A multimode excitation metasurface for microscale molecular thin film recognition and refractive index sensing

We propose a multi-mode all-dielectric metasurface using toroidal dipole (TD) resonance for microscale molecular recognition and refractive index sensing. CST electromagnetic simulation shows two mid-infrared resonance peaks with high sensitivity to refractive index and incident angle changes. The sensor has a theoretical Q value of 1.09×10^5 and can recognize AG proteins with significant mid-infrared absorption enhancement. It also has a high refractive index sensitivity with an FOM of 501.2. This provides a basis for the development of nanophotonics and ultra-sensitive optical sensors.