Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray...Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray angle,refractive index-based CLSs have an advantage over the commonly used alternative approaches.However,conventional high-index CLSs overheat at relatively low input power as the maximum temperature,located in a hot-spot,increases linearly with the input power.This applies particularly to CLSs in thulium-based fiber systems,where very low power can already lead to extreme heat generation due to the high cladding material absorption around 2μm.Here,we investigate materials with a highly negative thermooptical coefficient combined with a refractive index closely above glass to distribute the stripped power and heat uniformly along an increased fiber length.Analyzing multiple CLS geometries for fiber diameters of 125 and 400μm,we show record-high maximum input powers for single-material CLSs of 21.8 W for the signal(2039 nm)and 675 W for the pump wavelength(793 nm).Transmitting excess light instead of overheating,this wavelength-adaptable self-protecting CLS concept is fast to apply onsite in the lab and reaches stripping efficiencies of>40 dB in the bent version.展开更多
Sodium-ion batteries have emerged as promising alternatives to lithium-ion batteries due to their abundant raw material reserves,low cost,enhanced safety,and environmental sustainability.Na_(2)Fe_(2)OS_(2),featuring a...Sodium-ion batteries have emerged as promising alternatives to lithium-ion batteries due to their abundant raw material reserves,low cost,enhanced safety,and environmental sustainability.Na_(2)Fe_(2)OS_(2),featuring a layered anti-perovskite structure,has attracted significant interest for its high capacity and facile synthesis.In this study,density functional theory calculations were performed to systematically investigate the phase stability,ionic conductivity,and voltage characteristics of Na_(2)Fe_(2)OS_(2)as a model system for anti-perovskite layered cathode materials.The compound exhibits excellent phase stability,and its equilibrium potential was calculated for the series Na_(x)Fe_(2)OCh_(2)(0<±<2)(where Ch represents chalcogenides).Naion transport analysis using the climbing image nudged elastic band method reveals a relatively low migration barrier(~0.47eV)along a dingonal pathway,indicating efficient Na^(+)mobility.To expand the materials design space,we systematically explored the effects of substituting Fe with various transition metals and replacing S with Se in NaaTM_(2)OCh_(2)structures.Among the variants studied,Na_(2)Mn_(2)OS_(2) demonstrates the most favorable combination of high voltage(~2.51V),robust phase stability,and superior energy density(~427 W-h/kg).This comprehensive comparison of transition metal substitutions provides vnluable insights for the rational design and experimental development of next-generation anti-perovskite layered cathode materials for sodium-ion batteries.展开更多
Anti-perovskite cathodes,typified by Li_(2)FeSO,hold great promise for Li-ion batteries due to their high specific capacity,cost-effectiveness,and ease of production.However,their utilization in high-energydensity bat...Anti-perovskite cathodes,typified by Li_(2)FeSO,hold great promise for Li-ion batteries due to their high specific capacity,cost-effectiveness,and ease of production.However,their utilization in high-energydensity batteries is hindered by low Li intercalation voltage and limited rate performance.This study employs first-principles calculations to assess the impact of element substitutions and doping on the voltage and Li-ion migration energy barrier in Li_(2)TMSO(TM=Cu,Ni,Co,Fe,V,Cr,Ti)anti-perovskite materials.Our findings reveal that replacing the S element with Se or Te in Li_(2)FeSO and Li_(2)MnSO can reduce the voltage.For Li_(2)TMSO(TM=Cu,Ni,Co,Fe,V,Cr,Ti),the voltage increases as TM changes from Ti to Ni.This process closely related to the downward shift of the TM-3d electron orbital energy level.When the energy level difference between TM-3d and S-3p orbital energy levels is large,the voltage is determined by TM-3d orbitals.When the difference is small,S-3p participates in the reaction.Additionally,doping with the inactive element Mg could allow deeper energy level electrons to participate in the reaction,thus increasing the voltage.To simultaneously enhance intercalation voltage and rate performance,we investigated multi-element doping strategies for anti-perovskite cathode materials.Our study establishes a solid foundation the development of high-voltage anti-perovskite cathodes,holding promise for significant advancements in energy storage technology.展开更多
Energy storage plays a critical role in sustainable development,with secondary batteries serving as vital technologies for efficient energy conversion and utilization.This review provides a comprehensive summary of re...Energy storage plays a critical role in sustainable development,with secondary batteries serving as vital technologies for efficient energy conversion and utilization.This review provides a comprehensive summary of recent advancements across various battery systems,including lithium-ion,sodium-ion,potassium-ion,and multivalent metal-ion batteries such as magnesium,zinc,calcium,and aluminum.Emerging technologies,including dual-ion,redox flow,and anion batteries,are also discussed.Particular attention is given to alkali metal rechargeable systems,such as lithium-sulfur,lithium-air,sodium-sulfur,sodium-selenium,potassium-sulfur,potassium-selenium,potassium-air,and zinc-air batteries,which have shown significant promise for high-energy applications.The optimization of key components—cathodes,anodes,electrolytes,and interfaces—is extensively analyzed,supported by advanced characterization techniques like time-of-flight secondary ion mass spectrometry(TOF-SIMS),synchrotron radiation,nuclear magnetic resonance(NMR),and in-situ spectroscopy.Moreover,sustainable strategies for recycling spent batteries,including pyrometallurgy,hydrometallurgy,and direct recycling,are critically evaluated to mitigate environmental impacts and resource scarcity.This review not only highlights the latest technological breakthroughs but also identifies key challenges in reaction mechanisms,material design,system integration,and waste battery recycling,and presents a roadmap for advancing high-performance and sustainable battery technologies.展开更多
Optical metasurfaces,which consist of subwavelength scale meta-atoms,represent a novel platform to manipulate the polarization and phase of light.The optical performance of metasurfaces heavily relies on the quality o...Optical metasurfaces,which consist of subwavelength scale meta-atoms,represent a novel platform to manipulate the polarization and phase of light.The optical performance of metasurfaces heavily relies on the quality of nanofabrication.Retrieving the Jones matrix of an imperfect metasurface optical element is highly desirable.We show that this can be realized by decomposing the generalized Jones matrix of a meta-atom into two parallel ones,which correspond to the ideal matrix and a phase retardation.To experimentally verify this concept,we designed and fabricated metasurface polarizers,which consist of geometric phase-controlled dielectric meta-atoms.By scanning the polarization states of the incident and transmitted light,we are able to extract the coefficients of the two parallel matrices of a metasurface polarizer.Based on the results of the Jones matrix decomposition,we also demonstrated polarization image encryption and spin-selective optical holography.The proposed Jones matrix retrieval protocol may have important applications in computational imaging,optical computing,optical communications,and so on.展开更多
