Department of Physics, Rensselaer Polytechnic Institute, 110 8th St., Troy, NY, 12180, USA.
Department of Photonics, National Chiao-Tung University, No. 1001, Daxue Rd, East District, Hsinchu City, 300, Taiwan.
Sci Rep. 2017 Jun 23;7(1):4171. doi: 10.1038/s41598-017-03800-y.
A 900 nm thick TiO simple cubic photonic crystal with lattice constant 450 nm was fabricated and used to experimentally validate a newly-discovered mechanism for extreme light-bending. Absorption enhancement was observed extending 1-2 orders of magnitude over that of a reference TiO film. Several enhancement peaks in the region from 600-950 nm were identified, which far exceed both the ergodic fundamental limit and the limit based on surface-gratings, with some peaks exceeding 100 times enhancement. These results are attributed to radically sharp refraction where the optical path length approaches infinity due to the Poynting vector lying nearly parallel to the photonic crystal interface. The observed phenomena follow directly from the simple cubic symmetry of the photonic crystal, and can be achieved by integrating the light-trapping architecture into the absorbing volume. These results are not dependent on the material used, and can be applied to any future light trapping applications such as phosphor-converted white light generation, water-splitting, or thin-film solar cells, where increased response in areas of weak absorption is desired.
我们制备了一个 900nm 厚的 TiO 简单立方光子晶体，其晶格常数为 450nm，并将其用于实验验证一种新发现的极端光弯曲机制。与参考 TiO 薄膜相比，观察到吸收增强扩展了 1-2 个数量级。在 600-950nm 区域中鉴定出了几个增强峰，其远超过了遍历基本极限和基于表面光栅的极限，其中一些峰值超过了 100 倍的增强。这些结果归因于由于光矢量几乎平行于光子晶体界面，因此光程长度接近无穷大的急剧折射。观察到的现象直接源于光子晶体的简单立方对称性，并且可以通过将光捕获结构集成到吸收体积中来实现。这些结果不依赖于所使用的材料，并且可以应用于任何未来的光捕获应用，例如磷光体转化的白光产生、水分解或薄膜太阳能电池，其中希望在弱吸收区域中增加响应。
