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Temporal pulse shaping of Laser Beams by Optical-Fiber Stacker

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Chinese Journal of Lasers 1999年第1期8卷 46-49页

作者： WANG Chun XU Shixiang CHEN Shaohe DENG Ximing LIN Zunqi FAN Dianyuan (Shanghai Institute of Optics and Fine Mechanics, The Chinese Academy of Sciences, Shanghai 201800, China) 中科院上海光学精密机械所上海 201800 中科院上海光学精密机械所上海

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１ＩｎｔｒｏｄｕｃｔｉｏｎＰｒｅｃｉｓｅｔｅｍｐｏｒａｌｐｕｌｓｅｓｈａｐｉｎｇｏｆｔｈｅｌａｓｅｒｂｅａｍｓｆｏｒｉｎｅｒｔｉａｌｃｏｎｆｉｎｅｍｅｎｔｆｕｓｉｏｎ（ＩＣＦ）ｅｘｐｅｒｉｍｅｎｔｓｈａｓｂｅｃｏｍｅｉｎｃｒｅａｓｉｎｇｉｍｐｏｒｔ...

关键词： inertial confinement fusion pulse shaping optical fiber stacker

Optical pulse shaping based on a double-phase-shifted fiber Bragg grating

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Optoelectronics Letters 2015年第2期11卷 100-102页

作者：董小伟郭盼 College of Information Engineering North China University of Technology

Based on the transfer matrix method,a detailed theoretical and numerical study on double-phase-shifted fiber Bragg grating(FBG)is *** responses of the double-phase-shifted FBG to optical pulse are analyzed and the influence of the two phase-shifts’position on the reflected output pulse is *** demonstrate that very different temporal pulse waveforms can be achieved by adjusting the length ratio(α=L2/L1).Specifically,a transform-limited Gaussian input optical pulse can be shaped into flat-top square pulse(α=1.81)or two identical optical pulse sequences(α=1.93).

关键词： Bragg gratings Fiber Bragg gratings Numerical methods Phase shift Phase shifters pulse shaping Transfer matrix method

pulse shaping by a discrete microstrip

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Chinese Journal of Lasers 1992年第4期 67-74页

作者： Dongsheng Zhao, Tingting Zhi, Weihan Tan(Shanghai Institute of Optics and Fine Mechanics, Aedemia Sinica,P. 0. Box 800-211 ,Shanghai 201800 China)

Method for laser pulse shaping by a discrete transmission line has been improvedand *** calculations are given about deformation of the shaped pulse,passingthrough a laser *** required profile of electrical pulse can ... 详细信息

关键词： pulse shaping microstrip recursive differential method

pulse-shaping method for real-time neutron/gamma discrimination at low sampling rates

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Nuclear Science and Techniques 2023年第11期34卷 51-63页

作者： Jia‑Xin Li Hui‑Liang Hou Yue‑Feng Huang Mao‑Song Cheng Zhi‑Min Dai Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

The Na I:Tl scintillator is an innovative material for dual-gamma-ray and neutron detection with a low ^(6)Li *** achieve real-time n/γ discrimination,a zero-crossing time comparison algorithm based on trapezoidal pulse shaping was *** algorithm can operate efficiently at low sampling rates and was implemented on a single-probe portable digital n/γ discriminator based on a field-programmable gate *** discriminator and Na I:Tl,^(6)Li detector were tested in a neutron-gamma mixed field produced by an ^(241)Am-Be neutron source to evaluate the performance of the *** figure of merits was measured as 2.88 at a sampling rate of 50 MHz,indicating that the discriminator with its embedded algorithm has a promising n/γ discrimination *** discrimination at sampling rates of 40 and 25 MHz demonstrates that the capability of this method is not limited by low sampling rates.

