基于狄拉克半金属超材料的太赫兹吸波体研究

Research of Terahertz Absorber Based on Dirac Semimetal Metamaterials

设计了一种基于狄拉克半金属的超材料太赫兹宽频及双频吸波体.该吸波体由三层结构组成,上层为狄拉克半金属层,中间为介质层,底层为金属基底.首先设计了U型的单峰吸波体,该吸波体能够实现在6.02 THz处的完美吸收.通过研究单峰吸波体的表面电流分布可知,入射太赫兹能量的吸收主要来自沿U型臂方向上电场引起的电偶极子振荡.然后通过多个吸收峰叠加扩展带宽的原理,设计出了双频和宽频吸波体.仿真结果表明,本文设计的双频吸波体能够在5.33 THz和5.86 THz处实现94.7%及91%的吸收率,宽频吸波体在5.59 THz到5.90 THz之间吸收率可达90%以上.同时,利用狄拉克半金属电导率的可调节性,通过改变狄拉克半金属的费米能级,无需优化几何结构和重新制造结构,便可以实现共振吸收峰频率的动态调谐.

In this paper,dual band and broadband terahertz absorbers based on Dirac semimetal metamaterials are designed,The proposed absorbers consist of three layers.The upper layer is a Dirac semimetal layer,middle layer is dielectric layer,and the lower layer is gold which consider as the metal back plate.The U-type single absorber is designed at first which can achieve perfect absorption at 6.02 THz.By analyzing the surface current distribution of the single absorber,it is known that the energy of the incident THz wave is absorbed by the electric dipole oscillation which caused by the electric field in the U-type arm direction.Then,the dual-band and broadband absorbers are designed by superimposing the extended bandwidth of multiple absorption peaks.The dual-band absorber can achieve 94.7%and 91%absorption at 5.33 THz and 5.86 THz respectively.The broadband absorber can achieve the over 90%absorption between 5.59 THz and 5.90 THz.In addition,due to the tunability of Dirac semimetal's conductivity,the dynamic tuning of the resonance absorption peak can be achieved by changing the Fermi energy of the Dirac semimetal without optimize the geometry and re-manufacture the structure.