Author Affiliations
Abstract
1 Key Laboratory of Photonic Control Technology (Tsinghua University), Ministry of Education, Beijing 100084, China
2 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
3 Shanghai Institute of Laser Plasma, China Academy of Engineering Physics, Shanghai 201800, China
We present a spatiotemporal model of pulse amplification in the double-pass active mirror (AM) geometry. Three types of overlap condition are studied, and the spatiotemporal scaling under the four-pulse overlapping (4PO) condition is fully characterized for the first time, by mapping the temporal and spatial segments of beam to the instantaneous gain windows. Furthermore, the influence of spatiotemporal overlaps on the amplified energy, pulse distortion and intensity profile is unraveled for both AM and zigzag configurations. The model, verified by excellent agreement between the predicted and measured results, can be a powerful tool for designing and optimizing high energy multi-pass solid-state laser amplifiers with AM, zigzag and other geometries.
active mirror amplifier pulse overlap spatiotemporal characterization double-pass High Power Laser Science and Engineering
2020, 8(3): 03000e30
Author Affiliations
Abstract
1 Department of Advanced Green Energy and Environment
,
Handong Global University
,
Pohang 37554
,
Korea
2 Global Institute of Laser Technology
,
Global Green Research and Development Center
,
Handong Global University
,
Pohang 37554
,
Korea
We have optimized the input pulse width and injection time to achieve the highest possible output pulse energy in a double-pass laser amplifier using two Nd:YAG rods. For this purpose, we have extended the Frantz–Nodvik equation by simultaneously including both spontaneous emission and pump energy variation. The effective pump energy of the flash lamp was 8.84 J for each gain medium. The energy of 1 J could be amplified to an output energy of 12.17 J with the maximum achieved extraction efficiency of 63.18% when an input pulse having a pulse width of 168
s is sent 10
s after the absorbed pump energy becomes the maximum value.
High Power Laser Science and Engineering
2018, 6(4): 04000e60
华南师范大学 广东省微纳光子功能材料与器件重点实验室, 广州 510006
为了提高聚氨酯(PU)合成革透湿性，分别使用343 nm飞秒激光和作为对比的1030 nm飞秒激光及1064 nm纳秒激光制备微孔阵列。采用扫描电镜 (SEM)和3D激光扫描显微镜对比研究了微孔形貌。结果表明，343 nm飞秒激光可以制备出效果最佳的微孔。此外，分析了3种激光与PU涂层的作用机理，揭示了343 nm飞秒激光合成革微钻孔过程仅表现为光化学烧蚀，光化学和光热烧蚀同时发生于1030 nm飞秒激光钻孔过程，而1064 nm纳秒激光只显示了光热烧蚀。激光合成革表面钻孔后，测量其透湿性和抗张力。结果显示:微孔密度越大，皮革透湿性(WVP)越大而抗张力越低，脉冲重叠的增加会导致WVP的增加和抗张力的下降；同时，随着脉冲重叠从91.7%降到50%，微孔直径从45 μm降低到30 μm，而微孔锥度从0.7°增加到12.1°；当脉冲重叠率为91.7%，微孔密度为2550/cm2时，最大的WVP增长率为306%。
343 nm飞秒激光 微孔密度 脉冲重叠 聚氨酯合成革 透湿性 抗张力 343 nm femtosecond laser micro-hole density pulse overlap polyurethane synthetic leather water vapor permeability tensile resistance 强激光与粒子束
2018, 30(4): 049001
1 青岛理工大学 机械工程学院, 青岛 266520
2 温州大学 机电工程学院, 温州 325035
3 浙江久恒光电科技有限公司, 温州 325035
为了解决毫/纳秒激光加工微孔质量低的问题,利用脉冲宽度为200ps的脉冲激光,采用高速旋切法对厚度为0.2mm的SUS 304不锈钢薄板进行直径为200μm的微孔加工试验,用激光共聚焦显微镜观察孔的外观形貌,研究旋切速率、激光功率和离焦量等因素对孔径、锥度和热影响区等加工质量的影响。结果表明,旋切速率对微孔内壁质量有直接的影响; 通过提高转速来降低激光脉冲重叠率可以减小微孔内壁的热影响区; 适当增加激光功率,能够改善旋切加工微孔切口处的加工质量; 采用正离焦加工能够一定程度减小孔的锥度。优化工艺参量能够加工出热影响区小、边缘质量好的小锥度微孔。
激光技术 微孔 高速旋切法 皮秒激光 脉冲重叠率 锥度 laser technique micro hole high speed rotary cutting method picosecond laser pulse overlap ratio taper
