52 results on '"Dongxia, Hu"'
Search Results
2. Optical element sub-surface defect detection combining fluorescence and scattering imaging
- Author
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Rui Dong, Fang Wang, Ye Tian, Qinxiao Liu, Liu Hongjie, and Dongxia Hu
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Lossless compression ,Materials science ,Photoluminescence ,Microscope ,business.industry ,Scattering ,Image processing ,Laser ,Homogenization (chemistry) ,law.invention ,Optics ,Experimental system ,law ,business - Abstract
Fused silica optical elements are widely used in large high-power laser devices, and the subsurface defects of optical elements directly affect the laser damage threshold and imaging quality. These defects are distributed within a few to tens of microns from the surface and cannot be detected by conventional imaging methods. The characteristics of small size, low density and wide distribution range make it difficult to detect nondestructively, effectively and quickly with conventional methods. In order to solve the above problems, an experimental system was built based on the principles of photoluminescence and dark field scattering. Use the different characteristics of fluorescence image and scattering image to carry out the research of subsurface defect detection. First, preprocess the original image. Second, calculate the offset of adjacent images, perform background homogenization processing on the image, and stitch the sub-aperture images, and then segment the full-aperture image. Then, a more effective subsurface defect extraction algorithm is proposed. Finally, etch the sample with HF and observe it under a microscope. Experimental results show that this method can detect weak defects on the surface and sub-surface at the same time, and can effectively separate individual sub-surface defects. This method has the advantages of lossless, fast and high precision. Moreover, based on a large amount of data, analysis and summary of the causes of defects, distribution characteristics, etc.. This method can provide certain guidance for the evaluation of laser damage threshold and processing technology of optical components in high-power laser devices.
- Published
- 2021
3. Design & Optimization of F-Theta Focusing Lens Based on ZEMAX
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Fang Wang, Hong Zhu, Qinxiao Liu, Dongxia Hu, and Chaoyuan Ding
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Diffraction ,Materials science ,Aperture ,Infrared ,business.industry ,Distortion (optics) ,Physics::Optics ,Image plane ,law.invention ,Lens (optics) ,Optics ,law ,Limit (music) ,business ,Zemax - Abstract
In this paper, an optical simulation system f-theta lens composed of three ordinary glass spherical lenses is optimized by using optical design software. The lens is made of quartz glass which is commonly used in infrared band. The total length of the lens is 139mm, forming area is 85mm × 85mm. It is compact, simple and low cost. Additionally, the focal spot is very small, and the moving aperture is in a large range of 10-40mm. The focusing performance is close to the diffraction limit, and the spot size of the image plane reaches the diffraction limit of 3μm. The relative linear distortion is less than 0.005%. Therefore, our design meets the requirements of high precision for optical devices.
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- 2021
4. A detection method of weak and small defects based on fluorescence imaging technology
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Liu Hongjie, Dongxia Hu, Chaoyuan Ding, Rui Dong, Fang Wang, Ye Tian, and Qinxiao Liu
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Fluorescence-lifetime imaging microscopy ,Contrast enhancement ,Materials science ,business.industry ,media_common.quotation_subject ,Laser ,Signal ,law.invention ,Optics ,law ,Contrast (vision) ,Segmentation ,Bilateral filter ,business ,Intensity (heat transfer) ,media_common - Abstract
In large high-power laser devices,the surface and subsurface defects of fused silica optical components directly affect the laser damage threshold and imaging quality. In this paper, fluorescence imaging technology is used to obtain images of defects in the subsurface layer of optical components that will absorb laser. Because the original image has the characteristics of sparse signal, weak intensity, low contrast, etc. In order to efficiently and reliably evaluate the surface and subsurface defects, this paper proposes a weak and small defect detection method based on local adaptive contrast enhancement and seed region growth. Firstly, the local adaptive contrast enhancement method is used to enhance the contrast of the original image. Secondly, the method of bilateral filtering is used to denoise. Thirdly, seed region growth method is used to segment the defective regions and perform morphological processing. Finally, defect detection is performed. The experiment uses different segmentation methods to detect images in different regions. The results show that this method can significantly enhance the contrast of the original fluorescence image, and detect pixel-level defects, and the detection rate is stable at about 95%. Meanwhile, the reasons, size distribution and other characteristics of the sub-surface defects of fused silica optical components are analyzed. This paper provides a nondestructive method of detecting weak and small defects in the subsurface layer of the optical element faster and higher accuracy.
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- 2021
5. 1178 J, 527 nm near diffraction limited laser based on a complete closed-loop adaptive optics controlled off-axis multi-pass amplification laser system
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Yang Ying, Xudong Xie, Wanguo Zheng, Lei Huang, Qihua Zhu, Xin Zhang, Xuewei Deng, Zhang Xiaomin, Feng Jing, Deen Wang, Dongxia Hu, Qiang Yuan, Wanjun Dai, Xiaofeng Wei, Zeping Yang, and Lin Chen
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Wavefront ,Diffraction ,Nuclear and High Energy Physics ,Materials science ,business.industry ,Amplifier ,Energy conversion efficiency ,Laser ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Crystal ,Optics ,Nuclear Energy and Engineering ,law ,Laser beam quality ,business ,Adaptive optics - Abstract
A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics (AO) controlled off-axis multi-pass amplification laser system. Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier, a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62% conversion efficiency, 1178 J and beam quality of 7.93 times the diffraction limit (DL). By using a complete closed-loop AO configuration, the static and dynamic wavefront distortions of the laser system are measured and compensated. After correction, the diameter of the circle enclosing 80% energy is improved remarkably from 7.93DL to 1.29DL. The focal spot is highly concentrated and the 1178 J, 527 nm near diffraction limited laser is achieved.
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- 2021
6. Multiscale enhancement combined with local maxima for infrared filter defect detection
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Zemin Li, Qinxiao Liu, Fang Wang, Dongxia Hu, and Chaoyuan Ding
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business.industry ,Computer science ,Gaussian ,Feature extraction ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Pattern recognition ,02 engineering and technology ,Filter (signal processing) ,Image segmentation ,01 natural sciences ,010309 optics ,Maxima and minima ,Statistical classification ,symbols.namesake ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,020201 artificial intelligence & image processing ,Segmentation ,Artificial intelligence ,business ,Infrared cut-off filter - Abstract
Due to the problems that some defects on the surface are very weak and the low contrast of the background, adaptive local contrast enhancement was adopted. Then multiscale gaussian side window filter was proposed to enhance the defect details. By looking for appropriate local maxima to locate the defect area for segmentation. The broken scratches were connected by the morphological method, then scratches and stains were classified by the geometric features parameters. By comparing and analyzing various methods of image detail enhancement and defect segmentation, the results show that the accuracy of the algorithm proposed in this paper is 91.3% in defect detection, faster than the traditional algorithms, and has higher detection efficiency and precision.
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- 2020
7. Design of laser beam dump with high laser-induced-damage threshold
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Liu Hongjie, Chen Yuan, Xiang Yong, Fang Wang, Zheng Tianran, Zhufeng Shao, Ye Tian, Dongxia Hu, and Xiaodong Yuan
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Materials science ,Geometrical optics ,business.industry ,Stray light ,Physics::Optics ,Laser ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Power (physics) ,law.invention ,Optics ,law ,Physics::Accelerator Physics ,Physics::Atomic Physics ,Beam dump ,Electrical and Electronic Engineering ,business ,Absorption (electromagnetic radiation) ,Laser beams ,Energy (signal processing) - Abstract
Laser beam dumps are necessary for laser systems designed to deliver high power or high energy to achieve effective control of stray light. However, the energy density of the stray light destroys the absorption glass of the beam dump with an increase in the output energy. To solve this problem, the initial laser-induced-damage threshold (LIDT) of a new optical absorption material was tested. A new type of laser beam dump was designed with this new optical material based on geometrical optics and light-field distribution analysis.
