Femtosecond laser machining of biomimetic micro/nanostructures with high aspect ratio (larger than 10) on ultrahard materials, such as sapphire, is a challenging task, because the uncontrollable surface damage usually results in poor surface structures, especially for deep scribing. Here, we report an inside-out femtosecond laser deep scribing technology in combination with etching process for fabricating bio-inspired micro/nanostructures with high-aspect-ratio on sapphire. To effectively avoid the uncontrollable damage at the solid/air interface, a sacrificial layer of silicon oxide was employed for surface protection. High-quality microstructures with an aspect ratio as high as 80:1 have been fabricated on sapphire surface. As a proof-of-concept application, we produced a moth-eye inspired antireflective window with sub-wavelength pyramid arrays on sapphire surface, by which broadband (3–5 μm) and high transmittance (98% at 4 μm, the best results reported so far) have been achieved. The sacrificial layer assisted inside-out femtosecond laser deep scribing technology is effective and universal, holding great promise for producing micro/nanostructured optical devices.

针对Er3+共掺增强BaSi2O2N2∶Eu2+发光效果的内在差异和可能机理进行了研究。通过XRD测试展示了共掺下的晶体结构, 分析确认了样品纯度以及生长差异; 为进一步研究差异的来源, 监控了不同价态掺杂离子的发射光谱, 对随Er3+含量变化的发射光谱规律性变化进行展示, 进而分析得出Er3+共掺增强发光的内部物理机理是控制择优取向和对价态进行定向竞争调节; 从发光体应用场景的温度范围需求进行了温度特性测试, 展示了温度变化下的发射光谱变化。这项研究为调控发光强度、提高量子效率的工作提供了新的思路。

With high hardness, high thermal and chemical stability and excellent optical performance, hard materials exhibit great potential applications in various fields, especially in harsh conditions. Femtosecond laser ablation has the capability to fabricate three-dimensional micro/nanostructures in hard materials. However, the low efficiency, low precision and high surface roughness are the main stumbling blocks for femtosecond laser processing of hard materials. So far, etching-assisted femtosecond laser modification has demonstrated to be the efficient strategy to solve the above problems when processing hard materials, including wet etching and dry etching. In this review, femtosecond laser modification that would influence the etching selectivity is introduced. The fundamental and recent applications of the two kinds of etching assisted femtosecond laser modification technologies are summarized. In addition, the challenges and application prospects of these technologies are discussed.

为了解决飞秒激光加工硬质材料所带来的表面质量差的问题, 提出了离子束刻蚀与飞秒激光复合加工技术.利用飞秒激光加工技术在碳化硅表面制备微纳结构图形, 然后通过离子束刻蚀技术对碳化硅微纳结构进行刻蚀, 以调控结构的线宽和深度, 使结构表面粗糙度由约106 nm降低到11.8 nm.研究表明, 利用该技术制备的碳化硅菲涅尔波带片展现出良好的聚焦和成像效果.