• Special Issue
  • High Energy Density Physics and High Power Laser 2016
  • 21 Article (s)
Research and development of new neodymium laser glasses
Dongbing He, Shuai Kang, Liyan Zhang, Lin Chen, Yajun Ding, Qianwen Yin, and LiLi Hu
This work presents a brief introduction on three kinds of newly developed $\text{Nd}^{3+}$-doped laser glasses in Shanghai Institute of Optics and Fine Mechanics (SIOM), China. Two $\text{Nd}^{3+}$-doped phosphate glasses with lower thermal expansion coefficient and thermal shock resistance 4 times higher than that of N31 glass are developed for laser processing. Nd:Silicate and Nd:Aluminate glasses with peak emission wavelength at 1061 and 1065 nm, effective emission bandwidth of 34 and 50 nm, respectively, are developed for Exawatt-class laser system application. Fluorophosphate glasses with low nonlinear refractive index ($n_{2}=0.6{-}0.86$) and long fluorescence lifetime ($430{-}510~\unicode[STIX]{x03BC}\text{s}$) are investigated for the purpose of decreasing B integral in high-power laser system. The properties of all these glasses are presented and compared with those of commercial neodymium laser glasses.
High Power Laser Science and Engineering
  • Publication Date: Jan. 09, 2017
  • Vol.5 Issue, 1 010000e1 (2017)
Ultrashort pulse capability at the L2I high intensity laser facility
Gonçalo Figueira, Joana Alves, João M. Dias, Marta Fajardo, Nuno Gomes, Victor Hariton, Tayyab Imran, Celso P. João, Jayanath Koliyadu, Swen Künzel, Nelson C. Lopes, Hugo Pires, Filipe Ruão, and Gareth Williams
High Power Laser Science and Engineering
  • Publication Date: Jan. 26, 2017
  • Vol.5 Issue, 1 010000e2 (2017)
Proton probing of laser-driven EM pulses travelling in helical coils|On the Cover
H. Ahmed, S. Kar, A.L. Giesecke, D. Doria, G. Nersisyan, O. Willi, C.L.S. Lewis, and M. Borghesi
The ultrafast charge dynamics following the interaction of an ultra-intense laser pulse with a foil target leads to the launch of an ultra-short, intense electromagnetic (EM) pulse along a wire connected to the target. Due to the strong electric field (of the order of $\text{GV m}^{-1}$) associated to such laser-driven EM pulses, these can be exploited in a travelling-wave helical geometry for controlling and optimizing the parameters of laser accelerated proton beams. The propagation of the EM pulse along a helical path was studied by employing a proton probing technique. The pulse-carrying coil was probed along two orthogonal directions, transverse and parallel to the coil axis. The temporal profile of the pulse obtained from the transverse probing of the coil is in agreement with the previous measurements obtained in a planar geometry. The data obtained from the longitudinal probing of the coil shows a clear evidence of an energy dependent reduction of the proton beam divergence, which underpins the mechanism behind selective guiding of laser-driven ions by the helical coil targets.
High Power Laser Science and Engineering
  • Publication Date: Feb. 13, 2017
  • Vol.5 Issue, 1 010000e4 (2017)
Raman–Brillouin interplay for inertial confinement fusion relevant laser–plasma interaction
C. Riconda, and S. Weber
The co-existence of the Raman and Brillouin backscattering instability is an important issue for inertial confinement fusion. The present paper presents extensive one-dimensional (1D) particle-in-cell (PIC) simulations for a wide range of parameters extending and complementing previous findings. PIC simulations show that the scenario of reflectivity evolution and saturation is very sensitive to the temperatures, intensities, size of plasma and boundary conditions employed. The Langmuir decay instability is observed for rather small $k_{epw}{\it\lambda}_{D}$ but has no influence on the saturation of Brillouin backscattering, although there is a clear correlation of Langmuir decay instability modes and ion-fractional decay for certain parameter ranges. Raman backscattering appears at any intensity and temperature but is only a transient phenomenon. In several configurations forward as well as backward Raman scattering is observed. For the intensities considered, $I{\it\lambda}_{o}^{2}$ above $10^{15}~\text{W}~{\rm\mu}\text{m}^{2}/\text{cm}^{2}$, Raman is always of bursty nature. A particular setup allows the simulation of multi-speckle aspects in which case it is found that Raman is self-limiting due to strong modifications of the distribution function. Kinetic effects are of prime importance for Raman backscattering at high temperatures. No unique scenario for the saturation of Raman scattering or Raman–Brillouin competition does exist. The main effect in the considered parameter range is pump depletion because of large Brillouin backscattering. However, in the low $k_{epw}{\it\lambda}_{D}$ regime the presence of ion-acoustic waves due to the Langmuir decay instability from the Raman created electron plasma waves can seed the ion-fractional decay and affect the Brillouin saturation.
