Author Affiliations
Abstract
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications (BUPT), Beijing 100876, China
A concept of divergence angle of light beams (DALB) is proposed to analyze the depth of field (DOF) of a 3D light-field display system. The mathematical model between DOF and DALB is established, and the conclusion that DOF and DALB are inversely proportional is drawn. To reduce DALB and generate clear depth perception, a triple composite aspheric lens structure with a viewing angle of 100° is designed and experimentally demonstrated. The DALB-constrained 3D light-field display system significantly improves the clarity of 3D images and also performs well in imaging at a 3D scene with a DOF over 30 cm.
3D light-field display depth of field divergence angle of light beams compound lens Chinese Optics Letters
2024, 22(1): 011101
电子科技大学格拉斯哥学院, 四川 成都 611731
在语义分割模型结构不变的前提下, 为提升模型对图像分割的精确度, 引入生成对抗网络结构用于训练语义分割模型(SS-GAN)。SS-GAN包含 3个设计环节: 构建全卷积网络(FCN)结构的生成模型, 进行初步的图像分割; 设计具备像素间高阶关系学习能力的对抗模型, 提高生成模型的学习能力; 加入对抗损失辅助生成模型学习, 进一步促进生成网络自主学习像素间关系。在计算机视觉竞赛数据集 (PASCAL VOC)和城市景观数据集 (Cityscapes)上的实验结果表明, 引入生成对抗网络后取得了更好的效果, 2个数据集的交并比 (IoU)指标分别提高了 1.56%/1.17%和1.93%/1.55%。
语义分割 生成对抗网络 全卷积神经网络 空间连续性 semantic segmentation Generative Adversarial Network Fully Convolutional Network spatial contiguity 太赫兹科学与电子信息学报
2023, 21(2): 235
河南理工大学物理与电子信息学院，河南 焦作 454003
提出了一种基于非均匀光频梳的多频率瞬时信号检测方案。以功率非均匀下降的光频梳功率比为参照，利用待测信号与光频梳的拍频功率比确定信号的频率范围，再由解调后的频率信息计算待测信号的精确频率。仿真实现了0~20 GHz范围内多频信号的瞬时测量，误差范围为0~23 MHz。此外，分析了激光器线宽、光纤布拉格光栅中心频率、调制器偏置电压和光混频器相差对测量结果的影响。结果显示：该系统对激光器线宽和混频器相差的改变不敏感，光纤布拉格光栅中心频率和调制器偏置电压会影响光频梳信号的功率比；当功率比区分度较大时，系统稳定性更高，误差更小。
光纤光学 射频光子学 瞬时频率测量 光频梳 光纤布拉格光栅 双平行马赫-曾德尔调制器 光学学报
2022, 42(23): 2306004
1 State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
2 Key Laboratory of Particle Acceleration Physics & Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
3 Spallation Neutron Source Science Center, Dongguan 523803, Guangdong , China
In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier. With properly chosen pump source and carefully designed cavity, Nd∶YVO4 crystal, and laser beam collimator, a maximum output pulse energy of 480 μJ has been achieved at the repetition rate of 10 kHz. The output laser has a nearly Gaussian transverse profile and a narrow bandwidth of 0.2 nm. Long-term monitoring shows an root mean square power fluctuation of about 1%. These characteristics satisfy all requirements for high repetition rate terahertz parametric amplifier.
regenerative amplifier terahertz parametric amplifiers thermal lens 激光与光电子学进展
2022, 59(21): 2136001
强激光与粒子束
2022, 34(10): 104011
强激光与粒子束
2022, 34(10): 104014
强激光与粒子束
2022, 34(10): 104016
1 北京大学 核物理与核技术国家重点实验室，北京 100871
2 北京大学 物理学院 重离子物理研究所，北京 100871
3 中国科学院 高能物理研究所，北京 100049
4 德国电子同步加速器研究中心，德国 汉堡 22603
现代光源的发展不断推动着人们从更深层次上理解物质的基本结构和动力学行为。X射线自由电子激光作为最先进的光源，其超高的峰值功率、超短的脉冲长度和优良的相干性，为人们以原子级时空分辨率探测和操控物质中的超快过程提供了可能。目前全世界已有多个X射线自由电子激光装置建成并投入使用，在原子分子物理、化学、生命科学、材料科学等各学科应用中都显示出了重要价值。同时大量的研究工作也集中于继续提高X射线自由电子激光的性能，包括把脉冲持续时间从fs量级进一步缩短至as量级，这将为超快科学的发展带来新突破。以超快脉冲产生为主线，综述了近年来超快X射线自由电子激光产生方案的研究进展，从产生原理、方案特性、最新成果等方面介绍了各类产生方案，总结对比了各方案的优缺点，最后对超快X射线自由电子激光的未来发展方向进行了展望。
X射线 自由电子激光 超快光学 阿秒脉冲 X-ray free-electron laser ultrafast optics attosecond pulse 强激光与粒子束
2022, 34(5): 054001
河南理工大学 物理与电子信息学院，河南 焦作 454003
提出了一种瞬时多频率微波信号测量方案，采用单个激光源，将待测微波信号调制的光载波作为泵浦光，利用波分复用形成多路结构，同时与分路后的光频梳一一对应送入色散位移光纤，利用受激布里渊散射原理实现频率到空间的映射，通过监测相应通道输出光信号强度的变化，即可判断待测微波信号的频率。在仿真实验中，分别对0~25 GHz范围内的单频信号和多频信号进行了瞬时测频，实验结果显示含有待测微波信号的通道与其他通道相比输出功率有明显增大。该方法可同时测量0.1~25 GHz的单频或多频的微波信号，频率测量分辨率为0.1 GHz，测量误差为±0.05 GHz。此外，分析了调制器偏置电压漂移对实验结果的影响。仿真结果表明，此方案对偏置电压漂移带来的影响有一定的抵抗能力。
微波光子 瞬时测频 受激布里渊散射 光频梳 马赫增德尔调制器 Microwave photon Instantaneous frequency measurement Stimulated Brillouin scattering Optical frequency comb Mach-Zehnder Modulator
Author Affiliations
Abstract
State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
A high repetition rate, picosecond terahertz (THz) parametric amplifier with a LiNbO3 (LN) crystal has been demonstrated in this work. At a 10 kHz repetition rate, a peak power of 200 W and an average power of 12 μW have been obtained over a wide range of around 2 THz; at a 100 kHz repetition rate, a maximum peak power of 18 W and an average power of 10.8 μW have been obtained. The parametric gain of the LN crystal was also investigated, and a modified Schwarz–Maier model was introduced to interpret the experimental results.
far infrared or terahertz nonlinear optics parametric processes parametric oscillators and amplifiers Chinese Optics Letters
2020, 18(5): 051901
