We report a numerical method to analyze the fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse (2-D TM) structures. The far-field diffraction patterns of the 2-D TM structures can...We report a numerical method to analyze the fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse (2-D TM) structures. The far-field diffraction patterns of the 2-D TM structures can be obtained by the numerical method, and they have a good agreement with the experimental ones. The analysis shows that the fractal characteristics of far-field diffraction patterns for the 2-D TM structures are determined by the inflation rule, which have potential applications in the design of optical diffraction devices.展开更多
Evidence for metallization in dense oxygen has been reported for over 30 years[Desgreniers et al.,J.Phys.Chem.94,1117(1990)]at a now routinely accessible 95 GPa[Shimizu et al.,Nature 393,767(1998)].However,despite the...Evidence for metallization in dense oxygen has been reported for over 30 years[Desgreniers et al.,J.Phys.Chem.94,1117(1990)]at a now routinely accessible 95 GPa[Shimizu et al.,Nature 393,767(1998)].However,despite the longevity of this result and the technological advances since,the nature of the metallic phase remains poorly constrained[Akahama et al.,Phys.Rev.Lett.74,4690(1995);Goncharov et al.,Phys.Rev.B 68,224108(2003);Ma,Phys.Rev.B 76,064101(2007);and Weck et al.,Phys.Rev.Lett.102,255503(2009)].In this work,through Raman spectroscopy,we report the distinct vibrational characteristics of metallicζ-O_(2) from 85 to 225 GPa.In comparison with numerical simulations,wefind reasonable agreement with the candidate structure up to about 150 GPa.At higher pressures,the C2/mstructure is found to be unstable and incompatible with experimental observations.Alternative candidate structures,and Ci,with C2/m C2/conly two molecules in the primitive unit cell,are found to be stable and more compatible with measurements above 175 GPa,indicative of the dissociation of(O_(2))4 units.Further,we report and discuss a strong hysteresis and metastability with the precursory phaseϵ-O_(2).Thesefindings will reinvigorate experimental and theoretical work into the dense oxygen system,which will have importance for oxygen-bearing chemistry,prevalent in the deep Earth,as well as fundamental physics.展开更多
Optical rotators based on the Faraday effect have been widely used in optical systems,such as optical isolation and circulators.However,due to the limitation of crystals,the application of such optical rotators in hig...Optical rotators based on the Faraday effect have been widely used in optical systems,such as optical isolation and circulators.However,due to the limitation of crystals,the application of such optical rotators in high-power lasers has been severely hindered.Here,we propose a novel plasma rotator based on the frequency-variable Faraday rotation(FVFR)in a compact manner,achieved by driving the magnetized underdense plasma with a relativistic linearly polarized laser.In the magnetized plasma,the drive laser undergoes photon deceleration and relativistic Faraday rotation,leading to the generation of relativistic polarization-tunable mid-infrared(mid-IR)pulse with intensity 1016 W cm^(-2)and a spectral width of 5-25μm.With different magnetic fields,the polarization angle of the generated mid-IR pulse can be well controlled.Especially,one can obtain a circularly polarized mid-IR pulse with the spatial average polarization degree of≥0:94 at a suitable external magnetic field.The robustness of the rotator has been well demonstrated through comprehensive three-dimensional particle-in-cell simulations across a wide range of laser and plasma parameters.Such a rotator via FVFR is valid from mid to far-infrared and even THz waveband,offering new opportunities for strong-field physics,attosecond science,laboratory astrophysics,etc,and paving the way for relativistic plasma magneto-optics and future relativistic plasma optical devices.展开更多
Photolithography experiments are performed by means of an optical phase mask with electrooptically tunable phase step. The phase mask consists of a 2-dimensional hexagonal lattice of inverted ferroelectric domains fab...Photolithography experiments are performed by means of an optical phase mask with electrooptically tunable phase step. The phase mask consists of a 2-dimensional hexagonal lattice of inverted ferroelectric domains fabricated on a z-cut/ithium niobate substrate. The electro-optically tunable phase step, between inverted domain, is obtained by the application of an external electric field along the z axis of the crystal via transparent electrodes. The collimated beam of an argon laser passes through the phase mask and the near field intensity patterns, at different planes of the Talbot length and for different values of the applied voltage, are used for photolithographic experiments. Preliminary results are shown and further applications are discussed.展开更多
On behalf of all at High Power Laser Science and Engineering we would like to congratulate the team at Lawrence Livermore National Laboratory(LLNL)on demonstrating fusion ignition at the National Ignition Facility.Thi...On behalf of all at High Power Laser Science and Engineering we would like to congratulate the team at Lawrence Livermore National Laboratory(LLNL)on demonstrating fusion ignition at the National Ignition Facility.This major scientific achievement was realized on the 5 December 2022 at the LLNL and announced at a press briefing on the 13 December 2022 by the United States Department of Energy’s National Nuclear Security Administration.This was a historic milestone and the culmination of decades of effort.展开更多
