1 中国科学院沈阳自动化研究所机器人学国家重点实验室，辽宁 沈阳 110016
2 中国科学院机器人与智能制造创新研究院，辽宁 沈阳 110169
3 中国科学院大学，北京 100049
为了改善水导激光制备单晶镍合金微孔的表面形貌，降低微孔锥度，采用控制变量法研究了在单步螺旋打孔方法下，激光单脉冲能量、扫描速度、进给次数和扫描圈数对微孔表面形貌及锥度的影响规律。提出了多步螺旋打孔方法，并在优选加工参数组合下与单步螺旋打孔方法进行了比较。结果表明，增加单脉冲能量和降低扫描速度可以改善微孔表面形貌，减小微孔锥度。随着进给次数的增多，微孔表面形貌逐渐变好，微孔锥度先减小后饱和。随着扫描圈数的增多，微孔表面形貌逐渐变差，微孔锥度先增大后减小。采用多步螺旋打孔方法加工的微孔锥度仅为0.29°，比单步螺旋打孔方法降低了70%，且尺寸偏差和圆度都控制在20 μm以内。
激光技术 水导激光 螺旋打孔 高温合金 表面形貌 锥度 中国激光
2024, 51(16): 1602404
1 长春理工大学高功率半导体激光国家重点实验室，吉林 长春 130022
2 长春理工大学中山研究院，广东 中山 528437
3 深圳市杰普特光电股份有限公司，广东 深圳 518110
针对传统高功率光纤激光器焊接不稳定、飞溅量大、难以实现精密焊接的问题，设计了一种光斑可调的信号合束器，首次以50 μm/70 μm/600 μm/620 μm/660 μm大芯径环形双芯光纤作为输出光纤，基于光束非相干合成技术，通过RSoft软件对合束器进行了模拟仿真，分析了其模场变化情况，设计的合束器满足绝热拉锥以及亮度守恒两个原则，调控拉锥比（）使其可以实现中心和外环独立工作。采用套管法将7根25 μm/250 μm光纤耦合到一起形成熔锥光纤束，再将其与输出光纤进行熔接，制成了高功率大芯径环形光斑可调信号合束器。此光纤合束器的传输效率≥98%，中心光束质量因子（M2）仅为1.76，此时中心端口输出功率为3.036 kW。而后对合束器进行了耐环境测试，合束器在低温与高温下表现出的传输特性良好。将该光斑可调的环形光斑信号合束器应用到激光器中，通过调节中心和外环激光功率，可以在任何温度环境下实现超高速焊接，为激光复合焊接提供了一种新途径。
激光器 光纤合束器 熔锥光纤束（TFB） 传输效率 光束质量 环境可靠性
1 华中科技大学武汉光电国家研究中心，湖北 武汉 430074
2 湖北光谷实验室，湖北 武汉 430074
采用五轴激光扫描技术研究了FR4覆铜板的深盲孔制造技术。通过实验研究了激光参数和扫描图形的填充间距对盲孔侧壁锥度和底部材料去除均匀性的影响，通过调节激光扫描策略，实现了盲孔锥度和孔径的连续调节。盲孔深度为925 μm，最大深径比可达4.9∶1，孔侧壁平直，孔底玻璃纤维复合材料被完全去除，铜层的损伤深度小于1 μm。实验结果表明，五轴激光扫描技术可以有效提升激光的盲孔制造能力。
激光技术 激光钻盲孔 五轴激光扫描 侧壁锥度 飞秒激光 中国激光
2023, 50(24): 2402401
强激光与粒子束
2023, 35(7): 073001
Author Affiliations
Abstract
1 Key Laboratory of In-fiber Integrated Optics, Ministry of Education, Harbin Engineering University, Harbin 150001, China
2 Photonics Research Center, Guilin University of Electronics Technology, Guilin 541004, China
Vector bending sensing has been consistently growing in many fields. A low-cost and high sensitivity vector bending sensor based on a chirped long-period fiber grating (LPFG) with an off-axis micro helix taper is proposed and experimentally demonstrated. The grating is composed of several sections of single-mode fiber with gradually larger lengths, and the off-axis micro helix tapers with fixed lengths when they are fabricated by using the arc discharge technology. The large refractive index modulation in the micro-helix taper greatly reduces the sensor size. The total length of the sensor is only 4.67 mm. The micro-helix taper-based LPFG can identify the bending direction due to the asymmetric structure introduced by the micro helix. The experimental results show that the transmission spectra of the sensor have distinct responses for different bending directions, and the maximum bending sensitivity is 14.08 nm/m-1 in the range from 0.128 m-1 to 1.28 m-1. The proposed bending sensor possesses pronounced advantages, such as high sensitivity, small size, low cost, and orientation identification, and offers a very promising method for bend measurement.
