All-dielectric magnetic resonance refractive index sensor based on asymmetric cross-shaped split ring metasurface

A refractive index sensor is a device that can convert small changes of the refractive index into an optical signal, which usually acts as a label-free sensing technology in the field of biomedicine. The traditional optical sensor, based on refractive index sensor, could realize sensing through the interaction of light and biochemical substance on the superstructure surface. The traditional refractive index sensors are usually composed of noble metals material, and the sensing is realized by exciting surface plasmons. However, due to the ohmic loss of the metal, the quality factor and the value of the FOM of the refractive index sensor based on the metal structure are low, generally, which greatly limits the development of refractive index sensors. In this paper, the magnetic resonance refractive index sensor based on the asymmetric all dielectric cross-shaped split ring is proposed which could achieve high sensitivity and high quality factor, by inducing the metal ohmic loss and enhancing the magnetic resonance. The cross-shaped split ring metamaterial structure is applied to wireless passive sensing and is simulated by the finite element method. Simulating the interation between the incident light TE wave and the meta-surface structure produces sharp magnetic resonance peaks. We can monitor the change in the concentration of the solution around the sensor through the moving of magnetic resonance peak. For this sensor, the resonance peak wavelength is between 8680nm-8800nm in the mid-infrared, the sensitivity is 500nm/RIU, and the FOM is 909.