High-performance, large-area optical gratings for applications like chirped pulse amplification, gravitational wave astronomy, and X-ray optics require sub-nanometer line placement control over several cm^(2). Electro...High-performance, large-area optical gratings for applications like chirped pulse amplification, gravitational wave astronomy, and X-ray optics require sub-nanometer line placement control over several cm^(2). Electron beam lithography with a variable shaped beam(VSB) is well suited but limited by tool-dependent address grid discretization. We adapted address grid interpolation to the VSB method, reducing the effective placement grid to 25 pm, as confirmed by stray light measurements.展开更多
Since the advent of femtosecond lasers,performance improvements have constantly impacted on existing applications and enabled novel applications.However,one performance feature bearing the potential of a quantum leap ...Since the advent of femtosecond lasers,performance improvements have constantly impacted on existing applications and enabled novel applications.However,one performance feature bearing the potential of a quantum leap for high-field applications is still not available:the simultaneous emission of extremely high peak and average powers.Emerging applications such as laser particle acceleration require exactly this performance regime and,therefore,challenge laser technology at large.On the one hand,canonical bulk systems can provide pulse peak powers in the multi-terawatt to petawatt range,while on the other hand,advanced solid-state-laser concepts such as the thin disk,slab or fibre are well known for their high efficiency and their ability to emit high average powers in the kilowatt range with excellent beam quality.In this contribution,a compact laser system capable of simultaneously providing high peak and average powers with high wall-plug efficiency is proposed and analysed.The concept is based on the temporal coherent combination(pulse stacking)of a pulse train emitted from a high-repetition-rate femtosecond laser system in a passive enhancement cavity.Thus,the pulse energy is increased at the cost of the repetition rate while almost preserving the average power.The concept relies on a fast switching element for dumping the enhanced pulse out of the cavity.The switch constitutes the key challenge of our proposal.Addressing this challenge could,for the first time,allow the highly efficient dumping of joule-class pulses at megawatt average power levels and lead to unprecedented laser parameters.展开更多
Ultrathin metasurfaces have shown the capability to influence all aspects of light propagation.This has made them promising options for replacing conventional bulky imaging optics while adding advantageous optical pro...Ultrathin metasurfaces have shown the capability to influence all aspects of light propagation.This has made them promising options for replacing conventional bulky imaging optics while adding advantageous optical properties or functionalities.We demonstrate that such metasurfaces can also be applied for single-lens three-dimensional(3-D)imaging based on a specifically engineered point-spread function(PSF).Using Huygens’metasurfaces with high transmission,we design and realize a phase mask that implements a rotating PSF for 3-D imaging.We experimentally characterize the properties of the realized double-helix PSF,finding that it can uniquely encode object distances within a wide range.Furthermore,we experimentally demonstrate wide-field depth retrieval within a 3-D scene,showing the suitability of metasurfaces to realize optics for 3-D imaging,using just a single camera and lens system.展开更多
Aperiodic sinusoidal patterns that are cast by a GOBO(GOes Before Optics)projector are a powerful tool for optically measuring the surface topography of moving or deforming objects with very high speed and accuracy.We...Aperiodic sinusoidal patterns that are cast by a GOBO(GOes Before Optics)projector are a powerful tool for optically measuring the surface topography of moving or deforming objects with very high speed and accuracy.We optimised the first experimental setup that we were able to measure inflating car airbags at frame rates of more than 50 kHz while achieving a 3D point standard deviation of~500μm.Here,we theoretically investigate the method of GOBO projection of aperiodic sinusoidal fringes.In a simulation-based performance analysis,we examine the parameters that influence the accuracy of the measurement result and identify an optimal pattern design that yields the highest measurement accuracy.We compare the results with those that were obtained via GOBO projection of phase-shifted sinusoidal fringes.Finally,we experimentally verify the theoretical findings.We show that the proposed technique has several advantages over conventional fringe projection techniques,as the easy-to-build and cost-effective GOBO projector can provide a high radiant flux,allows high frame rates,and can be used over a wide spectral range.展开更多
The effect of transverse mode instability (TMI) is currently the main limitation for thefurther average-power scaling of fiber laser systems with diffraction-limited beamquality. In this work a main driving force for ...The effect of transverse mode instability (TMI) is currently the main limitation for thefurther average-power scaling of fiber laser systems with diffraction-limited beamquality. In this work a main driving force for TMI in fiber amplifiers is identified. Ourexperiments and simulations illustrate that the performance of fiber laser systems interms of their diffraction-limited output power can be significantly reduced whenthe pump or seed radiation exhibit intensity noise. This finding emphasizes the factthat the TMI threshold is not only determined by the active fiber but, rather, by thewhole system. In the experiment an artificially applied pump intensity-noise of 2.9%led to a reduction of the TMI threshold of 63%, whereas a similar seed intensitynoisedecreased it by just 13%. Thus, even though both noise sources have animpact on the TMI threshold, the pump intensity-noise can be considered as themain driver for TMI in saturated fiber amplifiers. Additionally, the work unveils thatthe physical origin of this behavior is linked to the noise transfer function insaturated fiber amplifiers. With the gained knowledge and the experimental andtheoretical results, it can be concluded that a suppression of pump-noise frequenciesbelow 20 kHz could strongly increase the TMI threshold in high-power fiber lasersystems.展开更多
