Abstract

Planar waveguides interferometers provide a commercially viable sensor technology for the detection of an array of chemical and biological species. This presentation will follow the progress of one interferometric sensor from its inception to its current status. The current device had its beginning as a benchtop optical sensor that used discrete optical components from a lab grade He-Ne laser, optical beamsplitters, mirrors and lens, prisms for coupling light into and out of an ion-exchange waveguide, expensive photodectors to collect the signal and a chart recorder to record the sensor’s response. Optical design, fabrication and system design progressed over the years. Ion-exchange waveguides yielded to step index waveguides utilizing high refractive index materials as waveguides to enhance the evanescent field of the sensor. Prism couplers gave way to integrated gratings to couple the light into and out of the waveguide. The 1.5 inch He-Ne laser was replaced by a diode laser similar to those in laser pointers. The point photodetector with an optical slit was replaced with a 2-D CCD array taken from a commercial webcam. Signal processing of the interferometric data initially involved counting the fringes on a chart recorder. Specially written software currently analyzes the entire fringe pattern and converting to phase change and concentration.

© 2011 Optical Society of America