Reflex optical sensor based on dual metal gratings with high angular sensitivity

An interesting reflection phenomenon in a dual metal grating (DMG) structure is studied, which is related to the competition between Fabry-Perot (F-P) resonance effect and evanescent-field coupling effect inside the gap between the two composing single metal gratings. This competition leads to high angular sensitivity in response to the refractive index variation of the sample solution in the gap. A reflex optical sensor with high sensitivity based on DMG for detecting the change in refractive i