Achieving high sensitivity by adding rings to a plasmonic metasurface with nano-holes

Abstract

This report demonstrates a subwavelength plasmonic metasurface for a refractive index sensor at near-infrared (NIR) wavelengths. This sensor includes a two-dimensional periodic array of gold nano-rings and nano-holes in a gold film. The structure's potential for high-sensitivity sensing in reflection configuration has been demonstrated. We use a TiN layer in this structure. It prevents light transmission from the resonators, making the transmission spectrum near zero and causing a deeper reflection dip. This sensor can be suitable for biosensing applications like poliovirus sensing. Generally, high sensitivity is obtained for poliovirus of over 817 nm/RIU. It is shown that making ledges around nano-holes increases the resonance wavelength shift and, therefore, the sensitivity by more than 33 times.