bending sensor chirped long-period fiber grating off-axis micro helix taper orientation identification Chinese Optics Letters
2023, 21(6): 060604
1 华中科技大学光学与电子信息学院激光加工国家工程研究中心，湖北 武汉 430074
2 江苏先河激光技术有限公司，江苏 宿迁 223800
为实现孔径和锥度可调的微孔加工，设计研制了一种基于双振镜组联动与Z轴上下移动的五轴四联动激光旋切系统。建立了微孔激光旋切物理模型，首先利用边缘轮廓确定微孔形状，再通过分层回型填充方法确定每个激光作用点的位置；然后基于聚焦光束不被遮挡和振镜偏转整体运动量少的原则，确定四个振镜的偏转角度；通过改变边缘轮廓端点数据，可分别实现方孔尺寸和锥度的灵活可控。采用15 W紫外皮秒激光器、两套相同的振镜和焦距为32 mm的远心透镜，配合三维平移工作台，搭建了激光旋切硬件系统，自主开发了多边形激光旋切控制软件。实验采用分层降焦打孔的方式，在厚度为250 μm的氮化硅材料上实现了55 μm×55 μm规格的正锥、零锥、负锥方形微孔的加工，并且还实现了不同孔径（30~80 μm）零锥方形微孔和三角形、五边形、六边形等其他形状微孔的加工。
激光技术 激光旋切 微孔加工 双振镜组 分层填充 锥度调节 中国激光
2023, 50(12): 1202402
Author Affiliations
Abstract
1 Key Laboratory of In-fiber Integrated Optics, Ministry of Education, Harbin Engineering University, Harbin 150001, China
2 Qingdao Innovation and Development Center of Harbin Engineering University, Qingdao 266000, China
3 Photonics Research Center, School of Electronic Engineering and Automation, Guilin University of Electronic Technology, Guilin 541004, China
We propose a high-sensitivity bidirectional torsion sensor using a helical seven-core fiber taper embedded in multimode fiber (MHSTM). Sensors with different taper waists and helical pitches are fabricated, and their transmission spectra are obtained and analyzed. The waist and length of the sandwiched seven-core fiber are finally determined to be 68 µm and 3 mm, respectively. The experimental results show that the clockwise and counterclockwise torsion sensitivities of the proposed sensor are 2.253 nm/(rad/m) and -1.123 nm/(rad/m), respectively. When tapered waist diameter reduces to 48 µm, a superior torsion sensitivity of 5.391 nm/(rad/m) in the range of 0–4.24 nm/(rad/m) is obtained, which is 46 times as large as the traditional helical seven-core fiber structure. In addition, the MHSTM structure is also relatively stable to temperature variations.
torsion sensor Mach–Zehnder interferometer multicore fiber helical taper structure Chinese Optics Letters
2023, 21(4): 041205
Author Affiliations
Abstract
1 Key Laboratory of All Optical Network and Advanced Telecommunication Network of EMC, Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044, China
2 System Integration Department, China North Industries Corp., Beijing 100053, China
An in-fiber Mach-Zehnder interferometer is proposed for the discrimination of strain and temperature. The sensor is based on two cascaded standard single mode fibers using three peanut tapers fabricated by simple splicing. The cascaded structure excites more frequency components, which induce four sets of interference dips in the transmission spectrum. One set of the spectrum dips have different sensitivities to temperature and strain from those of the other three. The sensor can discriminate strain and temperature by monitoring the wavelength shifts of two spectrum dips. Repeated experiments are taken both for strain and temperature increasing and decreasing scenarios. Experimental results show that Dip 1 has an average strain sensitivity of -0.911 pm/με and an average temperature sensitivity of 49.98 pm/℃. The strain sensitivity for Dip 2 is negligible and its average temperature sensitivity is 60.52 pm/℃ The strain and temperature resolutions are ±3.82 με and ±0.33 ℃.
Mach-Zehnder interferometer peanut taper simultaneous measurement single mode fiber strain sensor temperature sensor Photonic Sensors
2023, 13(1): 230122
1 南京邮电大学电子与光学工程学院、柔性电子（未来技术）学院，江苏 南京 210023
2 中国科学院上海光学精密机械研究所高功率激光单元技术实验室，上海 201800
3 国科大杭州高等研究院物理与光电工程学院，浙江 杭州 310024
稀土掺杂石英光纤具有物化性能稳定、机械强度高、易于系统集成等优点，是目前光纤激光器最核心的增益介质，但其稀土掺杂浓度一般较低（<2%）。利用溶胶凝胶法和高温烧结工艺制备了Tm3+掺杂浓度为8.29×1020 cm-3的高硅氧玻璃，并表征了其光谱性能。采用溶胶镀膜和二次熔融拉锥方法制备了芯径约为4 μm、外径为125 μm的石英光纤，其可与商用无源光纤进行熔接。利用全光纤化线性腔结构，以制备的不同长度掺Tm3+石英光纤作为增益介质，均可实现1947 nm激光输出，光信噪比约为70 dB；当光纤长度为4.6 cm时，斜率效率高达14.1%；同时搭建了掺铥光纤放大器，测得光纤小信号净增益系数为0.48 dB/cm。研究结果表明，该新型光纤制备方法可为高浓度掺铥石英光纤提供新途径，有望推动其在2.0 μm单频及高重频锁模光纤激光器中的应用。
激光器 光纤激光器 Tm3+高掺石英光纤 溶胶凝胶法 熔融拉锥
1 江苏大学机械工程学院，江苏 镇江 212013
2 江苏大学材料科学与工程学院，江苏 镇江 212013
铝合金由于其优良的物理化学性能，在工业生产中得到了广泛应用，但铝合金的高反射率和高热导率限制了激光加工技术在铝合金精密加工中的应用。采用控制变量法研究了铝合金单步法旋切打孔技术中的激光重复频率、扫描次数、扫描速度、进给次数对微孔出入口形貌和锥度的影响规律。针对铝合金单步法旋切打孔中存在的锥度大和出入口形貌差等问题，提出了三步法旋切打孔方法。结果表明，该方法可以有效地减小微孔的锥度，改善出入口形貌，减少孔口周围的飞溅物堆积。主要原因是该方法可以有效地促进打孔过程中熔渣和等离子体的排出，减少其对激光能量的扰动，提高了激光能量的稳定性和均匀性。
激光技术 飞秒激光 旋切打孔 铝合金 锥度 中国激光
2022, 49(22): 2202020
