An integrated optical interferometer for direct detection of affinity reactions is presented. A modern version of a Young’s interferometer is built with a waveguide structure as beam splitter and as sensing element. Resistive waveguides were produced by plasma-enhanced chemical vapor deposition of silicon oxinitride. At the output of this device a fringe pattern is detected by a CCD line camera. The adsorption of molecules on top of the waveguides is observed with a detection limit of 750 fg/mm<sup>2</sup>. The resolvable variation of effective refractive index is 9 × 10<sup>−8</sup>.
© 2000 Optical Society of America
Albrecht Brandenburg, Ralf Krauter, Christa Künzel, Monika Stefan, and Heinrich Schulte, "Interferometric Sensor for Detection of Surface-Bound Bioreactions," Appl. Opt. 39, 6396-6405 (2000)