Omnidirectional, broadband light absorption using large-area, ultrathin lossy metallic film coatings.
Omnidirectional, broadband light absorption using large-area, ultrathin lossy metallic film coatings.
复制标题
DOI：
10.1038/srep15137
复制
发表时间：
2015-10-09
影响因子：
4.6
通讯作者：
Aydin K
中科院分区：
文献类型：
--
作者：
Li Z;Palacios E;Butun S;Kocer H;Aydin K
基于纳米结构材料的共振吸收体在光学滤波器、热光电转换器、热发射器和热电子收集等方面有着广泛的应用前景。然而，这种微米/纳米级特征介质或表面的重大挑战之一是用于结构图案化的昂贵的光刻工艺，其限制了复杂设计的工业生产。在这里，我们展示了光刻免费，宽带，偏振无关的光吸收器的基础上的三层的反射膜组成的亚波长铬（Cr）和氧化物膜涂层。我们已经测量了几乎完美的吸收高达99.5%，在整个可见光区和超越（400-800 nm）。除了接近理想的吸收，我们的吸收器还表现出对±60度入射角的全向独立性。在这项研究中引入的宽带吸收体比纳米结构等离子体吸收体在带宽，偏振和角度独立性方面表现得更好。基于均匀薄膜涂层的这种“黑体”样品的改进归因于非对称高损耗法布里-珀罗腔的极低品质因数。与基于碳纳米管的黑色材料相比，这种宽带吸收体设计是可接受的，并且不需要光刻工艺。该演示将宽带超吸收体设计重新导向到极端简单、更高性能和成本效益的制造便利性，以用于实际工业生产。
Resonant absorbers based on nanostructured materials are promising for variety of applications including optical filters, thermophotovoltaics, thermal emitters, and hot-electron collection. One of the significant challenges for such micro/nanoscale featured medium or surface, however, is costly lithographic processes for structural patterning which restricted from industrial production of complex designs. Here, we demonstrate lithography-free, broadband, polarization-independent optical absorbers based on a three-layer ultrathin film composed of subwavelength chromium (Cr) and oxide film coatings. We have measured almost perfect absorption as high as 99.5% across the entire visible regime and beyond (400–800 nm). In addition to near-ideal absorption, our absorbers exhibit omnidirectional independence for incidence angle over ±60 degrees. Broadband absorbers introduced in this study perform better than nanostructured plasmonic absorber counterparts in terms of bandwidth, polarization and angle independence. Improvements of such “blackbody” samples based on uniform thin-film coatings is attributed to extremely low quality factor of asymmetric highly-lossy Fabry-Perot cavities. Such broadband absorber designs are ultrathin compared to carbon nanotube based black materials, and does not require lithographic processes. This demonstration redirects the broadband super absorber design to extreme simplicity, higher performance and cost effective manufacturing convenience for practical industrial production.