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- 2022
8. Deformable mirror resolution-matching-based two-stage wavefront sensorless adaptive optics method
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Feng Jing, Qiang Yuan, Chuang Sun, Deen Wang, Xuewei Deng, Xin Zhang, Yang Ying, Dongxia Hu, Lei Huang, Yamin Zheng, and Wanjun Dai
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Wavefront ,Physics ,Continuous phase modulation ,business.industry ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Deformable mirror ,Intensity (physics) ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,Spatial frequency ,Electrical and Electronic Engineering ,Adaptive optics ,Actuator ,business ,Engineering (miscellaneous) - Abstract
In high-power laser facilities, the application of a traditional wavefront control method is limited under the influence of a continuous phase plate (CPP). In order to obtain a satisfactory far-field intensity distribution at the target of the beamline with the CPP, a novel deformable mirror (DM) resolution-matching-based two-stage wavefront sensorless adaptive optics method is proposed and demonstrated. The principles of the DM resolution-matching method and two-stage wavefront sensorless adaptive optics method are introduced, respectively. Based on the numerical model, the matching relationship between the actuator space of the DM and the spatial period of the CPP is investigated. By using the resolution-matched DM, the feasibility of the two-stage wavefront sensorless adaptive optics method is numerically and experimentally verified. Both the numerical and the experimental results show that the presented DM resolution-matching-based two-stage wavefront sensorless adaptive optics method could achieve the target focal spot control under the influence of the CPP, and the profile and the intensity uniformity of the corrected focal spot are optimized close to the designed ideal focal spot.
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- 2020
9. Design of long depth of field microscope lens for medium format
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Dongxia Hu, Zheng Tianran, Chaoyuan Ding, Qinxiao Liu, Fang Wang, and Liu Hongjie
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Optics ,Microscope ,Materials science ,business.industry ,law ,Lens (geology) ,Depth of field ,business ,law.invention - Published
- 2020
10. Analysis of wavefront effects for large-aperture tiled-grating compressor
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Yi Zhou, Xiaodong Wang, B. Deng, Zhang Junwei, Dongxia Hu, Shengtao Zhang, and Jingqin Su
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Wavefront ,Physics ,Diffraction ,business.industry ,Astrophysics::Instrumentation and Methods for Astrophysics ,Holography ,Physics::Optics ,02 engineering and technology ,Grating ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Pulse (physics) ,law.invention ,010309 optics ,020210 optoelectronics & photonics ,Optics ,law ,Pulse compression ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Adaptive optics ,business ,Diffraction grating - Abstract
Monolithic large-aperture diffraction grating tiling is desired to increase the output capability of multi-kilojoule petawatt laser facilities. However, the wavefront errors of input pulse and gratings will degrade the focal spot quality and the compressibility of the output pulse. In this work, the effects of wavefront error of input pulse, deformation and wave aberration of the grating for the large-aperture tiled-grating compressor are investigated theoretically. A series of numerical simulations are presented to discuss the changing trends of focal spot energy caused by wavefront error of input pulse and obtain the error tolerance for specific goals. The influences of coating stress and the wave aberration of holographic exposure gratings on the diffraction wavefront are also discussed. Some advice is proposed for improving the performance of large-aperture tiled-grating. This work paves the way for the design of practical large-aperture tiled-grating compressor for ultrahigh intensity laser facilities in the future.
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- 2018
11. Size Measurement of Laser-Induced Damage in Large-Aperture Final Optics
- Author
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Yong Xiang, Bin Feng, Fengdong Chen, Guodong Liu, Chengcheng Wang, Dongxia Hu, Qihua Zhu, Bingguo Liu, Jun Tang, Fupeng Wei, and Zhitao Peng
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size measurement ,Accuracy and precision ,General Computer Science ,02 engineering and technology ,Size measurement ,01 natural sciences ,Measure (mathematics) ,Light scattering ,law.invention ,010309 optics ,extreme learning machine ,Optics ,law ,Approximation error ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Physics ,Total internal reflection ,business.industry ,Laser-induced damage ,General Engineering ,Laser ,inhomogeneous ,Radiometry ,020201 artificial intelligence & image processing ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,business ,lcsh:TK1-9971 - Abstract
In this paper, a hierarchical kernel extreme learning machine (HK-ELM) is proposed to solve the problem that the size of laser-induced damage (LID) cannot be accurately measured under the condition of inhomogeneous total internal reflection illumination. The proposed method overcomes the limitations of the radiometric method, which depends on a single factor to measure the size of damage. After analyzing the light scattering characteristics of LID with the finite-difference time-domain method, we find that we should consider the influences of multiple factors when measuring the size of damage under the condition of uneven illumination. The experimental results show that HK-ELM can achieve ultra-resolution measurements, and the mean relative error of the measured size predicted by HK-ELM is within 5% on the testing samples. Compared with the traditional technology, the method proposed in this paper effectively improves the measurement accuracy.
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- 2018
12. Multi-feature fusion method based on WOSF and MSE for four-class MI EEG identification
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Jingjing Xie, Xiaolong Wu, Dongxia Hu, Changhui Pan, and Lingyan Hu
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medicine.diagnostic_test ,Spatial filter ,Computer science ,business.industry ,Process (engineering) ,Interface (computing) ,Biomedical Engineering ,Health Informatics ,Pattern recognition ,Electroencephalography ,Identification (information) ,Motor imagery ,Signal Processing ,medicine ,Artificial intelligence ,business ,Neurorehabilitation ,Brain–computer interface - Abstract
Background Brain-Computer Interface (BCI) can bring great convenience to patients in the process of rehabilitation training and prosthetic control. However, how to extract effective features is a core issue in a BCI system. Methods We proposes the Multi-Feature Fusion Method based on Wavelength Optimal Spatial Filter and Multiscale Entropy for classifying the electroencephalogram signals (EEG) in four kinds of motor imagery tasks. The method can combine Wavelength features with Multiscale Entropy. Results Two groups of experiments were conducted. One for simple four types of motor imagery (MI) tasks and another for unilateral limb. Experiments show that our proposed method has better performance compared to other methods. (82.55% versus 73.08% average accuracy respectively). Conclusions The proposed method can effectively improve the accuracy of EEG classification in multiclass motor imagery and will be useful for neurorehabilitation through motor imagery for hemiplegic patients.
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- 2021
13. Beam wavefront retrieval by convoluted spatial spectral benchmark
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Xin Zhang, Deen Wang, Yang Ying, Xuewei Deng, Dongxia Hu, and Xiaoxia Huang
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Wavefront ,Nuclear and High Energy Physics ,Computer science ,business.industry ,Fourier optics ,Astrophysics::Instrumentation and Methods for Astrophysics ,QC770-798 ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010305 fluids & plasmas ,Convolution ,symbols.namesake ,Fourier transform ,Optics ,Nuclear Energy and Engineering ,Nuclear and particle physics. Atomic energy. Radioactivity ,0103 physical sciences ,Benchmark (computing) ,symbols ,Spatial frequency ,Electrical and Electronic Engineering ,010306 general physics ,Focus (optics) ,business ,Beam (structure) - Abstract
We propose a method for retrieving a beam wavefront from its near-field intensity distribution after a 4f system by simply inserting a benchmark at the Fourier plane. Through a convolution of the mark-blocked spatial frequency component and the original optical field with the 4f system, the separation between the focus of any sub-aperture and the benchmark can be determined to reconstruct the beam wavefront. Theoretical and experimental studies demonstrate the validity of this method, which has potential applications in real-time wavefront sensing.
