检索结果-南通市图书馆

Photonics Research 2024年第4期12卷 774-783页

作者： LIHONG HONG YUANYUAN LIU ZHI-YUAN LI State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

We present a detailed theoretical and numerical analysis on the temporal-spectral-spatial evolution of a highpeak-power femtosecond laser pulse in two sets of systems:a pure lithium niobate(LN)plate and a periodically poled lithium niobate(PPLN)plate.We develop a modified unidimensional pulse propagation model that considers all the prominent linear and nonlinear processes and carried out the simulation process based on an improved split-step Fourier transformation method.We theoretically analyze the synergic action of the linear dispersion effect,the second-order nonlinearity(2nd-NL)second-harmonic generation(SHG)effect,and the third-order nonlinearity(3rd-NL)self-phase modulation(SPM)effect,and clarify the physical mechanism underlying the peculiar and diverse spectral broadening patterns previously reported in LN and PPLN thin plate experiments.Such analysis and discussion provides a deeper insight into the synergetic contribution of these linear and nonlinear effects brought about by the interaction of a femtosecond laser pulse with the LN nonlinear crystal and helps to draw a picture to fully understand these fruitful optical physical processes,phenomena,and laws.

关键词： pulse nonlinearity lithium

Ultra-high extinction ratio optical pulse generation with a thin film lithium niobate modulator for distributed acoustic sensing

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2024年第1期12卷 40-50页

作者： YUAN SHEN XIAOQIAN SHU LINGMEI MA SHAOLIANG YU GENGXIN CHEN LIU LIU RENYOU GE BIGENG CHEN YUNJIANG RAO Research Center for Optical Fiber Sensing Zhejiang LaboratoryHangzhou 311100China Research Center for Intelligent Optoelectronic Computing Zhejiang LaboratoryHangzhou 311100China International Research Center for Advanced Photonics College of Optical Science and EngineeringZhejiang UniversityHangzhou 310058China Fiber Optics Research Center(FORC) Key Laboratory of Optical Fiber Sensing and CommunicationsUniversity of Electronic Science and Technology of ChinaChengdu 611731China

We experimentally demonstrate ultra-high extinction ratio(ER)optical pulse modulation with an electro-optical modulator(EOM)on thin film lithium niobate(TFLN)and its application for fiber optic distributed acoustic sensing(DAS).An interface carrier effect leading to a relaxation-tail response of TFLN EOM is discovered,which can be well addressed by a small compensation component following the main driving signal.An ultrahigh ER>50 dB is achieved by canceling out the tailed response during pulse modulation using the EOM based on a cascaded Mach–Zehnder interferometer(MZI)structure.The modulated optical_(√)pulses are then utilized as a probe light for a DAS system,showing a sensitivity up to-62.9 dB·rad∕Hz~2(7 pε/Hz)for 2-km single-mode sensing fiber.Spatial crosstalk suppression of 24.9 dB along the fiber is also obtained when the ER is improved from 20 dB to 50 dB,clearly revealing its importance to the sensing performance.

关键词： modulator pulse interferometer

Heat management technology for solid-state high voltage and high repetitive pulse generators:Towards better effects and reliability

在线全文

学校读者我要写书评

暂无评论

High Voltage 2024年第1期9卷 2-21页

作者： Yanan Wang Linyuan Ren Zihao Yang Saikang Shen Zichen Deng Qi Yuan Weidong Ding Zhenjie Ding School of Electrical Engineering Xi'an Jiaotong UniversityXi'anChina School of Electronic and Information Engineering Xi'an Jiaotong UniversityXi'anChina

Solid-state high voltage high repetitive pulse generators have a broad prospect in various applications.The high power and high-frequency operation of the pulse generator suffer from the massive heat dissipation problem,which limits the improvement of the output parameters and even affects the lifetime.This article focuses on heat management technology for high voltage high repetitive pulse generators.Firstly,the typical circuit topology of the high repetitive pulse generators was summarised.From the perspective of different application requirements,the demands of the heat management design were concluded.Moreover,the heat generation characteristics and difficulties of solid-state high voltage high repetitive pulse generators were analysed.Then,the different stateof-art cooling techniques were reviewed,and their applicability and limitations for the high voltage high repetitive generators were discussed.Finally,a flow chart for heat management design was given.

