Liu Xinyu, Fan Kebin, Shadrivov Ilya V, Padilla Willie J
Opt Express. 2017 Jan 9;25(1):191-201. doi: 10.1364/OE.25.000191.
Metamaterial absorbers consisting of metal, metal-dielectric, or dielectric materials have been realized across much of the electromagnetic spectrum and have demonstrated novel properties and applications. However, most absorbers utilize metals and thus are limited in applicability due to their low melting point, high Ohmic loss and high thermal conductivity. Other approaches rely on large dielectric structures and / or a supporting dielectric substrate as a loss mechanism, thereby realizing large absorption volumes. Here we present a terahertz (THz) all dielectric metasurface absorber based on hybrid dielectric waveguide resonances. We tune the metasurface geometry in order to overlap electric and magnetic dipole resonances at the same frequency, thus achieving an experimental absorption of 97.5%. A simulated dielectric metasurface achieves a total absorption coefficient enhancement factor of FT=140, with a small absorption volume. Our experimental results are well described by theory and simulations and not limited to the THz range, but may be extended to microwave, infrared and optical frequencies. The concept of an all-dielectric metasurface absorber offers a new route for control of the emission and absorption of electromagnetic radiation from surfaces with potential applications in energy harvesting, imaging, and sensing.
由金属、金属-电介质或电介质材料组成的超材料吸收体已在大部分电磁频谱范围内实现，并展现出了新颖的特性和应用。然而，大多数吸收体使用金属，因此由于其低熔点、高欧姆损耗和高导热性，在适用性方面受到限制。其他方法依赖于大型电介质结构和/或支撑电介质基板作为损耗机制，从而实现较大的吸收体积。在此，我们展示了一种基于混合电介质波导共振的太赫兹（THz）全电介质超表面吸收体。我们调整超表面的几何形状，以便在同一频率下使电偶极子共振和磁偶极子共振重叠，从而实现了97.5%的实验吸收率。一个模拟的电介质超表面实现了总吸收系数增强因子FT = 140，且吸收体积较小。我们的实验结果在理论和模拟中得到了很好的描述，并且不仅限于太赫兹范围，还可扩展到微波、红外和光频。全电介质超表面吸收体的概念为控制表面电磁辐射的发射和吸收提供了一条新途径，在能量收集、成像和传感等方面具有潜在应用。
