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Sub-50 fs pulses at 2050 nm from a picosecond Ho:YLF laser using a two-stage kagome-fiber-based compressor

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Photonics Research 2022年第3期10卷 637-645页

作者： krishna Murari Giovanni Cirmi Hüseyin Cankaya Gregory J.Stein Benoit Debord Frederic Gerome Felix Ritzkosky Fetah Benabid Oliver Muecke franz x.kärtner Center for Free Electron Laser Science CFEL Deutsches Elektronen-Synchrotron DESY22607 HamburgGermany Max-Planck Institute for Structure and Dynamics of Matter(MPSD) 22761 HamburgGermany ELI-ALPS ELI-HU Non-Profit Ltd.Szeged H-6728Hungary The Hamburg Center for Ultrafast Imaging&Department of Physics University of Hamburg22761 HamburgGermany GPPMM Group XLIM Research InstituteUMR 7252 CNRSUniversity of LimogesLimogesFrance show less

The high-energy few-cycle mid-infrared laser pulse beyond 2μm is of immense importance for attosecond science and strong-field ***,the limited gain bandwidth of laser crystals such as Ho:YLF and Ho:YAG allows the generation of picosecond(ps)long pulses and,hence,makes it challenging to generate few-cycle pulse at 2μm without utilizing an optical parametric chirped-pulse amplifier(OPCPA).Moreover,the exclusive use of the near-infrared wavelength has limited the generation of wavelengths beyond 4μm(OPCPA).Furthermore,high harmonic generation(HHG)conversion efficiency reduces dramatically when driven by a long-wavelength *** schemes such as multi-color HHG have been proposed to enhance the harmonic ***,it is highly desirable to generate few-cycle to femtosecond pulses from a 2μm laser for driving these ***,we utilize two-stage nonlinear spectral broadening and pulse compression based on the kagome-type hollow-core photonic crystal fiber(HC-PCF)to compress few-ps pulses to sub-50 fs from a Ho:YLF amplifier at 2μm at 1 kHz repetition *** demonstrate both experimentally and numerically the compression of 3.3 ps at 140μJ pulses to 48 fs at 11μJ with focal intensity reaching 10^(13)W/cm^(***,this system can be used for driving HHG in solids at 2μ*** the first stage,the pulses are spectrally broadened in kagome fiber and compressed in a silicon-based prism compressor to 285 fs at a pulse energy of 90μ*** the second stage,the 285 fs pulse is self-compressed in air-filled *** fine-tuning of the group delay dispersion(GDD)externally in a 3 mm window,a compressed pulse of 48 fs is *** leads to a 70-fold compression of the ps pulses at 2050 *** further used the sub-50 fs laser pulses to generate white light by focusing the pulse into a thin medium of YAG.

关键词： fiber amplifier compressor

Attosecond precision multi-kilometer laser-microwave network

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Light(Science & Applications) 2016年第1期5卷 342-348页

作者： Ming xin kemalŞafak Michael Y Peng Aram kalaydzhyan Wen-Ting Wang Oliver D Mücke franz x kärtner Center for Free-Electron Laser Science Deutsches Elektronen-Synchrotron22607 HamburgGermany Department of Physics University of Hamburg and the Hamburg Center for Ultrafast Imaging22761 HamburgGermany Research Laboratory of Electronics Massachusetts Institute of TechnologyCambridgeMA 02139USA

Synchronous laser-microwave networks delivering attosecond timing precision are highly desirable in many advanced applications,such as geodesy,very-long-baseline interferometry,high-precision navigation and multi-telescope *** particular,rapidly expanding photon-science facilities like x-ray free-electron lasers and intense laser beamlines require system-wide attosecond-level synchronization of dozens of optical and microwave signals up to kilometer *** equipped with such precision,these facilities will initiate radically new science by shedding light on molecular and atomic processes happening on the attosecond timescale,such as intramolecular charge transfer,Auger processes and their impacts on x-ray *** we present for the first time a complete synchronous laser-microwave network with attosecond precision,which is achieved through new metrological devices and careful balancing of fiber nonlinearities and fundamental noise *** demonstrate timing stabilization of a 4.7-km fiber network and remote optical–optical synchronization across a 3.5-km fiber link with an overall timing jitter of 580 and 680 attoseconds root-mean-square,respectively,for over 40 ***,we realize a complete laser-microwave network with 950-attosecond timing jitter for 18 *** work can enable nextgeneration attosecond photon-science facilities to revolutionize many research fields from structural biology to material science and chemistry to fundamental physics.

