Refractive index sensor based on hybrid coupler with short-range surface plasmon polariton and dielectric waveguide

An integrated sensor based on a vertical hybrid coupler composed of a short-range surface plasmon polariton (SRSPP) waveguide and a SiNx dielectric waveguide has been realized. The output power of the sensor is observed to change drastically with the refractive index of the detection liquid, and the sensing region can be adjusted by varying the width of the SiNx waveguide. The resolution is estimated to be as high as 7.3 x 10(-6) refractive index units. This sensor is expected to have significantly high effective sensitivity for detecting a hundred-nanometer-thick layer owing to the highly bounded field of the SRSPP mode. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3693408]