Keywords: 
• 复合光波导 /
• 偏振干涉 /
• 高灵敏度 /
• 生化检测

Abstract: 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（Toq） for the tapered layer of Ta2O5 is theoretically analyzed based on a fourlayer homogeneous waveguide model.A comparison of the measured Sri with the simulated data leads to Teq≈33.021 nm for the COWG used.The sensitivity of the interferometer to thickness of the protein adlayer is determined to be Sad≈（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.