关键词： attosecond photonics attosecond timing metrology hard-x-ray free-electron laser laser-microwave network timing distribution

THz-Enhanced DC Ultrafast Electron Diffractometer

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Ultrafast Science 2021年第1期1卷 61-67页

作者： Dongfang Zhang Tobias kroh Felix Ritzkowsky Timm Rohwer Moein Fakhari Huseyin Cankaya Anne-Laure Calendron Nicholas H.Matlis franz x.kärtner Center for Free-Electron Laser Science Deutsches Elektronen SynchrotronNotkestrasse 8522607 HamburgGermany Collaborative Innovation Center for IFSA School of Physics and AstronomyShanghai Jiao Tong University200240 ShanghaiChina Department of Physics and The Hamburg Centre for Ultrafast Imaging Universität HamburgLuruper Chaussee 14922761 HamburgGermany

Terahertz-(THz-)based electron manipulation has recently been shown to hold tremendous promise as a technology for manipulating and driving the next generation of compact ultrafast electron ***,we demonstrate an ultrafast electron diffractometer with THz-driven pulse *** electron bunches from a conventional DC gun are compressed by a factor of 10 and reach a duration of~180 fs(FWHM)with 10,000 electrons/pulse at a 1 kHz repetition *** resulting ultrafast electron source is used in a proof-of-principle experiment to probe the photoinduced dynamics of single-crystal *** THz-compressed electron beams produce high-quality diffraction patterns and enable the observation of the ultrafast structural dynamics with improved time *** results validate the maturity of THz-driven ultrafast electron sources for use in precision applications.

关键词： pulse Electron repetition

Octave-spanning coherent supercontinuum generation in silicon on insulator from 1.06μm to beyond 2.4μm

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Light(Science & Applications) 2017年第1期6卷 235-242页

作者： Neetesh Singh Ming xin Diedrik Vermeulen katia Shtyrkova Nanxi Li Patrick T Callahan Emir Salih Magden Alfonso Ruocco Nicholas Fahrenkopf Christopher Baiocco Bill P-P kuo Stojan Radic Erich Ippen franz x kärtner Michael R Watts Research Laboratory of Electronics Massachusetts Institute of TechnologyCambridgeMA 02139USA John A.Paulson School of Engineering and Applied Science Harvard UniversityCambridgeMA 02138USA College of Nanoscale Science and Engineering SUNY Polytechnic InstituteAlbanyNY 12203USA Department of Electrical and Computer Engineering University of California San DiegoLa JollaCA 92039USA Centre for Free Electron Laser Science(CFEL)-DESY and University of Hamburg Hamburg 22607Germany

Efficient complementary metal-oxide semiconductor-based nonlinear optical devices in the near-infrared are in strong *** to two-photon absorption in silicon,however,much nonlinear research is shifting towards unconventional photonics *** this work,we demonstrate the generation of an octave-spanning coherent supercontinuum in a silicon waveguide covering the spectral region from the near-to *** input pulses of 18 pJ in energy,the generated signal spans the wavelength range from the edge of the silicon transmission window,approximately 1.06 to beyond 2.4μm,with a−20 dB bandwidth covering 1.124–2.4μ*** octave-spanning supercontinuum was also observed at the energy levels as low as 4 pJ(−35 dB bandwidth).We also measured the coherence over an octave,obtaining|g_()12^(1)(λ)>90%,in good agreement with the *** addition,we demonstrate optimization of the third-order dispersion of the waveguide to strengthen the dispersive wave and discuss the advantage of having a soliton at the long wavelength edge of an octave-spanning signal for nonlinear *** research paves the way for applications,such as chip-scale precision spectroscopy,optical coherence tomography,optical frequency metrology,frequency synthesis and wide-band wavelength division multiplexing in the telecom window.

关键词： coherence integrated photonics silicon supercontinuum

Distinct Electrical and Mechanical Responses of a Cu-10Fe Composite Prepared by Hot-Pressed Sintering and Post Treatment

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 255-265页

作者： x.Y.Yue S.Y.Peng x.Zhang C.N.He Y.Z.Tian key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang110819China School of Materials Science and Engineering and Tianjin key Laboratory of Composite and Functional Materials Tianjin UniversityTianjin300350China Research Centre for Metallic Wires Northeastern UniversityShenyang110819China

A Cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution *** hot-pressed sintered and solution treated materials were rolled and *** precipitation behavior and performance changes were systematically studied by using scanning electron microscopy and transmission electron *** contrast to the hot-pressed sintered specimen,the solution treatment significantly affects the thermal stability and properties of the Cu-10wt%Fe *** Cu-10wt%Fe composite was prepared after solid solution,cold rolling and aging at 773 k for 1 h,and it obtained excellent tensile strength of 494 MPa,uniform elongation of 16.3%,electrical conductivity of 51.1%IACS and softening temperature of 838 *** for the distinct difference in thermal stability and properties between hot-pressed sintered and solution treated specimens were *** findings provide a theoretical basis for designing high-performance Cu-based in-situ composites by post treatment.