We present an improved version of the superatom(SA)model to examine the slow-light dynamics of a few-photons signal field in cold Rydberg atoms with van der Waals(vdW)interactions.A main feature of this version is tha...We present an improved version of the superatom(SA)model to examine the slow-light dynamics of a few-photons signal field in cold Rydberg atoms with van der Waals(vdW)interactions.A main feature of this version is that it promises consistent estimations on total Rydberg excitations based on dynamic equations of SAs or atoms.We consider two specific cases in which the incident signal field contains more photons with a smaller detuning or less photons with a larger detuning so as to realize the single-photon-level light storage.It is found that vdW interactions play a significant role even for the slow-light dynamics of a single-photon signal field as distributed Rydberg excitations are inevitable in the picture of dark-state polariton.Moreover,the stored(retrieved)signal field exhibits a clearly asymmetric(more symmetric)profile because its leading and trailing edges undergo different(identical)traveling journeys,and higher storage/retrieval efficiencies with well preserved profiles apply only to weaker and well detuned signal fields.These findings are crucial to understand the nontrivial interplay of single-photon-level light storage and distributed Rydberg excitations.展开更多
Characterization of the state of polarization(SOP)of ultrafast laser emission is relevant in several application fields such as field manipulation,pulse shaping,testing of sample characteristics,and biomedical imaging...Characterization of the state of polarization(SOP)of ultrafast laser emission is relevant in several application fields such as field manipulation,pulse shaping,testing of sample characteristics,and biomedical imaging.Nevertheless,since high-speed detection and wavelength-resolved measurements cannot be simultaneously achieved by commercial polarization analyzers,single-shot measurements of the wavelength-resolved SOP of ultrafast laser pulses have rarely been reported.Here,we propose a method for single-shot,wavelength-resolved SOP measurements that exploits the method of division-of-amplitude under far-field transformation.A large accumulated chromatic dispersion is utilized to time-stretch the laser pulses via dispersive Fourier transform,so that spectral information is mapped into a temporal waveform.By calibrating our test matrix with different wavelengths,wavelength-resolved SOP measurements are achieved,based on the division-of-amplitude approach,combined with high-speed opto-electronic processing.As a proof-of-concept demonstration,we reveal the complex wavelength-dependent SOP dynamics in the build-up of dissipative solitons.The experimental results show that the dissipative soliton exhibits far more complex wavelength-related polarization dynamics,which are not shown in single-shot spectrum measurement.Our method paves the way for single-shot measurement and intelligent control of ultrafast lasers with wavelength-resolved SOP structures,which could promote further investigations of polarization-related optical signal processing techniques,such as pulse shaping and hyperspectral polarization imaging.展开更多
We report the characterization of the pump absorption and emission dynamic properties of a Tm:Lu2O3 ceramic lasing medium using a three-mirror folded laser cavity.We measured a slope efficiency of 73%,which allowed us...We report the characterization of the pump absorption and emission dynamic properties of a Tm:Lu2O3 ceramic lasing medium using a three-mirror folded laser cavity.We measured a slope efficiency of 73%,which allowed us to retrieve the cross-relaxation coefficient.The behavior of our system was modeled via a set of macroscopic rate equations in both the quasi continuous wave and the pulsed pumping regime.Numerical solutions were obtained,showing a good agreement with the experimental findings.The numerical solution also yielded a cross-relaxation coefficient in very good agreement with the measured one,showing that the cross-relaxation phenomenon approaches the maximum theoretical efficiency.展开更多
In photonic structures,bound states in the continuum(BICs)have recently attracted huge interest in both fundamental and applied research.Quasi-BIC leaky modes resulting from in-plane symmetry breaking in metasurfaces ...In photonic structures,bound states in the continuum(BICs)have recently attracted huge interest in both fundamental and applied research.Quasi-BIC leaky modes resulting from in-plane symmetry breaking in metasurfaces are particularly relevant to applications,due to their high quality factor,which scales as the squared inverse of the asymmetry parameter.Here,we theoretically propose an innovative approach to switch on quasi-BICs on sub-picosecond timescales via optically induced symmetry breaking in semiconductor metasurfaces.The desired effect is granted by exploiting the spatial inhomogeneities in the distribution of photo-excited hot carriers at the single meta-atom nanometric scale.In our simulations,the quasi-BIC state manifests itself as an ultra-sharp dip in transmission,emerging upon pump arrival,and disappearing completely within the carriers'diffusion timescale.Our strategy allows to envision reconfigurable platforms with switchable high-Q resonances,with ultrafast recovery beyond the limits of carrier relaxation,typical of previous approaches.展开更多
Accelerator-driven systems(ADSs)may offer a promising technology for energy production and transmutation of nuclear waste.Here we introduce the concept of utilizing high-intensity laser acceleration technology in real...Accelerator-driven systems(ADSs)may offer a promising technology for energy production and transmutation of nuclear waste.Here we introduce the concept of utilizing high-intensity laser acceleration technology in realizing an ADS,with a focus on the use of thorium fuel in subcritical systems.We explore state-of-the-art laser-driven particle sources for neutron generation by nuclear fusion,spallation or photonuclear reactions and the prospect of reaching the flux of 10^(15)n/s required to drive a subcritical reactor.We review recent advances in high-power laser amplification and assess their technological readiness in view of integration in an ADS.Finally,we present a risk analysis of a laser-driven ADS in terms of laser and target development,radiation safety and operational stability.Our conclusion highlights the potential of laser-driven ADSs as a transformative approach to nuclear fission energy.With continued research and development,technological hurdles can be overcome to fully realize sustainable,green energy production that can meet global energy demands while addressing safety and environmental concerns.展开更多
