Department of Mechanical Engineering, Northwestern University, Evanston, IL, 60208, USA.
Sci Rep. 2017 Jun 16;7(1):3752. doi: 10.1038/s41598-017-04013-z.
Despite their seemingly random appearances in the real space, quasi-random nanophotonic structures exhibit distinct structural correlations and have been widely utilized for effective photon management. However, current design approaches mainly rely on the deterministic representations consisting two-dimensional (2D) discretized patterns in the real space. They fail to capture the inherent non-deterministic characteristic of the quasi-random structures and inevitably result in a large design dimensionality. Here, we report a new design approach that employs the one-dimensional (1D) spectral density function (SDF) as the unique representation of non-deterministic quasi-random structures in the Fourier space with greatly reduced design dimensionality. One 1D SDF representation can be used to generate infinite sets of real space structures in 2D with equally optimized performance, which was further validated experimentally using light-trapping structures in a thin film absorber as a model system. The optimized non-deterministic quasi-random nanostructures improve the broadband absorption by 225% over the unpatterned cell.
尽管在真实空间中它们的出现看似是随机的，但准随机纳米光子结构表现出明显的结构相关性，并已被广泛用于有效的光子管理。然而，目前的设计方法主要依赖于在实空间中由二维（2D）离散图案组成的确定性表示。它们无法捕捉到准随机结构的固有非确定性特征，并且不可避免地导致设计维度的增加。在这里，我们报告了一种新的设计方法，该方法将一维（1D）光谱密度函数（SDF）用作傅里叶空间中具有大大降低设计维度的非确定性准随机结构的唯一表示。一个 1D SDF 表示可以用于在二维空间中生成无限数量的具有同等优化性能的结构，这通过使用薄膜吸收体中的光捕获结构作为模型系统进行了实验验证。优化后的非确定性准随机纳米结构将宽带吸收提高了 225%，超过了无图案单元。
