基于聚酰亚胺基底的太赫兹滤波器

超材料是通过人工方式做成的具有特殊电磁特性的亚波长周期性金属结构，通过合理的设计样品结构，可以实现自然界中传统材料无法实现的电磁现象。超材料可以广泛用于电磁隐身、完美吸收、负折射率等研究领域，近些年，随着太赫兹技术的发展，太赫兹超材料器件被广泛研究。由于硅（Si）对于太赫兹波的透过率较高，通常选取Si作为基底材料。但Si硬度较高、不易弯曲且易碎等缺点限制了THz超材料的应用。聚合物材料聚酰亚胺具有柔性，作为基底，克服了传统硅基底的缺点，透过率可以与Si匹敌，而且其表面光滑，适合传统光刻技术加工。对聚酰亚胺在太赫兹波段光学性质的测试结果表明，此种材料的折射率在1.9左右，透过率达到80%以上。设计了一种双开口谐振环结构，研究了其太赫兹波透射性质以及随太赫兹波的入射角度和样品曲率的变化规律，发现透射峰强度和峰位均不发生改变。此结果展示了将平面滤波延伸到曲面滤波领域的可能性，若将聚酰亚胺基底做薄，为今后太赫兹频段隐身衣的研究提供基础。将不同结构的两种样品叠加在一起制成宽谱滤波器, 50%的带宽达到181 GHz。此种宽带滤波器制作简单，滤波效果显著，为太赫兹波段宽带滤波器的制作提供一种新思路。

A Double Split Ring Terahertz Filter on Ploymide Substrate

Metamaterials are artificial composites that acquire their electromagnetic properties from embeded subwavelength metalic structure. With proper design of metamaterials, numerrous intriguing phenomena that not exhibited naturally can be realized, such as invisible cloaking, perfect absorption, negative refractive index and so on. In recent years, With the development of THz technology, the extensive research onTHz metamaterials devices areattracting more and more attentions. Since silicon(Si) has a higher transmittance for THz wave, it is usually selected as substrate in metamaterials structure. However, Si has the shortcomings of hardness, not easy to bend, and fragile, which limit the application of THz metamaterials.In this work, we use polyimide as the substrate to overcome the shortcomings of the Si substrate. Polyimide isflexible, smooth, suitable for conventional lithography process and the THz transmittance can compete with that of the Si. Frist, we test the THz optical properties of polymide, and get the refractive index of 1.9, and the transmittance of 80%. Second, we design a double splits ring resonators (DSRRs), and study the properties of transmission by changing the THz incidence angle and curvature of the sample. We find the resonant amplitude and resonant frequencies are unchanged.Fabricating metamaterials structures on a thin plastic substrate is a possible way to extend plane surface filtering to curved surface filtering. Third, we try to make a broadband filter by stacking two samples, and the 181GHz bandwidth at 50% has been achieved. By stacking several plane plastic metamaterial layers with different resonance responses into a multi-layer structure, a broadband THz filter can be built. The broadband filter has the advantages of simple manufacture, obvious filtering effect, which provides a new idea for the production of terahertz band filter.