All-dielectric refractive index sensor based on Fano resonance with high sensitivity in the mid-infrared region

We design and numerically analyze a Fano resonance device based on periodical all-dielectric lucky knot shaped nanostructure in the mid-infrared region with high sensitivity, which is insensitive to polarization and incident angle. The proposed nanostructure is sensitive to the change of the refractive index of the substance to be tested. We established the correspondence between the change of the refractive index and the peak position of the reflection spectrum. And then we propose an optical refractive index sensor with a sensitivity of 986 nm/RIU, and a maximum figure of merit of 32.7, which is much higher compared to the sensor based on metallic materials. The maximum Q-factor can reach 520. This study may provide a further step in optical sensing, bio-sensing and environmental monitoring.

Automated summary

A novel Fano resonance device based on periodical all-dielectric nanostructure was designed and analyzed for optical refractive index sensing, with high sensitivity, insensitivity to polarization and incident angle. The nanostructure showed a sensitivity of 986 nm/RIU and a maximum figure of merit of 32.7, outperforming metallic material sensors. This study could advance optical sensing, bio-sensing, and environmental monitoring.