Adaptive optics systems are used to compensate for wavefront distortions introduced by atmospheric turbulence.The distortions are corrected by an adaptable device,normally a deformable mirror.The control signal of the...Adaptive optics systems are used to compensate for wavefront distortions introduced by atmospheric turbulence.The distortions are corrected by an adaptable device,normally a deformable mirror.The control signal of the mirror is based on the measurement delivered by a wavefront sensor.Relevant characteristics of the wavefront sensor are the measurement accuracy,the achievable measurement speed and the robustness against scintillation.The modal holographic wavefront sensor can theoretically provide the highest bandwidth compared to other state of the art wavefront sensors and it is robust against scintillation effects.However,the measurement accuracy suffers from crosstalk effects between different aberration modes that are present in the wavefront.In this paper we evaluate whether the sensor can be used effectively in a closed-loop AO system under realistic turbulence conditions.We simulate realistic optical turbulence represented by more than 2500 aberration modes and take different signal-to-noise ratios into account.We determine the performance of a closed-loop AO system based on the holographic sensor.To counter the crosstalk effects,careful choice of the key design parameters of the sensor is necessary.Therefore,we apply an optimization method to find the best sensor design for maximizing the measurement accuracy.By modifying this method to take the changing effective turbulence conditions during closed-loop operation into account,we can improve the performance of the system,especially for demanding signal-to-noise-ratios,even more.Finally,we propose to implement multiple holographic wavefront sensors without the use of additional hardware,to perform multiple measurement at the same time.We show that the measurement accuracy of the sensor and with this the wavefront flatness can be increased significantly without reducing the bandwidth of the adaptive optics system.展开更多
Quasicrystal metasurfaces,a kind of two-dimensional artificial optical materials with subwavelength meta-atoms arranged in quasi-periodic tiling schemes,have attracted extensive attentions due to their novel optical p...Quasicrystal metasurfaces,a kind of two-dimensional artificial optical materials with subwavelength meta-atoms arranged in quasi-periodic tiling schemes,have attracted extensive attentions due to their novel optical properties.In a recent work,a dual-functional quasicrystal metasurface,which can be used to simultaneously generate the diffraction pattern and holographic image,is experimentally demonstrated.The proposed method expands the manipulation dimensions for multi-functional quasicrystal metasurfaces and may have important applications in microscopy,optical information processing,optical encryption,etc.展开更多
Dynamic control of Airy beam has been attracting scientists’attention due to its potential applications in imaging,optical manipulation and laser manufacturing.However,traditional way of dynamic tuning of free space ...Dynamic control of Airy beam has been attracting scientists’attention due to its potential applications in imaging,optical manipulation and laser manufacturing.However,traditional way of dynamic tuning of free space Airy beam usually requires bulky optics and will inevitably limit its practical applications.To solve this issue,a recent work proposes to use a compact meta-device which consists of two cascaded dielectric metasurfaces working in the visible regime.展开更多
In this review,we address the emerging field of quantum photonic sensing leveraging the polarization degree of freedom.We briefly discuss the main aspects of treating polarization in quantum optics,and provide an over...In this review,we address the emerging field of quantum photonic sensing leveraging the polarization degree of freedom.We briefly discuss the main aspects of treating polarization in quantum optics,and provide an overview of the main trends in the development of the field and the strategies to realize quantum-enhanced polarization-based sensing as well as a comprehensive survey of the main advancements in the field.We aim at promoting quantum approaches to the researchers in classical optical polarimetry as well as underscoring the sustainability and resourcefulness of the field for prospective applications and attracting the researchers in quantum optics to this new emerging field.展开更多
Ultrafast modulation of light is of great importance in optical communications,optical spectroscopy,precision measurement and so on.To achieve better modulation performance,various materials platforms including photon...Ultrafast modulation of light is of great importance in optical communications,optical spectroscopy,precision measurement and so on.To achieve better modulation performance,various materials platforms including photonic crystals,two-dimensional materials and plasmonic metasurfaces have been extensively explored.In this work,we demonstrate that a thinβ-BaB_(2)O_(4)which has wide band transparence and large nonlinear coefficient can be used to realize ultrafast modulation of second harmonic waves(SHWs).Under the pumping of two femtosecond laser pulses with perpendicular polarizations and variable time delay,the modulation of SHWs exhibits either slow or fast varying characteristics by using the concept of polarization selective interferometric autocorrelation.Interestingly,these two kinds of modulation behaviors depend on the real and imaginary parts of the pulse-width parameter of the chirped laser pulse.The observed physical mechanism is then utilized to generate and modulate the SHWs carrying orbital angular momentum.The proposed strategy in this work may have important applications in parallel ultrafast optical information processing and optical computing.展开更多
Rare earth-doped fibres are a diode-pumped,solid-state laser architecture that is highly scalable in average power.The performance of pulsed fibre laser systems is restricted due to nonlinear effects.Hence,fibre desig...Rare earth-doped fibres are a diode-pumped,solid-state laser architecture that is highly scalable in average power.The performance of pulsed fibre laser systems is restricted due to nonlinear effects.Hence,fibre designs that allow for very large mode areas at high average powers with diffraction-limited beam quality are of enormous interest.Ytterbium-doped,rod-type,large-pitch fibres(LPF)enable extreme fibre dimensions,i.e.,effective single-mode fibres with mode sizes exceeding 100 times the wavelength of the guided radiation,by exploiting the novel concept of delocalisation of higher-order transverse modes.The non-resonant nature of the operating principle makes LPF suitable for high power extraction.This design allows for an unparalleled level of performance in pulsed fibre lasers.展开更多
