High-Sensitivity Plasmonic Sensor Based on Metal–Insulator–Metal Waveguide and Hexagonal-Ring Cavity

Abstract

We have proposed and analyzed a compact refractive index sensor in 2-D plasmonic waveguide by hexagonal-ring cavity. The metal-insulator-metal waveguides are coupled to a cavity that is filled with liquid/gaseous material under sensing of refractive index. According to the linear relationship, the refractive index changes of the dielectric material inside the cavity and temperature changes of environment medium can be obtained from the detection of the resonance wavelength. The finite-difference time-domain simulations reveal that by designing the structure carefully, refractive index and temperature sensitivity values can be obtained as high as 4270 nm per refractive index unit (RIU) and 0.56 nm/°C, respectively. The effects of structural parameters, such as length and refractive index of hexagonal-ring cavity on the sensing spectra, are studied as well. The proposed structure with such high sensitivity will be useful in compact optical devices for optical communications and integrated photonics circuits.