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.

In this paper, a plasmonic nanosensor, by using a nanorod array in a square resonator coupled with two slot cavities, with properties for the detection of glucose concentration in water, is proposed and analyzed. We investigated the sensing feature by changing the concentration of the glucose from 0 to 60%. Obtained results show that, by placing different water samples in a square resonator and two cavities, resonance wavelengths can be changed. These resonances demonstrate different dependence on the glucose concentration of water samples. Further, varying the physical parameters of the configuration can also change the resonance wavelength and can be simply tuned. These features recommend flexibility to propose the structure. Simulation results show that the values of sensitivity and figure of merit can be obtained as 892 nm/RIU and $3.5\times {10}^6{\mathrm{RIU}}^{-1}$, respectively, which can help researchers to discover applications in the plasmonic sensor domain.