The process of high harmonic generation(HHG)enables the development of table-top sources of coherent extreme ultraviolet(XUV)light.Although these are now matured sources,they still mostly rely on bulk laser technology...The process of high harmonic generation(HHG)enables the development of table-top sources of coherent extreme ultraviolet(XUV)light.Although these are now matured sources,they still mostly rely on bulk laser technology that limits the attainable repetition rate to the low kilohertz regime.Moreover,many of the emerging applications of such light sources(e.g.,photoelectron spectroscopy and microscopy,coherent diffractive imaging,or frequency metrology in the XUV spectral region)require an increase in the repetition rate.Ideally,these sources are operated with a multi-MHz repetition rate and deliver a high photon flux simultaneously.So far,this regime has been solely addressed using passive enhancement cavities together with low energy and high repetition rate lasers.Here,a novel route with significantly reduced complexity(omitting the requirement of an external actively stabilized resonator)is demonstrated that achieves the previously mentioned demanding parameters.A krypton-filled Kagome photonic crystal fiber is used for efficient nonlinear compression of 9 μJ,250 fs pulses leading to,7 μJ,31 fs pulses at 10.7 MHz repetition rate.The compressed pulses are used for HHG in a gas jet.Particular attention is devoted to achieving phase-matched(transiently)generation yielding.10^(13) photons s^(-1)(.50 μW)at 27.7 eV.This new spatially coherent XUV source improved the photon flux by four orders of magnitude for direct multi-MHZ experiments,thus demonstrating the considerable potential of this source.展开更多
In recent years,femtosecond(fs)-lasers have evolved into a versatile tool for high precision micromachining of transparent materials because nonlinear absorption in the focus can result in refractive index modificatio...In recent years,femtosecond(fs)-lasers have evolved into a versatile tool for high precision micromachining of transparent materials because nonlinear absorption in the focus can result in refractive index modifications or material disruptions.However,when high pulse energies or low numerical apertures are required,nonlinear side effects such as self-focusing,filamentation or white light generation can decrease the modification quality.In this paper,we apply simultaneous spatial and temporal focusing(SSTF)to overcome these limitations.The main advantage of SSTF is that the ultrashort pulse is only formed at the focal plane,thereby confining the intensity distribution strongly to the focal volume and suppressing detrimental nonlinear side effects.Thus,we investigate the optical breakdown within a water cell by pump-probe shadowgraphy,comparing conventional focusing and SSTF under equivalent focusing conditions.The plasma formation is well confined for low pulse energies,2 mJ,but higher pulse energies lead to the filamentation and break-up of the disruptions for conventional focusing,thereby decreasing the modification quality.In contrast,plasma induced by SSTF stays well confined to the focal plane,even for high pulse energies up to 8 mJ,preventing extended filaments,side branches or break-up of the disruptions.Furthermore,while conventional focusing leads to broadband supercontinuum generation,only marginal spectral broadening is observed using SSTF.These experimental findings are in excellent agreement with numerical simulations of the nonlinear pulse propagation and interaction processes.Therefore,SSTF appears to be a powerful tool to control the processing of transparent materials,e.g.,for precise ophthalmic fs-surgery.展开更多
The development of high-power,broadband sources of coherent mid-infrared radiation is currently the subject of intense research that is driven by a substantial number of existing and continuously emerging applications...The development of high-power,broadband sources of coherent mid-infrared radiation is currently the subject of intense research that is driven by a substantial number of existing and continuously emerging applications in medical diagnostics,spectroscopy,microscopy,and fundamental science.One of the major,long-standing challenges in improving the performance of these applications has been the construction of compact,broadband mid-infrared radiation sources,which unify the properties of high brightness and spatial and temporal coherence.Due to the lack of such radiation sources,several emerging applications can be addressed only with infrared(IR)-beamlines in largescale synchrotron facilities,which are limited regarding user access and only partially fulfill these properties.Here,we present a table-top,broadband,coherent mid-infrared light source that provides brightness at an unprecedented level that supersedes that of synchrotrons in the wavelength range between 3.7 and 18μm by several orders of magnitude.This result is enabled by a high-power,few-cycle Tm-doped fiber laser system,which is employed as a pump at 1.9μm wavelength for intrapulse difference frequency generation(IPDFG).IPDFG intrinsically ensures the formation of carrierenvelope-phase stable pulses,which provide ideal prerequisites for state-of-the-art spectroscopy and microscopy.展开更多
High harmonic generation(HHG)enables coherent extreme-ultraviolet(XUV)radiation with ultra-short pulse duration in a table-top setup.This has already enabled a plethora of applications.Nearly all of these applications...High harmonic generation(HHG)enables coherent extreme-ultraviolet(XUV)radiation with ultra-short pulse duration in a table-top setup.This has already enabled a plethora of applications.Nearly all of these applications would benefit from a high photon flux to increase the signal-to-noise ratio and decrease measurement times.In addition,shortest pulses are desired to investigate fastest dynamics in fields as diverse as physics,biology,chemistry and material sciences.In this work,the up-to-date most powerful table-top XUV source with 12.9±3.9mW in a single harmonic line at 26.5 eV is demonstrated via HHG of a frequency-doubled and post-compressed fibre laser.At the same time the spectrum supports a Fourier-limited pulse duration of sub-6 fs in the XUV,which allows accessing ultrafast dynamics with an order of magnitude higher photon flux than previously demonstrated.This concept will greatly advance and facilitate applications of XUV radiation in science and technology and enable photonhungry ultrafast studies.展开更多
文摘Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray angle,refractive index-based CLSs have an advantage over the commonly used alternative approaches.However,conventional high-index CLSs overheat at relatively low input power as the maximum temperature,located in a hot-spot,increases linearly with the input power.This applies particularly to CLSs in thulium-based fiber systems,where very low power can already lead to extreme heat generation due to the high cladding material absorption around 2μm.Here,we investigate materials with a highly negative thermooptical coefficient combined with a refractive index closely above glass to distribute the stripped power and heat uniformly along an increased fiber length.Analyzing multiple CLS geometries for fiber diameters of 125 and 400μm,we show record-high maximum input powers for single-material CLSs of 21.8 W for the signal(2039 nm)and 675 W for the pump wavelength(793 nm).Transmitting excess light instead of overheating,this wavelength-adaptable self-protecting CLS concept is fast to apply onsite in the lab and reaches stripping efficiencies of>40 dB in the bent version.
