一种基于耦合共振的太赫兹双频超材料吸收器设计

A design of dual-band terahertz metamaterial absorber based on coupling resonance for sensing application

以两个相耦合的非对称十字金属条带结构作为基元,设计了一种新型双频带太赫兹超材料吸收器。该吸收器由周期性排列的基元、金属接地板以及介质层组成。通过基元之间的耦合,可利用单一基元实现太赫兹波段的双频带吸收特性。仿真结果表明,设计的超材料吸收器在具有基频共振所形成的吸收峰外,还具有耦合共振所形成的耦合吸收峰。通过调节耦合强度、介质层厚度和金属条带的对称性,可以在保持磁共振模式的耦合共振峰频率基本稳定的同时,对基频共振峰频率进行调控,以满足不同的吸收要求。此外,该超材料吸收器也展现出对气体折射率变化的敏感性,灵敏度可达2.5 THz/RIU,使这种吸收器在气体传感方面具有巨大的潜力。

In this paper, a new type of dual-band terahertz metamaterial absorber was designed. The unit cell of this absorber was consisted of two coupled asymmetrical metallic cross strips and a dielectric layer on top of a metallic ground plane. The dual- band absorption effect was realized by the the coupling between the unit cells. The dual-band absorption effect was confirmed by the simulation results. The absorption peak frequency of the fundamental mode resonance can be further adjusted by modifying the distance between the unit cell, the thickness of dielectric layer and the symmetry of the cross stripe, according to the simulated results. Moreover, this metamaterial absorber demonstrates high sensitivity to the change of refractive index of the gas, which makes it promising for gas sensing applications.