Author Affiliations
Abstract
1 Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, China
2 School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
With different interactions between material and femtosecond lasers, two-dimensional (2D) and three-dimensional (3D) waveguide couplers, whose separation distances are fabricated in z-cut lithium niobate crystal by femtosecond laser writing, are reported. Experimentally and numerically, it is shown from results that the guidance is only propagating along TM polarization due to the Type I modification and holds equal splitting ratios, which are the same as power splitters at 632.8 nm. The propagation losses of 2D and 3D waveguide couplers exhibit better transmission properties than those of the previously reported Type I Y-junction waveguide splitters.
femtosecond laser writing beam splitters lithium niobate Chinese Optics Letters
2023, 21(11): 112201
1 中国科学院合肥物质科学研究院，安徽 合肥 230031
2 中国科学技术大学，安徽 合肥 230026
3 龙岩烟草工业有限责任公司，福建 龙岩 364030
为提高活性炭含量检测的效率与精度，基于微波谐振技术设计了一种活性炭滤棒微波幅值变化信号采集装置，并将高斯滤波和惩罚最小二乘算法相结合对微波幅值变化信号进行降噪和基线扣除处理。首先，比较了不同高斯窗口长度的滤波效果，选用非对称最小二乘法、自适应迭代重加权惩罚最小二乘法、非对称重加权惩罚最小二乘法和多约束重加权惩罚最小二乘法等4种处理方法对微波幅值变化信号进行基线校正，再求出基线校正后微波幅值变化信号的峰高、峰面积与半峰全宽，然后比较了基于支持向量回归机、偏最小二乘算法与反向传播神经网络建立的模型的预测结果。结果显示，活性炭质量的最佳模型为“峰面积-活性炭质量”，模型决定系数为0.9924，平均绝对误差为0.7979 mg，相对标准偏差为1.4962%。活性炭质量重复性检测最大标准差为1.85 mg，活性炭质量检测的最小绝对偏差为0.03 mg，活性炭质量检测最小相对偏差为0.05%。该方法为烟用活性炭滤棒中活性炭的定量分析提供了一种快速有效的方法。
测量 微波谐振技术 基线校正 惩罚最小二乘法 活性炭 质量 measurement microwave resonance technology baseline correction penalized least squares activated carbon weight 激光与光电子学进展
2023, 60(17): 1712007
Author Affiliations
Abstract
1 Zhejiang Lab, Hangzhou 310000, China
2 Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
3 Graduate School of China Academy of Engineering Physics, Beijing 100088, China
Diagnosis of fluids is extremely significant at high temperatures and high pressures. As an advanced imaging technique, high-energy proton radiography has great potential for application to the diagnosis of high-density fluids. In high-energy proton radiography, an angular collimator can control the proton flux and thus enable material diagnosis and reconstruction of density. In this paper, we propose a multi-material diagnostic method using angular collimators. The method is verified by reconstructing the density distribution from the proton flux obtained via theoretical calculations and numerical simulations. We simulate a 20 GeV proton imaging system using the Geant4 software toolkit and obtain the characteristic parameters of single-material objects. We design several concentric spherical objects to verify the method. We discuss its application to detonation tests. The results show that this method can determine the material and boundary information about each component of a multi-material object. Thus, it can be used to diagnose a mixed material and reconstruct densities in a detonation.
Matter and Radiation at Extremes
2023, 8(4): 046902
1 山东大学物理学院晶体材料国家重点实验室，山东 济南 250100
2 南开大学电子信息与光学工程学院微尺度光学信息基础科学重点实验室，天津 300350
3 山东师范大学物理与电子科学学院山东省光场调控工程技术中心，山东省光学与光子器件重点实验室，山东 济南 250358
利用飞秒激光直写技术制备Tm∶YAP光波导并实现1.9 μm波导调Q锁模激光输出。结合具有金属特性的NbSe2薄膜作为可饱和吸收元件进行光学调制，波导激光输出的激光脉冲重复频率为7.8 GHz，最短脉宽为62 ps。这也是已报道的从Tm∶YAP波导中获得的最短激光脉宽。通过调整泵浦光的偏振，可以获得1855.87/1892.54 nm的双波长激光输出。结果表明，具有金属特性的NbSe2薄膜在调制中红外超快脉冲激光器方面具有较大的应用价值。此外，双波长输出的紧凑型Tm∶YAP波导脉冲激光器在多功能集成光子学研究方面具有较好的应用前景。
激光器 飞秒激光直写 波导激光 Tm∶YAP NbSe2 lasers femtosecond laser direct writing waveguide laser Tm∶YAP NbSe2 光学学报
2023, 43(16): 1623018
Author Affiliations
Abstract
1 State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information, School of Electronic Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
2 School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Wettability is one of a solid surface’s fundamental physical and chemical properties, which involves a wide range of applications. Femtosecond laser microfabrication has many advantages compared to traditional laser processing. This technology has been successfully applied to control the wettability of material surfaces. This review systematically summarizes the recent progress of femtosecond laser microfabrication in the preparation of various superwetting surfaces. Inspired by nature, the superwettabilities such as superhydrophilicity, superhydrophobicity, superamphiphobicity, underwater superoleophobicity, underwater superaerophobicity, underwater superaerophilicity, slippery liquid-infused porous surface, underwater superpolymphobicity, and supermetalphobicity are obtained on different substrates by the combination of the femtosecond laser-induced micro/nanostructures and appropriate chemical composition. From the perspective of biomimetic preparation, we mainly focus the methods for constructing various kinds of superwetting surfaces by femtosecond laser and the relationship between different laser-induced superwettabilities. The special wettability of solid materials makes the femtosecond laser-functionalized surfaces have many practical applications. Finally, the significant challenges and prospects of this field (femtosecond laser-induced superwettability) are discussed.