基金supported by the National Natural Science Foundation of China(Grant Nos.12404264 and 22209067)Shenzhen Basic Research Program(Natural Science Foundation)Key Project of Basic Research(Grant No.JCYJ20241202123916023)Shenzhen Science and Technology Program(Grant No.KQTD20200820113047086)。
文摘Sodium-ion batteries have emerged as promising alternatives to lithium-ion batteries due to their abundant raw material reserves,low cost,enhanced safety,and environmental sustainability.Na_(2)Fe_(2)OS_(2),featuring a layered anti-perovskite structure,has attracted significant interest for its high capacity and facile synthesis.In this study,density functional theory calculations were performed to systematically investigate the phase stability,ionic conductivity,and voltage characteristics of Na_(2)Fe_(2)OS_(2)as a model system for anti-perovskite layered cathode materials.The compound exhibits excellent phase stability,and its equilibrium potential was calculated for the series Na_(x)Fe_(2)OCh_(2)(0<±<2)(where Ch represents chalcogenides).Naion transport analysis using the climbing image nudged elastic band method reveals a relatively low migration barrier(~0.47eV)along a dingonal pathway,indicating efficient Na^(+)mobility.To expand the materials design space,we systematically explored the effects of substituting Fe with various transition metals and replacing S with Se in NaaTM_(2)OCh_(2)structures.Among the variants studied,Na_(2)Mn_(2)OS_(2) demonstrates the most favorable combination of high voltage(~2.51V),robust phase stability,and superior energy density(~427 W-h/kg).This comprehensive comparison of transition metal substitutions provides vnluable insights for the rational design and experimental development of next-generation anti-perovskite layered cathode materials for sodium-ion batteries.
基金financially supported by the Program of the National Natural Science Foundation of China(No.22209067)Stable Support Plan Program for Higher Education Institutions(No.20220814235931001)+4 种基金Shenzhen Science and Technology Program(No.KQTD20200820113047086)supported by XXX-Project(No.2020-XXXX-XX-246-00)supported by the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.22hytd01)supported by 21C Innovation Laboratory,Contemporary Amperex Technology Ltd.(No.C-ND-21C LAB-210044-1.0)by Center for Computational Science and Engineering at Southern University of Science and Technology。
文摘Anti-perovskite cathodes,typified by Li_(2)FeSO,hold great promise for Li-ion batteries due to their high specific capacity,cost-effectiveness,and ease of production.However,their utilization in high-energydensity batteries is hindered by low Li intercalation voltage and limited rate performance.This study employs first-principles calculations to assess the impact of element substitutions and doping on the voltage and Li-ion migration energy barrier in Li_(2)TMSO(TM=Cu,Ni,Co,Fe,V,Cr,Ti)anti-perovskite materials.Our findings reveal that replacing the S element with Se or Te in Li_(2)FeSO and Li_(2)MnSO can reduce the voltage.For Li_(2)TMSO(TM=Cu,Ni,Co,Fe,V,Cr,Ti),the voltage increases as TM changes from Ti to Ni.This process closely related to the downward shift of the TM-3d electron orbital energy level.When the energy level difference between TM-3d and S-3p orbital energy levels is large,the voltage is determined by TM-3d orbitals.When the difference is small,S-3p participates in the reaction.Additionally,doping with the inactive element Mg could allow deeper energy level electrons to participate in the reaction,thus increasing the voltage.To simultaneously enhance intercalation voltage and rate performance,we investigated multi-element doping strategies for anti-perovskite cathode materials.Our study establishes a solid foundation the development of high-voltage anti-perovskite cathodes,holding promise for significant advancements in energy storage technology.
基金supported by the National Natural Science Foundation of China(Nos.U21A20311 and 22409147)。
文摘Energy storage plays a critical role in sustainable development,with secondary batteries serving as vital technologies for efficient energy conversion and utilization.This review provides a comprehensive summary of recent advancements across various battery systems,including lithium-ion,sodium-ion,potassium-ion,and multivalent metal-ion batteries such as magnesium,zinc,calcium,and aluminum.Emerging technologies,including dual-ion,redox flow,and anion batteries,are also discussed.Particular attention is given to alkali metal rechargeable systems,such as lithium-sulfur,lithium-air,sodium-sulfur,sodium-selenium,potassium-sulfur,potassium-selenium,potassium-air,and zinc-air batteries,which have shown significant promise for high-energy applications.The optimization of key components—cathodes,anodes,electrolytes,and interfaces—is extensively analyzed,supported by advanced characterization techniques like time-of-flight secondary ion mass spectrometry(TOF-SIMS),synchrotron radiation,nuclear magnetic resonance(NMR),and in-situ spectroscopy.Moreover,sustainable strategies for recycling spent batteries,including pyrometallurgy,hydrometallurgy,and direct recycling,are critically evaluated to mitigate environmental impacts and resource scarcity.This review not only highlights the latest technological breakthroughs but also identifies key challenges in reaction mechanisms,material design,system integration,and waste battery recycling,and presents a roadmap for advancing high-performance and sustainable battery technologies.
基金supported by the National Key Technologies R&D Program of China (Grant No.2022YFA1404301)the Zhangjiang Laboratory,the National Natural Science Foundation of China (Grant Nos.91950114 and 12161141010)+2 种基金the Guangdong Provincial Innovation and Entrepreneurship Project (Grant No.2017ZT07C071)the Guangdong Provincial Key Laboratory Program (Grant No.2021B1212040001)the Natural Science Foundation of Shenzhen Innovation Commission (Grant No.JCYJ20200109140808088).
文摘Optical metasurfaces,which consist of subwavelength scale meta-atoms,represent a novel platform to manipulate the polarization and phase of light.The optical performance of metasurfaces heavily relies on the quality of nanofabrication.Retrieving the Jones matrix of an imperfect metasurface optical element is highly desirable.We show that this can be realized by decomposing the generalized Jones matrix of a meta-atom into two parallel ones,which correspond to the ideal matrix and a phase retardation.To experimentally verify this concept,we designed and fabricated metasurface polarizers,which consist of geometric phase-controlled dielectric meta-atoms.By scanning the polarization states of the incident and transmitted light,we are able to extract the coefficients of the two parallel matrices of a metasurface polarizer.Based on the results of the Jones matrix decomposition,we also demonstrated polarization image encryption and spin-selective optical holography.The proposed Jones matrix retrieval protocol may have important applications in computational imaging,optical computing,optical communications,and so on.
