An All-Metal Metasurface for High-Efficiency Refractive Index Sensing Based on Reflection-Type Surface Lattice Resonance

This paper reports an all-metal metasurface with reflection-type surface lattice resonance (SLR), which is more suitable for high-efficiency refractive index (RI) sensing than transmission-type SLR metasurfaces due to direct and strong light-matter interaction. The measured full width at half maximum (FWHM) of the SLR is 13.5 nm, keeping a balance between the noise immunity and sensing efficiency. Notably, the RI sensitivity is determined by the lattice period with regularity and controllability, which provides a theoretical guide to designing a sensor with a target sensitivity. Besides, the SLR phenomenon can also be realized by the different nanostructures and lattice arrays flexibly. This research can support diverse applications involving not only RI sensing but also nonlinear optics, nano-laser, etc.