Shanghai Institute of Laser Plasma

Shanghai, China

Shanghai Institute of Laser Plasma

Shanghai, China

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PubMed | National Laboratory on High Power Lasers and Physics, Shanghai JiaoTong University, CAS Institute of High Energy Physics, Beijing Normal University and 4 more.
Type: | Journal: Scientific reports | Year: 2016

Neutron energy is directly correlated with the energy of the incident ions in experiments involving laser-driven nuclear reactions. Using high-energy incident ions reduces the energy concentration of the generated neutrons. A novel laser-collider method was used at the Shenguang II laser facility to produce monoenergetic neutrons via (7)Li (d, n) nuclear reactions. The specially designed K-shaped target significantly increased the numbers of incident d and Li ions at the keV level. Ultimately, 13.3MeV neutrons were obtained. Considering the time resolution of the neutron detector, we demonstrated that the produced neutrons were monoenergetic. Interferometry and a Multi hydro-dynamics simulation confirmed the monoenergetic nature of these neutrons.

An N.,Shanghai Institute of Laser Plasma | Chen X.,Shanghai JiaoTong University
Proceedings - 2016 International Conference Laser Optics, LO 2016 | Year: 2016

We reveal a variety of nonlinear Cerenkov radiation patterns that occurs in a single photonic crystal modulated by domain walls, which manifest themselves as normal, degenerated and anomalous-dispersion-like nonlinear Cerenkov radiation type sum-frequency generation. © 2016 IEEE.

Chen J.,Shanghai JiaoTong University | Zheng Y.,Shanghai JiaoTong University | An N.,Shanghai Institute of Laser Plasma | Chen X.,Shanghai JiaoTong University
Optics Letters | Year: 2015

The scheme of prefocusing to focus sum frequency generation (SFG) without a lens is proposed and experimentally verified in this study. Noncollinear type-I noncritical phasematching SFG to generate a third-harmonic wave with large angular acceptance is presented. The principle of broad angular acceptance and the advantages of this PM configuration are also described in detail. External angular bandwidth of 7.33° for noncollinear SFG was measured in a 2 mm long KH2PO4 (KDP) crystal, which is in reasonably good agreement with the theoretical calculation. The mechanism of broadband SFG and the prefocusing scheme make it possible for the realization of convergent third-harmonic generation without involving a lens, which provides a promising way to avoid damage to optical components during the focusing of high-energy UV light in high-power laser facilities. © 2015 Optical Society of America.

Uematsu Y.,Osaka University | Ivancic S.,Laboratory for Laser Energetics | Iwawaki T.,Osaka University | Habara H.,Osaka University | And 3 more authors.
Review of Scientific Instruments | Year: 2014

In order to investigate the intense laser propagation and channel formation in dense plasma, we conducted an experiment with proton deflectometry on the OMEGA EP Laser facility. The proton image was analyzed by tracing the trajectory of mono-energetic protons, which provides understanding the electric and magnetic fields that were generated around the channel. The estimated field strengths (E ∼1011 V/m and B ∼108 G) agree with the predictions from 2D-Particle-in-cell (PIC) simulations, indicating the feasibility of the proton deflectometry technique for over-critical density plasma. © 2014 AIP Publishing LLC.

Xu Z.,Shanghai Institute of Laser Plasma | Xu Z.,Tsinghua University | Li Y.,Tsinghua University | Wang L.,Tsinghua University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Optical microfibers functionalized with surface microstructures, have attracted great attentions and been widely used in various optical devices. In this work, we demonstrated a technique to fabricate microstructures on polymer coated optical microfibers via ultraviolet inscription. Optical microfibers were firstly functionalized with ultraviolet photosensitivity by surface PMMA jackets. Microstructures were fabricated on optical microfibers via point-by-point ultraviolet inscription since the photo-etching in PMMA jackets. As an illustration, a 2-mm-long microfiber long period grating (MLPG) with a pitch of 80 μm was inscribed. The diameter of optical microfiber is 5.4 μm and a resonant dip of 15dB was observed at 1377 nm. The MLPG showed a high sensitivity of strain and axial force, i.e.,-1.93 pm/μÎμ and-867 μN/nm. Sealed by a PMMA housing, the temperature sensitivity of MLPG could be enhanced from-12.75 pm/°C to-385.11 pm/°C. This technique demonstrates ultraviolet inscription of MLPGs and also provides an approach to fabricate microstructures on optical microfiber via ultraviolet exposure. © 2016 SPIE.

Gao Y.-Q.,Shanghai Institute of Laser Plasma | Ma W.-X.,Shanghai Institute of Laser Plasma | Zhu B.-Q.,CAS Shanghai Institute of Optics and fine Mechanics | Liu D.-Z.,CAS Shanghai Institute of Optics and fine Mechanics | And 3 more authors.
Applied Optics | Year: 2012

Aiming at getting the general requirements of the beam combine for ignition scale laser facilities, the analytical expressions including the factors affecting the combine results are derived. The physical meanings of every part are illustrated. Based on these expressions, the effects of the factors, including the beam configuration, piston error, and tip/tilt error, are studied analytically and numerically. The results show that the beam configuration cannot affect the Strehl ratio (SR) of the combined beam, but it influences the FWHM of the main peak and the ratio of the main peak and the side peak. The beam separation shouldbe nomore than 1.24 times the individual beam width for the multibeam combine, and be close to the individual beam width for the two-beam combine as much as possible. The piston error can change the characteristics of the combine beam focus, including the peak intensity, the focal spot morphology, the fractional energy contained within a certain area, and the center of mass. For the two-beam combine, a piston error less than 2π/5 rad is suitable, and for the multibeam combine, the standard deviation of the piston error should be no more than 2π/10 rad. The tip/tilt error has a great influence on the combined results. It affects the superposition degree of the focal spots of the combined elements directly. A requirement of 0.5 ∼ 1 μrad for the standard deviation of the tip/tilt error is adequate. © 2012 Optical Society of America.

