Tunable phase detection sensitivity of transmitted-type guided-mode resonance sensor in a heterodyne interferometer.

A transmitted-type guided-mode resonance (GMR) sensor is presented for using an electro-optic heterodyne interferometer to tune phase detection sensitivity. The GMR grating waveguide structure is fabricated using a low-cost nanoimprinting SiO(2) sol-gel process and sputtering TiO(2) film. The phase properties of the GMR sensor are numerically investigated to verify its phase detection capability in a heterodyne interferometer. The phase curves for both transmitted- and reflected-type GMR sensors are experimentally obtained and compared. We conclude that the transmitted-type GMR sensor is more feasible for tuning phase detection sensitivity by rotating the analyzer in the electro-optic heterodyne interferometer. In our experiment, we achieved the GMR sensor phase detection sensitivity as high as 1.8 × 10(-7) RIU.