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- 2021
14. Research of beam conditioning technologies using continuous phase plate, Multi-FM smoothing by spectral dispersion and polarization smoothing
- Author
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Na Zhu, Rui Zhang, Wanguo Zheng, Jingqin Su, Huaiting Jia, Dongxia Hu, Haoyu Yuan, Qihua Zhu, and Xiaocheng Tian
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Continuous phase modulation ,Birefringence ,Materials science ,business.industry ,Mechanical Engineering ,Near and far field ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Polarization (waves) ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Inertial confinement fusion ,Smoothing ,Beam (structure) - Abstract
In the research of inertial confinement fusion, laser plasma interaction (LPI) is becoming a key problem that affects ignition. Here, multi-frequency modulation (Multi-FM) smoothing by spectral dispersion (SSD), continuous phase plate (CPP) and polarization smoothing (PS) were experimentally studied and implemented on the SG-III laser facility. After using these techniques, the far field distribution of SG-Ⅲ laser facility can be adjusted, controlled and repeated accurately. The output spectrums of the cascade phase modulators used for Multi-FM SSD were stable and the FM-to-AM effect can be restrained. Experiments on SG-III laser facility indicate that when the number of color cycles adopts 1, imposing SSD with 3.3 times diffraction limit (TDL) did not lead to pinhole closure in the spatial filters of preamplifier and main amplifiers with 30-TDL pinhole size. The nonuniformity of the focal spots using Multi-FM SSD, CPP and PS drops to 0.18, comparing to 0.26 with CPP+SSD, 0.57 with CPP+PS and 0.84 with only CPP and wedged lens. Polarization smoothing using flat birefringent plate in the convergent beam of final optics assembly (FOA) was studied. The PS plates were manufactured and equipped on SG-III laser facility for LPI research. Combined beam smoothing and polarization manipulation were also studied to solve the LPI problem. Results indicate that through adjusting dispersion directions of SSD beams in a quad, two dimensional SSD can be obtained. Using polarization control plate (PCP), polarization on the near field and far field can be manipulated, providing new method to solve LPI problem in indirect drive laser fusion.
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- 2016
15. Designing of converging stray light focal spot absorber in high power laser system
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Liu Hongjie, Zheng Tianran, Sun Xibo, Dongxia Hu, Fang Wang, Deen Wang, and Chen Liangming
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Materials science ,business.industry ,Stray light ,Laser ,Fluence ,Pulse (physics) ,law.invention ,Optics ,Quality (physics) ,Transmission (telecommunications) ,law ,Light cone ,business ,Absorption (electromagnetic radiation) - Abstract
In high power solid-state laser facilities, stray lights may do great damage to optical glass and metal structure and affect the transmission of the main laser and the environment cleanliness inside the facility. On the other hand, the stray may also form noise signal of the main laser pulse and affect the output quality. There are mature solutions for the controlling and absorption of parallel and divergent stray light[2]. However there are no reliable solution for the absorption of the converging stray light near its focal spot. An absorber design are proposed using multiple materials and small angle light cone. And this design can realize effective absorption of the stray light focal spot with the peak fluence up to 40J/cm2.
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- 2019
16. Amplification of 200-ps high-intensity laser pulses via frequency matching stimulated Brillouin scattering
- Author
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Can Cui, Hang Yuan, Dongxia Hu, Sensen Li, Yi Chen, Feng Jing, Qiang Yuan, Yulei Wang, Zhaohong Liu, and Zhiwei Lu
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Nuclear and High Energy Physics ,Materials science ,business.industry ,Acoustic wave ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Intensity (physics) ,law.invention ,Pulse (physics) ,010309 optics ,Ignition system ,Brillouin zone ,Optics ,Nuclear Energy and Engineering ,law ,Brillouin scattering ,0103 physical sciences ,010306 general physics ,business ,Inertial confinement fusion - Abstract
Laser pulses of 200 ps with extremely high intensities and high energies are sufficient to satisfy the demand of shock ignition, which is an alternative path to ignition in inertial confinement fusion (ICF). This paper reports a type of Brillouin scheme to obtain high-intensity 200-ps laser pulses, where the pulse durations are a challenge for conventional pulsed laser amplification systems. In the amplification process, excited Brillouin acoustic waves fulfill the nonlinear optical effect through which the high energy of a long pump pulse is entirely transferred to a 200-ps laser pulse. This method was introduced and achieved within the SG-III prototype system in China. Compared favorably with the intensity of $2~\text{GW}/\text{cm}^{2}$ in existing ICF laser drivers, a 6.96- $\text{GW}/\text{cm}^{2}$ pulse with a width of 170 ps was obtained in our experiment. The practical scalability of the results to larger ICF laser drivers is discussed.
- Published
- 2019
17. Fast automatic classification of input and exit surface laser-induced damage in large-aperture final optics
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Bin Feng, Fengdong Chen, Bingguo Liu, Qihua Zhu, Jun Tang, Dongxia Hu, Fupeng Wei, Chengcheng Wang, Yong Xiang, Guodong Liu, and Zhitao Peng
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Surface (mathematics) ,Total internal reflection ,business.industry ,Computer science ,Feature vector ,02 engineering and technology ,Laser ,01 natural sciences ,Autoencoder ,law.invention ,Image (mathematics) ,010309 optics ,Light intensity ,Optics ,law ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,business ,Extreme learning machine - Abstract
Under the condition of inhomogeneous total internal reflection illumination, a fast automatic classification method based on machine learning is proposed to solve the problem of determining the location of surface damage sites. First, the far-field light intensity distributions of damage sites on the input and exit surfaces are calculated by using numerical calculations. After analyzing the optical properties, we present a feature vector for characterizing all damage sites in the image captured by the final optics damage inspection system. Finally, an autoencoder-based extreme learning machine is used to identify the surface on which a damage site resides. The experimental results show that the maximum testing accuracy of this method is 97.66%. Compared to the method used at Lawrence Livermore National Laboratory, the method proposed in this paper shows improved accuracy and faster speed of classification in practical applications. In particular, the proposed algorithm for damage classification outperforms several state-of-the-art methods on our experimental dataset.
- Published
- 2018
18. Progress in octahedral spherical hohlraum study
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Wei Zhou, Sanwei Li, Yang Zhiwen, Xuewei Deng, Jingqin Su, Zheng Yuan, Runchang Zhao, Keli Deng, Liang Guo, Wei Wang, Huaiting Jia, Bobin Jiang, Yuan Guanghui, Xiayu Zhan, Xian-Tu He, Xiao-Ying Han, Jie Liu, Feng Wang, Kai Du, Ping Li, Ke Lan, Wanguo Zheng, Wen Yi Huo, Yukun Li, Shu Li, Yongkun Ding, Lifei Hou, Dongxia Hu, Xufei Xie, Yaohua Chen, Guoli Ren, Lizhen Huang, Chunyang Zheng, Zhang Haijun, Zhichao Li, Wei Zhang, Dong Yang, Mingyu Zhang, and Chuanlei Zhai
- Subjects
Physics ,Nuclear and High Energy Physics ,business.industry ,Octahedral symmetry ,Implosion ,Shields ,Plasma ,Radius ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Symmetry (physics) ,010305 fluids & plasmas ,law.invention ,Optics ,Nuclear Energy and Engineering ,Hohlraum ,law ,0103 physical sciences ,lcsh:QC770-798 ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,Electrical and Electronic Engineering ,Atomic physics ,010306 general physics ,business - Abstract
In this paper, we give a review of our theoretical and experimental progress in octahedral spherical hohlraum study. From our theoretical study, the octahedral spherical hohlraums with 6 Laser Entrance Holes (LEHs) of octahedral symmetry have robust high symmetry during the capsule implosion at hohlraum-to-capsule radius ratio larger than 3.7. In addition, the octahedral spherical hohlraums also have potential superiority on low backscattering without supplementary technology. We studied the laser arrangement and constraints of the octahedral spherical hohlraums, and gave a design on the laser arrangement for ignition octahedral hohlraums. As a result, the injection angle of laser beams of 50°–60° was proposed as the optimum candidate range for the octahedral spherical hohlraums. We proposed a novel octahedral spherical hohlraum with cylindrical LEHs and LEH shields, in order to increase the laser coupling efficiency and improve the capsule symmetry and to mitigate the influence of the wall blowoff on laser transport. We studied on the sensitivity of the octahedral spherical hohlraums to random errors and compared the sensitivity among the octahedral spherical hohlraums, the rugby hohlraums and the cylindrical hohlraums, and the results show that the octahedral spherical hohlraums are robust to these random errors while the cylindrical hohlraums are the most sensitive. Up till to now, we have carried out three experiments on the spherical hohlraum with 2 LEHs on Shenguang(SG) laser facilities, including demonstration of improving laser transport by using the cylindrical LEHs in the spherical hohlraums, spherical hohlraum energetics on the SGIII prototype laser facility, and comparisons of laser plasma instabilities between the spherical hohlraums and the cylindrical hohlraums on the SGIII laser facility. PACS codes: 52.70.La, 52.35.Tc, 47.40.Nm, Keywords: Indirect-drive inertial confinement fusion, Novel spherical hohlraum with 6 LEHs, High and robust radiation symmetry, High energy coupling efficiency, Theoretical study, Experiments
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- 2016
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19. Comparative study on coherent noise in optical parametric and quasi-parametric chirped-pulse amplification
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Jingui Ma, Dongxia Hu, Liejia Qian, Yudong Tao, Peng Yuan, Heyuan Zhu, and Jing Wang
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Chirped pulse amplification ,Physics ,business.industry ,Amplifier ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Signal ,Noise (electronics) ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Pulse (physics) ,010309 optics ,Optics ,Orders of magnitude (time) ,law ,0103 physical sciences ,Time domain ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,business - Abstract
The coherent noise inherent to optical parametric chirped-pulse amplification (OPCPA) poses a fundamental limitation on the temporal quality of current ultrashort ultraintense lasers as well as their applications in strong-field physics research. Here we present a peer comparison of coherent noise between OPCPA and one of its alternatives — quasi-parametric chirped-pulse amplification (QPCPA). In the initial amplification stage termed as small-signal regime, the spectrum of chirped signal pulse in either OPCPA or QPCPA is exposed to the imperfections in pump pulse and optics, resulting in coherent noise pedestals in the time domain. While in the final amplification stage featured by amplifier saturation, the nonlinear growths of coherent noise become sharply different. We demonstrate that the non-parametric saturation behavior of QPCPA can greatly smooth the spectral distortions of signal, and thus bring down the coherent noise. Consequently, QPCPA scheme allows an improvement of pulse contrast by 2–3 orders of magnitude. The results presented in this paper provide a new perspective on high-contrast amplification of ultrashort pulses.
