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基于倏逝波理论和光学谐振原理,研究了倏逝波在光子晶体中的存在形式及空气栅光子晶体F-P腔的折射率传感机理,并建立谐振波长与待测气体折射率的关系模型。当入射光以大于全反射临界角的角度入射到光子晶体中,由于倏逝波的作用,在中心介质层形成F-P腔并产生谐振,电磁场被局部增强,与待测气体充分作用,从而使该传感结构对待测气体的折射率具有较高的敏感性。利用传输矩阵理论进行数值模拟,结果表明,折射率传感的Q值可达3447.0,灵敏度可达1260.0 nm/RIU,证明该光子晶体F-P腔折射率传感结构具有很好的传感特性,可为高精度气体折射率传感器的设计与应用提供一定的理论参考。
Based on evanescent wave theory and optical resonance principle, the existence form of evanescent wave in photonic crystal and the refractive index sensing mechanism of F-P cavity in air-grid photonic crystal are studied, and the relation model between resonant wavelength and refractive index of gas to be measured is established. When the incident light is incident on the photonic crystal at an angle larger than the critical angle of total reflection, the FP cavity is formed in the central dielectric layer and resonates due to the action of evanescent wave, and the electromagnetic field is locally enhanced to fully interact with the gas to be measured, The sensing structure has a high sensitivity to the refractive index of the gas to be measured. The numerical simulation of transmission matrix theory shows that the Q value of refractive index sensing can reach 3447.0 and the sensitivity can reach 1260.0 nm / RIU. It is proved that the refractive index sensing structure of FP photonic crystal has good sensing properties. It provides a theoretical reference for the design and application of high-precision gas refractive index sensor.