Department of Physics, Chalmers University of Technology , 412 96 Göteborg, Sweden.
School of Science and Technology, Örebro University , 701 82 Örebro, Sweden.
Nano Lett. 2017 May 10;17(5):3054-3060. doi: 10.1021/acs.nanolett.7b00416. Epub 2017 Apr 4.
Optically thin perfect light absorbers could find many uses in science and technology. However, most physical realizations of perfect absorption for the optical range rely on plasmonic excitations in nanostructured metallic metasurfaces, for which the absorbed light energy is quickly lost as heat due to rapid plasmon decay. Here we show that a silicon metasurface excited in a total internal reflection configuration can absorb at least 97% of incident near-infrared light due to interferences between coherent electric and magnetic dipole scattering from the silicon nanopillars that build up the metasurface and the reflected wave from the supporting glass substrate. This "near-perfect" absorption phenomenon loads more than 50 times more light energy into the semiconductor than what would be the case for a uniform silicon sheet of equal surface density, irrespective of incident polarization. We envisage that the concept could be used for the development of novel light harvesting and optical sensor devices.
光学薄完美光吸收体在科学和技术中有许多用途。然而，光学范围内的大多数完美吸收体的物理实现都依赖于纳米结构金属超表面中的等离子体激发，由于等离子体的快速衰减，超表面吸收的光能量很快就会以热的形式损失掉。在这里，我们展示了一种在全内反射配置下激发的硅超表面，由于构建超表面的硅纳米柱和支撑玻璃衬底的反射波之间的相干电偶极子和磁偶极子散射之间的干涉，可以吸收至少 97%的近红外光。这种“近完美”吸收现象将比同等表面密度的均匀硅片多吸收 50 多倍的光能量，与入射偏振无关。我们设想这个概念可以用于开发新型的光收集和光学传感器设备。
