基于激光诱导表面周期结构的微纳防伪结构色
Laser-induced periodic surface structure for microscale anti-counterfeiting structural colors
1 暨南大学光子技术研究院，广东省光纤传感与通信技术重点实验室，广东 广州 510632
2 广东工业大学先进光子技术研究院，广东 广州 510006
摘要
激光诱导表面周期结构由于其周期相关的光栅衍射特性在明场下显示出鲜艳的结构色，备受研究人员的广泛关注，而微纳结构在显微镜暗场显示的颜色通常容易被忽略。本文报道通过飞秒激光对氧化铟锡薄膜加工形成双周期光栅结构，利用其在明场和暗场的观察下具有不同的颜色特性实现图像加密应用。通过控制飞秒激光的偏振、脉冲能量和扫描速度在氧化铟锡薄膜上形成与偏振和波长相关的亚波长周期光栅，通过控制激光加工线条行间距形成大周期光栅。本文研究了激光加工能量和加工线条之间的间距对其形成双周期结构在明场和暗场显色的影响，利用不同加工参数结构在明场和暗场下显示不同的颜色实现图像加密。激光直写加工可以快速制备大面积区域，有望在商品防伪、图案装饰、超表面设计等方面发挥潜在的应用价值。
Abstract
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The vivid color appearance of laser-induced periodic surface structures (LIPSS) has received intense research interests. The vibrant structural color associated with the periodicity of LIPSS is normally concerned under bright -field illumination, while the colors of structures under dark-field illumination are commonly overlooked. In this paper, we report an image encryption method based on laser-induced dual-period grating structures in indium tin oxide thin films, exhibiting different colors under bright-field and dark-field illumination. Following the standard laser recipe by judiciously controlling the polarization, pulse energy and scanning speed, subwavelength period LIPSS can be fabricated. By controlling the space between the fabricated lines, another grating with a larger periodicity can be formed. Consequently, the dual-period grating structure displays different colors under bright-field and dark-field illumination depending on the laser recipe with different pulse energies and line spaces. Leveraging this effect, information can be encoded in the color image, which displays the same color appearance under bright -field illumination while revealing different colors under dark-field illumination has been demonstrated. Combing the flexibility and scalability of laser fabrication, we envisage the potential applications in anti-counterfeiting, pattern decoration, metasurface, etc.
欧阳旭, 谢子健, 张孟瑞, 杨清帅, 李晨辉, 曹耀宇, 徐毅, 李向平. 基于激光诱导表面周期结构的微纳防伪结构色[J]. 光电工程, 2022, 49(1): 210320. Xu Ouyang, Zijian Xie, Mengrui Zhang, Qingshuai Yang, Chenhui Li, Yaoyu Cao, Yi Xu, Xiangping Li. Laser-induced periodic surface structure for microscale anti-counterfeiting structural colors[J]. Opto-Electronic Engineering, 2022, 49(1): 210320.
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