The fluence threshold of femtosecond laser blackening of metals: The effect of laser-induced ripples
The fluence threshold of femtosecond laser blackening of metals: The effect of laser-induced ripples
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飞秒激光金属黑化的注量阈值：激光诱导波纹的影响
DOI：
10.1016/j.optlastec.2015.11.018
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发表时间：
2016-05-01
影响因子：
5
通讯作者：
Zhao, Fuli
中科院分区：
文献类型：
--
作者：
Ou, Zhigui;Huang, Min;Zhao, Fuli
以激光通量为主要控制因素，对不锈钢、黄铜和铝在可见光范围内的飞秒激光发黑进行了研究。一般情况下，在适当的激光能量范围内，所有处理的金属表面都可以获得约5%的低反射率。值得注意的是，对于不锈钢和黄铜，变黑的通量阈值异常出现：在特定的狭窄通量范围内，反射率显著下降。相反，对于铝，反射率在很大的通量范围内稳步下降，而不是钢和黄铜的阈值行为。表面的形貌特征和相应的反射光谱表明，不锈钢和黄铜的发黑阈值对应于激光诱导的亚波长波纹的通量阈值。这种在烧蚀阈值附近快速增长的周期波纹通过表面等离子体激元促进的光栅耦合和腔陷阱有效地吸收可见光。然而，对于铝来说，随着通量的增加，隐约可见的波纹被重新沉积的纳米颗粒聚集体大大抑制，这些纳米颗粒聚集体呈现出除黑色之外的本征颜色，直到形成具有强烈捕光能力的大规模沟壑，才能实现足够的发黑。总之，飞秒激光发黑金属具有不同的光通量依赖关系，某些金属在可见光范围内的比发黑光通量阈值来源于飞秒激光诱导波纹的特定光通量阈值。(C)2015爱思唯尔有限公司。保留所有权利。
With the primary controlling factor of the laser fluence, we have investigated femtosecond laser blackening of stainless steel, brass, and aluminum in visible light range. In general, low reflectance about 5% can be achieved in appropriate ranges of laser fluences for all the treated metal surfaces. Significantly, towards stainless steel and brass a fluence threshold of blackening emerges unusually: a dramatic reflectance decline occurs in a specific, narrow fluence range. In contrast, towards aluminum the reflectance declines steadily over a wide fluence range instead of the threshold-like behavior from steel and brass. The morphological characteristics and corresponding reflectance spectra of the treated surfaces indicates that the blackening threshold of stainless steel and brass corresponds to the fluence threshold of laser-induced subwavelength ripples. Such periodic ripples growing rapidly near ablation threshold absorb visible light efficiently through grating coupling and cavity trapping promoted by surface plasmon polaritons. Whereas, for aluminum, with fluence increasing the looming ripples are greatly suppressed by re-deposited nanoparticle aggregates that present intrinsic colors other than black, and until the formation of large scale "ravines" provided with strong light-trapping, sufficient blackening is achieved. In short, there are different fluence dependencies for femtosecond laser blackening of metals, and the specific blackening fluence threshold for certain metals in the visible range originates in the definite fluence threshold of femtosecond laser-induced ripples. (C) 2015 Elsevier Ltd. All rights reserved.