Refractive index sensing of spoof surface plasmon polaritons excited on graphene strips based on cylindrical dielectric metasurface coupling

• Published in: Results in physics Vol. 58; p. 107539
• Main Authors: Yan, Dexian, Cui, Jing, Yang, Ji, Wang, Yi, Li, Xiangjun, Zhang, Le, Li, Jining
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2024; Elsevier
• Subjects: Dielectric metasurface; Graphene strips; Spoof surface plasmon polaritons; Terahertz sensor; Spoof surface plasmon polaritons; Dielectric metasurface; Graphene strips; Terahertz sensor
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2024.107539

In this paper, we present a novel mechanism based on metasurface coupling to efficiently excite SSP on graphene strips, and further investigate its sensing applications. In comparison with previous studies, this work has several advantages and innovative points: (1) The metasurface unit cell structure consists of two cylindrical dielectric gratings with different sizes on the substrate, which can defect vertically incident terahertz waves at specific angles. This ensures that the wave-vector of the deflected wave couples with the graphene strips, thereby exciting SSPs. (2) Replacing the commonly used metal groove arrays with graphene strips to excite SSPs offers the advantage of reducing device volume and enhancing the system integration. (3) This structure enables highly sensitive sensing of different target analytes, with a high sensitivity of 110 GHz/RIU. [Display omitted] •Efficient excitation of spoof surface plasmon polaritons (SSPs) modes can be realized on the graphene strip surface.•SSP can be excited using vertically incident terahertz waves without the need for specific incident angles.•A high sensitivity of 110 GHz/RIU can be achieved based on the designed structure. In this paper, we present a novel terahertz plasmonic sensing concept that utilizes a metasurface coupler to excite spoof surface plasmon polaritons (SSPs) modes on graphene strips. The dielectric metasurface unit cell consists of two silicon cylindrical rods with different radii on a quartz substrate. Vertically incident terahertz waves are deflected by the metasurface, resulting in a transverse wave-vector within the substrate that matches the SSPs wave-vector supported by the graphene strips. This enables efficient excitation of SSPs modes on the graphene strips surface, leading to absorption resonances in the range of 0.420–0.430 THz with a high quality (Q) factor of 152. We then applied this device for refractive index sensing, and the investigation results indicate that the high Q resonances in the absorption spectrum experience shifts with changes in the refractive index of the target substance, with a sensitivity of 110 GHz/RIU. The designed structure in this study exhibits significant potential for applications in trace substance absorption spectrum detection.