- Published
- 2020
20. First Octahedral Spherical Hohlraum Energetics Experiment at the SGIII Laser Facility
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Ke Lan, Wen Yi Huo, Huabing Du, Xiaohua Jiang, Kuixing Zheng, Yaohua Chen, Xiaoshi Peng, Sanwei Li, Jiamin Yang, Deng Bo, He Zhibing, Zhichao Li, Dong Yang, Qianqian Gu, Wang Qiangqiang, Wei Zhang, Jie Liu, Guanghui Yuan, Kai Du, Shenye Liu, Wei Zhou, Feng Wang, Yuancheng Wang, Yonggang Liu, Guoli Ren, Hui Cao, Baibin Jiang, Zhebin Wang, Yongsheng Li, Chaoguang Li, Haijun Zhang, Yongkun Ding, Tao Xu, Shaoen Jiang, Xufei Xie, Shu Li, Xuewei Deng, Lifei Hou, Wang Liquan, Qihua Zhu, Xiaoxia Huang, Keli Deng, Liang Guo, Dongxia Hu, and Xiayu Zhan
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Shock wave ,Range (particle radiation) ,Materials science ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Energy conversion efficiency ,General Physics and Astronomy ,Flux ,Laser ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Radiation flux ,Optics ,law ,Hohlraum ,0103 physical sciences ,Black-body radiation ,010306 general physics ,business - Abstract
The first octahedral spherical hohlraum energetics experiment is accomplished at the SGIII laser facility. For the first time, the 32 laser beams are injected into the octahedral spherical hohlraum through six laser entrance holes. Two techniques are used to diagnose the radiation field of the octahedral spherical hohlraum in order to obtain comprehensive experimental data. The radiation flux streaming out of laser entrance holes is measured by six flat-response x-ray detectors (FXRDs) and four M-band x-ray detectors, which are placed at different locations of the SGIII target chamber. The radiation temperature is derived from the measured flux of FXRD by using the blackbody assumption. The peak radiation temperature inside hohlraum is determined by the shock wave technique. The experimental results show that the octahedral spherical hohlraum radiation temperature is in the range of 170-182 eV with drive laser energies of 71 kJ to 84 kJ. The radiation temperature inside the hohlraum determined by the shock wave technique is about 175 eV at 71 kJ. For the flat-top laser pulse of 3 ns, the conversion efficiency of gas-filled octahedral spherical hohlraum from laser into soft x rays is about 80% according to the two-dimensional numerical simulation.
- Published
- 2018
21. Temporal self-modifying characteristics of pulse propagation in multiphoton absorbers
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Dongxia Hu, Li Wei, Wanjun Dai, Feng Jing, Kun Cheng, and Sujuan Zhang
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Coupling ,Physics ,3D optical data storage ,business.industry ,Rate equation ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Amplitude modulation ,Optics ,Modulation ,Attenuation coefficient ,Electrical and Electronic Engineering ,business ,Absorption (electromagnetic radiation) ,Transformation optics - Abstract
In this Letter, temporal self-modifying behavior of amplitude modulation pulse propagation characteristics in multiphoton absorbers is presented by solving the underlying theoretical model coupling the propagation equation with the rate equations. The characteristics of the output temporal shapes are of primary concern and are discussed in detail. Amplitude modulation suppressing effects of multiphoton absorbers are numerically demonstrated; they have not been reported previously, to our knowledge. By taking a time resolved absorption coefficients, the corresponding physical mechanism is explicitly interpreted.
- Published
- 2015
22. Generation and measurement of complex laser pulse shapes in the SG-III laser facility
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Dangpeng Xu, Qihua Zhu, Xiaocheng Tian, Wei Zhou, Xiaoxia Huang, Dongxia Hu, Wei Zhong, Jun Dong, Zhou Dandan, Xuewei Deng, Huaiwen Guo, and Wanguo Zheng
- Subjects
Femtosecond pulse shaping ,Materials science ,business.industry ,Optical engineering ,Laser ,Pulse shaping ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Pulse (physics) ,law.invention ,Optics ,Multiphoton intrapulse interference phase scan ,law ,Ultrafast laser spectroscopy ,Laser power scaling ,Electrical and Electronic Engineering ,business - Abstract
The generation and measurement of complex ultraviolet laser pulse shapes is demonstrated in the SG-III laser facility. Relatively high contrast ratio of 300∶1 required by the physics experiment is achieved and successfully measured. Two continuous main shots validate the reproduction and the stability of the pulse shape, which provide solid foundation for precise physics experiment and laser power balance.
- Published
- 2015
23. Numerical analysis of a novel two-stage enlargement and adaptive correction approach for the annular aberration compensation
- Author
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Xuewei Deng, Licheng Sun, Lei Huang, Yamin Zheng, Chuang Sun, Qiang Yuan, Dongxia Hu, and Deen Wang
- Subjects
Physics ,Wavefront ,Zernike polynomials ,business.industry ,Numerical analysis ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Deformable mirror ,Compensation (engineering) ,010309 optics ,symbols.namesake ,Optics ,0103 physical sciences ,symbols ,Prism ,Laser power scaling ,Laser beam quality ,0210 nano-technology ,business - Abstract
The annular laser beam (ALB) is widely used in many fields, which could be affected by laser power and beam quality. To effectively and flexibly improve the beam quality of high-power large-aperture thin-wall ALB, a two-stage enlargement and adaptive correction configuration (TEACC) consisting of a novel outer-surface tubular deformable mirror (OTDM) and two extra prism groups (EPGs) is proposed in this paper. The correction principle and design principle of the TEACC are derived and analyzed. Based on the principle, a typical OTDM prototype and EPG structure are designed. Annular aberrations are compensated by applying the OTDM’s influence functions and the least-square algorithm in simulation. The results show that the TEACC could perfectly compensate the wavefront distortions described by the 2nd to 36th order Zernike annular aberrations.
