High sensitivity metal-insulator-metal sensor based on ring-hexagonal resonator with a couple of square cavities connected

Abstract

The necessity for cheaper and more efficient sensors has been the main motivation for the use of Metal-Insulator-Metal (MIM) sensors. In this paper, a micro-dimensional refractive index MIM sensor based on surface plasmon polaritons is presented. This sensor has a ring-hexagonal resonator and a pair of squares-ring resonators that are connected to each other. For the proposed structure, magnetic field profile, transmission spectrum, and important sensor parameters such as sensitivity are obtained through the finite-difference time-domain (FDTD) method. By optimizing the dimensions of the resonators, we achieved a sensitivity equivalent to 2115 nm/RIU in the first mode and 2180 nm/RIU in the second mode. The FOM values for the first and second modes were 118.25 RIU−1 and 120.208 RIU−1, respectively. The results show that the ring-hexagonal resonator significantly improves the sensor parameters in both modes. These enhancements can be considered unique due to the simple structure presented and as a result the reduction of construction costs.