High Sensitivity and Tunable Nanoscale Sensor Based on Plasmon-Induced Transparency in Plasmonic Metasurface

A nanoscale sensor which comprises dielectric-metal-dielectric waveguide and plasmonic metasurface resonators is proposed to realize plasmon-induced transparency responses. The properties of the device are numerically and analytically investigated with different physical parameters. The effect of the incident polarization, geometrical parameters, plasmonic metasurface materials, prism dielectric constant, and the shape of metasurface in near infrared region are then studied to enhance the performance parameters of the structure including the sensitivity, figure-of-merit, and tunability. Our calculations show that the proposed devices are able to operate as a high-sensitivity and tunable sensor with maximum figure-of-merit of 480, and sensitivity of 497.8 nm/refractive index unit for slight change of Δn = 0.24, in the refractive index, which stems from its ultra-narrow transparency window and long coupling length between resonators. Furthermore, the structure can be utilized for harnessing light propagation. It is shown that by using silver plasmonic metasurface and appropriate dielectric, a slow up factor as high as 800 is achievable in the proposed structure. We believe that the proposed sensor can be used as a promising platform for future sensing applications such as nanostructure biosensors.