- Published
- 2019
24. Theoretical research on the novel adaptive optics configuration based on the tubular deformable mirror for the aberration correction of the annular laser beam
- Author
-
Yamin Zheng, Chuang Sun, Xuewei Deng, Dongxia Hu, Deen Wang, Lei Huang, and Licheng Sun
- Subjects
Wavefront ,Physics ,Aperture ,Zernike polynomials ,business.industry ,Coordinate system ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Deformable mirror ,010309 optics ,symbols.namesake ,Optics ,0103 physical sciences ,symbols ,Ray tracing (graphics) ,Laser beam quality ,0210 nano-technology ,Adaptive optics ,business - Abstract
The annular laser beam (ALB) has been widely used in many fields for its unique intensity distribution. Especially, in the materials processing, the power and the beam quality of the large-aperture thin-wall ALB are of vital. However, limited by the aperture, the actuators’ spacing or the damage threshold, the existing deformable mirrors (DMs) are not suitable for the correction of the ALB. Considering the stretching effect of the oblique incidence, in this paper, by using the tubular DM (TDM), a novel adaptive optics (AO) configuration is promoted to increase the number of the effective actuators covered by the input ALB. The coordinate transformation equations and correction principle of the novel AO configuration are derived based on the ray tracing. A typical TDM prototype is designed based on the coordinate transformation equations. The influence function characteristics of the TDM is analyzed using the finite element method, and the correction ability of the novel AO configuration based on the TDM is verified. Simulation results show that the TDM could perfectly compensate the wavefront distortions described by the 2th to 15th order Zernike annular aberrations.
- Published
- 2019
25. Non-collinear phase-matching sum-frequency generation based on boundary total reflection in bulk KDP
- Author
-
Guan Yan, Qiang Yuan, Huaijin Ren, Deen Wang, Yang Ying, Xuewei Deng, Xin Zhang, Wei Zhou, Dongxia Hu, and Fang Wang
- Subjects
Total internal reflection ,Sum-frequency generation ,business.industry ,Energy conversion efficiency ,Boundary (topology) ,Space (mathematics) ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,010309 optics ,Optics ,Reflection (mathematics) ,0103 physical sciences ,High harmonic generation ,Electrical and Electronic Engineering ,business ,Transformation optics - Abstract
Collinear phase-matching of sum-frequency generation (SFG) has been studied thoroughly previously, while non-collinear schemes are sometimes more flexible in application. However, this phase-matching type is more difficult to meet and control. We employ a convenient method to obtain harmonic generation in bulk potassium dihydrogen phosphate (KDP), using an incident wave vector and a reflected wave vector to create a triangle phase-matching relationship. With a simple, flexible set-up, we can observe 351 nm SFG, and the conversion efficiency is up to ∼3.6% per reflection. Furthermore, we believe this approach has potential application value and improvement space.
- Published
- 2019
26. Optical zooming based on focusing grating in direct drive ICF
- Author
-
Wanjun Dai, Feng Jing, Xuewei Deng, Wei Zhou, Qiang Yuan, Xiaoxia Huang, Qihua Zhu, and Dongxia Hu
- Subjects
Wavefront ,Physics ,Distributed feedback laser ,business.industry ,Aperture ,Grating ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Collimated light ,010305 fluids & plasmas ,Wavelength ,Optics ,0103 physical sciences ,Optoelectronics ,010306 general physics ,business ,Inertial confinement fusion ,Diffraction grating - Abstract
In direct drive ICF, optical zooming is an effective way to mitigate cross-beam energy transfer and increase the hydrodynamic efficiency, by reducing the spot size of the laser beams while target compressing. In this paper, a novel optical zooming scheme is proposed, which employs a focusing grating to focus the broadband laser pulse, changing the spot size on the target within single beamlet. Experimentally, a focusing grating with clean aperture of 40-mm × 40-mm placed after the collimated light successfully realized the peak-valley of defocusing wavefront distribution of 0.73 µm as the wavelength ranging from 1052.43 nm to 1053.23 nm. Extended to the full-sized focusing grating with laser beam of 360-mm × 360-mm, it is derived that the focal spot reduction reaches to 21.8% with the 3rd harmonic light ranging from 350.81 nm to 351.08 nm, decreasing from 375 µm to 294 µm with 300 µm shaping continuous phase plate.
- Published
- 2016
27. Shannon entropy method of small-scale self-focusing assessment in high-power laser systems
- Author
-
Sheng Yang, Min Li, Wei Zhou, Junpu Zhao, Liu Rende, Dongxia Hu, Wanjun Dai, Wenyi Wang, Xuewei Deng, and Xiaoxia Huang
- Subjects
Computer science ,02 engineering and technology ,01 natural sciences ,Beam parameter product ,law.invention ,010309 optics ,Entropy (classical thermodynamics) ,Optics ,law ,0103 physical sciences ,Entropy (information theory) ,Laser power scaling ,Entropy (energy dispersal) ,Entropy (arrow of time) ,B Integral ,business.industry ,Entropy (statistical thermodynamics) ,Spectral density ,Self-focusing ,021001 nanoscience & nanotechnology ,Laser ,Atomic and Molecular Physics, and Optics ,Laser beam quality ,0210 nano-technology ,business ,Entropy (order and disorder) - Abstract
Through analysis of near-field beam profiles, we propose a method using Shannon entropy to assess the development of small-scale self-focusing during laser propagation and amplification in high-power laser systems. In this method, the entropy curve that corresponds to increasing B integral displays an evident turning point at which small-scale self-focusing starts to rapidly develop. In contrast to classical methods using contrast, modulation, or power spectral density, the proposed method provides the B integral criterion more clearly and objectively. This approach is an optimization method that can be utilized in the design and operation of high-power laser systems.
- Published
- 2016
28. Laser performance of the SG-III laser facility
- Author
-
Bin Feng, Xiaodong Yuan, Lanqin Liu, Qihua Zhu, Zhang Xiongjun, Jingqin Su, Yuanbin Chen, Xiaofeng Wei, Wanguo Zheng, Xudong Xie, Fang Wang, Dangpeng Xu, Xuewei Deng, Zhou Hai, Zhao Dang, Yong Xiang, Wei Zhou, Zhitao Peng, Wanjun Dai, Dongxia Hu, Donghui Lin, Kuixing Zheng, Feng Jing, and Liangfu Guo
- Subjects
Nuclear and High Energy Physics ,Materials science ,business.industry ,medicine.disease_cause ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010305 fluids & plasmas ,Electronic, Optical and Magnetic Materials ,law.invention ,Power (physics) ,010309 optics ,Optics ,Nuclear Energy and Engineering ,law ,Power Balance ,0103 physical sciences ,medicine ,business ,Inertial confinement fusion ,Ultraviolet ,Energy (signal processing) - Abstract
SG-III laser facility is now the largest laser driver for inertial confinement fusion research in China. The whole laser facility can deliver 180 kJ energy and 60 TW power ultraviolet laser onto target, with power balance better than 10%. We review the laser system and introduce the SG-III laser performance here.
- Published
- 2016
29. Research of time fiducial and imaging VISAR laser for Shenguang-III laser facility
- Author
-
Mingzhong Li, Zhenguo Wang, Wanguo Zheng, Dongxia Hu, Na Zhu, Qihua Zhu, Zhou Dandan, Feng Wang, Xiaocheng Tian, Jianjun Wang, Zhao Dang, Dangpeng Xu, and Rui Zhang
- Subjects
Distributed feedback laser ,Optical fiber ,Materials science ,business.industry ,Laser ,law.invention ,Optics ,Optical modulator ,law ,Ultrafast laser spectroscopy ,Laser power scaling ,Fiducial marker ,business ,Inertial confinement fusion - Abstract
Time fiducial laser is an important tool for the precise measurement in high energy density physics experiments. The VISAR probe laser is also vital for shock wave diagnostics in ICF experiments. Here, time fiducial laser and VISAR light were generated from one source on SG-III laser facility. After generated from a 1064-nm DFB laser, the laser is modulated by an amplitude modulator driven by 10 GS/s arbitrary waveform generator. Using time division multiplexing technology, the ten-pulse time fiducial laser and the 20-ns VISAR pulse were split by a 1×2 multiplexer and then chosen by two acoustic optic modulators. Using the technique, cost of the system was reduced. The technologies adopted in the system also include pulse polarization stabilization, high precision fiber coupling and energy transmission. The time fiducial laser generated synchronized 12-beam 2ω and 4-beam 3ω laser, providing important reference marks for different detectors and making it convenient for the analysis of diagnostic data. After being amplified by fiber amplifiers and Nd:YAG rod amplifiers, the VISAR laser pulse was frequency-converted to 532-nm pulse by a thermally controlled LBO crystal with final output energy larger than 20 mJ. Finally, the green light was coupled into a 1-mm core diameter, multimode fused silica optical fiber and propagated to the imaging VISAR. The VISAR laser has been used in the VISAR diagnostic physics experiments. Shock wave loading and slowdown processes were measured. Function to measure velocity history of shock wave front movement in different kinds of materials was added to the SG-III laser facility.
