Liu Hailong, Wang Hongtao, Wang Hao, Deng Jie, Ruan Qifeng, Zhang Wang, Abdelraouf Omar A M, Ang Norman Soo Seng, Dong Zhaogang, Yang Joel K W, Liu Hong
Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, Singapore, 138634, Singapore.
Engineering Product Development, Singapore University of Technology and Design, 8 Somapah Road, Singapore, 487372, Singapore.
ACS Nano. 2022 May 24;16(5):8244-8252. doi: 10.1021/acsnano.2c01999. Epub 2022 May 9.
It remains a challenge to directly print arbitrary three-dimensional shapes that exhibit structural colors at the micrometer scale. Woodpile photonic crystals (WPCs) fabricated two-photon lithography (TPL) are elementary building blocks to produce 3D geometries that generate structural colors due to their ability to exhibit either omnidirectional or anisotropic photonic stop bands. However, existing approaches produce structural colors on WPCs when illuminating from the top, requiring print resolutions beyond the limit of commercial TPL, which necessitates postprocessing techniques. Here, we devised a strategy to support high-order photonic cavity modes upon side illumination on WPCs that surprisingly generate prominent reflectance peaks in the visible spectrum. Based on that, we demonstrate one-step printing of 3D photonic structural colors without requiring postprocessing or subwavelength features. Vivid colors with reflectance peaks exhibiting a full width at half-maximum of ∼25 nm, a maximum reflectance of 50%, a gamut of ∼85% of sRGB, and large viewing angles were achieved. In addition, we also demonstrated voxel-level manipulation and control of colors in arbitrary-shaped 3D objects constituted with WPCs as unit cells, which has potential for applications in dynamic color displays, colorimetric sensing, anti-counterfeiting, and light-matter interaction platforms.
直接打印出在微米尺度上呈现结构色的任意三维形状仍然是一项挑战。通过双光子光刻（TPL）制造的木堆光子晶体（WPC）是产生三维几何结构的基本构建块，由于它们能够展现全向或各向异性光子禁带，因而能产生结构色。然而，现有方法在从顶部照射时会在WPC上产生结构色，这需要超出商业TPL极限的打印分辨率，因此需要后处理技术。在这里，我们设计了一种策略，在对WPC进行侧面照射时支持高阶光子腔模，令人惊讶的是，这在可见光谱中产生了显著的反射峰。基于此，我们展示了三维光子结构色的一步打印，无需后处理或亚波长特征。实现了具有反射峰的鲜艳颜色，其半高宽约为25纳米，最大反射率为50%，色域约为sRGB的85%，并且具有大视角。此外，我们还展示了以WPC为晶胞构成的任意形状三维物体中颜色的体素级操纵和控制，这在动态色彩显示、比色传感、防伪和光与物质相互作用平台等方面具有应用潜力。
