Glass/Ta₂O₅ Composite Waveguides for Application as an Integrated Polarimetric Interferometer

A tapered thin film of Ta₂O₅ was deposited by the masked sputtering method on a single−mode slab glass waveguide to form a composite optical waveguide (COWG) with a great modal birefringence. With the prism-coupling method the COWG was used as an integrated polarimetric interferometer for real-time detection of chemical and biological measurands. The refractive-index sensitivity of the interferometer was examined, and the refractive-index increments of different aqueous solutions were determined with the device. Response of the interferometer to protein adsorption and that to water temperature were investigated. The experimental results indicate that an increase of ΔT=1^°C for the temperature of water in the measuring chamber can lead to a phase−difference change of Δφ= -28.5^°.