Robust all-dielectric high Q-factor metasurface for sensing

All-dielectric metasurfaces have seen a recent surge of interest as an alternative to plasmonic devices, due to low losses and desirable optical properties. High Q-factor quasi-bound state in the continuum resonances can be manufactured and manipulated via designed asymmetry in the nanostructures. The presented metasurface design, based on a slotted disk nanostructure, produces strong E-Field enhancement with good surface coverage external to the structure. The design transition from structure-in-air to structure-on-substrate in a water-based sensing medium is presented, along with the robust tunability and multiplexing potential of our fabricated resonances. Our structure maintains a high Q-factor and refractive index sensitivity over a wide wavelength range in the visible and near-IR.