The Yb:Lu_(2)O_(3)precursor made up of spherical particles was synthesized through the co-precipitation method in the water/ethanol solvent.The 5 at% Yb:Lu_(2)O_(3)powder is in the cubic phase after calcination at 110...The Yb:Lu_(2)O_(3)precursor made up of spherical particles was synthesized through the co-precipitation method in the water/ethanol solvent.The 5 at% Yb:Lu_(2)O_(3)powder is in the cubic phase after calcination at 1100℃ for 4 h.The powder also consists of spherical nanoparticles with the average particle and grain sizes of 96 and 49 nm,respectively.The average grain size of the pre-sintered ceramic sample is 526 nm and that of the sample by hot isostatic pressing grows to 612 nm.The 1.0 mm-thick sample has an in-line transmittance of 81.6%(theoretical value of 82.2%)at 1100 nm.The largest absorption cross-section at 976 nm is 0.96×1^(0-20)cm^(2) with the emission cross-section at 1033 nm of 0.92×10^(-20)cm^(2) and the gain cross sections are calculated with the smallest population inversion parameter β of 0.059.The highest slope efficiency of 68.7% with the optical efficiency of 65.1% is obtained at 1033.3 nm in quasi-continuous wave(QCW)pumping.In the case of continuous wave(CW)pumping,the highest slope efficiency is 61.0% with the optical efficiency of 54.1%.The obtained laser performance indicates that Yb:Lu_(2)O_(3)ceramics have excellent resistance to thermal load stresses,which shows great potential in high-power solid-state laser applications.展开更多
Machine learning(ML)is one of the most acclaimed areas of science and technology,leading to countless real-world benefits,from industry to healthcare.ML involves creating algorithms to perform specific tasks by recogn...Machine learning(ML)is one of the most acclaimed areas of science and technology,leading to countless real-world benefits,from industry to healthcare.ML involves creating algorithms to perform specific tasks by recognizing patterns in the data and without requiring extensive instructions,namely without being explicitly programmed.This possibility has recently attracted the attention of a broad community of scientists interested in learning,controlling,and making optimal use of quantum systems of increasing complexity,1,2 potentially leading to revolutionary progresses in many fields.展开更多
A study of the structure of the electric and magnetic fields of ultraintense laser pulses focused by an off-axis parabolic mirror is reported. At first, a theoretical model is laid out, whose final equations integrati...A study of the structure of the electric and magnetic fields of ultraintense laser pulses focused by an off-axis parabolic mirror is reported. At first, a theoretical model is laid out, whose final equations integration allows the space and time structure of the fields to be retrieved. The model is then employed to investigate the field patterns at different times within the optical cycle, for off-axis parabola parameters normally employed in the context of ultraintense laser–plasma interaction experiments. The results show that nontrivial, complex electromagnetic field patterns are observed at the time at which the electric and magnetic fields are supposed to vanish. The importance of this effect is then studied for different laser polarizations, f numbers and off-axis angles.展开更多
Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual d...Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual design of reactors for the production of electricity.A major milestone has recently been announced in laser fusion by the Lawrence Livermore National Laboratory and is giving new thrust to laser-fusion energy research worldwide.Here we discuss how these circumstances strongly suggest the need for a European intermediate-energy facility dedicated to the physics and technology of laser-fusion ignition,the physics of fusion materials and advanced technologies for high-repetitionrate,high-average-power broadband lasers.We believe that the participation of the broader scientific community and the increased engagement of industry,in partnership with research and academic institutions,make most timely the construction of this infrastructure of extreme scientific attractiveness.展开更多
In the 2015 review paper‘Petawatt Class Lasers Worldwide’a comprehensive overview of the current status of highpower facilities of>200 TW was presented.This was largely based on facility specifications,with some ...In the 2015 review paper‘Petawatt Class Lasers Worldwide’a comprehensive overview of the current status of highpower facilities of>200 TW was presented.This was largely based on facility specifications,with some description of their uses,for instance in fundamental ultra-high-intensity interactions,secondary source generation,and inertial confinement fusion(ICF).With the 2018 Nobel Prize in Physics being awarded to Professors Donna Strickland and Gerard Mourou for the development of the technique of chirped pulse amplification(CPA),which made these lasers possible,we celebrate by providing a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed.We are now in the era of multi-petawatt facilities coming online,with 100 PW lasers being proposed and even under construction.In addition to this there is a pull towards development of industrial and multi-disciplinary applications,which demands much higher repetition rates,delivering high-average powers with higher efficiencies and the use of alternative wavelengths:mid-IR facilities.So apart from a comprehensive update of the current global status,we want to look at what technologies are to be deployed to get to these new regimes,and some of the critical issues facing their development.展开更多
Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams,coupled with novel nonlinear optics-based applications.However,optical fiber breakdown occurs when be...Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams,coupled with novel nonlinear optics-based applications.However,optical fiber breakdown occurs when beam intensities exceed a certain critical value.Optical breakdown associated with irreversible modifications of the refractive index,triggered by multiphoton absorption,has been largely exploited for fiber material microstructuration.Here we show that,for light beam intensities slightly below the breakdown threshold,nonlinear absorption strongly affects the dynamics of a propagating beam as well.We experimentally analyze this subthreshold regime and highlight the key role played by spatial self-imaging in graded-index fibers for enhancing nonlinear optical losses.We characterize the nonlinear power transmission properties of multimode fibers for femtosecond pulses propagating in the near-infrared spectral range.We show that an effective N-photon absorption analytical model is able to describe the experimental data well.展开更多
The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research.This accomplishment paves the way for using laser ine...The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research.This accomplishment paves the way for using laser inertial fusion as a viable approach for future energy production.Europe has a unique opportunity to empower research in this field internationally,and the scientific community is eager to engage in this journey.We propose establishing a European programme on inertial-fusion energy with the mission to demonstrate laser-driven ignition in the direct-drive scheme and to develop pathway technologies for the commercial fusion reactor.The proposed roadmap is based on four complementary axes:(ⅰ)the physics of laser-plasma interaction and burning plasmas;(ⅱ)high-energy high repetition rate laser technology;(ⅲ)fusion reactor technology and materials;and(ⅳ)reinforcement of the laser fusion community by international education and training programmes.We foresee collaboration with universities,research centres and industry and establishing joint activities with the private sector involved in laser fusion.This project aims to stimulate a broad range of high-profile industrial developments in laser,plasma and radiation technologies along with the expected high-level socio-economic impact.展开更多
We develop a spatiotemporal mode decomposition technique to study the spatial and temporal mode power distribution of ultrashort pulses in long spans of graded-index multimode fiber,for different input laser condition...We develop a spatiotemporal mode decomposition technique to study the spatial and temporal mode power distribution of ultrashort pulses in long spans of graded-index multimode fiber,for different input laser conditions.We find that the beam mode power content in the dispersive pulse propagation regime can be described by the Bose-Einstein law,as a result of the process of power diffusion from linear and nonlinear mode coupling among nondegenerate mode groups.In the soliton regime,the output mode power distribution approaches the Rayleigh-Jeans law.展开更多
Spatio-temporal imaging of light propagation is very important in photonics because it provides the most direct tool available to study the interaction between light and its host environment.Sub-ps time resolution is ...Spatio-temporal imaging of light propagation is very important in photonics because it provides the most direct tool available to study the interaction between light and its host environment.Sub-ps time resolution is needed to investigate the fine and complex structural features that characterize disordered and heterogeneous structures,which are responsible for a rich array of transport physics that have not yet been fully explored.A newly developed wide-field imaging system enables us to present a spatiotemporal study on light transport in various disordered media,revealing properties that could not be properly assessed using standard techniques.By extending our investigation to an almost transparent membrane,a configuration that has been difficult to characterize until now,we unveil the peculiar physics exhibited by such thin scattering systems with transport features that go beyond mainstream diffusion modeling,despite the occurrence of multiple scattering.展开更多
We demonstrate a squeezing experiment exploiting the association of integrated optics and telecom technology as key features for compact, stable, and practical continuous variable quantum optics. In our setup, squeeze...We demonstrate a squeezing experiment exploiting the association of integrated optics and telecom technology as key features for compact, stable, and practical continuous variable quantum optics. In our setup, squeezed light is generated by single-pass spontaneous parametric down conversion on a lithium niobate photonic circuit and detected by a homodyne detector whose interferometric part is directly integrated on the same platform. The remaining parts of the experiment are implemented using commercial plug-and-play devices based on guided-wave technologies. We measure, for a CW pump power of 40 mW, a squeezing level of -2.00±0.05 dB (anti-squeezing 2.80 ±0.05 dB), thus confirming the validity of our approach and opening the way toward miniaturized and easy-to-handle continuous variable-based quantum systems.展开更多
基金supported by the National Natural Science Foundation of China (No.60977048)the International Bilateral Italy-China Joint Projects (CNR/CAS Agreement 2008-2010)+1 种基金the International Collaboration Program of Ningbo (No.2010D10018)the K. C. Wong Magna Fund in Ningbo University, China
文摘We report a numerical method to analyze the fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse (2-D TM) structures. The far-field diffraction patterns of the 2-D TM structures can be obtained by the numerical method, and they have a good agreement with the experimental ones. The analysis shows that the fractal characteristics of far-field diffraction patterns for the 2-D TM structures are determined by the inflation rule, which have potential applications in the design of optical diffraction devices.
基金The computational resources were provided by the Cambridge Tier-2 sys-tem operated by the University of Cambridge Research Computing Service and funded by the UK EPSRC(Grant No.EP/P020259/1).
