• Special Issue
  • Focus on National Laboratory of High Power Laser and Physics, SIOM
  • 14 Article (s)
Optimizing the cleanliness in multi-segment disk amplifiers based on vector flow schemes|On the Cover
Zhiyuan Ren, Jianqiang Zhu, Zhigang Liu, and Xiaowei Yang
The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II (SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation of contaminant particles, is a key factor affecting the cleanliness level in the multi-segment disk amplifier. We developed a gas–solid coupling and three-dimensional flow numerical simulation model. The three-dimensional and two-phase flow model is verified by the flow-field smog experiment and the particle concentration measurement experiment with the 130-disk amplifier in SG-II. By optimizing the boundary conditions with the same flow rate, the multi-inlet vector flow scheme can not only effectively reduce the purging time, but also prevent the reverse diffusion of contaminant particles in the multi-segment disk amplifier and the deposition of contaminant particles on the surface of the Nd:glass.
High Power Laser Science and Engineering
  • Publication Date: Jan. 24, 2018
  • Vol.6 Issue, 1 010000e1 (2018)
Directly writing binary multi-sector phase plates on fused silica using femtosecond laser
Li Zhou, Youen Jiang, Peng Zhang, Wei Fan, and Xuechun Li
Light carrying orbital angular momentum (OAM) has a spatial distribution of intensity and phase, which attracts considerable interest regarding several potential applications in optical and quantum scenarios recently. Spiral phase plates are commonly used elements for generating and analyzing OAM states. In this study, we put forward a method of directly writing binary multi-sector phase plates using the femtosecond laser. These phase plates are engraved on fused silica, which could be applied in high-intensity regimes. Different binary multi-sector phase plates were generated with high quality, which were proved by the observation of their structures, accompanied by detecting the beam patterns with the Gaussian beams. The proposed method provides a crucial basis for the rapid manufacturing of phase plates using convenient equipment, which can generate the superposition OAM states and may lead to the capability of measuring the high-dimensional entanglement.
High Power Laser Science and Engineering
  • Publication Date: Mar. 05, 2018
  • Vol.6 Issue, 1 010000e6 (2018)
Systematic study of spatiotemporal influences on temporal contrast in the focal region in large-aperture broadband ultrashort petawatt lasers
Ping Zhu, Xinglong Xie, Jun Kang, Qingwei Yang, Haidong Zhu, Ailin Guo, Meizhi Sun, Qi Gao, Ziruo Cui, Xiao Liang, Shunhua Yang, Dongjun Zhang, and Jianqiang Zhu
Temporal contrast is one of the crucial physical determinants which guarantee the successful performance of laser–matter interaction experiments. We generally reviewed the influences on the temporal contrast in three categories of noises based on the requirement by the physical mechanisms. The spatiotemporal influences on temporal contrast at the focal region of the chromatic aberration and propagation time difference introduced by large-aperture broadband spatial filters, which were spatiotemporally coupled with compression and focusing, were calculated and discussed with a practical case in SG-II 5 PW ultrashort petawatt laser. The system-wide spatiotemporal coupling existing in large-aperture broadband ultrashort petawatt lasers was proved to be one of the possible causes of temporal contrast degradation in the focal region.
High Power Laser Science and Engineering
  • Publication Date: Mar. 19, 2018
  • Vol.6 Issue, 1 010000e8 (2018)
Target alignment in the Shen-Guang II Upgrade laser facility
Lei Ren, Ping Shao, Dongfeng Zhao, Yang Zhou, Zhijian Cai, Neng Hua, Zhaoyang Jiao, Lan Xia, Zhanfeng Qiao, Rong Wu, Lailin Ji, Dong Liu, Lingjie Ju, Wei Pan, Qiang Li, Qiang Ye, Mingying Sun, Jianqiang Zhu, and Zunqi Lin
The Shen-Guang II Upgrade (SG-II-U) laser facility consists of eight high-power nanosecond laser beams and one short-pulse picosecond petawatt laser. It is designed for the study of inertial confinement fusion (ICF), especially for conducting fast ignition (FI) research in China and other basic science experiments. To perform FI successfully with hohlraum targets containing a golden cone, the long-pulse beam and cylindrical hohlraum as well as the short-pulse beam and cone target alignment must satisfy tight specifications (30 and $20~\unicode[STIX]{x03BC}\text{m}$ rms for each case). To explore new ICF ignition targets with six laser entrance holes (LEHs), a rotation sensor was adapted to meet the requirements of a three-dimensional target and correct beam alignment. In this paper, the strategy for aligning the nanosecond beam based on target alignment sensor (TAS) is introduced and improved to meet requirements of the picosecond lasers and the new six LEHs hohlraum targets in the SG-II-U facility. The expected performance of the alignment system is presented, and the alignment error is also discussed.
