介质层对超材料太赫兹响应特性的控制规律

作为超材料的重要组成部分,介质层是影响超材料响应特性的关键因素.固定超材料的尺寸和表层金属图形,通过理论推导和仿真模拟详细分析了在太赫兹波段下介质层的介电常数和厚度两个参数对超材料响应特性的控制规律,并首次确定了响应频率与介电常数的关系方程.结果表明,在其他参数不变的情况下,超材料的响应频率主要取决于介质层的介电常数的实部大小,而其吸收率则主要取决于介质层的厚度.据此,提出一种设计超材料的新方法:首先将设计要求的响应频率代入频率方程计算出相应介质层的介电常数,由此挑选合适的介质材料;然后固定介电常数、调节介质层厚度,获得在特定频率具有特定吸收率的超材料.

Control of terahertz response properties of metamaterials by dielectric layer

As an important part of metamaterials, the dielectric layer is one of the key factors influencing the properties of metamaterials. When the size and surface metal-pattern of metamaterials had been fixed, control rules related to the permittivity and thickness of dielectric layer were analyzed within terahertz band. For the first time, the formula related with the frequency and permittivity was defined in this article. The results show that, with other parameters kept constant, the frequency response of metamaterials mainly depends on the real part of permittivity, while the absorption mainly depends on the thickness of the dielectric layer. According to the conclusions, we further proposed a new method for designing the metamaterials: firstly, putting the required response frequency into the deduced frequency equation and calculating the permittivity, by which suitable dielectric material in accordance with the calculation can be chosen; secondly, under the chosen frequency, the highest or desirable terahertz absorption can be obtained by adjusting the thickness of the dielectric layer. This design method can effectively predict and control the response properties of the metamaterials just by changing the parameters of the dielectric layer. Importantly, our method not only can obviously shorten the design cycle, but can also greatly reduce the difficulty in designing the metamaterials.