School of Information and Communications Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
Nanoscale. 2023 Feb 16;15(7):3398-3407. doi: 10.1039/d2nr05820k.
In this paper, a dual-band metamaterial absorber in the terahertz frequencies is proposed and its refractive index sensing characteristics is analyzed. The metamaterial structure is designed using a square metal ring with four T-shaped strips loaded outside of the ring, where the metal periodic array is on top of a silicon wafer backed with a metal ground plane. The resonant frequencies of the absorber are at 0.89 and 1.36 THz, whose absorption rates are both over 99% under normal TE and TM polarized incidences. The full widths at half maximum of them are 4.4 and 11.2 GHz, respectively, resulting in high quality factors (-factors) for these two frequency bands. The absorption rate of the absorber remains stable as the incident and polarized angles are changed. Several proposed metamaterial absorbers are experimentally fabricated and electron beam lithography (EBL) technology is employed. Good measurement results of the dual-band absorption performance are obtained using a terahertz time-domain spectroscopy system based on photoconductive antennas. Furthermore, the metamaterial absorber also shows sensing properties for analytes with different refractive indices or thicknesses. This work provides a new choice for the design of high- dual-band terahertz metamaterial absorbers and their application to refractive index sensing.
本文提出了一种工作在太赫兹频段的双频超材料吸波器，并分析了其折射率传感特性。该超材料结构采用正方形金属环，环外加载四个 T 型条，金属周期性阵列位于硅片上，硅片背面有金属接地板。吸波器的谐振频率分别为 0.89 和 1.36 THz，在正常 TE 和 TM 偏振入射下，其吸收率均超过 99%。它们的半最大值全宽分别为 4.4 和 11.2 GHz，这两个频带具有较高的品质因数（Q 值）。吸波器的吸收率在改变入射角和偏振角时保持稳定。几个提出的超材料吸波器被实验制造出来，并采用电子束光刻（EBL）技术。使用基于光导天线的太赫兹时域光谱系统获得了双频吸收性能的良好测量结果。此外，超材料吸波器还表现出对不同折射率或厚度的分析物的传感特性。这项工作为设计高性能双频太赫兹超材料吸波器及其在折射率传感中的应用提供了新的选择。
