V-shaped cavity and X-shaped cavity are constructed.The V-shaped cavity is composed of two inclined cavities and the X-shaped cavity is composed of two V-shaped cavities.The finite difference time domain method is used to simulate the coupling effect of the three cavities and the waveguide,and the coupled mode theory is applied to verify the transmission spectrum.The standing wave theory is used to analyze the physical mechanism of three kinds of intracavity resonance.It is found that there is one resonance circuit in the inclined cavity and the V-shaped cavity,and there are two resonance paths in the X-shaped cavity.Compared with the inclined cavity,there is a connection mode in the V-shaped cavity;there are both symmetrical and antisymmetric connection modes in the X-shaped cavity.When the symmetry of the X-shaped cavity structure is broken,its resonance mode splits.Considering the differential sensing characteristics of the three resonant cavity structures,the average measurement errors of the gas refractive index sensor composed of the inclined cavity,the V-shaped cavity and the X-shaped cavity are respectively 0.00391,0.00185 and 0.00037,and the X-shaped cavity sensing is the most accurate.The multiple resonance circuits in the X-shaped cavity form multiple resonance modes,which effectively eliminates the interference of the changes of multiple environmental factors on sensing,thereby obtaining higher sensing measurement accuracy,which provides valuable theoretical reference for the application of differential sensors.