Liu X.,CAS Shanghai Institute of Optics and fine Mechanics | Zhao Y.,CAS Shanghai Institute of Optics and fine Mechanics | Li D.,CAS Shanghai Institute of Optics and fine Mechanics | Hu G.,CAS Shanghai Institute of Optics and fine Mechanics | And 3 more authors.
Applied Optics | Year: 2011

Plasma scalding is one of the most typical laser damage morphologies induced by a nanosecond laser with a wavelength of 1053nm in HfO 2=SiO2 multilayer films. In this paper, the characteristics of plasma scalds are systematically investigated with multiple methods. The scalding behaves as surface discoloration under a microscope. The shape is nearly circular when the laser incidence angle is close to normal incidence and is elliptical at oblique incidence. The nodular-ejection pit is in the center of the scalding region when the laser irradiates at the incidence angle close to normal incidence and in the right of the scalding region when the laser irradiates from left to right at oblique incidence. The maximum damage size of the scalding increases with laser energy. The edge of the scalding is high compared with the unirradiated film surface, and the region tending to the center is concave. Plasma scald is proved to be surface damage. The maximum depth of a scald increases with its size. Tiny pits of nanometer scale can be seen in the scalding film under a scanning electronic microscope at a higher magnification. The absorptions of the surface plasma scalds tend to be approximately the same as the lower absorptions of test sites without laser irradiation. Scalds do not grow during further illumination pulses until 65 J=cm2. The formation of surface plasma scalding may be related to the occurrence of the laser-supported detonation wave. © 2011 Optical Society of America.

Liu X.,CAS Shanghai Institute of Optics and fine Mechanics | Zhao Y.,CAS Shanghai Institute of Optics and fine Mechanics | Gao Y.,Shanghai Institute of Laser Plasma | Li D.,CAS Shanghai Institute of Optics and fine Mechanics | And 4 more authors.
Applied Optics | Year: 2013

HfO2/Si2 coatings are always fluence-limited by a class of rare catastrophic failures induced by a nanosecond laser with a wavelength of 1053 nm. The catastrophic damage in Hf2/Si2 coatings behaves as the damage growth with repeated laser irradiation, and thus eventually limits the mirror performance. Understanding the damage processes and mechanisms associated with the catastrophic damage are important for reducing the occurrence of the catastrophic failure and allowing the Hf 2/Si2 coatings to survive at the high fluence required by high laser systems. The rough damage behavior of the catastrophic failure at the proper critical fluence is present. The pit and delamination in the catastrophic failure are investigated to find the possible reasons leading to the catastrophic failure. The experimental results indicate that nodular defect originated from the substrate easily incurs the catastrophic damage. The electric field enhancements of the pit and the substrate impurities may contribute to this phenomenon. The delamination is always present on the left of the pit when laser irradiates from left to right at oblique incidence, which may be related to the plasma plume toward the laser incidence. © 2013 Optical Society of America.

Wang R.-R.,Shanghai Institute of Laser Plasma | Wang W.,Shanghai Institute of Laser Plasma
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2014

This paper explores the parameter measurement in laser produced plasma by X-ray line profile spectrscopy. The experiment was conducted on the SG-II laser facility. A 0.35 μm laser beam was focused on a solid chlorine (Cl) target in a vacuum chamber to produce a laser chlorine plasma and the high resolution X-ray elliptical bent crystal spectrograph was used to obtain the X-ray fine structure energy spectrum of the chlorine plasma radiation. The line integrated intensity ratio between H-like Cl (1s-3p) (Lyman-) and He-like Cl (1s2-1s3p) (He-) transitions was used for calculation of the electron temperature. By assuming optically thin, the Lyman-stark broadened profile was utilized to measure the electron density. Obtained experimental results show that the volume averaged electron temperature of Te is about 450 eV and the electron density of Ne is approximately 7.5×1022 cm-3. In addition, the line Full Width at Half Maximum (FWHM) was analyzed. The uncertainty in Ne due to uncertainties in the temperature and the assumed background level was also simply discussed and it is estimated to be within 25%. As a result, the experimental spectroscopic method may become a reference for diagnosing future higher-compression implosions.

Shu H.,Shanghai Institute of Laser Plasma | Fu S.,Shanghai Institute of Laser Plasma | Huang X.,Shanghai Institute of Laser Plasma | Wu J.,Shanghai Institute of Laser Plasma | And 2 more authors.
Measurement Science and Technology | Year: 2012

A line-imaging optically recording velocity interferometer system (L-ORVIS) fitting the high-strain rate motion of solids as in shock wave experiments requires a high power single-mode laser. We have put forward a new illumination method which can increase threefold the luminosity of such a diagnostic. A modified illumination system is applied to the L-ORVIS which was implemented at 'Shenguang-II' laser facility. The modified L-ORVIS is applied to laser-driven shock wave experiments and platinum Hugoniots were obtained at both high pressure and low pressure. © 2012 IOP Publishing Ltd.

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