High-performance localized surface plasmon resonance fiber sensor based on nano-metal-gear array

Utilizing the outstanding-sensitivity characteristic of localized surface plasmon resonance (LSPR), this study developed a new high-performance sensor design model. Based on a cross-sectional view of the component, the proposed new LSPR fiber sensor comprises a single-mode fiber (SMF), nano-metal rings, and nano-metal gears. The numerical simulation method that combines the finite element method (FEM) and eigenmode expansion method (EEM) was used to design and analyze the sensor. In addition, to increase the accuracy of the numerical simulation results, the proposed numerical simulation method included a perfectly matched layer (PML) and a perfectly reflecting boundary condition (PRB). In other words, the FEM and EEM numerical methods involve not only discrete guided modes and discrete LSPR modes in the simulation and design process, but also discrete radiation modes, that is, continuous radiation modes converted using PML and PRB. This study found that the current metallic patterns in the fiber sensor can trigger the LSPR by the electric field Er of the core mode HE11, which is the main reason the novel fiber sensor yields a high performance. After algorithms were performed, images showed evident excitation of the LSPR. The LSPR fiber sensor designed in this study possesses the advantageous attributes of a short length (77.01764 μm), high resolution (approximately −80 dB), and high sensitivity (approximately 45,062 nm/RIU).