Realization of a multichannel integrated Young interferometer chemical sensor

We report on the design, realization, and characterization of a four-channel integrated optical Young interferometer device that enables simultaneous and independent monitoring of three binding processes. The generated interference pattern is recorded by a CCD camera and analyzed with a fast-Fourier-transform algorithm. We present a thorough theoretical analysis of such a device. The realized device is tested by monitoring glucose solutions that induce well defined phase changes between output channels. The simultaneous measurement of three different glucose concentrations shows the multipurpose feature of such devices. The observed errors, caused by the mismatching of spatial frequencies of individual interference patterns with those determined from the CCD camera, are reduced with different reduction schemes. The phase resolution for different pairs of channels was ~1 * 10^-4 fringes, which corresponds to a refractive-index resolution of ~8.5 * 10^-8 . The measured sensitivity coefficient of the phase change versus refractive-index change of ~1.22 * 10^3 * 2 (pi) agrees well with the calculated coefficient of ~1.20 * 10^3 * 2 (pi)