INTEGRATED OPTICAL-DIFFERENCE INTERFEROMETER AS REFRACTOMETER AND CHEMICAL SENSOR

We have successfully used an integrated optical (10) difference (or polarimetric) interferometer (1) as a refractometer for liquid samples, (2) for monitoring protein adsorption, and (3) as an affinity sensor. The affinity reaction between avidin adsorbed on the waveguide surface and biotinylated bovine serum albumin is investigated. The simplicity of the IO difference interferometer is advantageous; only a planar waveguide is required. We use dipcoated SiO2-TiO2 waveguides (prepared by a sol-gel process) on silicon wafers with SiO2 buffer layers as substrates; depending on the firing temperature, the 140-200 nm thick waveguiding films are microporous or compact, the latter showing superior stability in sensor applications.