Loaded Slot Cavity Induced Sensing Enhancement and Transparency Based on Plasmonic Structure

Abstract

Biosensors have proved immensely useful in numerous vital areas for detection and testing. Here, a novel plasmonic nanosensor, based on loaded slot cavity, is proposed and studied. We conduct a detailed analysis of the influence of the load’s parameters on the transmission characteristics based on the finite element method and surface charge and current model. Simulation results reveal that the existence of the load can cause the resonant wavelength to have a linear or nonlinear red shift, and yield an enhanced plasmonic nanosensor with sensitivity about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}={2900}$ </tex-math></inline-formula> nm/RIU and a detection limit about 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,10^{\text {-3}}$ </tex-math></inline-formula> . In addition, the proposed structure is well used in actual biosensing for blood plasma concentration, glucose concentration, ethanol temperature and diseased cell detection with high sensitivity. Finally, an extended structure with detuned loaded slot cavities is proposed to realize PIT/multi-PIT and slow light effect. The special features of our proposed structure are applicable in the realization of various integrated components for the development of high-performance plasmonic biosensor.