1 湖北工业大学 超快激光加工研究中心，湖北 武汉 430068
2 上海海鹰机械厂，上海 200436
采用波长为1 064 nm的纳秒激光器脉冲模式和连续模式分别对玻璃纤维增强树脂基复合材料表面涂覆的浅灰色防雨蚀涂层和抗静电涂层进行激光清洗实验，研究不同模式下激光参数对清洗效果的影响规律。通过SEM观察清洗后材料表面及清洗产物的微观形貌，运用EDS、FTIR分别检测清洗前后材料表面元素含量与化学官能团，采用COMSOL Multiphysics对清洗过程中的温度场进行分析。结果表明：去除单层抗静电涂层时，脉冲激光能完全去除该涂层且防雨蚀涂层损伤较小；去除双层涂层时，脉冲激光作用下试板表面有残余涂层，且易损伤下层清漆、树脂和纤维，而连续激光则可完全去除表面双层涂层，获得清洁的清漆表面。脉冲模式的去除机制主要为热弹性振动效应，连续模式下涂层的去除机制主要为热烧蚀效应。研究结果可为航空复合材料表面激光脱漆技术的激光模式选择提供参考。
激光清洗 激光模式 玻璃纤维 表面形貌 工艺参数 去除机制 laser cleaning laser mode GFRP surface appearance process parameters removing mechanism 红外与激光工程
2023, 52(2): 20220836
1 哈尔滨工业大学仪器科学与工程学院，黑龙江 哈尔滨 150006
2 哈尔滨工业大学（威海）光电科学系，山东 威海 264209
超材料吸波体凭借其可以在特定波长处实现接近100%的“完美”吸收而被广泛应用在各个领域中。具有可饱和吸收特性的超材料可以用来调控激光脉冲，但超材料光学性质的研究主要集中于红外或太赫兹波段，可见光波段研究较少。基于传统的超材料吸波体三层结构模型，借助二氧化钒的电磁参数随温度变化的相变特性，设计了一种实用的可见光波段超材料饱和吸收体。该超材料的吸收率会随着入射电磁波引起的温度升高而饱和，最终其会转变为高反射状态，具有类似半导体饱和吸收镜的特性。对该结构进行数值模拟，发现其在405~650 nm波长范围内，平均饱和深度为16%。
材料 超材料 可饱和吸收 二氧化钒 可见光激光器 激光锁模 光学学报
2022, 42(15): 1516001
Author Affiliations
Abstract
National Key Laboratory of High-power Semiconductor Lasers, Changchun University of Science and Technology, Changchun 130022, China
A novel harmonic mode-locked fiber laser based on nonlinear multimode interference (NL-MMI) in a microfiber-assisted ultrafast optical switch is proposed in this Letter. The microfiber-assisted ultrafast optical switch can be obtained by tapering the splicing point of the graded-index multimode fiber (GIMF) and single-mode fiber, which not only helps to shorten the self-imaging period in GIMF to relax the strict requirement of NL-MMI on the length of multimode fiber, but also improves the harmonic order. In the experiment, with the waist diameter of , the repetition rates of the fiber laser can be stably locked at 285 MHz, corresponding to the 16th-order harmonic mode-locking, with the pulse duration of 1.52 ps. Our results provide novel insight into the design of a high-repetition-rate laser and the application of microfibers in the mode-locking device.
multimode interference optical fiber devices laser mode-locking Chinese Optics Letters
2022, 20(1): 010601
Author Affiliations
Abstract
National Key Laboratory on High-power Semiconductor Lasers, Changchun University of Science and Technology, Changchun 130022, China
The vector dynamics of solitons are crucial but easily neglected for realizing vortex solitons. In this Letter, we investigate the effect of vector dynamics on cylindrical vector beams (CVBs) implementation and propose a novel technical method to realize femtosecond CVBs based on vector-locked solitons, which are presented as group-velocity-locked vector solitons (GVLVSs) in the experiment. The outstanding vector properties of GVLVSs not only greatly improve the efficiency of solitons converted into CVBs and output power of CVBs (2.4 times and 4.1 times that of scalar solitons and vector change periodical solitons, with the purity of 97.2%), but also relax the obstacle of ultrafast CVBs from the fundamental frequency to the harmonic regime (up to 198 MHz) for the first time, to the best of our knowledge. This is the highest repetition rate reported for ultrafast CVBs based on passive mode-locking. The investigation of the influence of solitons vector dynamics evolution on the realization of CVBs provides guidance for the excellent performance of ultrafast CVBs.