基金Bundesministerium für Bildung und Forschung(03Z1H534, 13N16028)Deutsche Forschungsgemeinschaft(448663633, 455425131)。
文摘High-performance, large-area optical gratings for applications like chirped pulse amplification, gravitational wave astronomy, and X-ray optics require sub-nanometer line placement control over several cm^(2). Electron beam lithography with a variable shaped beam(VSB) is well suited but limited by tool-dependent address grid discretization. We adapted address grid interpolation to the VSB method, reducing the effective placement grid to 25 pm, as confirmed by stray light measurements.
基金This work has been partly supported by the German Federal Ministry of Education and Research(BMBF)under contract 13N12082‘NEXUS’,by the Thuringian Ministry of Education,Science and Culture(TMBWK)under contract 12037-515‘BURST’by the European Research Council under the ERC grant agreement no.[617173]‘ACOPS’+3 种基金by the Deutsche Forschungsgemeinschaft Cluster of Excellence‘Munich-Centre for Advanced Photonics’(munich-photonics.de).AK acknowledges financial support by the Helmholtz-Institute Jena.TE acknowledges financial support by the CarlZeiss-Stiftung.IP and SH acknowledge financial support by the BMBF under PhoNa-Photonische Nanomaterialien,contract number 03IS2101B.
文摘Since the advent of femtosecond lasers,performance improvements have constantly impacted on existing applications and enabled novel applications.However,one performance feature bearing the potential of a quantum leap for high-field applications is still not available:the simultaneous emission of extremely high peak and average powers.Emerging applications such as laser particle acceleration require exactly this performance regime and,therefore,challenge laser technology at large.On the one hand,canonical bulk systems can provide pulse peak powers in the multi-terawatt to petawatt range,while on the other hand,advanced solid-state-laser concepts such as the thin disk,slab or fibre are well known for their high efficiency and their ability to emit high average powers in the kilowatt range with excellent beam quality.In this contribution,a compact laser system capable of simultaneously providing high peak and average powers with high wall-plug efficiency is proposed and analysed.The concept is based on the temporal coherent combination(pulse stacking)of a pulse train emitted from a high-repetition-rate femtosecond laser system in a passive enhancement cavity.Thus,the pulse energy is increased at the cost of the repetition rate while almost preserving the average power.The concept relies on a fast switching element for dumping the enhanced pulse out of the cavity.The switch constitutes the key challenge of our proposal.Addressing this challenge could,for the first time,allow the highly efficient dumping of joule-class pulses at megawatt average power levels and lead to unprecedented laser parameters.
基金We thank Waltraud Gräf,Daniel Voigt,Michael Banasch,and Thomas Käsebier for help with the fabrication.Financial support by the German Research Foundation within the Emmy-Noether program and the SPP“Tailored Disorder”(STA 1426/1-1,STA 1426/2-1,PE 1524/10-2)is gratefully acknowledged.Part of this research was funded by the German Federal Ministry of Education and Research(BMBF)under the project identifiers 13N14147 and 03ZZ0434.
文摘Ultrathin metasurfaces have shown the capability to influence all aspects of light propagation.This has made them promising options for replacing conventional bulky imaging optics while adding advantageous optical properties or functionalities.We demonstrate that such metasurfaces can also be applied for single-lens three-dimensional(3-D)imaging based on a specifically engineered point-spread function(PSF).Using Huygens’metasurfaces with high transmission,we design and realize a phase mask that implements a rotating PSF for 3-D imaging.We experimentally characterize the properties of the realized double-helix PSF,finding that it can uniquely encode object distances within a wide range.Furthermore,we experimentally demonstrate wide-field depth retrieval within a 3-D scene,showing the suitability of metasurfaces to realize optics for 3-D imaging,using just a single camera and lens system.
基金supported by the German Federal Ministry of Education and Research(BMBF)under project number 03ZZ0436.
文摘Aperiodic sinusoidal patterns that are cast by a GOBO(GOes Before Optics)projector are a powerful tool for optically measuring the surface topography of moving or deforming objects with very high speed and accuracy.We optimised the first experimental setup that we were able to measure inflating car airbags at frame rates of more than 50 kHz while achieving a 3D point standard deviation of~500μm.Here,we theoretically investigate the method of GOBO projection of aperiodic sinusoidal fringes.In a simulation-based performance analysis,we examine the parameters that influence the accuracy of the measurement result and identify an optimal pattern design that yields the highest measurement accuracy.We compare the results with those that were obtained via GOBO projection of phase-shifted sinusoidal fringes.Finally,we experimentally verify the theoretical findings.We show that the proposed technique has several advantages over conventional fringe projection techniques,as the easy-to-build and cost-effective GOBO projector can provide a high radiant flux,allows high frame rates,and can be used over a wide spectral range.
基金Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-416342637,416342891,GRK 2101(259607349)Fraunhofer Gesellschaft–Fraunhofer Cluster of Excellence“Advanced Photon Sources”.
文摘The effect of transverse mode instability (TMI) is currently the main limitation for thefurther average-power scaling of fiber laser systems with diffraction-limited beamquality. In this work a main driving force for TMI in fiber amplifiers is identified. Ourexperiments and simulations illustrate that the performance of fiber laser systems interms of their diffraction-limited output power can be significantly reduced whenthe pump or seed radiation exhibit intensity noise. This finding emphasizes the factthat the TMI threshold is not only determined by the active fiber but, rather, by thewhole system. In the experiment an artificially applied pump intensity-noise of 2.9%led to a reduction of the TMI threshold of 63%, whereas a similar seed intensitynoisedecreased it by just 13%. Thus, even though both noise sources have animpact on the TMI threshold, the pump intensity-noise can be considered as themain driver for TMI in saturated fiber amplifiers. Additionally, the work unveils thatthe physical origin of this behavior is linked to the noise transfer function insaturated fiber amplifiers. With the gained knowledge and the experimental andtheoretical results, it can be concluded that a suppression of pump-noise frequenciesbelow 20 kHz could strongly increase the TMI threshold in high-power fiber lasersystems.