关键词： pulse state high

Observation of regular pulse train in a narrow-band optoelectronic oscillator

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Optoelectronics Letters 2024年第2期20卷 94-99页

作者： ZHAO Chunbo TUO Zhuoyue YAO Jiali HE Yuling ZHAI Shenghua MENG Yansong China Academy of Space Technology(Xi’an) Xi’an 710000China National Key Laboratory of Science and Technology on Space Microwave Xi’an 710000China1

We have experimentally observed a new operating state of a regular pulse train in a narrow-band optoelectronic oscillator(OEO) system, where the direct-current(DC) bias of the Mach-Zehnder modulator is set at the maximum value of the transmission transfer function instead of the usual quadrature point. The observed quasi-steady-state pulse train is distinctly periodic, with a period of 10.5 μs and a center frequency of 10 GHz, and resembles a mode-locked OEO in its waveform. The formation of regular pulses here may arise from the dynamic balance of nonlinearity and narrow-band filter effects, with the transient characteristics of the pulses arising mainly from instabilities between the gain and cavity loss. Our results are of great importance for deepening the understanding of the nonlinear dynamical processes in OEO systems.

关键词： optoelectronic pulse modulator

On the generation of high-quality Nyquist pulses in mode-locked fiber lasers

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第3期33卷 424-427页

作者：任俞宣葛锦蔓李小军彭俊松曾和平 State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062China National Key Laboratory of Science and Technology on Space Microwave China Aerospace Science and TechnologyXi'an 710100China Chongqing Key Laboratory of Precision Optics Chongqing Institute of East China Normal UniversityChongqing 401120China Jinan Institute of Quantum Technology Jinan 250101China

Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.

关键词： mode locking laser soliton fiber pulse

Intense Mid-Infrared Laser pulse Generated via Flying-Mirror Red-Shifting in Near-Critical-Density Plasmas

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第2期41卷 42-46页

作者：鲁瑜李东澳李倩妮邵福球余同普 Department of Physics National University of Defense TechnologyChangsha 410073China

Relativistic femtosecond mid-infrared pulses can be generated efficiently by laser interaction with near-criticaldensity plasmas.It is found theoretically and numerically that the radiation pressure of a circularly polarized laser pulse first compresses the plasma electrons to form a dense flying mirror with a relativistic high speed.The pulse reflected by the mirror is red-shifted to the mid-infrared range.Full three-dimensional simulations demonstrate that the central wavelength of the mid-infrared pulse is tunable from 3µm to 14µm,and the laser energy conversion efficiency can reach as high as 13%.With a 0.5–10 PW incident laser pulse,the generated mid-infrared pulse reaches a peak power of 10–180 TW,which is interesting for various applications in ultrafast and high-field sciences.

关键词： mirror Infrared pulse

Nonstationary laser-supported ionization wave in layer of porous substance with subcritical density

在线全文

学校读者我要写书评

暂无评论

Matter and Radiation at Extremes 2024年第1期9卷 58-70页

作者： S.Yu Gus’kov R.A.Yakhin P.N.Lebedev Physical Institute of Russian Academy of Sciences Leninskii Prospect 53Moscow 119991Russia

A time-dependent analytical solution is found for the velocity of a plane ionization wave generated under nanosecond laser pulse action on the surface of a flat layer of low-Z porous substance with density less than the critical density of the produced plasma.With corrections for the two-dimensional nature of the problem when a laser beam of finite radius interacts with a flat target,this solution is in quantitative agreement with measurements of ionization wave velocity in various experiments.The solution compared with experimental data covering wide ranges of performance conditions,namely,(3-8)×10^(14)W cm^(−2)for laser pulse intensity,0.3-3 ns for pulse duration,0.35-0.53μm for laser wavelength,100-1000μm for laser beam radius,380-950μm for layer thickness,4.5-12 mg cm^(−3)for average density of porous substance,and 1-25μm for average pore size.The parameters of the laser beam that ensure the generation of a plane ionization wave in a layer of subcritical porous matter are determined for the problem statements and are found to meet the requirements of practical applications.