关键词： Cu-Fe composite Hot-pressed sintering Thermal stability Strength Electrical conductivity

Fast efficient photon deceleration in plasmas by using two laser pulses at different frequencies

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Matter and Radiation at Extremes 2024年第3期9卷 11-18页

作者： Y.x.Wang x.L.Zhu S.M.Weng P.Li x.F.Li H.Ai H.R.Pan Z.M.Sheng key Laboratory for Laser Plasmas(moe) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Research Center of Laser Fusion of China Academy of Engineering Physics MianyangSichuan 621900China State key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Tsung-dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

The generation of ultrashort high-power light sources in the mid-infrared(mid-IR)to terahertz(THz)range is of interest for applications in a number of fields,from fundamental research to biology and *** conventional laser technology,photon deceleration in plasma wakes provides an alternative approach to the generation of ultrashort mid-IR or THz ***,we present a photon deceleration scheme for the efficient generation of ultrashort mid-IR or THz pulses by using an intense driver laser pulse with a relatively short wavelength and a signal laser pulse with a relatively long *** signal pulse trails the driver pulse with an appropriate time delay such that it sits at the front of the second wake bubble that is driven by the driver *** to its relatively long wavelength,the signal pulse will be subjected to a large gradient of the refractive index in the plasma wake ***,the photon deceleration in the plasma wake becomes faster and more efficient for signal pulses with longer *** greatly enhances the capacity and efficiency of photon deceleration in the generation of ultrashort high-power light sources in the long-wavelength IR and THz spectral ranges.

关键词： laser ultrashort photon

Large non-pedunculated colorectal polyp management: The elephant in the room

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World Journal of Gastroenterology 2024年第25期30卷 3126-3131页

作者： Shirley x Jiang Neal Shahidi Department of Medicine University of British ColumbiaVancouver V6Z 2K5BCCanada

Minimally invasive innovations have transformed *** to colorectal cancer(CRC),there has been a shift towards less invasive surgical techniques and use of endoscopic resection as an alternative for low risk T1 *** role of endoscopic resection is however much more extensive:It is now considered the first line management strategy for most large(≥20 mm)non-pedunculated colorectal polyps,the majority of which are *** is due to the well-established efficacy,safety,and cost-effectiveness of endoscopic techniques compared to *** endoscopic modalities now exist with distinct risk-benefit profiles and their outcomes are further improved by site-specific technical modifications,auxiliary techniques,and adverse event miti-gation *** capacity continues to evolve with emerging endoscopic techniques and expanding applications,particularly in the confines of a multi-disciplinary setting.

关键词： Cancer Colonoscopy Endoscopy Polyp Endoscopic mucosal resection Endoscopic submucosal dissection

Long Term x-Ray Spectral Variations of the Seyfert-1 Galaxy Mrk 279

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Research in Astronomy and Astrophysics 2024年第6期24卷 307-314页

作者： k.Akhila Ranjeev Misra Savithri H.Ezhikode k.Jeena Department of Physics Providence Women’s CollegeUniversity of CalicutKerala 673009India Inter-University Centre for Astronomy and Astrophysics(IUCAA) PB No.4GaneshkhindPune 411007India Department of Physics and Electronics CHRIST(Deemed to be University)Hosur Main RoadBangalore 560029India

We present the results from a long term x-ray analysis of Mrk 279 during the period 2018–*** use data from multiple missions–AstroSat,NuSTAR and xMM-Newton,for the *** x-ray spectrum can be modeled as a double Comptonization along with the presence of neutral Fe kαline emission,at all *** determined the source’s x-ray flux and luminosity at these different *** find significant variations in the source’s flux *** also investigate the variations in the source’s spectral components during the observation *** find that the photon index and hence the spectral shape follow the variations only over longer time *** probe the correlations between fluxes of different bands and their photon indices,and found no significant correlations between the parameters.

关键词： galaxies:Seyfert galaxies:individual(Mrk 335) x-rays:galaxies

An adaptive machine learning-based optimization method in the aerodynamic analysis of a finite wing under various cruise conditions

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Theoretical & Applied Mechanics Letters 2024年第1期14卷 27-34页

作者： Zilan Zhang Yu Ao Shaofan Li Grace x.Gu Department of Mechanical Engineering University of CaliforniaBerkeley 94720USA Department of Engineering Peking UniversityBeijing 100871China Department of Civil and Environmental Engineering University of CaliforniaBerkeley 94720USA

Conventional wing aerodynamic optimization processes can be time-consuming and imprecise due to the complexity of versatile flight *** of existing literature has considered two-dimensional infinite airfoil optimization,while three-dimensional finite wing optimizations are subject to limited study because of high computational *** we create an adaptive optimization methodology built upon digitized wing shape deformation and deep learning algorithms,which enable the rapid formulation of finite wing designs for specific aerodynamic performance demands under different cruise *** methodology unfolds in three stages:radial basis function interpolated wing generation,collection of inputs from computational fluid dynamics simulations,and deep neural network that constructs the surrogate model for the optimal wing *** has been demonstrated that the proposed methodology can significantly reduce the computational cost of numerical *** also has the potential to optimize various aerial vehicles undergoing different mission environments,loading conditions,and safety requirements.

关键词： Aerodynamic optimization Computational fluid dynamics Radial basis function Finite wing Deep learning neural network