Author Affiliations
Abstract
1 China MOE Key Laboratory of Advanced Micro-structured Materials, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
2 State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
3 University of Chinese Academy of Sciences, Beijing, 100049, China
We report the upconversion luminescence of lithium fluoride single crystals excited by an infrared femtosecond laser at room temperature. The luminescence spectra demonstrate that upconversion luminescence originates from the color center of F3+. The dependence of fluorescence intensity on pump power reveals that a two-photon excitation process dominates the conversion of infrared radiation into visible emission. Simultaneous absorption of two infrared photons is suggested to produce the F3+ center population, which leads to the characteristic visible emission. The results are on the reveal and evaluation of the simultaneous two-photon absorption on the green upconversion process.
320.2250 Femtosecond phenomena 300.6410 Spectroscopy, multiphoton 190.7220 Upconversion 160.2220 Defect-center materials Chinese Optics Letters
2016, 14(8): 083201
1 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室, 上海 201800
2 中国科学院大学, 北京 100049
3 上海交通大学材料科学与工程学院, 上海 200240
4 同济大学物理科学与工程学院, 上海 200092
提出一种利用线偏振飞秒脉冲激光制备超疏水钛表面的方法。利用飞秒脉冲激光在钛片上辐照扫描诱导出表面微纳结构，以提高钛表面的粗糙度，并结合低表面能物质的超声处理得到具有超疏水特性的钛表面。通过改变飞秒脉冲激光辐照的能流密度来改变钛表面的粗糙度，得到不同润湿性能的钛表面。将制备的疏水和超疏水钛表面在大气环境中放置三个月，并对其表面润湿性能进行测量，结果表明，与三个月前相比，其表面润湿性能基本保持不变，即制备的钛表面具有稳定的疏水和超疏水性。
激光制造 飞秒激光加工 超疏水 钛表面 表面微纳结构
1 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室, 上海 201800
2 中国科学院大学, 北京 100049
研究了光斑重叠率对飞秒激光硅材料表面着色的影响。实验结果表明：飞秒激光在硅材料表面着色是由于在其表面诱导出了周期纳米条纹结构；在飞秒激光功率一定的情况下，较高和较低的光斑重叠率都不能实现着色；在选定激光功率范围内，光斑重叠率越大，呈现的颜色越丰富，着色效率越高。另外反射率的测量结果表明着色后样品在可见光范围内反射率下降了50%左右。得到了飞秒激光硅材料表面着色的参数窗口，为飞秒激光半导体着色的推广提供了技术参考。
材料 激光着色 飞秒激光 光斑重叠率 硅材料
Author Affiliations
Abstract
1 State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
3 Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
Anisotropic dewetting polydimethylsiloxane (PDMS) surfaces, which consist of groove-like micro/nanostructures (so-called hierarchical structures), are fabricated using an ultrashort pulsed laser. The contact angles (CAs) are measured parallel to the microgrooves, which are always larger than those measured perpendicular to the microgrooves, exhibiting a superhydrophobic anisotropy of approximately 4° on these fabricated PDMS surfaces at optimized parameters. These pulsed-laser irradiated surfaces exhibit enhanced hydrophobicity with CAs that increase from 116° to 156° while preserving the anisotropic dewetting. Additionally, the wettability of the surfaces with different morphologies is investigated. The temporal evolution of the wettability of the pulsed-laser irradiated PDMS surface is also observed within the first few hours after pulsed laser irradiation.
140.3390 Laser materials processing 140.3538 Lasers, pulsed 160.1435 Biomaterials 160.4236 Nanomaterials Chinese Optics Letters
2015, 13(3): 031404