关键词： laser pulse porous

Comparison of ultrashort pulse ablation of gold in air and water by time-resolved experiments

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2022年第4期11卷 615-627页

作者： Maximilian Spellauge Carlos Donate-Buendia Stephan Barcikowski Bilal Gokce Heinz P.Huber Department of Applied Sciences and Mechatronics Munich University of Applied SciencesLothstraBe 3480335 MunichGermany Technical Chemistry I and Center for Nanointegration Duisburg-Essen(CENIDE) University of Duisburg-Essen45141 EssenGermany Materials Science and Additive Manufacturing School of Mechanical Engineering and Safety EngineeringUniversity of Wuppertal42119 WuppertalGermany

Laser ablation in liquids is a highly interdisciplinary method at the intersection of physics and chemistry that offers the unique opportunity to generate surfaaant-free and stable nanoparticles from virtually any material.Over the last decades,numerous experimental and computational studies aimed to reveal the transient processes governing laser ablation in liquids.Most experimental studies investigated the involved processes on timescales ranging from nanoseconds to microseconds.However,the ablation dynamics occurring on a sub-nanosecond timescale are of fundamental importance,as the conditions under which nanoparticles are generated are established within this timeframe.Furthermore,experimental investigations of the early timescales are required to test computational predictions.We visualize the complete spatiotemporal picosecond laser-induced ablation dynamics of gold immersed in air and water using ultrafast pump-probe microscopy.Transient reflectivity measurements reveal that the water confinement layer significantly influences the ablation dynamics on the entire investigated timescale from picoseconds to microseconds.The influence of the water confinement layer includes the electron injection and subsequent formation of a dense plasma on a picosecond timescale,the confinement of ablation products within hundreds of picoseconds,and the generation of a cavitation bubble on a nanosecond timescale.Moreover,we are able to locate the temporal appearance of secondary nanoparticles at about 600 ps after pulse impact.The results support computational predictions and provide valuable insight into the early-stage ablation dynamics governing laser ablation in liquids.

关键词： pulse ultrashort pump

Ultrashort pulse laser ablation in liquids:probing the first nanoseconds of underwater phase explosion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2022年第6期11卷 1005-1007页

作者： Chaobo Chen Leonid V.Zhigilei Department of Materials Science and Engineering University of Virginia395 McCormick RoadCharlottesvilleVA 22904-4745USA

The ultrafast pump-probe microscopy has shed new light on the complex dynamics of laser-induced explosive phase transformations and highlighted the importance of close integration of experimental,computational,and the... 详细信息

关键词： laser pump pulse

Arterial stiffness expressed as brachial–ankle pulse wave velocity and gait assessment independent of lower extremity strength:a cross-sectional study in the older men population

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Geriatric Cardiology 2023年第2期20卷 91-99页

作者： Tae Kyung Yoo Seunghee Lee Sae-Jong Park Jong-Young Lee Department of Medicine MetroWest Medical CenterFraminghamUSA Department of Physical Education Korea UniversitySeoulSouth Korea Division of Sports Science Korea Institute of Sport ScienceSeoulSouth Korea Division of Cardiology Department of Internal MedicineKangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoulSouth Korea

BACKGROUND Older men are more vulnerable to fatal falls than women,and gait disturbances contribute to the risk of falls.Studies have assessed the association between arterial stiffness and gait dysfunction,but the results have been inconclusive.This study aimed to conduct a cross-sectional analysis to evaluate the association between brachial–ankle pulse wave velocity(baPWV)and gait assessment in older men.METHODS Data from the 2014–2015 Korea Institute of Sport Science Fitness Standards project were used for the analysis.The inclusion criteria were men aged>65 years with gait assessment[the 30-s chair stand test(30s-CST),the timed up and go(TUG)test,the figure-of-8 walk(F8W)test,the 2-min step test(2MST),and the 6-min walk test(6MWT)]and baPWV measurement data.Generalized linear regression analysis was conducted with multiple confounding factor adjustments,including lower extremity isometric strength.RESULTS A total of 291 participants were included in the analysis.The mean age was 71.38±4.40 years.The mean values were as follows:(1)30s-CST,17.48±5.00;(2)TUG test,6.01±1.10 s;(3)F8W test,25.65±4.71 s;(4)2MST,102.40±18.83 per 2 min;and(5)6MWT,500.02±85.65 m.After multivariable adjustment,baPWV was associated with the 6MWT(β=−0.037,95%CI:−0.072–−0.002),TUG test(β=0,95%CI:0.000–0.001),and F8W test(β=0.002,95%CI:0.000–0.004).baPWV was not associated with the 30s-CST and 2MST.CONCLUSIONS The current study showed a statistically significant association between gait assessments and arterial stiffness,independent of lower extremity strength.However,this association was modest.Future prospective studies are needed to elucidate the complex relationship between arterial stiffness and gait dysfunction.

关键词： stiffness sectional pulse