高灵敏度集成光偏振干涉仪特性及生化传感应用研究

利用射频溅射技术在平面单模玻璃波导表面局部淀积一层Ta₂O₅梯度薄膜, 形成复合光波导芯片, 结合棱镜耦合法制备了一种集成光偏振干涉传感器. 基于四层平板波导模型理论分析了复合光波导表面折射率灵敏度S_RI与Ta₂O₅梯度薄膜等效厚度T_eq的关系, 结合实验测定的S_RI得出了本工作中所使用Ta₂O₅梯度薄膜的T_eq ≈ 33.021 nm, 进一步得出芯片吸附层厚度灵敏度S_ab≈ (2.412× 2π) nm^-1. 利用该复合波导偏振干涉仪结合Lorentz-Lorenz有效介质理论测得了市售食用白醋中醋酸的浓度, 并以市售牛栏山二锅头酒为例进行了白酒掺水和掺甲醇的测试, 结果表明, 白酒掺水或甲醇前后的折射率改变量与掺杂量成准线性变化关系; 原位实时监测了丁酰胆碱酯酶的动态吸附过程及细胞色素c/聚苯乙烯磺酸钠的分子自组装过程, 并利用测得的位相差变化结合芯片吸附层厚度灵敏度S_ab 获得了蛋白质表面覆盖度.

Characterization and chemical/biosensing application of a high-sensitivity integrated optical polarimetric interferometer

A tapered thin film of Ta₂O₅ is sputtered on a single-mode slab glass waveguide to form a composite optical waveguide（COWG） for serving as a prism-coupled integrated optical polarimetric interferometer.The relationship between the refractive-index sensitivity （Sri） of the interferometer and the equivalent thickness(T_oq) for the tapered layer of Ta₂O₅ is theoretically analyzed based on a fourlayer homogeneous waveguide model.A comparison of the measured S_ri with the simulated data leads to T_eq≈33.021 nm for the COWG used.The sensitivity of the interferometer to thickness of the protein adlayer is determined to be S_ad≈（2.412×2n）/nm. The acetic-acid concentration of a commercial Chinese vinegar is investigated,for the first time,by use of the interferometer combined with the Lorentz-Lorenz effective-medium theory.Water and methanol adulterations of a commercial Chinese liquor are detected with the interferometer.The results indicate that the refractive-index change induced by the adulteration is a quasi-linear function of the adulteration amount.Both the dynamic adsorption process of butyrylchohnesterase and the self-assembly process of cytochrome c/PSS multilayer film are monitored in real time with the sensor.The protein surface coverage is obtained from the combination of the measured phase-difference change and the adlayer-thickness sensitivity.