文摘Evidence for metallization in dense oxygen has been reported for over 30 years[Desgreniers et al.,J.Phys.Chem.94,1117(1990)]at a now routinely accessible 95 GPa[Shimizu et al.,Nature 393,767(1998)].However,despite the longevity of this result and the technological advances since,the nature of the metallic phase remains poorly constrained[Akahama et al.,Phys.Rev.Lett.74,4690(1995);Goncharov et al.,Phys.Rev.B 68,224108(2003);Ma,Phys.Rev.B 76,064101(2007);and Weck et al.,Phys.Rev.Lett.102,255503(2009)].In this work,through Raman spectroscopy,we report the distinct vibrational characteristics of metallicζ-O_(2) from 85 to 225 GPa.In comparison with numerical simulations,wefind reasonable agreement with the candidate structure up to about 150 GPa.At higher pressures,the C2/mstructure is found to be unstable and incompatible with experimental observations.Alternative candidate structures,and Ci,with C2/m C2/conly two molecules in the primitive unit cell,are found to be stable and more compatible with measurements above 175 GPa,indicative of the dissociation of(O_(2))4 units.Further,we report and discuss a strong hysteresis and metastability with the precursory phaseϵ-O_(2).Thesefindings will reinvigorate experimental and theoretical work into the dense oxygen system,which will have importance for oxygen-bearing chemistry,prevalent in the deep Earth,as well as fundamental physics.
基金supported by National Natural Science Foundation of China(Grant Nos.12375244,12475252,12135009,12205186,U2267204,and 12475249)the Natural Science Foundation of Hunan Province of China(Grant No.2025JJ30002).
文摘Optical rotators based on the Faraday effect have been widely used in optical systems,such as optical isolation and circulators.However,due to the limitation of crystals,the application of such optical rotators in high-power lasers has been severely hindered.Here,we propose a novel plasma rotator based on the frequency-variable Faraday rotation(FVFR)in a compact manner,achieved by driving the magnetized underdense plasma with a relativistic linearly polarized laser.In the magnetized plasma,the drive laser undergoes photon deceleration and relativistic Faraday rotation,leading to the generation of relativistic polarization-tunable mid-infrared(mid-IR)pulse with intensity 1016 W cm^(-2)and a spectral width of 5-25μm.With different magnetic fields,the polarization angle of the generated mid-IR pulse can be well controlled.Especially,one can obtain a circularly polarized mid-IR pulse with the spatial average polarization degree of≥0:94 at a suitable external magnetic field.The robustness of the rotator has been well demonstrated through comprehensive three-dimensional particle-in-cell simulations across a wide range of laser and plasma parameters.Such a rotator via FVFR is valid from mid to far-infrared and even THz waveband,offering new opportunities for strong-field physics,attosecond science,laboratory astrophysics,etc,and paving the way for relativistic plasma magneto-optics and future relativistic plasma optical devices.
基金This research was partially funded by the MIUR within the FIRB project ( No. RBNE01KZ94 )partially by the MIUR project(No.77 DD N.1105/2002).
文摘Photolithography experiments are performed by means of an optical phase mask with electrooptically tunable phase step. The phase mask consists of a 2-dimensional hexagonal lattice of inverted ferroelectric domains fabricated on a z-cut/ithium niobate substrate. The electro-optically tunable phase step, between inverted domain, is obtained by the application of an external electric field along the z axis of the crystal via transparent electrodes. The collimated beam of an argon laser passes through the phase mask and the near field intensity patterns, at different planes of the Talbot length and for different values of the applied voltage, are used for photolithographic experiments. Preliminary results are shown and further applications are discussed.
文摘On behalf of all at High Power Laser Science and Engineering we would like to congratulate the team at Lawrence Livermore National Laboratory(LLNL)on demonstrating fusion ignition at the National Ignition Facility.This major scientific achievement was realized on the 5 December 2022 at the LLNL and announced at a press briefing on the 13 December 2022 by the United States Department of Energy’s National Nuclear Security Administration.This was a historic milestone and the culmination of decades of effort.
基金supported by the National Natural Science Foundation of China(Nos.11534002 and 12074061)the Cooperative Program by the Italian Ministry of Foreign Affairs and International Cooperation(No.PGR00960)the National Natural Science Foundation of China(No.11861131001).
文摘We present an improved version of the superatom(SA)model to examine the slow-light dynamics of a few-photons signal field in cold Rydberg atoms with van der Waals(vdW)interactions.A main feature of this version is that it promises consistent estimations on total Rydberg excitations based on dynamic equations of SAs or atoms.We consider two specific cases in which the incident signal field contains more photons with a smaller detuning or less photons with a larger detuning so as to realize the single-photon-level light storage.It is found that vdW interactions play a significant role even for the slow-light dynamics of a single-photon signal field as distributed Rydberg excitations are inevitable in the picture of dark-state polariton.Moreover,the stored(retrieved)signal field exhibits a clearly asymmetric(more symmetric)profile because its leading and trailing edges undergo different(identical)traveling journeys,and higher storage/retrieval efficiencies with well preserved profiles apply only to weaker and well detuned signal fields.These findings are crucial to understand the nontrivial interplay of single-photon-level light storage and distributed Rydberg excitations.
