Pronounced Linewidth Narrowing of Vertical Metallic Split-Ring Resonators via Strong Coupling with Metal Surface

• Main Authors: Wei Du, Youcheng Zhu, Zhendong Yan, Xiulian Xu, Xiaoyong Xu, Jingguo Hu, Pinggen Cai, Chaojun Tang
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Nanomaterials
• Subjects: magnetic plasmon resonances; split-ring resonators; ultranarrow-band hybrid mode; metamaterial
• Online Access: https://www.mdpi.com/2079-4991/11/9/2194

We theoretically study the plasmonic coupling between magnetic plasmon resonances (MPRs) and propagating surface plasmon polaritons (SPPs) in a three-dimensional (3D) metamaterial consisting of vertical Au split-ring resonators (VSRRs) array on Au substrate. By placing the VSRRs directly onto the Au substrate to remove the dielectric substrates effect, the interaction between MPRs of VSRRs and the SPP mode on the Au substrate can generate an ultranarrow-band hybrid mode with full width at half maximum (<i>FWHM</i>) of 2.2 nm and significantly enhanced magnetic fields, compared to that of VSRRs on dielectric substrates. Owing to the strong coupling, an anti-crossing effect similar to Rabi splitting in atomic physics is also obtained. Our proposed 3D metamaterial on a metal substrate shows high sensitivity (<i>S</i> = 830 nm/RIU) and figure of merit (<i>FOM</i> = 377), which could pave way for the label-free biomedical sensing.