• Special Issue
  • High Intensity Laser and Attosecond
  • 12 Article (s)
Attosecond twisted beams from high-order harmonic generation driven by optical vortices
Carlos Hernández-García, Laura Rego, Julio San Román, Antonio Picón, and Luis Plaja
Optical vortices are structures of the electromagnetic field with a spiral phase ramp about a point-phase singularity, carrying orbital angular momentum (OAM). Recently, OAM has been imprinted to short-wavelength radiation through high-order harmonic generation (HHG), leading to the emission of attosecond twisted beams in the extreme-ultraviolet (XUV) regime. We explore the details of the mapping of the driving vortex to its harmonic spectrum. In particular, we show that the geometry of the harmonic vortices is convoluted, arising from the superposition of the contribution from the short and long quantum paths responsible of HHG. Finally, we show how to take advantage of transverse phase-matching to select twisted attosecond beams with different spatiotemporal properties.
High Power Laser Science and Engineering
  • Publication Date: Feb. 09, 2017
  • Vol.5 Issue, 1 010000e3 (2017)
Coherent X-ray mirage: discovery and possible applications
Tatiana Pikuz, Anatoly Faenov, Sergey Magnitskiy, Nikolay Nagorskiy, Momoko Tanaka, Masahiko Ishino, Masaharu Nishikino, Yuji Fukuda, Masaki Kando, Yoshiaki Kato, and Tetsuya Kawachi
In the far field of the intensity distribution of the beam delivered by a two-stage transient–collisional excitation X-ray laser (XRL), a non-expected interference pattern that is stable from shot to shot has been discovered. It is demonstrated that the interference is caused by the emergence of an imaginary source in the amplifying plasma, which is phase matched to the radiation of the generator. The observed phenomenon is called an X-ray coherent mirage. To explain the obtained results, a new theoretical approach is developed. The basic essential conditions for formation of the X-ray mirage are formulated, and possible applications are discussed. This paper details the experiments, including the formulation of the necessary and sufficient conditions for formation of the X-ray mirage, and possible applications are discussed.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.2 Issue, 2 02000e12 (2014)
Exploring novel target structures for manipulating relativistic laser–plasma interaction
Liangliang Ji, Sheng Jiang, Alexander Pukhov, Richard Freeman, and Kramer Akli
The improved laser-to-pedestal contrast ratio enabled by current high-power laser pulse cleaning techniques allows the fine features of the target survive before the main laser pulse arrives. We propose to introduce the nano-fabrication technologies into laser–plasma interaction to explore the novel effects of micro-structures. We found out that not only laser-driven particle sources but also the laser pulse itself can be manipulated by specifically designed micro-cylinder and -tube targets, respectively. The proposal was supported by full-3D particle-in-cell simulations and successful proof-of-principle experiments for the first time. We believe this would open a way to manipulate relativistic laser–plasma interaction at the micro-size level.
High Power Laser Science and Engineering
  • Publication Date: Jun. 29, 2017
  • Vol.5 Issue, 2 02000e14 (2017)
Laser-induced damage tests based on a marker-based watershed algorithm with gray control
Yajing Guo, Shunxing Tang, Xiuqing Jiang, Yujie Peng, Baoqiang Zhu, and Zunqi Lin
An effective damage test method based on a marker-based watershed algorithm with gray control (MWGC) is proposed to study the properties of damage induced by near-field laser irradiation for large-aperture laser facilities. Damage tests were performed on fused silica samples and information on the size of damage sites was obtained by this new algorithm, which can effectively suppress the issue of over-segmentation of images resulting from non-uniform illumination in dark-field imaging. Experimental analysis and results show that the lateral damage growth on the exit surface is exponential, and the number of damage sites decreases sharply with damage site size in the damage site distribution statistics. The average damage growth coefficients fitted according to the experimental results for Corning-7980 and Heraeus-Suprasil 312 samples at 351 nm are and , respectively.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.2 Issue, 3 03000e21 (2014)
Bragg accelerator optimization
Adi Hanuka, and Levi Schächter
We present the first steps of a design of the optimal parameters for a full Bragg X-Ray free electron laser (BX-FEL). Aiming towards a future source of coherent X-ray radiation, operating in the strong Compton regime, we envisage the system to be the seed for an advanced light source or compact medical X-ray source. Here we focus on the design of the accelerator parameters: maximum gradient, optimal accelerated charge, maximum efficiency, and ‘wake coefficient’, which relates to the decelerating electric field generated due to the motion of a charged-line or train of charged-lines. Specifically, we demonstrate that the maximum efficiency has optimal value and given the fluence of the materials, the maximum accelerated charge in the train is constant. These two results might be important in any future design.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.2 Issue, 3 03000e24 (2014)
Physics and applications with laser-induced relativistic shock waves
S. Eliezer, J. M. Martinez-Val, Z. Henis, N. Nissim, S. V. Pinhasi, A. Ravid, M. Werdiger, and E. Raicher
High Power Laser Science and Engineering
  • Publication Date: Aug. 04, 2016
  • Vol.4 Issue, 3 03000e25 (2016)
EUV ablation of organic polymers at a high fluence
Chiara Liberatore, Klaus Mann, Matthias Müller, Ladislav Pina, Libor Juha, Jorge J. Rocca, Akira Endo, and Tomas Mocek
A preliminary investigation on short-wavelength ablation mechanisms of poly(methyl methacrylate) (PMMA) and poly (1,4-phenylene ether ether-sulfone) (PPEES) by extreme ultraviolet (EUV) radiation at 13.5 nm using a table-top laser-produced plasma from a gas-puff target at LLG (G ttingen) and at 46.9 nm by a 10 Hz desktop capillary discharge laser operated at the Institute of Physics (Prague) is presented. Ablation of polymer materials is initiated by photo-induced polymer chain scissions. The ablation occurs due to the formation of volatile products by the EUV radiolysis removed as an ablation plume from the irradiated material into the vacuum. In general, cross-linking of polymer molecules can compete with the chain decomposition. Both processes may influence the efficiency and quality of micro(nano)structuring in polymer materials. Wavelength is a critical parameter to be taken into account when an EUV ablation process occurs, because different wavelengths result in different energy densities in the near-surface region of the polymer exposed to nanosecond pulses of intense EUV radiation.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.2 Issue, 3 03000e26 (2014)
Nonlinear wake amplification by an active medium in a cylindrical waveguide using a modulated trigger bunch
Zeev Toroker, Miron Voin, and Levi Schächter
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.2 Issue, 3 03000e29 (2014)
302 W triple-frequency, single-mode, linearly polarized Yb-doped all-fiber amplifier
Xiang Zhao, Yifeng Yang, Hui Shen, Xiaolong Chen, Gang Bai, Jingpu Zhang, Yunfeng Qi, Bing He, and Jun Zhou
High Power Laser Science and Engineering
  • Publication Date: Dec. 15, 2017
  • Vol.5 Issue, 4 04000e31 (2017)