High Power Laser Science and Engineering
  • Publication Date: Jul. 27, 2016
  • Vol.4 Issue, 3 03000e23 (2016)
Generation of high-quality electron beams by ionization injection in a single acceleration stage
Nasr A.M. Hafz, Song Li, Guangyu Li, Mohammad Mirzaie, Ming Zeng, and Jie Zhang
Ionization-induced electron injection in laser wakefield accelerators, which was recently proposed to lower the laser intensity threshold for electron trapping into the wake wave, has the drawback of generating electron beams with large and continuous energy spreads, severely limiting their future applications. Complex target designs based on separating the electron trapping and acceleration stages were proposed as the only way for getting small energy-spread electron beams. Here, based on the self-truncated ionization-injection concept which requires the use of unmatched laser–plasma parameters and by using tens of TW laser pulses focused onto a gas jet of helium mixed with low concentrations of nitrogen, we demonstrate single-stage laser wakefield acceleration of multi-hundred MeV electron bunches with energy spreads of a few percent. The experimental results are verified by PIC simulations.
High Power Laser Science and Engineering
  • Publication Date: Aug. 02, 2016
  • Vol.4 Issue, 3 03000e24 (2016)
Laboratory astrophysics with laser-driven strong magnetic fields in China
Fei-Lu Wang, Xiao-Xing Pei, Bo Han, Hui-Gang Wei, Da-Wei Yuan, Gui-Yun Liang, Gang Zhao, Jia-Yong Zhong, Zhe Zhang, Bao-Jun Zhu, Yan-Fei Li, Fang Li, Yu-Tong Li, Si-Liang Zeng, Shi-Yang Zou, and Jie Zhang
High Power Laser Science and Engineering
  • Publication Date: Aug. 05, 2016
  • Vol.4 Issue, 3 03000e27 (2016)
Study and design of cladding power stripper for high power fiber laser systems
Haixia An, Xiaogang Liu, and Zhiyue Bi
Heat handling has been a significant problem of the high power fiber laser systems as the output power increases rapidly. Cladding power stripper (CPS) which is used to deal with the unwanted optical power and light is required for higher cooling ability. So the methods of stripping the unwanted light attracted much attention recently, and the thermal effect is given. However, few investigations focus on the dissipation of the heat converted from the unwanted light. In this paper,an approach of active cooling for CPS is demonstrated. This is achieved by using microchannel cooling technology in heat sinking in CPS to improve the efficiency of heat exchange. In order to explain the mechanism of CPS the function of it and consistence of categories of the unwanted light are detailed firstly. Then microchannel heat sinking is proposed and verified by the heat exchange theory. At last, the design of the CPS with microchannel heat sinking is shown and following experiment is conducted. The final temperature of the device with 1000 W cladding power was demonstrated at last to verify the ability of heat distribution of the CPS component. This suggests that these CPSs can be used to stripe a thousand of watts of light in high power double cladding fiber lasers.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.4 Issue, 3 03000e28 (2016)
Short-pulse laser-driven x-ray radiography
E. Brambrink, S. Baton, M. Koenig, R. Yurchak, N. Bidaut, B. Albertazzi, J. E. Cross, G. Gregori, A. Rigby, E. Falize, A. Pelka, F. Kroll, S. Pikuz, Y. Sakawa, N. Ozaki, C. Kuranz, M. Manuel, C. Li, P. Tzeferacos, and D. Lamb
High Power Laser Science and Engineering
  • Publication Date: Sep. 21, 2016
  • Vol.4 Issue, 3 03000e30 (2016)
Review of fiber superluminescent pulse amplifications
Haitao Zhang, Xinglai Shen, He Hao, Qinghua Li, and Mali Gong
High coherence of the laser is indispensable light sources in modern long or short-distance imaging systems, because the high coherence leads to coherent artifacts such as speckle that corrupt image formation. To deliver low coherence pulses in fiber amplifiers, we utilize the superluminescent pulsed light with broad bandwidth, nonlongitudinal mode structure and chaotic mode phase as the seed source of the cascaded fiber amplifiers. The influence of fiber superluminescent pulse amplification (SPA) on the limitations of the performance is analyzed. A review of our research results for SPA in the fibers are present, including the nonlinear theories of this low coherent light sources, i.e., self-focusing (SF), stimulated Raman scattering (SRS) and self-phase modulation (SPM) effects, and the experiment results of the nanosecond pulses with peak power as high as 4.8 MW and pulse energy as much as 55 mJ. To improve the brightness of SPA light in the future work, we introduce our novel evaluation term and a more reasonable criterion, which is denoted by a new parameter of brightness factor for active large mode area fiber designs. A core-doped active large pitch fiber with a core diameter of $190~\unicode[STIX]{x03BC}\text{m}$ and a mode-field diameter of $180~\unicode[STIX]{x03BC}\text{m}$ is designed by this method. The designed fiber allows near diffracted limited beam quality operation, and it can achieve 100 mJ pulse energy and 540 W average power by analyzing the mode coupling effects induced by heat.
High Power Laser Science and Engineering
  • Publication Date: Sep. 27, 2016
  • Vol.4 Issue, 3 03000e31 (2016)