Sensitivity enhancement of integrated optical sensors by use of thin high-index films

摘要

The proportion of power carried in the superstrate medium by the guided modes of integrated optical waveguides can be increased by the addition of a thin high-index film. Enhanced refractive-index sensing is demonstrated with Channel waveguide Mach-Zehnder interferometers with Ta_(2)O_(5) overlays. Sensitivity increases by a factor greater than 50, and a detection limit better than 5 × 10~(-7) is obtained. This approach is broadly applicable to sensing at waveguide surfaces where the strength of evanescent fields dictates performance.