- Published
- 2015
30. Object-oriented wavefront correction in an asymmetric amplifying high-power laser system
- Author
-
Zhang Xiaolu, Wanjun Dai, Fa Zeng, Wang Shenzhen, Xin Zhang, Deen Wang, Yang Ying, Dongxia Hu, Qiao Xue, Yuan Qiang, Qihua Zhu, Wei Zhou, Wanguo Zheng, and Zhao Junpu
- Subjects
Wavefront ,Physics ,Object-oriented programming ,Physics and Astronomy (miscellaneous) ,business.industry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Power (physics) ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,0210 nano-technology ,business ,Instrumentation - Published
- 2018
31. FM-to-AM modulations induced by a weak residual reflection stack of sine-modulated pulses in inertial confinement fusion laser systems
- Author
-
Zhou Wei, Deng Wu, Dongxia Hu, Zhao Bowang, Wang Yuancheng, Wei Zhong, Deng Xuewei, Huaiwen Guo, and Huang Xiaoxia
- Subjects
Physics ,business.industry ,Condensed Matter Physics ,Residual ,Laser ,01 natural sciences ,Industrial and Manufacturing Engineering ,Atomic and Molecular Physics, and Optics ,law.invention ,010309 optics ,Optics ,Stack (abstract data type) ,law ,0103 physical sciences ,Reflection (physics) ,Sine ,010306 general physics ,business ,Instrumentation ,Inertial confinement fusion - Published
- 2018
32. Analysis and evaluation of idler absorption for quasi-parametric chirped-pulse amplification
- Author
-
Dongxia Hu, Jing Wang, Liejia Qian, Heyuan Zhu, Jingui Ma, and Yudong Tao
- Subjects
Chirped pulse amplification ,business.industry ,Laser ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,law ,Attenuation coefficient ,Electrical and Electronic Engineering ,business ,Absorption (electromagnetic radiation) ,Saturation (chemistry) ,Inertial confinement fusion ,Transformation optics ,Parametric statistics - Abstract
Quasi-parametric chirped-pulse amplification (QPCPA) can improve the signal amplification efficiency and stability by inhibiting the back-conversion, in which the idler absorption plays a critical role. This Letter theoretically studies the impacts of idler absorption on the QPCPA performance in both the small-signal and saturation regimes. We demonstrate that there exists an optimal idler absorption that enables the achievement of maximum pump depletion within a minimum crystal length. To overcome the reduction in small-signal gain induced by idler absorption, the configuration of gradient idler absorption is proposed and demonstrated as a superior alternative to constant idler absorption. The results provide guidelines to the design of state-of-the-art QPCPA lasers.
- Published
- 2018
33. Beam alignment based on two-dimensional power spectral density of a near-field image
- Author
-
Kehong Li, Qiang Yuan, Zhang Xiaolu, Yuanchen Wang, Dongxia Hu, Qihua Zhu, Qiao Xue, Junpu Zhao, Wanjun Dai, Fa Zeng, Wei Zhou, Jingqin Su, Yang Ying, Wang Shenzhen, Xin Zhang, and Kuixing Zheng
- Subjects
Physics ,Spatial filter ,business.industry ,Spectral density ,Near and far field ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010305 fluids & plasmas ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,Pinhole (optics) ,Fiducial marker ,business ,Inertial confinement fusion ,Beam (structure) - Abstract
Beam alignment is crucial to high-power laser facilities and is used to adjust the laser beams quickly and accurately to meet stringent requirements of pointing and centering. In this paper, a novel alignment method is presented, which employs data processing of the two-dimensional power spectral density (2D-PSD) for a near-field image and resolves the beam pointing error relative to the spatial filter pinhole directly. Combining this with a near-field fiducial mark, the operation of beam alignment is achieved. It is experimentally demonstrated that this scheme realizes a far-field alignment precision of approximately 3% of the pinhole size. This scheme adopts only one near-field camera to construct the alignment system, which provides a simple, efficient, and low-cost way to align lasers.
- Published
- 2017
34. Polarization smoothing for single beam by a nematic liquid crystal scrambler
- Author
-
Wang Yuancheng, Ying Zhang, Dongxia Hu, Wanguo Zheng, Xiaoxia Huang, Xuewei Deng, Rihong Zhu, and Fang Wang
- Subjects
Materials science ,business.industry ,Single beam ,02 engineering and technology ,Plasma ,021001 nanoscience & nanotechnology ,Polarization (waves) ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Scrambler ,law.invention ,010309 optics ,Optics ,Liquid crystal ,law ,0103 physical sciences ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Engineering (miscellaneous) ,Inertial confinement fusion ,Smoothing - Abstract
Polarization smoothing (PS) is a key approach to suppress laser plasma instabilities (LPI) in inertial confinement fusion (ICF) experiments. Here, we propose a liquid crystal (LC) PS element to realize single beam smoothing and demonstrate its smoothing effect, in principle, with a 2×2 LC polarization checkerboard, which reduces the laser intensity variation in the focal spot to 78.4%. LC PS elements, which have potential applications in high-power ICF laser drivers, have many advantages because they are easy to fabricate, cost effective, flexible, and large.
- Published
- 2017
35. Study on improving output capability of high-power lasers providing short pulses by using different laser glasses together in the amplifier chain
- Author
-
Feng Jing, Shengzhi Zhao, Dongxia Hu, Wang Wenyi, Jing Yang, Jingqin Su, and Xiaomin Zhang
- Subjects
Materials science ,High power lasers ,business.industry ,Amplifier ,Nonlinear refractive index ,Laser ,Growth ratio ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,Chain (algebraic topology) ,law ,Electrical and Electronic Engineering ,business ,Refractive index ,B Integral - Abstract
We have discussed the optical and laser properties of different laser glass types. According to the properties of the gain and the B integral in the high-power laser amplifier chain, an optimal configuration is pointed out to improve the output capability at short pulses based on reducing nonlinear refractive index n 2 . In this way, high gain glasses and low n 2 glasses are used in different amplifier stages simultaneously. The simulated results show that on the condition that the maximal output energies of both the configurations are same at 3 and 5 ns, the maximal output capability growth ratio of 30.48% ( n 2 = 0.25 × 1 0 - 13 esu ) and 42.24% ( n 2 = 0.3 × 1 0 - 13 esu ) for the optimal configuration can be obtained at 1 ns, respectively.
- Published
- 2007
36. Progress on the suppression of FM-to-AM modulations in SG-III laser facility
- Author
-
Zhang Xiaolu, Jianjun Wang, Dangpeng Xu, X. C. Tian, Zhou Dandan, Mingzhong Li, Dongxia Hu, Na Zhu, and Rui Zhang
- Subjects
Materials science ,business.industry ,Preamplifier ,Laser ,law.invention ,Amplitude modulation ,Optics ,law ,Fiber laser ,Laser power scaling ,business ,Frequency modulation ,Phase modulation ,Fabry–Pérot interferometer - Abstract
FM-to-AM modulations are harmful to output characteristics of large-scale laser facility. In SG-III laser facility, some key techniques have been employed to suppress FM-to-AM modulations. Firstly, phase modulator was arranged at the end of fiber laser injection system to avoid GVD and PMD in the SM fiber system. Secondly, a fiber-based polarization rotated filter was proposed to suppress FM-to-AM modulations independently on each beam. Finally, less wave plates were employed and liquid crystal modulators were coated for decreasing weak etalon effect in preamplifier system. The results indicated that it can reduce the modulation depth less than 10% at a modulation frequency of 2.488GHz in SG-III laser facility.
