Preparation of silicon carbide nitride films on Si substrate by pulsed high-energy density plasma

Thin films of silicon carbide nitride （SiCN） were prepared on （111） oriented silicon substrates by pulsed high-energy density plasma （PHEDP）. The evolution of the chemical bonding states between silicon, nitrogen and carbon was investigated as a function of discharge voltage using X-ray photoelectron spectroscopy. With an increase in discharge voltage both the C 1s and N 1s spectra shift to lower binding energy due to the formation of C--Si and N--Si bonds. The Si--C--N bonds were observed in the deconvolved C ls and N ls spectra. The X-ray diffractometer （XRD） results show that there were no crystals in the films. The thickness of the films was approximately 1-2 μm with scanning electron microscopy （SEM）.

Mechanism of high-energy pulsed current-assisted rolling of 08AL carbon steel ultra-thin strip

To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.

High-Stability High-Energy Picosecond Optical Parametric Chirped Pulse Amplifier as a Preamplifier in Nd：Glass Petawatt System for Contrast Enhancement

We demonstrate a novel picosecond optical parametric preamplification to generate high-stability, high-energy and high-contrast seed pulses. The 5ps seed pulse is amplified from 60pJ to 300μJ with an 8.6ps/ 3mJ pump laser in a signal stage of short pulse non-collinear optical parametric chirped pulse amplification. The total gain is more than 106 and the rms energy stability is under 1.35%. The contrast ratio is higher than 10s within a scale of 20ps before the main pulse. Consequently, the improvement factor of the signal contrast is approximately equal to the gain 106 outside the pump window.

DEGRADATION DUE TO ENERGY PULSE IN HIGH-ENERGY ZnO VARISTORS

The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing the energy stored in an inductor, can be equivalent to the combination of the DC field components and the energy component. The variations of the characterized voltages, nonlinear coefficients and pre-breakdown V-A characteristics, increase with the number of the applied energy pulse. The asymmetrical variations of the electric properties of the high-energy ZnO varistors after the energy pulse arise from the deformation of the double Schottky barriers due to the ion migration occuring in the depletion layer and in the grain boundary.

Generation of high-energy dual-wavelength domain wall pulse with low repetition rate in an HNLF-based fiber ring laser

The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-induced spectral filtering effect, the dual-wavelength lasing operation can be achieved. In order to enhance the cross coupling effect between the two lasing beams for domain wall pulse formation, a 215-m HNLF is incorporated into the laser cavity. Experimentally, it is found that the dual-wavelength domain wall pulse with a repetition rate of 77.67 kHz could be efficiently obtained through simply rotating the polarization controller （PC）. At a maximum pump power of 322 mW, the 655-nJ single pulse energy in cavity is obtained. The proposed configuration provides a simpler and more efficient way to generate high energy pulse with a low repetition rate.

High-energy femtosecond Yb-doped all-fiber monolithic chirped-pulse amplifier at repetition rate of 1 MHz

A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification（CPA） technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillator is studied.We find that the compressed pulse duration is dependent on the amplified energy,the pulse duration of 804 fs corresponds to the maximum amplified energy of 10.5 μJ,while the shortest pulse duration of 424 fs corresponds to the amplified energy of 6.75 μJ.The measured energy fluctuation is approximately 0.46% root mean square（RMS） over 2 h.The low-cost femtosecond fiber laser source with super-stability will be widely used in industrial micromachines,medical therapy,and scientific studies.

High-energy,hundred-picosecond pulsed 266 nm mid-ultraviolet generation by a barium borate crystal

We present a high-energy,hundred-picosecond(ps)pulsed mid-ultraviolet solid-state laser at 266 nm by a direct second harmonic generation(SHG)in a barium borate(BaB_(2)O_(4),BBO)nonlinear crystal.The green pump source is a 710 mJ,330 ps pulsed laser at a wavelength of 532 nm with a repetition rate of 1 Hz.Under a green pump energy of 710 mJ,a maximum output energy of 253.3 mJ at 266 nm is achieved with 250 ps pulse duration resulting in a peak power of more than 1 GW,corresponding to an SHG conversion efficiency of 35.7%from 532 to 266 nm.The experimental data were well consistent with the theoretical prediction.To the best of our knowledge,this laser exhibits both the highest output energy and highest peak power ever achieved in a hundred-ps/ps regime at 266 nm for BBO-SHG.

Generating femtosecond coherent X-ray pulses in a diffractionlimited storage ring with the echo-enabled harmonic generation scheme

To study ultrafast processes at the sub-picosecond level, novel methods based on coherent harmonic generation technologies have been proposed to generate ultrashort radiation pulses in existing ring-based light sources. Using the High Energy Photon Source as an example, we numerically test the feasibility of implementing one coherent harmonic generation technology, i.e.,the echo-enabled harmonic generation(EEHG) scheme, in a diffraction-limited storage ring(DLSR). Two different EEHG element layouts are considered, and the effect of the EEHG process on the electron beam quality is also analyzed. Studies suggest that soft X-ray pulses, with pulse lengths of a few femtoseconds and peak powers of up to1 MW, can be generated by using the EEHG scheme, while causing little perturbation to the regular operation of a DLSR.

