High sensitive plasmonic sensor with simple design of the ring and the disk resonators

Abstract

In this paper, we investigated a plasmonic sensor based on silicon dioxide $\left( {{\text{SiO}}_{2} } \right)$ ring and disk resonator with high sensitivity. The ${\text{SiO}}_{2}$ ring and disk are placed inside the Au layer and the Au layer is on Topas substrate. The proposed structure operates in the wavelength range of 1200 nm to 2000 nm and by tailoring geometrical parameters of the structure, the sensor achieved high optical absorption. In addition, we changed the disk and the ring resonator to the hollow disk and ring resonator which the inside of the ring and disk is surrounded by different refractive index materials (n). We use the finite difference time domain method. We reached high absorption and sensitivity for different materials. When the refractive index of the material is n = 1.7, the maximum sensitivity is achieved. The maximum sensitivity of this proposed sensor is 1122 nm/RIU corresponding to the resonance wavelength of 1806 nm. The figure of merit is 9.83 ${\text{RIU}}^{ - 1}$, while the quality factor of this sensor is 18.53. The variation of sensitivity is from 785 to 1122 nm/RIU.