High Power Laser Science and Engineering
  • Publication Date: Mar. 19, 2018
  • Vol.6 Issue, 1 01000e10 (2018)
Review of special issue on high power facility and technical development at the NLHPLP
Jianqiang Zhu
Achieving ignition of ICF (inertial confinement fusion) has been the great dream that scientists all over the world pursue. As a grand challenge, this aim requires energetic and high quality lasers. High power laser facilities, for this purpose, have therefore flourished over the past several decades. Meanwhile high power laser facilities, also essential for high-energy-density (HED) scientific research and astrophysics, drive rapid progress of material science, electronics, precision machinery and so on. Many countries have successfully established a succession of facilities to study ICF and HED physics, such as National Ignition Facility (NIF)[1] in the United States and the Laser Megajoule (LMJ) in France[2]. China, conducted such research activities early, as one of the few countries having the capability of developing high power facilities independently. As the major pioneer dedicated to high power laser technology and ICF research in China, the National Laboratory on High Power Laser and Physics (NLHPLP) and its precursor have established a succession of facilities since 1973. In 1986 NLHPLP was formally established at Shanghai Institute of Optics and Fine Mechanics; this opened up a new era of laser fusion research in China. Since then the facilities at NLHPLP entered into ‘Shen Guang’ families. Since the SG-I facility dismantled in 1994, NLHPLP has successively constructed SG-II laser facility, SG-II 9th beam, SG-II upgrade (SG-II UP) facility, and SG-II 5PW facility. These operational facilities constitute a multifunctional experimental platform, which provide important experimental capabilities by combining different pulse widths of nanosecond, picosecond and femtosecond scales. SG-II facility, greatly promoting Chinese ICF research, has had a stable and excellent operation for approximately 20 years. A newly built SG-II UP facility, consisting of a single petawatt picosecond system with kJ-class output and eight-beam nanosecond capability with multi-pass amplifier configuration, has achieved the required outputs. This facility marks a major step of increasing capability of designing and constructing high power facilities. In addition, SG-II 5 PW facility is already operational for physical experiments. Construction of these facilities has driven the fabrication and processing of large optical components. Furthermore, many advanced technologies have been developed that ensured good performance of these systems. Apparently with operations spanning 30 years, NLHPLP is an important scientific research base on high power laser scientific research in China.
High Power Laser Science and Engineering
  • Publication Date: Feb. 22, 2019
  • Vol.7 Issue, 1 01000e12 (2019)
Design and performance of final optics assembly in SG-II Upgrade laser facility
Zhaoyang Jiao, Ping Shao, Dongfeng Zhao, Rong Wu, Lailin Ji, Li Wang, Lan Xia, Dong Liu, Yang Zhou, Lingjie Ju, Zhijian Cai, Qiang Ye, Zhanfeng Qiao, Neng Hua, Qiang Li, Wei Pan, Lei Ren, Mingying Sun, Jianqiang Zhu, and Zunqi Lin
In high power laser facility for inertial confinement fusion research, final optics assembly (FOA) plays a critical role in the frequency conversion, beam focusing, color separation, beam sampling and debris shielding. The design and performance of FOA in SG-II Upgrade laser facility are mainly introduced here. Due to the limited space and short focal length, a coaxial aspheric wedged focus lens is designed and applied in the FOA configuration. Then the ghost image analysis, the focus characteristic analysis, the B integral control design and the optomechanical design are carried out in the FOA design phase. In order to ensure the FOA performance, two key technologies are developed including measurement and adjustment technique of the wedged focus lens and the stray light management technique based on ground glass. Experimental results show that the design specifications including laser fluence, frequency conversion efficiency and perforation efficiency of the focus spot have been achieved, which meet the requirements of physical experiments well.
High Power Laser Science and Engineering
  • Publication Date: Apr. 19, 2018
  • Vol.6 Issue, 2 02000e14 (2018)
LD-pumped gas-cooled multislab Nd:glass laser amplification to joule level
Wenfa Huang, Jiangfeng Wang, Xinghua Lu, Tingrui Huang, Jiangtao Guo, Wei Fan, and Xuechun Li
High Power Laser Science and Engineering
  • Publication Date: Apr. 22, 2018
  • Vol.6 Issue, 2 02000e15 (2018)
Wavefront control of laser beam using optically addressed liquid crystal modulator
Dajie Huang, Wei Fan, He Cheng, Gang Xia, Lili Pei, Xuechun Li, and Zunqi Lin
An optically addressed liquid crystal modulator for wavefront control of 1053 nm laser beam is reported in this paper. Its working principle, control method and spatial phase modulation capability are mainly introduced. A new method of measuring the relationship between gray level and phase retardation is proposed. The rationality of the curve is further confirmed by designing special experiments. According to the curve, several spatial phase distributions have been realized by this home-made device. The results show that, not only the maximum phase retardation is larger than for 1053 nm wavelength, but also the control accuracy is high. Compared with the liquid crystal on silicon type spatial light modulator, this kind of modulator has the advantages of generating smooth phase distribution and avoiding the black-matrix effect.
High Power Laser Science and Engineering
  • Publication Date: May. 18, 2018
  • Vol.6 Issue, 2 02000e20 (2018)