- Published
- 2015
37. Research of beam smoothing technologies using CPP, SSD, and PS
- Author
-
Wei Zhou, Jun Dong, Xiaocheng Tian, Hao-yu Yuan, Qihua Zhu, Dongxia Hu, Wang Yuancheng, Dangpeng Xu, Jingqin Su, Ping Li, Qiang Yuan, and Rui Zhang
- Subjects
Continuous phase modulation ,Birefringence ,Materials science ,business.industry ,Near and far field ,Polarization (waves) ,Laser ,law.invention ,Transverse plane ,Optics ,law ,business ,Inertial confinement fusion ,Smoothing - Abstract
Precise physical experiments place strict requirements on target illumination uniformity in Inertial Confinement Fusion. To obtain a smoother focal spot and suppress transverse SBS in large aperture optics, Multi-FM smoothing by spectral dispersion (SSD) was studied combined with continuous phase plate (CPP) and polarization smoothing (PS). New ways of PS are being developed to improve the laser irradiation uniformity and solve LPI problems in indirect-drive laser fusion. The near field and far field properties of beams using polarization smoothing were studied and compared, including birefringent wedge and polarization control array. As more parameters can be manipulated in a combined beam smoothing scheme, quad beam smoothing was also studies. Simulation results indicate through adjusting dispersion directions of one-dimensional (1-D) SSD beams in a quad, two-dimensional SSD can be obtained. Experiments have been done on SG-III laser facility using CPP and Multi-FM SSD. The research provides some theoretical and experimental basis for the application of CPP, SSD and PS on high-power laser facilities.
- Published
- 2015
38. High-accuracy arithmetic for cavity mirror automatic alignment in multi-pass beam system
- Author
-
Wei Zhou, Xuewei Deng, Wu Deng, Deen Wang, Qiang Yuan, Xingquan Xie, Wanjun Dai, Dongxia Hu, Xin Zhang, and Wang Yuancheng
- Subjects
Diffraction ,business.industry ,Image quality ,Image processing ,Laser ,Symmetry (physics) ,law.invention ,Power (physics) ,Optics ,law ,Path (graph theory) ,Physics::Accelerator Physics ,Arithmetic ,business ,Beam (structure) ,Mathematics - Abstract
Beam alignment of multi-pass amplification is based on cavity mirror alignment. To optimize multi-segmental parallel cavity mirror alignment arithmetic of high power solid-state lasers, propose a new type of arithmetic of multi-pass beam path cavity mirror based on diffraction symmetry, and the accuracy of multi-pass amplification beam path alignment is improved by 10μrad up to 3.96μrad. The arithmetic avoids low accuracy of CM alignment caused by poor image quality, It makes SG-Ⅲ facility operate long term and properly.
- Published
- 2015
39. The entire beam wavefront control of high power laser facility
- Author
-
Qiang Yuan, Deen Wang, Wang Yuancheng, Wu Deng, Xuewei Deng, Xin Zhang, Wanjun Dai, Qihua Zhu, Feng Jing, Dongxia Hu, Yang Ying, and Wei Zhou
- Subjects
Wavefront ,Physics ,business.industry ,Irradiance ,Wavefront sensor ,Laser ,Deformable mirror ,law.invention ,Optics ,Beamline ,law ,Adaptive optics ,business ,Beam (structure) - Abstract
Experiment of entire beam wavefront compensation was carried out in a beamline of a high power laser facility, and two adaptive optics systems with different intentions were applied in the chosen beamline. After correction, the far-filed irradiance distribution is concentrated evidently and the entrance rate of 3ω focal spot to a 500-μm hole is improved to be about 95% under number kilojoules energy.
- Published
- 2015
40. Process-oriented adaptive optics control method in the multi-pass amplifiers
- Author
-
Yang Ying, Gao Song, Qiao Xue, Qihua Zhu, Qiang Yuan, Zhang Xiaolu, Deen Wang, Xin Zhang, Wanjun Dai, Dongxia Hu, Yao Ke, Kuixing Zheng, Xie Xudong, Fa Zeng, and Junpu Zhao
- Subjects
Wavefront ,business.industry ,Computer science ,Amplifier ,Process (computing) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Deformable mirror ,010309 optics ,Optics ,Quality (physics) ,0103 physical sciences ,Electronic engineering ,Laser beam quality ,0210 nano-technology ,Adaptive optics ,business ,Beam (structure) - Abstract
In this talk, we propose and demonstrate the process-oriented adaptive optics (AO) wavefront control method, for optimizing the beam quality in the multi-pass amplifiers. Different from the conventional target-oriented wavefront control approach, the novel method divides the aberration correction process into several steps, to optimize the wavefront quality in time during the courses of the beam's transport and amplification. The experimental results show that the proposed method can effectively prevent the beam quality from worsening and ensure the successful reality of multi-pass amplification, so it has obvious advantages both in efficiency and accuracy over the traditional target-oriented method.
- Published
- 2017
41. Theoretical investigations of broadband mid-infrared optical parametric amplification based on a La_3Ga_55Nb_05O_14 crystal
- Author
-
Haohai Yu, Dongxia Hu, Heyuan Zhu, Liejia Qian, Jiyang Wang, Guoqiang Xie, Huaijin Zhang, Peng Yuan, Jing Wang, and Jingui Ma
- Subjects
Materials science ,Uniaxial crystal ,business.industry ,Amplifier ,Bandwidth (signal processing) ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Optical parametric amplifier ,Atomic and Molecular Physics, and Optics ,010309 optics ,Crystal ,Wavelength ,Optics ,0103 physical sciences ,Broadband ,0210 nano-technology ,business ,Astrophysics::Galaxy Astrophysics ,Parametric statistics - Abstract
Recent progress in strong-field physics has stimulated the quest for intense mid-infrared ultrashort light sources. Optical parametric amplification (OPA) is one promising method to build up such sources, however, its development significantly relies on the availability of suitable nonlinear crystals. Here, we introduce a positive uniaxial crystal La3Ga5.5Nb0.5O14 (LGN), which exhibits a favorable set of optical properties for the application in a mid-IR OPA. We theoretically evaluate the performance of LGN as the nonlinear crystal of a mid-infrared OPA, with an emphasis on the bandwidth characteristic. We find that this crystal can support broadband amplifications across its entire mid-infrared transparent region up to 6 μm, outperforming other commonly-used mid-infrared crystals in terms of gain bandwidth. Few-cycle mid-infrared pulses at various wavelengths can be generated from the LGN-based optical parametric chirped-pulse amplifiers.
- Published
- 2016
42. Research and construction progress of the SG-III laser facility
- Author
-
Lanqin Liu, Liangfu Guo, Wei Zhou, Dongxia Hu, Xuewei Deng, Donghui Lin, Yuanbin Chen, Qihua Zhu, Wanguo Zheng, Zhao Dang, Ding Lei, Bing Feng, Xiaofeng Wei, Zhitao Peng, Jianjun Wang, and Feng Jing
- Subjects
business.industry ,law ,Bundle ,Pulse duration ,Nanotechnology ,Aerospace engineering ,business ,Diagnostic system ,Laser ,Inertial confinement fusion ,Energy (signal processing) ,Beam (structure) ,law.invention - Abstract
The under-construction SG-III laser facility is a huge high power solid laser driver, which contains 48 beams and is designed to deliver 180kJ energy at 3ns pulse duration. The testing ending up at September 2012 validated that the first bundle lasers of SG-III facility had achieved all the designed requirements. And shortly later in December 2012, the first round of running-in physics experiment provided a preliminary X-ray diagnostic result. In the testing experiment, detailed analysis of the laser energy, the temporal characteristics, the spatial distribution and the focusing performance was made by using the Beam Integrated Diagnostic System. The 25kJ 3ω energy produced by the first bundle lasers created the new domestic record in China. These great progresses in the laser performance and the physics experiment have already demonstrated that the facility is in excellent accordance with the designs, which establish a solid foundation for completing all the construction goals.