Ultrafast Science
2022, 2(1): 9895418
通过理论仿真和实际制备测试, 分析比较了基于非对称量子阱结构(10nm厚和6nm厚的量子阱组合)的光放大芯片与对称量子阱结构(10nm厚量子阱)的光放大芯片的性能。两种结构的理论模式增益同最终实测值符合较好。最终光谱测试结果显示, 对称量子阱结构的光放大芯片存在基态增益饱和的现象, 在大电流注入情况下, 激态跃迁占据优势, 从而造成光谱宽度急剧下降。而非对称量子阱结构的光放大芯片的光谱宽度随着注入电流的增加不断拓宽, 在600mA下实现199.7nm光谱带宽, 覆盖S+C波段。由此可见, 非对称量子阱结构更有利于实现高功率、宽光谱的光放大芯片。
宽光谱 S+C波段 对称和非对称多量子阱 wide spetrum S+C band InGaAlAs/InP InGaAlAs/InP symmetric and asymmetric multi-quantum-well
Author Affiliations
Abstract
1 State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information, School of Electronic Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
2 School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
Underwater transportation of bubbles and gases has essential applications in manipulating and using gas, but achieving this function at the microscopic level remains a significant challenge. Here, we report a strategy to self-transport gas in water along a laser-induced open superhydrophobic microchannel with a width less than 100 μm. The femtosecond laser can directly write superhydrophobic and underwater superaerophilic microgrooves on the polytetrafluoroethylene (PTFE) surfaces. In water, the single laser-induced microgroove and water medium generate a hollow microchannel. When the microchannel connects two superhydrophobic regions in water, the gas spontaneously travels from the small region to the large area along this hollow microchannel. Gas self-transportation can be extended to laser-drilled microholes through a thin PTFE sheet, which can even achieve anti-buoyancy unidirectional penetration. The gas can overcome the bubble’s buoyance and spontaneously travel downward. The Laplace pressure difference drives the processes of spontaneous gas transportation and unidirectional bubble passage. We believe the property of gas self-transportation in the femtosecond laser-structured open superhydrophobic and underwater superaerophilic microgrooves/microholes has significant potential applications related to manipulating underwater gas.
femtosecond laser gas transportation superhydrophobicity underwater superaerophilicity water/gas separation International Journal of Extreme Manufacturing
2022, 4(1): 015002
1 山东大学物理学院 晶体材料国家重点实验室,山东 济南 250100
2 南开大学电子信息与光学工程学院 微尺度光学信息基础科学重点实验室, 天津 300350
作为三维超构材料的衍生物，具有亚波长厚度的人工超构表面结构能够在紧凑的平台上灵活操纵光与物质的相互作用，有利于多功能、超紧凑光子器件的研发，对于微纳光子学和集成光子学具有重要意义。铁电晶体铌酸锂凭借其跨越可见光至中红外波段的宽透明窗口以及较大的非线性光学、电光系数，被认为是最有前途的多功能集成光子平台之一。近年来，基于铌酸锂薄膜(lithium-niobate-on-insulator，LNOI)的集成光子学器件研究也得到了迅猛发展。本文总结了几种有潜力制备高质量铌酸锂超构表面的微纳加工技术，同时介绍了近年来铌酸锂超构表面结构的研究进展，并对其未来的研究方向进行了展望。
超构表面 铌酸锂 微纳加工 非线性光学 metasurface lithium-niobate micro-nanofabrication nonlinear optics 
