Ultra-sensitive gas sensor using Fano resonance in hybrid nano-bar/nano-elliptic dielectric metasurface

Fano resonance is an intriguing physical phenomenon that could be achieved by engineering a destructive interference between a superradiant bright mode and a subradiant dark mode. A variety of hybrid systems of metasurfaces have been widely explored demonstrating sharp Fano resonances with high sensitivity. However, plasmonic metasurfaces have limitations of Ohmic losses that constrain the achievable quality factor. Meanwhile, the dielectric metasurfaces provide sharp Fano resonance but with limited sensitivity and figure-of-merit (FOM) compared to plasmonic metasurfaces. In this paper, we report an ultra-sharp, ultra-sensitive refractormetric gas sensor based on Fano resonance using all dielectric metasurface. Our proposed design is composed of hybrid system of nano-bar/nano-elliptic all dielectric silicon. The proposed design has reported a sensitivity of 1,852 nm/RIU with a significant quality factor of 1225, leading to a figure-of-merit (FOM) of 411 at the operating wavelength of 5.5128 μm, within the spectral window of the nitric oxide. Our design brings a considerable impact as a cheap and easily fabricated sensor for gas chemical recognition.