基金National Natural Science Foundation of China(62075021)Graduate Research and Innovation Foundation of Chongqing,China(CYB20061)+1 种基金National Science Fund for Distinguished Young Scholars(61825501)European Union’s Horizon 2020 Research and Innovation Programme(740355)。
文摘Characterization of the state of polarization(SOP)of ultrafast laser emission is relevant in several application fields such as field manipulation,pulse shaping,testing of sample characteristics,and biomedical imaging.Nevertheless,since high-speed detection and wavelength-resolved measurements cannot be simultaneously achieved by commercial polarization analyzers,single-shot measurements of the wavelength-resolved SOP of ultrafast laser pulses have rarely been reported.Here,we propose a method for single-shot,wavelength-resolved SOP measurements that exploits the method of division-of-amplitude under far-field transformation.A large accumulated chromatic dispersion is utilized to time-stretch the laser pulses via dispersive Fourier transform,so that spectral information is mapped into a temporal waveform.By calibrating our test matrix with different wavelengths,wavelength-resolved SOP measurements are achieved,based on the division-of-amplitude approach,combined with high-speed opto-electronic processing.As a proof-of-concept demonstration,we reveal the complex wavelength-dependent SOP dynamics in the build-up of dissipative solitons.The experimental results show that the dissipative soliton exhibits far more complex wavelength-related polarization dynamics,which are not shown in single-shot spectrum measurement.Our method paves the way for single-shot measurement and intelligent control of ultrafast lasers with wavelength-resolved SOP structures,which could promote further investigations of polarization-related optical signal processing techniques,such as pulse shaping and hyperspectral polarization imaging.
基金EU Horizon 2020 Research and Innovation Program EuPRAXIA Preparatory Phase,under Grant Agreement No.101079773,EU Horizon IFAST,under Grant Agreement No.101004730This research has been co-funded by the European Union-NextGeneration EU‘Integrated infrastructure initiative in Photonic and Quantum Sciences’-I-PHOQS(IR0000016,ID D2B8D520,CUP B53C22001750006)+1 种基金‘EuPRAXIA Advanced Photon Sources’-EuAPS(IR0000030,CUP I93C21000160006)the Project‘Tuscany Health Ecosystem-THE’‘Spoke 1-Advanced Radiotherapies and Diagnostics in Oncology’funded by the NextGenerationEU(PNRR),Codice progetto ECS00000017,D.D.MUR No.105523 May 2022.
文摘We report the characterization of the pump absorption and emission dynamic properties of a Tm:Lu2O3 ceramic lasing medium using a three-mirror folded laser cavity.We measured a slope efficiency of 73%,which allowed us to retrieve the cross-relaxation coefficient.The behavior of our system was modeled via a set of macroscopic rate equations in both the quasi continuous wave and the pulsed pumping regime.Numerical solutions were obtained,showing a good agreement with the experimental findings.The numerical solution also yielded a cross-relaxation coefficient in very good agreement with the measured one,showing that the cross-relaxation phenomenon approaches the maximum theoretical efficiency.
基金funding from the European Union Horizon 2020 Research and Innovation programme under grant agreement no.899673G.D.V.acknowledges the support from the HOTMETA project under the PRIN 2022 MUR programme funded by the European Union-Next Generation EU-“PNRR-M4C2,investimento 1.1-“Fondo PRIN 2022”-HOT-carrier METasurfaces for Advanced photonics(HOTMETA),contract no.2022LENW33-CUP:D53D23002290006”+3 种基金by the European Union’s NextGenerationEU Programme with the I-PHOQS Infrastructure[IR0000016,ID D2B8D520,CUPB53C22001750006]“Integrated infrastructure initiative in Photonic and Quantum Sciences”A.S.and G.D.V.acknowledge financial support from the European Union’s Horizon Europe research and innovation programme under the Marie Skaodowska-Curie Action PATHWAYS HORIZON-MSCA-2023-PF-GF grant agreement no.101153856G.C.acknowledges financial support from the ERC-StG ULYSSES grant agreement no.101077181 funded by the European Unionsupported by the Federal Academic Leadership Program Priority 2030.
文摘In photonic structures,bound states in the continuum(BICs)have recently attracted huge interest in both fundamental and applied research.Quasi-BIC leaky modes resulting from in-plane symmetry breaking in metasurfaces are particularly relevant to applications,due to their high quality factor,which scales as the squared inverse of the asymmetry parameter.Here,we theoretically propose an innovative approach to switch on quasi-BICs on sub-picosecond timescales via optically induced symmetry breaking in semiconductor metasurfaces.The desired effect is granted by exploiting the spatial inhomogeneities in the distribution of photo-excited hot carriers at the single meta-atom nanometric scale.In our simulations,the quasi-BIC state manifests itself as an ultra-sharp dip in transmission,emerging upon pump arrival,and disappearing completely within the carriers'diffusion timescale.Our strategy allows to envision reconfigurable platforms with switchable high-Q resonances,with ultrafast recovery beyond the limits of carrier relaxation,typical of previous approaches.
