Detection of high-refractive index media by a surface plasmon sensor using a one-dimensional metal diffraction grating

We aim to detect high-refractive index media by substituting metal diffraction grating with a metal film. The advantages of this structure are miniaturization, wide-range detection, and versatility. The Au gratings were fabricated on a glass substrate by electron beam lithography and lift-off process. Using a 635 nm laser, we measured the dependence of reflectance on the light incident angle. At a grating period of 600 nm, the sensor detected 1-bromonaphthalene (refractive index n =1.65) and ethyl alcohol (n = 1.36).