Generation of coexisting high-energy pulses in a mode-locked all-fiber laser with a nonlinear multimodal interference technique

We demonstrate a passively mode-locked all-fiber laser incorporating a piece of graded-index multimode fiber as a mode-locking modulator based on a nonlinear multimodal interference technique, which generates two types of coexisting high-energy ultrashort pulses [i.e., the conventional soliton(CS) and the stretched pulse(SP)]. The CS with pulse energy as high as 0.38 n J is obtained at the pump level of 130 mW. When the pump increases to175 mW, the high-energy SP occurs at a suitable nonlinear phase bias and its pulse energy can reach 4 n J at a 610 mW pump. The pulse durations of the generated CS and SP are 2.3 ps and 387 fs, respectively. The theory of nonlinear fiber optics, single-shot spectral measurement by the dispersive Fourier-transform technique, and simulation methods based on the Ginzburg–Landau equation are provided to characterize the laser physics and reveal the underlying principles of the generated CS and SP. A rogue wave, observed between the CS and SP regions, mirrors the laser physics behind the dynamics of generating a high-energy SP from a CS. The proposed all-fiber laser is versatile, cost-effective and easy to integrate, which provides a promising solution for high-energy pulse generation.

Ceramic coating electric-deposited by high-energy pulse

A novel method to prepare ceramic coatings has been developed by making use of plasma energy produced from the pulsed discharge between electric conductor and aqueous electrolyte. A ZrO2-8%Y2O3 coating was obtained by this method, which had excellent adhesion with substrate, smooth surface and good resistance to high temperature oxidation.

High-energy plain and composite pulses in a laser modeled by the complex Swift–Hohenberg equation

In this work, new plain and composite high-energy solitons of the cubic–quintic Swift–Hohenberg equation were numerically found. Starting from a composite pulse found by Soto-Crespo and Akhmediev and changing some parameter values allowed us to find these high energy pulses. We also found the region in the parameter space in which these solutions exist. Some pulse characteristics, namely, temporal and spectral profiles and chirp, are presented. The study of the pulse energy shows its independence of the dispersion parameter but its dependence on the nonlinear gain. An extreme amplitude pulse has also been found.

High-energy plain and composite pulses in a laser modeled by the complex Swift–Hohenberg equation:publisher's note

This publisher's note reports corrections to three of the figures in [Photon. Res. 4, 49(2016)].

Effects of Dissipative Terms on Dissipative Soliton Resonance Curve

Dissipative soliton resonance (DSR) is a phenomenon where the energy of a soliton in a dissipative system increases without limit at certain values of the system parameters. Using the method of collective variable approach, we have found an approximate relation between the parameters of the normalized complex cubic-quintic Ginzburg-Landau equation where the resonance manifests itself. Comparisons between the results obtained by collective variable approach, and those obtained by the method of moments show good qualitative agreement. This choice also helps to see the influence of the active terms on the resonance curve, so can be very useful in constructing passively mode-locked laser that generate solitons with the highest possible energies.

Monolithic tapered Yb‑doped fber chirped pulse amplifer delivering 126μJ and 207 MW femtosecond laser with near difraction‑limited beam quality

In this work,a high-energy and high peak power chirped pulse amplifcation system with near difraction-limited beam quality based on tapered confned-doped fber(TCF)is experimentally demonstrated.The TCF has a core numerical aperture of 0.07 with core/cladding diameter of 35/250µm at the thin end and 56/400μm at the thick end.With a backward-pumping confguration,a maximum single pulse energy of 177.9μJ at a repetition rate of 504 kHz is realized,corresponding to an average power of 89.7 W.Through partially compensating for the accumulated nonlinear phase during the amplifcation process via adjusting the high order dispersion of the stretching chirped fber Bragg grating,the duration of the amplifed pulse is compressed to 401 fs with a pulse energy of 126.3μJ and a peak power of 207 MW,which to the best of our knowledge represents the highest peak power ever reported from a monolithic ultrafast fber laser.At the highest energy,the polarization extinction ratio and the M2 factor were respectively measured to be~19 dB and 1.20.In addition,the corresponding intensity noise properties as well as the short-and long-term stability were also examined,verifying a stable operation of the system.It is believed that the demonstrated laser source could fnd important applications in,for example,advanced manufacturing and photomedicine.

Laser-system model for enhanced operational performance and flexibility on OMEGA EP

The development of laser performance models having real-time prediction capability for the OMEGA EP laser system has been essential in meeting requests from its user community for increasingly complex pulse shapes that span a wide range of energies. The laser operations model PSOPS provides rapid and accurate predictions of OMEGA EP lasersystem performance in both forward and backward directions, a user-friendly interface and rapid optimization capability between shots. We describe the model’s features and show how PSOPS has allowed real-time optimization of the lasersystem configuration in order to satisfy the demands of rapidly evolving experimental campaign needs. We also discuss several enhancements to laser-system performance accuracy and flexibility enabled by PSOPS.

Observation of an EPIR Effect in Nd_(1-x)Sr_xMnO_3 Ceramics with Secondary Phases

Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transport character of the grain/phase boundary （inner interface） and electrode-bulk interface （outer interface）, respectively, and the results indicate that there is a similar nonlinear I-V behaviour for both of the inner and outer interfaces, however, the electric pulse induced resistance change （EPIR） effect can only be observed at the outer interface.