复合石墨烯/硅半球的宽带太赫兹超材料吸收器

Wideband terahertz metamaterial absorber for composite graphene/silicon hemispheres

提出了一种性能可调的宽带、极化与入射角不敏感的超材料太赫兹吸收器,该吸收器自上而下分为四层结构,分别是:硅半椭球/半球体复合结构、连续石墨烯层、PDMS介质层和金属背板。通过在TE波垂直入射条件下仿真,在已知结果基础上,对不同石墨烯化学势和不同结构条件下的电场结果分析表明,在硅半椭球/半球体亚波长复合结构所形成的连续、多模法布里-珀罗共振,以及由石墨烯所激发的多个离散的等离子体共振的协同作用下,其吸收光谱得到平滑和扩展,使该结构可实现吸收率宽范围可调,以及接近100%吸收率的宽频带吸收特性。特别的,当石墨烯化学势分别为0.2与0.9 eV时,其分别可获得约5.7 THz与7 THz的宽带太赫兹波吸收(吸收率超过90%),且其最大吸收率接近完美吸收(约99.8%)。此外,该结构还具有360°极化不敏感和高于60°的入射角不敏感等优异特性,在以上角度范围内,吸收器吸收率仍可保持到90%以上。在太赫兹波探测、光谱成像以及隐身技术等方面具有潜在的应用前景。

A tunable broadband, polarization insensitive and incident angle insensitive metamaterial terahertz absorber is proposed, which consists of silicon semi-ellipsoid/semi-spherical structure, graphene, dielectric layer and metal back plate. Based on the known results, the electric field results under different chemical potentials of graphene and different structural conditions were analyzed by simulation under the condition of vertical incident TE wave show that under the synergism of continuous and multimode Fabry-Perot resonances formed by silicon semi-ellipsoid/semi-spherical subwavelength structure and multiple discrete plasma resonances excited by graphene the absorption spectrum is smoothed and expanded so that the structure can achieve a wide range of adjustable absorptivity and a broadband absorption characteristic of nearly 100% absorptivity. When the chemical potential of graphene is around 0.2 eV and 0.9 eV, it can obtain about 5.7 THz and 7 THz wideband terahertz wave absorption(the absorption rate is more than 90%), respectively, and its maximum absorption rate is close to perfect absorption(about 99.8%). In addition, the structure is insensitive to 360° polarization and incident angle higher than 60°. In the above angle range, the absorptivity of the absorber can still be maintained to more than90%. and the structure has potential applications in terahertz wave detection, spectral imaging and stealth technology.