关键词： FPGA NaI:Tl ^(6)Li Real time Neutron/gamma discrimination pulse shaping

Fast Fading Channel Neural Equalization Using Levenberg-Marquardt Training Algorithm and pulse shaping Filters

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International Journal of Communications, Network and System Sciences 2014年第2期7卷 71-74页

作者： Tiago Mota Jorgean Leal Antonio Lima Departament of Mechatronics Federal University of BahiaBahiaBrazil National Telecommunications Agency of Brazil BahiaBrazil Departament of Electrical Engineering Federal University of BahiaBahiaBrazil

Artificial Neural Network (ANN) equalizers have been successfully applied to mitigate Inter symbolic Interference (ISI) due to distortions introduced by linear or nonlinear communication channels. The ANN architecture is chosen according to the type of ISI produced by fixed, fast or slow fading channels. In this work, we propose a combination of two techniques in order to minimize ISI yield by fast fading channels, i.e., pulse shape filtering and ANN equalizer. Levenberg-Marquardt algorithm is used to update the synaptic weights of an ANN comprise only by two recurrent perceptrons. The proposed system outperformed more complex structures such as those based on Kalman filtering approach.

关键词： Decision Feedback Equalizers Levenberg-Marquardt Algorithm pulse shaping Recurrent Neural Networks

Polarization shaping of Poincare´ beams by polariton oscillations

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Light(Science & Applications) 2015年第1期4卷 122-128页

作者： David Colas Lorenzo Dominici Stefano Donati Anastasiia A Pervishko Timothy CH Liew Ivan A Shelykh Dario Ballarini Milena de Giorgi Alberto Bramati Giuseppe Gigli Elena del Valle Fabrice P Laussy Alexey V Kavokin Daniele Sanvitto Departamento de Fı´sica Teorica de la Materia Condensada and Condensed Matter Physics Center(IFIMAC) Universidad Autonoma de MadridE-28049Spain NANOTEC Istituto di Nanotecnologia-CNRVia Arnesano73100 LecceItaly Istituto Italiano di Tecnologia IIT-LecceVia Barsanti73010 LecceItaly Universita del Salento Via Arnesano73100 LecceItaly Division of Physics and Applied Physics Nanyang Technological University637371 SingaporeSingapore Science Institute University of IcelandDunhagi 3IS-107ReykjavikIceland Laboratory of Light-Matter Coupling in Nanostructures ITMO University197101 St.PetersburgRussia Laboratoire Kastler Brossel UPMC-Paris 6ENS et CNRS75005 ParisFrance Russian Quantum Center Novaya 100143025 SkolkovoMoscow RegionRussia CNR-SPIN Tor Vergataviale del Politechnico 1I-00133 RomeItaly

We propose theoretically and demonstrate experimentally the generation of light pulses whose polarization varies temporally to cover selected areas of the Poincare´sphere with both tunable swirling speed and total duration(1 ps and 10 ps,respectively,in our implementation).The effect relies on the Rabi oscillations of two polariton polarized fields excited by two counter-polarized and delayed *** superposition of the oscillating fields result in the precession of the Stokes vector of the emitted light while polariton lifetime imbalance results in its drift from a circle of controllable radius on the Poincare´sphere to a single point at long *** positioning of the initial circle and final point allows to engineer the type of polarization spanning,including a full sweeping of the Poincare´*** universality and simplicity of the scheme should allow for the deployment of time-varying full-Poincare´polarization fields in a variety of platforms,timescales,and regimes.

关键词： full Poincare beams polaritons polarization pulse shaping Rabi oscillations

Electrons dynamics control by shaping femtosecond laser pulses in micro/nanofabrication: modeling, method, measurement and application

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Light(Science & Applications) 2017年第1期6卷 249-275页

作者： Lan Jiang An-Dong Wang Bo Li Tian-Hong Cui Yong-Feng Lu Laser Micro/Nano-Fabrication Laboratory School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China Department of Mechanical Engineering University of MinnesotaMinneapolisMN 55455USA Department of Electrical Engineering University of Nebraska-LincolnLincolnNE 68588-0511USA

