A compact dual-band/broadband polarization in-sensitive terahertz (THz) metamaterial absorber (MMA) is discussed in this article. It consists of a simple planar structure as a unit cell and an optically transparent indium tin oxide (ITO) ground plane, which are separated by a 50 µm dielectric substrate. We designed three combinations of MMA, which are ITO–SiO2–ITO, ITO–polyimide–ITO and ITO–polyethylene terephthalate (PET)–ITO for the same planar structure. The proposed structure has dual-band absorbance with peak absorptivity of >98% for all three given combinations. By changing the substrate of the structure, the resonant frequency and bandwidth of the absorber structure is varied and by adjusting the design parameters, broadband absorbance is achieved for the same planar structure. The numerical simulation of the absorber shows that the broadband absorptivity is >98% for all three substrates. Polyimide, PET and SiO2 based absorbers are demonstrated with bandwidth of 0.467, 0.527 and 0.6 THz with covered broadband frequency range of 0.390–0.857, 0.407–0.934 and 0.433–1.03 THz, respectively. ITO–PET–ITO absorber structures also possess optical transparency. These bandwidths are convenient and compatible with electronic and magnetic sources in the terahertz region. This study provides applications in THz detection, sensing, bolometric imaging, and stealth and communication systems. All three absorbers have greater absorbance characteristics for transverse electric and transverse magnetic polarizations. The proposed structure is working well for wide angles of incident and polarization angles wave up to 90°.

中文翻译：

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由 SiO2 实现的太赫兹双频/宽带超材料吸收器：具有吸收特性的聚酰亚胺和 PET 介电基板

本文讨论了一种紧凑的双波段/宽带偏振不敏感太赫兹 (THz) 超材料吸收器 (MMA)。它由一个简单的平面结构作为一个单元和一个光学透明的氧化铟锡 (ITO) 接地平面组成，它们被一个 50 µm 的介电基板隔开。我们为相同的平面结构设计了三种 MMA 组合，即 ITO-SiO2-ITO、ITO-聚酰亚胺-ITO 和 ITO-聚对苯二甲酸乙二醇酯 (PET)-ITO。所提出的结构具有双波段吸光度，所有三种给定组合的峰值吸光度均大于 98%。通过改变结构的基片，改变吸收体结构的谐振频率和带宽，通过调整设计参数，对同一平面结构实现宽带吸收。吸收体的数值模拟表明，所有三种基材的宽带吸收率均 >98%。聚酰亚胺、PET 和 SiO2 基吸收剂的带宽分别为 0.467、0.527 和 0.6 THz，覆盖的宽带频率范围分别为 0.390-0.857、0.407-0.934 和 0.433-1.03 THz。ITO-PET-ITO 吸收体结构也具有光学透明性。这些带宽很方便，并且与太赫兹区域的电子和磁源兼容。这项研究提供了在太赫兹探测、传感、辐射热成像以及隐身和通信系统中的应用。所有三种吸收体对于横向电极化和横向磁极化都具有更大的吸收特性。所提出的结构适用于高达 90° 的宽入射角和偏振角波。