基金This work was sponsored by WTD 91(Technical Center of Weapons and Ammunition)of the Federal Defence Forces of Germany-Bundeswehr in the project ABU-SLSby the Office of Naval Research Global under award no.N62909-17-1-2037.
文摘Adaptive optics systems are used to compensate for wavefront distortions introduced by atmospheric turbulence.The distortions are corrected by an adaptable device,normally a deformable mirror.The control signal of the mirror is based on the measurement delivered by a wavefront sensor.Relevant characteristics of the wavefront sensor are the measurement accuracy,the achievable measurement speed and the robustness against scintillation.The modal holographic wavefront sensor can theoretically provide the highest bandwidth compared to other state of the art wavefront sensors and it is robust against scintillation effects.However,the measurement accuracy suffers from crosstalk effects between different aberration modes that are present in the wavefront.In this paper we evaluate whether the sensor can be used effectively in a closed-loop AO system under realistic turbulence conditions.We simulate realistic optical turbulence represented by more than 2500 aberration modes and take different signal-to-noise ratios into account.We determine the performance of a closed-loop AO system based on the holographic sensor.To counter the crosstalk effects,careful choice of the key design parameters of the sensor is necessary.Therefore,we apply an optimization method to find the best sensor design for maximizing the measurement accuracy.By modifying this method to take the changing effective turbulence conditions during closed-loop operation into account,we can improve the performance of the system,especially for demanding signal-to-noise-ratios,even more.Finally,we propose to implement multiple holographic wavefront sensors without the use of additional hardware,to perform multiple measurement at the same time.We show that the measurement accuracy of the sensor and with this the wavefront flatness can be increased significantly without reducing the bandwidth of the adaptive optics system.
基金supported by National Key Technologies R&D Program of China(2022YFA1404301)National Natural Science Foundation of China(12161141010).
文摘Quasicrystal metasurfaces,a kind of two-dimensional artificial optical materials with subwavelength meta-atoms arranged in quasi-periodic tiling schemes,have attracted extensive attentions due to their novel optical properties.In a recent work,a dual-functional quasicrystal metasurface,which can be used to simultaneously generate the diffraction pattern and holographic image,is experimentally demonstrated.The proposed method expands the manipulation dimensions for multi-functional quasicrystal metasurfaces and may have important applications in microscopy,optical information processing,optical encryption,etc.
文摘Dynamic control of Airy beam has been attracting scientists’attention due to its potential applications in imaging,optical manipulation and laser manufacturing.However,traditional way of dynamic tuning of free space Airy beam usually requires bulky optics and will inevitably limit its practical applications.To solve this issue,a recent work proposes to use a compact meta-device which consists of two cascaded dielectric metasurfaces working in the visible regime.
基金support from the German Federal Ministry of Education and Research(BMBF,Projekt QUANCER-FKZ13N16441)the China Scholarship Council(No.201904910805)for funding and initiating the PhD exchange programthe Pro Chancecareer program of the Friedrich Schiller University Jena for funding this work。
文摘In this review,we address the emerging field of quantum photonic sensing leveraging the polarization degree of freedom.We briefly discuss the main aspects of treating polarization in quantum optics,and provide an overview of the main trends in the development of the field and the strategies to realize quantum-enhanced polarization-based sensing as well as a comprehensive survey of the main advancements in the field.We aim at promoting quantum approaches to the researchers in classical optical polarimetry as well as underscoring the sustainability and resourcefulness of the field for prospective applications and attracting the researchers in quantum optics to this new emerging field.
基金supported by the National Natural Science Foundation of China(12161141010)the National Key Technologies R&D Program of China(2022YFA1404301).
文摘Ultrafast modulation of light is of great importance in optical communications,optical spectroscopy,precision measurement and so on.To achieve better modulation performance,various materials platforms including photonic crystals,two-dimensional materials and plasmonic metasurfaces have been extensively explored.In this work,we demonstrate that a thinβ-BaB_(2)O_(4)which has wide band transparence and large nonlinear coefficient can be used to realize ultrafast modulation of second harmonic waves(SHWs).Under the pumping of two femtosecond laser pulses with perpendicular polarizations and variable time delay,the modulation of SHWs exhibits either slow or fast varying characteristics by using the concept of polarization selective interferometric autocorrelation.Interestingly,these two kinds of modulation behaviors depend on the real and imaginary parts of the pulse-width parameter of the chirped laser pulse.The observed physical mechanism is then utilized to generate and modulate the SHWs carrying orbital angular momentum.The proposed strategy in this work may have important applications in parallel ultrafast optical information processing and optical computing.
基金The research leading to these results received funding from the European Research Council under the European Union’s Seventh Framework Programme(FP7/2007-2013)/ERC Grant Agreement No.[240460]the Thuringian Ministry of Education,Science and Culture under contract PE203-2-1(MOFA)and contract B514-10061(Green Photonics).FJ acknowledges financial support from the Abbe School of Photonics.
文摘Rare earth-doped fibres are a diode-pumped,solid-state laser architecture that is highly scalable in average power.The performance of pulsed fibre laser systems is restricted due to nonlinear effects.Hence,fibre designs that allow for very large mode areas at high average powers with diffraction-limited beam quality are of enormous interest.Ytterbium-doped,rod-type,large-pitch fibres(LPF)enable extreme fibre dimensions,i.e.,effective single-mode fibres with mode sizes exceeding 100 times the wavelength of the guided radiation,by exploiting the novel concept of delocalisation of higher-order transverse modes.The non-resonant nature of the operating principle makes LPF suitable for high power extraction.This design allows for an unparalleled level of performance in pulsed fibre lasers.
基金This work was partly supported by the German Federal Ministry of Education and Research(BMBF)the European Research Council under the European Union’s Seventh Framework Programme(FP7/2007-2013)/ERC Grant Agreement No.240460Arno Klenke and Jan Rothhardt acknowledge financial support by the Helmholtz-Institute Jena.
