为实现二极管泵浦激光器在宽温度环境下免温控稳定工作,分析了激光器泵浦源发射光谱对激光系统稳定性的影响。综合考虑了泵浦过程中的能量利用率,提出了激光器免温控泵浦源光谱优化设计方案。所提方案可有效降低泵浦源波长漂移对激光器系统吸收率和热焦距的影响,实现激光器宽温度范围内免温控工作。在-40~60 ℃工作温区内,计算了不同吸收长度和掺杂浓度(原子数分数)的Nd∶YAG激光器系统泵浦源的最优发射光谱。从理论角度而言,与一般无温控单波长激光二极管(LD)泵浦源相比,利用所提优化方案获得的泵浦源,可以将激光器系统的工作稳定性明显提高,将系统的泵浦光吸收率波动和晶体热焦距波动分别降低到13%和16%以内。对吸收长度为30 mm,掺杂浓度为0.8%的Nd∶YAG激光器系统,设计了一种双波长LD泵浦源(中心波长为803.7 nm@10 ℃和809.2 nm@10 ℃,对应比重为68.4%和31.6%)。模拟结果表明,在-40~60 ℃温度范围内,晶体对该泵浦光的吸收率可保持在90.7%以上,泵浦光吸收稳定性和晶体热焦距稳定性分别为91.4%和85.4%。
激光器 二极管泵浦 光谱优化 多波长泵浦
为了提高高重频掺钕钒酸钇激光器的放大效率, 提出了一种针对Nd∶YVO4单轴晶体的新型双程放大方式, 采用法拉第隔离器与Nd∶YVO4晶体旋转45°放置的方式, 使得种子激光在往返通过晶体时的线偏方向均为π偏振方向。结果表明, 在100W抽运功率下, 1W种子激光采用该双程放大方式的输出功率能够达到36.2W, 放大效果较之偏振片与λ/4波片组成的双程放大结构提高了41.5%。本研究对以Nd∶YVO4单轴晶体为放大级的弱种子激光放大有重要意义。
激光器, 双程放大, Nd∶YVO4晶体, 窄脉冲, π偏振 lasers, double-pass amplification, Nd∶YVO4 narrow pulse π polarization
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 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3 School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China
A deep convolutional neural network is employed to simultaneously measure the beam-pointing and phase difference of sub-beams from a single far-field interference fringe for coherent beam combining systems. The amplitudes of sub-beams in the measurement path are modulated in order to prevent measuring mistakes caused by the symmetry of beam-pointing. This method is able to measure beam-pointing and phase difference with an RMS accuracy of about 0.2 μrad and λ/250, respectively, in a two-beam coherent beam combining system.
coherent beam combining pattern recognition deep learning Chinese Optics Letters
2020, 18(4): 041402