基金funding from the EU Horizon 2020 Eu PRAXIA Preparatory Phase,under Grant Agreement No.101079773,and EU Horizon IFAST,under Grant Agreement No.101004730co-funded by the European Union–Next Generation EU‘Integrated infrastructure initiative in Photonic and Quantum Sciences’–I-PHOQS(IR0000016,ID D2B8D520,CUP B53C22001750006)and‘Eu PRAXIA Advanced Photon Sources’–Eu APS(IR0000030,CUP I93C21000160006)the funding from the National Research,Development,and Innovation Office through the National Laboratory program(contract#NKFIH 877-2/2020,and 476-4/2021)。
文摘Accelerator-driven systems(ADSs)may offer a promising technology for energy production and transmutation of nuclear waste.Here we introduce the concept of utilizing high-intensity laser acceleration technology in realizing an ADS,with a focus on the use of thorium fuel in subcritical systems.We explore state-of-the-art laser-driven particle sources for neutron generation by nuclear fusion,spallation or photonuclear reactions and the prospect of reaching the flux of 10^(15)n/s required to drive a subcritical reactor.We review recent advances in high-power laser amplification and assess their technological readiness in view of integration in an ADS.Finally,we present a risk analysis of a laser-driven ADS in terms of laser and target development,radiation safety and operational stability.Our conclusion highlights the potential of laser-driven ADSs as a transformative approach to nuclear fission energy.With continued research and development,technological hurdles can be overcome to fully realize sustainable,green energy production that can meet global energy demands while addressing safety and environmental concerns.
基金supported by the National Key R&D Program of China(Grant No.2017YFB0310500)the National Natural Science Foundation of China(Grant No.61575212)the Key Research Project of the Frontier Science of the Chinese Academy of Sciences(No.QYZDB-SSW-JSC022).
文摘The Yb:Lu_(2)O_(3)precursor made up of spherical particles was synthesized through the co-precipitation method in the water/ethanol solvent.The 5 at% Yb:Lu_(2)O_(3)powder is in the cubic phase after calcination at 1100℃ for 4 h.The powder also consists of spherical nanoparticles with the average particle and grain sizes of 96 and 49 nm,respectively.The average grain size of the pre-sintered ceramic sample is 526 nm and that of the sample by hot isostatic pressing grows to 612 nm.The 1.0 mm-thick sample has an in-line transmittance of 81.6%(theoretical value of 82.2%)at 1100 nm.The largest absorption cross-section at 976 nm is 0.96×1^(0-20)cm^(2) with the emission cross-section at 1033 nm of 0.92×10^(-20)cm^(2) and the gain cross sections are calculated with the smallest population inversion parameter β of 0.059.The highest slope efficiency of 68.7% with the optical efficiency of 65.1% is obtained at 1033.3 nm in quasi-continuous wave(QCW)pumping.In the case of continuous wave(CW)pumping,the highest slope efficiency is 61.0% with the optical efficiency of 54.1%.The obtained laser performance indicates that Yb:Lu_(2)O_(3)ceramics have excellent resistance to thermal load stresses,which shows great potential in high-power solid-state laser applications.
文摘Machine learning(ML)is one of the most acclaimed areas of science and technology,leading to countless real-world benefits,from industry to healthcare.ML involves creating algorithms to perform specific tasks by recognizing patterns in the data and without requiring extensive instructions,namely without being explicitly programmed.This possibility has recently attracted the attention of a broad community of scientists interested in learning,controlling,and making optimal use of quantum systems of increasing complexity,1,2 potentially leading to revolutionary progresses in many fields.
基金support from the EU’s Horizon 2020 research and innovation programme through the project ‘EuPRAXIA’(grant agreement No.653782)from the Italian Ministry of Education,University and Research(MIUR)through the PRIN project‘Preclinical Tool for Advanced Translational Research with Ultrashort and Ultraintense xray Pulses’(prot.20154F48P9)from the MIUR through the research network funding ELI-Italy(‘Attoseconds’)
文摘A study of the structure of the electric and magnetic fields of ultraintense laser pulses focused by an off-axis parabolic mirror is reported. At first, a theoretical model is laid out, whose final equations integration allows the space and time structure of the fields to be retrieved. The model is then employed to investigate the field patterns at different times within the optical cycle, for off-axis parabola parameters normally employed in the context of ultraintense laser–plasma interaction experiments. The results show that nontrivial, complex electromagnetic field patterns are observed at the time at which the electric and magnetic fields are supposed to vanish. The importance of this effect is then studied for different laser polarizations, f numbers and off-axis angles.
文摘Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual design of reactors for the production of electricity.A major milestone has recently been announced in laser fusion by the Lawrence Livermore National Laboratory and is giving new thrust to laser-fusion energy research worldwide.Here we discuss how these circumstances strongly suggest the need for a European intermediate-energy facility dedicated to the physics and technology of laser-fusion ignition,the physics of fusion materials and advanced technologies for high-repetitionrate,high-average-power broadband lasers.We believe that the participation of the broader scientific community and the increased engagement of industry,in partnership with research and academic institutions,make most timely the construction of this infrastructure of extreme scientific attractiveness.