文摘The process of high harmonic generation(HHG)enables the development of table-top sources of coherent extreme ultraviolet(XUV)light.Although these are now matured sources,they still mostly rely on bulk laser technology that limits the attainable repetition rate to the low kilohertz regime.Moreover,many of the emerging applications of such light sources(e.g.,photoelectron spectroscopy and microscopy,coherent diffractive imaging,or frequency metrology in the XUV spectral region)require an increase in the repetition rate.Ideally,these sources are operated with a multi-MHz repetition rate and deliver a high photon flux simultaneously.So far,this regime has been solely addressed using passive enhancement cavities together with low energy and high repetition rate lasers.Here,a novel route with significantly reduced complexity(omitting the requirement of an external actively stabilized resonator)is demonstrated that achieves the previously mentioned demanding parameters.A krypton-filled Kagome photonic crystal fiber is used for efficient nonlinear compression of 9 μJ,250 fs pulses leading to,7 μJ,31 fs pulses at 10.7 MHz repetition rate.The compressed pulses are used for HHG in a gas jet.Particular attention is devoted to achieving phase-matched(transiently)generation yielding.10^(13) photons s^(-1)(.50 μW)at 27.7 eV.This new spatially coherent XUV source improved the photon flux by four orders of magnitude for direct multi-MHZ experiments,thus demonstrating the considerable potential of this source.
基金This study was supported by the Thuringian Ministry of Education,Science and Culture(OptiMi 2020-Graduate Research School‘Green Photonics’,B514-10061)the German Research Foundation(Leibniz program)the Carl Zeiss Foundation.
文摘In recent years,femtosecond(fs)-lasers have evolved into a versatile tool for high precision micromachining of transparent materials because nonlinear absorption in the focus can result in refractive index modifications or material disruptions.However,when high pulse energies or low numerical apertures are required,nonlinear side effects such as self-focusing,filamentation or white light generation can decrease the modification quality.In this paper,we apply simultaneous spatial and temporal focusing(SSTF)to overcome these limitations.The main advantage of SSTF is that the ultrashort pulse is only formed at the focal plane,thereby confining the intensity distribution strongly to the focal volume and suppressing detrimental nonlinear side effects.Thus,we investigate the optical breakdown within a water cell by pump-probe shadowgraphy,comparing conventional focusing and SSTF under equivalent focusing conditions.The plasma formation is well confined for low pulse energies,2 mJ,but higher pulse energies lead to the filamentation and break-up of the disruptions for conventional focusing,thereby decreasing the modification quality.In contrast,plasma induced by SSTF stays well confined to the focal plane,even for high pulse energies up to 8 mJ,preventing extended filaments,side branches or break-up of the disruptions.Furthermore,while conventional focusing leads to broadband supercontinuum generation,only marginal spectral broadening is observed using SSTF.These experimental findings are in excellent agreement with numerical simulations of the nonlinear pulse propagation and interaction processes.Therefore,SSTF appears to be a powerful tool to control the processing of transparent materials,e.g.,for precise ophthalmic fs-surgery.
基金supported by the German Federal Ministry of Education and Research(BMBF)under contract“NUKLEUS”(13N13973)the United States AFOSR(FA9550-15-10041)+2 种基金the United States ARO(W911NF-12-1-0450 and W911NF-17-1-0501)support by the Helmholtz-Institute Jenasupport by the Carl Zeiss Stiftung.
文摘The development of high-power,broadband sources of coherent mid-infrared radiation is currently the subject of intense research that is driven by a substantial number of existing and continuously emerging applications in medical diagnostics,spectroscopy,microscopy,and fundamental science.One of the major,long-standing challenges in improving the performance of these applications has been the construction of compact,broadband mid-infrared radiation sources,which unify the properties of high brightness and spatial and temporal coherence.Due to the lack of such radiation sources,several emerging applications can be addressed only with infrared(IR)-beamlines in largescale synchrotron facilities,which are limited regarding user access and only partially fulfill these properties.Here,we present a table-top,broadband,coherent mid-infrared light source that provides brightness at an unprecedented level that supersedes that of synchrotrons in the wavelength range between 3.7 and 18μm by several orders of magnitude.This result is enabled by a high-power,few-cycle Tm-doped fiber laser system,which is employed as a pump at 1.9μm wavelength for intrapulse difference frequency generation(IPDFG).IPDFG intrinsically ensures the formation of carrierenvelope-phase stable pulses,which provide ideal prerequisites for state-of-the-art spectroscopy and microscopy.
基金supported by the Fraunhofer Cluster of Excellence Advanced Photon Sources(CAPS),by the Innovation Pool of the Research Field Matter of the Helmholtz Association of German Research Centers in project(ECRAPS)by APPA R&D:Licht-Materie Wechselwirkung mit hochgeladenen Ionen(13 N12082)+2 种基金by the Thüringer Ministerium für Bildung,Wissenschaft und Kultur(501100004404,2017 FGR 0076)by the Thüringer Aufbaubank(TAB Forschergruppe 2015FGR0094)by the Helmholtz association under grant agreement HGF ExNet-0019-Phase 2-3.
文摘High harmonic generation(HHG)enables coherent extreme-ultraviolet(XUV)radiation with ultra-short pulse duration in a table-top setup.This has already enabled a plethora of applications.Nearly all of these applications would benefit from a high photon flux to increase the signal-to-noise ratio and decrease measurement times.In addition,shortest pulses are desired to investigate fastest dynamics in fields as diverse as physics,biology,chemistry and material sciences.In this work,the up-to-date most powerful table-top XUV source with 12.9±3.9mW in a single harmonic line at 26.5 eV is demonstrated via HHG of a frequency-doubled and post-compressed fibre laser.At the same time the spectrum supports a Fourier-limited pulse duration of sub-6 fs in the XUV,which allows accessing ultrafast dynamics with an order of magnitude higher photon flux than previously demonstrated.This concept will greatly advance and facilitate applications of XUV radiation in science and technology and enable photonhungry ultrafast studies.
