基于钛酸锶的可调太赫兹超材料吸波器设计

摘要：

热敏钛酸锶（SrTiO3）作为铁电晶体， 在微波和太赫兹波段有很强的可调性， 具有潜在价值。 利用热电磁的可调性实现智能操作， 提出了一种基于SrTiO3晶体的具有太赫兹波段吸收的热可调超材料。 吸收超材料（AM）由Floquet线性周期排列单元形成， 该单元由金属接地平面和菱形金属贴片中嵌入的交叉SrTiO3材料组成， 并由FR-4介电层隔开。 该超材料吸波器通过改变温度来实现频率的可调。 详细讨论了SrTiO3的介电常数， 以说明如何产生与热转换的可重构性。 数值结果表明， 当温度从280 K增加到360 K时， 吸收带的可调谐带宽达到90 GHz， 相应的吸收率达到99％以上。 随着温度的升高， 共振频率将产生蓝移。 本文提出的被动热可调谐超材料可作为传感、 材料检测和频率选择性热发射器的潜在候选材料。

Abstract： Thermosensitive strontium titanate (SrTiO3) as a ferroelectric crystal with great tunability in microwave and terahertz band shows unparalleled potential value. Utilizing the thermal electromagnetic tunability to achieve the intelligent manipulation, a thermal-tunable metamaterial with terahertz-band absorption based on SrTiO3 crystal was proposed in this paper. The absorbent metamaterial (AM) is formed by Floquet’s linear periodic arranged unit, which is composed of a metallic ground plane and embedded cross SrTiO3 material in rhombic metallic patch, and separated by FR-4 dielectric spacer. The broadband frequency tunability of AM was operated by changing the temperature. The permittivity of SrTiO3 was discussed in detail to illustrate how the reconfigurability with thermal transformation is generated. The numerical results show that the tunable broadband of the absorbent band has reached 90 GHz and the corresponding absorptivity is above 99% when the temperature increases from 280 K to 360 K. The resonance frequency will produce a blue-shift with the increase of the temperature. This paper presents a passive thermal-tunable metamaterial as a potential candidate for sensing, materials detection and frequency selective thermal emitters.