Enhancing plasmonic effect in periodic nanometal square prisms with fences and cavities for refractive index and temperature sensing applications

Abstract

This paper investigates the enhancing plasmonic effect of periodic arrays of silver-shell square prisms employing a three-dimensional finite element method for refractive index and temperature sensing applications in the near-infrared region. We found that the connected metal-shell square prisms could simultaneously generate surface, gap, and cavity plasmon resonances modes in a single structure and remarkably enhance the sensing performance. The proposed design, constructed using silver-shell square prisms with linked fences, as a plasmon resonance source in the center of the unit cell, can sense refractive index and temperature with outstanding sensitivity as 940 nm/RIU and 0.5 nm/°C, respectively. Simulation results reveal that the proposed structure’s absorptance is approximately perfect, significantly larger than its concrete counterpart without the center cavity and linked fences. The proposed system has a strong dipolar effect generated from the mutual inductance on metal and coupled fences, and the capacitive coupling in cavity regions of nanostructures. These distinctive advantages enable the linkage-based plasmonic sensor, a multi-functional biosensor, and a potential label-free photonic device.