结合光子晶体的局域特性与多孔硅特有的光学特性，提出一种镜像对称多孔硅光子晶体折射率传感结构。基于分层传输矩阵法建立传感理论模型，得出缺陷波长与其基本结构参数的关系。改变多孔硅高低折射率层的结构参数，可使缺陷峰的半峰全宽变窄，进而使其品质因数(Q 值)得到提高。根据传输矩阵理论，对不同浓度甲醇蒸汽进入到该传感结构前后的反射光谱进行理论仿真，得出其光谱特性，推导出由于环境折射率影响引起的传感层等效折射率改变与缺陷峰漂移之间的数学模型，并进行数值模拟分析。结果显示：该传感器结构的Q 值为3114.75，灵敏度为903.9 nm/RIU，可为微型化与高分辨率传感器的设计提供一定的技术参考。

Based on the local characteristics of photonic crystals and the optical sensing principle of porous silicon, the mirror symmetrical porous silicon photonic crystal index sensing structure is proposed. The sensing theoretical model is obtained based on layered transfer matrix method. The relationship between the resonant wavelength and the structural parameters of the porous silicon photonic crystal is deduced. By adjusting the structure parameters of porous silicon for both high and low refractive index layers, the full width at half maximum of the band gap will be narrowed and the quality factor (Q value) can be improved. Based on the transfer matrix method, when the methanol vapors with different concentrations enter the porous silicon photonic crystal index sensor structure, the theoretical simulation is performed using MATLAB. The relationship model between the change of the resonant peak wavelength and the variation of the effective refractive index for the porous silicon layer is established, and the refractive index sensing properties are analyzed in the numerical simulation. The simulation results show that the Q value of the refractive index sensing structure is 3114.75 and the sensitivity can attain to 903.9 nm/RIU, which demonstrate the effectiveness of the sensing structure, and it can provide certain practical reference value for the design of high Q and high sensitive refractive index sensors.