基于圆台结构的超宽带极化不敏感太赫兹吸收器

摘要

In this paper, we present an ultra-broadband polarization-independent terahertz (THz) metamaterial absorber (MA) made of circular truncated cone metamaterial. Absorptivity higher than 92.3%at normal incidence is obtained in a wide range of frequencies from 2 to 10 THz. We employ an isotropic metamaterial cell which consists of alternating layers of Au metal and SiO2 dielectric spacer. The absorption spectra of the THz MA are calculated using the finite-difference time domain (FDTD) method within the CST Microwave Studio 2009 in the frequency range of 0-10 THz. Our broadband absorber can be regarded as a group of micro-absorbers perpendicularly stacked and their absorption peaks coupling to each other to form an ultra broadband absorption. This THz MA has the advantages of broadband, polarization-independent and fabrication facility, and thus can be widely applied in THz wave harvesting, detection, spectrum imaging and stealthy technology.%本文提出一种基于圆台形吸收单元的超宽带、极化不敏感的超材料太赫兹吸收器.该超材料吸收器采用金属薄膜金和介质层二氧化硅交替叠加的多层结构.采用商业软件CST Studio Suite 2009时域求解器计算了其在0-10 THz波段内的吸收率A(ω),在2-10 THz之间实现了对入射太赫兹波的超宽频带强吸收.仿真结果表明,由于其圆台形单元结构,在器件垂直方向上形成一系列不同尺寸的微型吸收器,产生了吸收频点相连的多频吸收峰.利用不同吸收峰的耦合叠加效应,获得超过8 THz的超宽带太赫兹波吸收,吸收强度达到92.3%以上.这一结构具有超宽带强吸收,360◦极化不敏感以及易于加工等优越特性,因而在太赫兹波探测器、光谱成像以及隐身技术方面具有潜在的应用.