cylindrical vector beam ultrafast optical switch laser mode-locking Chinese Optics Letters
2021, 19(11): 111903
1 中国科学院空间光电精密测量技术重点实验室, 成都 610209
2 中国科学院光电技术研究所, 成都 610209
3 中国科学院大学, 北京 100049
4 中国民用航空飞行学院, 四川 德阳 618300
为了消除激光跳模对调频连续波激光测距的影响, 提出了一种基于重采样信号相位拼接的跳模影响消除方法。该方法利用重采样信号相位展开求导的结果来定位激光跳模发生的时间, 并对重采样信号跳模处两端的峰值进行相位拼接来去除跳模段的重采样信号。通过对相位拼接后的重采样信号进行Chirp-Z变换可以得到不受激光跳模影响的目标距离谱。系统对光程约为21.16m的延时光纤进行多次测量, 实验效果证明此方法可以消除调频激光跳模对距离测量的影响, 并实现了12μm的测距标准差。
调频连续波激光雷达 激光跳模 相位拼接 测距 FMCW lidar laser mode hopping phase splicing ranging
华中科技大学 光学与电子信息学院 激光加工国家工程中心, 武汉 430074
为了提升激光器径向偏振光的输出功率, 改进了原有W形轴锥镜内锥角为90°的结构。为研究光束在轴锥尾镜单元的传输特性, 采用几何光学分析了轴向入射下、W形轴锥镜底角为90°时, 内锥角的改变对出射光的影响, 发现出射光的位置及方向不发生变化; 为研究轴锥镜的热畸变特性, 模拟了W形轴锥镜的温度形变, 可知内锥角变大时整体温度变小且分布更加均匀。结果表明, 随着内锥角的变大, 光束中心的光程减少量相对于光束边沿的光程减少量增大;采用Fox-Li数值迭代法模拟了引入上述形变后谐振腔的激光模式, 得出在内锥角为100°时温度形变对光束模式的影响最小。通过对W形轴锥镜温度形变的研究, 可为优化W形轴锥镜的设计提供参考。
光学设计 温度形变 几何光学 组合轴锥镜 径向偏振光 激光模式 optical design temperature deformation geometric optics combined axicon radially polarized light laser mode
Author Affiliations
Abstract
1 Institute of Physics of the ASCR, ELI-Beamlines, Na Slovance 2, 18221 Prague, Czech Republic
2 Institute of Modern Physics, Fudan University, Shanghai 200433, Peoples Republic of China
3 FNSPE, Czech Technical University in Prague, 11519 Prague, Czech Republic
4 Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa-shi, Kyoto, 619-0215, Japan
Fast magnetic field annihilation in a collisionless plasma is induced by using TEM(1,0) laser pulse. The magnetic quadrupole structure formation, expansion and annihilation stages are demonstrated with 2.5-dimensional particle-in-cell simulations. The magnetic field energy is converted to the electric field and accelerate the particles inside the annihilation plane. A bunch of high energy electrons moving backwards is detected in the current sheet. The strong displacement current is the dominant contribution which induces the longitudinal inductive electric field.were provided by the MetaCentrum under the program LM2010005, IT4Innovations Centre of Excellence under projects CZ.1.05/1.1.00/02.0070 and LM2011033 and by ECLIPSE cluster of ELI-Beamlines. The EPOCH code was developed as part of the UK EPSRC funded projects EP/G054940/1.
high order laser mode high order laser mode laser–plasma interaction laser–plasma interaction magnetic annihilation magnetic annihilation High Power Laser Science and Engineering
2016, 4(2): 02000e19
利用马赫-曾德尔点衍射干涉仪，通过一幅干涉图，直接恢复激光模式的强度和相位信息，重建模式复振幅。在理论上分析了利用快速傅里叶变换的点衍射干涉法重建激光复振幅分布的原理；推导了激光模式在自由空间中传输时强度和相位的分布情况。将模拟的分布与实验结果做了比较，结果表明，点衍射干涉法可以恢复激光模式的强度和相位信息。
测量 激光模式 马赫-曾德尔点衍射干涉仪 复振幅
Author Affiliations
Abstract
Applied Optics Group, School of Physical Sciences, University of Kent, Canterbury, Kent, CT2 7NH, UK
An optical akinetic swept source (AKSS) at 1060 nm, comprising a 5 m length fiber ring cavity, a semiconductor optical amplifier (SOA) as gain medium, and a 98% reflective chirped fiber Bragg grating as a dispersive element, is described. Active mode-locking was achieved by directly modulating the current of the SOA with sinusoidal signal of frequency equal to 10 times and 20 times the cavity resonance frequency. In the static regime, linewidths as narrow as 60 pm and a tuning bandwidth of 30 nm were achieved, while a 2 mW output power, without any optical booster, was measured dynamically at a sweep speed of 100 kHz. The axial range of the AKSS was evaluated by scanning through the channeled spectrum of a Mach-Zehnder interferometer.
Semiconductor optical amplifier laser mode locking ring laser dispersive element Photonic Sensors
2015, 5(3): 251–256