文摘In the 2015 review paper‘Petawatt Class Lasers Worldwide’a comprehensive overview of the current status of highpower facilities of>200 TW was presented.This was largely based on facility specifications,with some description of their uses,for instance in fundamental ultra-high-intensity interactions,secondary source generation,and inertial confinement fusion(ICF).With the 2018 Nobel Prize in Physics being awarded to Professors Donna Strickland and Gerard Mourou for the development of the technique of chirped pulse amplification(CPA),which made these lasers possible,we celebrate by providing a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed.We are now in the era of multi-petawatt facilities coming online,with 100 PW lasers being proposed and even under construction.In addition to this there is a pull towards development of industrial and multi-disciplinary applications,which demands much higher repetition rates,delivering high-average powers with higher efficiencies and the use of alternative wavelengths:mid-IR facilities.So apart from a comprehensive update of the current global status,we want to look at what technologies are to be deployed to get to these new regimes,and some of the critical issues facing their development.
基金Ministero dell’Istruzione,dell’Universitàe della Ricerca(R18SPB8227)European Research Council(740355,874596)+1 种基金Region Nouvelle Aquitaine(F2MH,SIP2)National Research Agency under the Investments for the future program(ANR-10-LABX-0074-01 Sigma-LIM)。
文摘Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams,coupled with novel nonlinear optics-based applications.However,optical fiber breakdown occurs when beam intensities exceed a certain critical value.Optical breakdown associated with irreversible modifications of the refractive index,triggered by multiphoton absorption,has been largely exploited for fiber material microstructuration.Here we show that,for light beam intensities slightly below the breakdown threshold,nonlinear absorption strongly affects the dynamics of a propagating beam as well.We experimentally analyze this subthreshold regime and highlight the key role played by spatial self-imaging in graded-index fibers for enhancing nonlinear optical losses.We characterize the nonlinear power transmission properties of multimode fibers for femtosecond pulses propagating in the near-infrared spectral range.We show that an effective N-photon absorption analytical model is able to describe the experimental data well.
文摘The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research.This accomplishment paves the way for using laser inertial fusion as a viable approach for future energy production.Europe has a unique opportunity to empower research in this field internationally,and the scientific community is eager to engage in this journey.We propose establishing a European programme on inertial-fusion energy with the mission to demonstrate laser-driven ignition in the direct-drive scheme and to develop pathway technologies for the commercial fusion reactor.The proposed roadmap is based on four complementary axes:(ⅰ)the physics of laser-plasma interaction and burning plasmas;(ⅱ)high-energy high repetition rate laser technology;(ⅲ)fusion reactor technology and materials;and(ⅳ)reinforcement of the laser fusion community by international education and training programmes.We foresee collaboration with universities,research centres and industry and establishing joint activities with the private sector involved in laser fusion.This project aims to stimulate a broad range of high-profile industrial developments in laser,plasma and radiation technologies along with the expected high-level socio-economic impact.
基金HORIZON EUROPE European Research Council(101081871,740355)H2020 Marie Sk?odowskaCurie Actions(101023717,101064614)+2 种基金Ministero dell'Istruzionedell'Universitàe della Ricerca(R18SPB8227)Sapienza University of Rome(SP12218480C7D1E9)。
文摘We develop a spatiotemporal mode decomposition technique to study the spatial and temporal mode power distribution of ultrashort pulses in long spans of graded-index multimode fiber,for different input laser conditions.We find that the beam mode power content in the dispersive pulse propagation regime can be described by the Bose-Einstein law,as a result of the process of power diffusion from linear and nonlinear mode coupling among nondegenerate mode groups.In the soliton regime,the output mode power distribution approaches the Rayleigh-Jeans law.
基金supported by the European Network of Excellence Nanophotonics for Energy Efficiency and the ERC through the Advanced Grant PhotBots(Proj.Ref.291349).
文摘Spatio-temporal imaging of light propagation is very important in photonics because it provides the most direct tool available to study the interaction between light and its host environment.Sub-ps time resolution is needed to investigate the fine and complex structural features that characterize disordered and heterogeneous structures,which are responsible for a rich array of transport physics that have not yet been fully explored.A newly developed wide-field imaging system enables us to present a spatiotemporal study on light transport in various disordered media,revealing properties that could not be properly assessed using standard techniques.By extending our investigation to an almost transparent membrane,a configuration that has been difficult to characterize until now,we unveil the peculiar physics exhibited by such thin scattering systems with transport features that go beyond mainstream diffusion modeling,despite the occurrence of multiple scattering.
基金European Regional Development Fund(ERDF)(Optimal)Agence Nationale de la Recherche(ANR)(ANR-14-CE32-0019,ANR-15-IDEX-01,ANR-17-CE30-0006-01,PN-II-ID-JRPRO-FR-2014-0013)
文摘We demonstrate a squeezing experiment exploiting the association of integrated optics and telecom technology as key features for compact, stable, and practical continuous variable quantum optics. In our setup, squeezed light is generated by single-pass spontaneous parametric down conversion on a lithium niobate photonic circuit and detected by a homodyne detector whose interferometric part is directly integrated on the same platform. The remaining parts of the experiment are implemented using commercial plug-and-play devices based on guided-wave technologies. We measure, for a CW pump power of 40 mW, a squeezing level of -2.00±0.05 dB (anti-squeezing 2.80 ±0.05 dB), thus confirming the validity of our approach and opening the way toward miniaturized and easy-to-handle continuous variable-based quantum systems.