- Published
- 2013
43. Optical limiting characteristics of zinc phthalocyanine
- Author
-
Kun Cheng, Feng Jing, Dongxia Hu, Xiaomin Zhang, Kun Zhang, Wu Deng, Xin Zhang, Wanjun Dai, Jiang Xuejun, Junpu Zhao, and Wei Zhou
- Subjects
Zinc phthalocyanine ,Materials science ,business.industry ,Reverse saturable absorption ,Physics::Optics ,Nonlinear optics ,Light scattering ,chemistry.chemical_compound ,chemistry ,Optical limiter ,Optical limiting ,Optoelectronics ,Dimethylformamide ,Absorption (electromagnetic radiation) ,business - Abstract
In this paper, it is the first time to experimentally demonstrate the dependence of optical limiting performance of zinc phthalocyanine (ZnPc) dimethylformamide (DMF) solution on concentration and optical length. The optical limiting characteristics are measured at various concentrations and optical lengths. By employing a reverse saturable absorption (RSA) equation, the physical mechanism of such optical limiting is interpreted, leading to excellent agreement with the experimental results. The obtained results imply that the optical limiting effects are quite sensitive to both concentration and optical length, giving parameter guidance for designing optical limiter in practice.
- Published
- 2011
44. Optimum Design of Spatial Filter Pinhole in High Power Solid Laser System
- Author
-
Xin Zhang, Junpu Zhao, Dongxia Hu, Xuejun Jiang, Wu Deng, Wanjun Dai, Wei Zhou, and Kun Zhang
- Subjects
Spatial filter ,business.industry ,Computer science ,Material Design ,Laser ,Power (physics) ,law.invention ,Optics ,Filter (video) ,law ,Pinhole (optics) ,Laser beam quality ,Optical filter ,business - Abstract
Spatial filter is the key unit of high power solid laser system for nonlinear increase control. However, the plasma closure occurred in pinhole is easily happened when long pulse running which may reduce the beam quality. The optimum design of pinhole will meet the needs for long pulse running which is important for spatial filter application. This paper based the key problems, such as suppression of nonlinear growth and plasma closure, discussed the optimum design in three aspects: filter size design, geometry design and the material design. Provide the reasonable principle for pinhole design.
- Published
- 2011
45. Application of Cavity Deformable Mirror in PW Facility with U-Turn Reverser
- Author
-
Kun Zhang, Dongxia Hu, Xuejun Jiang, Wanjun Dai, Wu Deng, Xin Zhang, Wei Zhou, and Feng Jing
- Subjects
Physics ,Optical amplifier ,business.industry ,Amplifier ,Physics::Optics ,Rotation ,Laser ,Deformable mirror ,law.invention ,Optics ,law ,Physics::Accelerator Physics ,Stimulated emission ,business ,Adaptive optics ,Beam (structure) - Abstract
For beam passing through cavity mirror twice in multi-pass amplifier laser facility, deformable mirror is often applied at location of cavity mirror for the goal of improving correction range. However, multi-pass amplifier with U-turn for improving optical quality has its own feature different from other facilities. Beam has 90° rotation and size change between 1~2 pass and 3~4 pass propagation. A new mathematical method is described to prove the solution existence of cavity deformable mirror and the application of cavity deformable mirror is verified in XG-PW facility with U-turn reverser. The results are important for the adaptive optics system design of succeeding large-scale laser facility.
- Published
- 2011
46. Far field irradiance profile control with high spatial frequency deformable mirror
- Author
-
Xiaoqun Li, Junpu Zhao, Dongxia Hu, Yuan Qiang, Dai Wanjun, Feng Jing, Deen Wang, and Ping Li
- Subjects
Physics ,Optics ,Aperture ,business.industry ,Phase (waves) ,Near and far field ,Spatial frequency ,business ,Adaptive optics ,Image resolution ,Coupling coefficient of resonators ,Deformable mirror - Abstract
A novel method based on diffraction theory to control the far-field irradiance profile by deformable mirror is presented. Special near-field phase which determines the contour of the focal spot is obtained by a high spatial frequency deformable mirror. Numerical simulations show that, we can control the far-field intensity envelope as CPP by adopting adaptive optics technique when the spatial resolution of deformable mirror is high enough, here 16×16 actuators in 320mm×320mm aperture. The coupling coefficient is an important factor influencing control effect, and its best value range is round 0.6.
- Published
- 2010
47. Beam wavefront and farfield control for ICF laser driver
- Author
-
Dongxia Hu, Wu Deng, Wanjun Dai, Xuejun Jiang, Xin Zhang, Kun Zhang, Junpu Zhao, and Wei Zhou
- Subjects
Wavefront ,Engineering ,Optics ,Wave propagation ,business.industry ,law ,Control (management) ,Systems design ,Divergence angle ,business ,Laser ,Beam (structure) ,law.invention - Abstract
Five main problems of beam wavefront and farfield control in ICF laser driver are synthetically discussed, including control requirements, beam propagation principle, distortions source control, system design and adjustment optimization, active wavefront correction technology. We demonstrate that beam can be propagated well and the divergence angle of the TIL pulses can be improved to less than 60μrad with solving these problems, which meets the requirements of TIL. The results can provide theoretical and experimental support for wavefront and farfield control designing requirements of the next large scale ICF driver.
- Published
- 2010
48. Effect of Transmitted Wavefront Error of Large Aperture Nd-glass Slab by Two Polishing Process on Beam Quality
- Author
-
Wenyi Wang, Dongxia Hu, Jingqin Su, Zhou Hai, Zhitao Peng, Xiaofeng Wei, Fang Wang, Runchang Zhao, Haiwu Yu, Feng Jing, Fuquan Li, Lanqin Liu, Xiaomin Zhang, and Dong Yang
- Subjects
Wavefront ,Materials science ,business.industry ,Astrophysics::Instrumentation and Methods for Astrophysics ,Physics::Optics ,Mathematics::General Topology ,Polishing ,Nonlinear optics ,Mathematics::Logic ,Optics ,Modulation ,Slab ,Physics::Accelerator Physics ,Laser beam quality ,Adaptive optics ,business ,Frequency modulation - Abstract
Numerical modeling and experiment research for quantitative analysis of beam quality influenced by transmitted wavefront errors of large aperture Nd-glass slabs by conventional polishing and computer-controlled polishing processes were performed.
- Published
- 2007
49. Online determination of the source of stray light in the SG-III high-power laser facility
- Author
-
Dandan Zhou, Dongxia Hu, Yuanchen Wang, Wei Zhou, Huaiting Jia, Fan Zhang, Wei Zhong, Xuewei Deng, and Huaiwen Guo
- Subjects
Physics ,business.industry ,Stray light ,Amplifier ,Laser ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Power (physics) ,Optical path ,Optics ,law ,Optoelectronics ,Electrical and Electronic Engineering ,business - Abstract
Stray light in high-power laser facilities not only decreases the gain capacity of the main amplifier, but can also cause permanent damage to optical components, greatly threatening the safety operation of the SG-III. This Letter reports a technique for quickly pinpointing the source of stray light in the main amplification optical path of the SG-III. The achieved results indicate that the accuracy of our method is up to 1 m in an optical path of 100 m. The judging method is effective for examining and removing harmful stray light in the SG-III laser facility and it can be promoted in huge laser facilities of this kind.
- Published
- 2015
50. The code SG99 for high-power laser propagation and its applications
- Author
-
Jingqin Su, Feng Jing, Wang Wenyi, Xiaofeng Wei, Xiaomin Zhang, Xiaofeng Cheng, Jing Yuan, Zhitao Peng, Lianqin Liu, Dongxia Hu, and Qingquan Zhang
- Subjects
Physical model ,Computer simulation ,Computer science ,business.industry ,Laser ,law.invention ,Pulse (physics) ,Power (physics) ,Optics ,law ,Line (geometry) ,Code (cryptography) ,Electronic engineering ,Laser power scaling ,business - Abstract
In this paper, the physical models of the code SG99, which is used to simulate the pulse behavior in high power laser system, are presented in details. The experimental results are also presented to show that SG99 is capable of simulating pulse propagation well and yields reasonable results. In the last, some results in design of TIL(Technical Integrated Experiment Line), the prototype of ShenGuangIII, are also introduced.
- Published
- 2005
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