During femtosecond laser fabrication,photons are mainly absorbed by electrons,and the subsequent energy transfer from electrons to ions is of picosecond ***,lattice motion is negligible within the femtosecond pulse duration,whereas femtosecond photon-electron interactions dominate the entire fabrication ***,femtosecond laser fabrication must be improved by controlling localized transient electron dynamics,which poses a challenge for measuring and controlling at the electron level during fabrication ***-probe spectroscopy presents a viable solution,which can be used to observe electron dynamics during a chemical *** fact,femtosecond pulse durations are shorter than many physical/chemical characteristic times,which permits manipulating,adjusting,or interfering with electron ***,we proposed to control localized transient electron dynamics by temporally or spatially shaping femtosecond pulses,and further to modify localized transient materials properties,and then to adjust material phase change,and eventually to implement a novel fabrication *** review covers our progresses over the past decade regarding electrons dynamics control(EDC)by shaping femtosecond laser pulses in micro/nanomanufacturing:(1)Theoretical models were developed to prove EDC feasibility and reveal its mechanisms;(2)on the basis of the theoretical predictions,many experiments are conducted to validate our EDC-based femtosecond laser fabrication *** examples are reported,which proves that the proposed method can significantly improve fabrication precision,quality,throughput and repeatability and effectively control micro/nanoscale structures;(3)a multiscale measurement system was proposed and developed to study the fundamentals of EDC from the femtosecond scale to the nanosecond scale and to the millisecond scale;and(4)As an example of practical applications,our method was employed to fabricate some key structures in one of the 16 Ch

关键词： electrons dynamics control femtosecond laser micro/nano fabrication pulse shaping

Diversity of photonic differentiators based on flexible demodulation of phase signals

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Chinese Physics B 2014年第3期23卷 212-218页

作者：郑傲凌董建绩雷蕾杨婷张新亮 Wuhan National Laboratory for Optoelectronics School of Optoelectronic Science and EngineeringHuazhong University of Science and Technology

We theoretically propose a multifunctional photonic differentiation （DIFF） scheme based on phase demodulation using two cascaded linear filters. The photonic D1FF has a diversity of output forms, such as the 1 st order intensity DIFF, the 1 st order field DIFF and its inversion, and the 2nd-order field DIFF, depending on the relative shift between the optical carrier and the filter＇s resonant notches. As a proof, we also experimentally demonstrate the DIFF diversity using a phase modulator and two delay interferometers （Dis）. The calculated average deviation is less than 7% for all DIFF waveforms. Our schemes show the advantages of flexible DIFF functions and forms, which may have different optical applications. For example, high order field differentiators can be used to generate complex temporal waveforms, and intensity differentiators are useful for the ultra-wideband pulse generation.

关键词： photonic differentiator pulse shaping microwave photonics

Excitation and relaxation dynamics in ultrafast laser irradiated optical glasses

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High Power Laser Science and Engineering 2016年第4期4卷 1-8页

作者： C.Mauclair A.Mermillod-Blondin K.Mishchik J.Bonse A.Rosenfeld J.P.Colombier R.Stoian Laboratoire Hubert Curien UMR 5516 CNRSUniversité de LyonUniversité Jean Monnet Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie Bundesanstalt für Materialforschung und-prüfung (BAM)

We discuss the dynamics of ultrashort pulsed laser excitation in bulk optical silica-based glasses(fused silica and borosilicate BK7) well-above the permanent modification threshold. We indicate subsequent structural and thermomechanical energy relaxation paths that translate into positive and negative refractive index changes, compression and rarefaction zones. If fast electronic decay occurs at low excitation levels in fused silica via self-trapping of excitons,for carrier densities in the vicinity of the critical value at the incident wavelength, persistent long-living absorptive states indicate the achievement of low viscosity matter states manifesting pressure relaxation, rarefaction, void opening and compaction in the neighboring domains. An intermediate ps-long excited carrier dynamics is observed for BK7 in the range corresponding to structural expansion and rarefaction. The amount of excitation and the strength of the subsequent hydrodynamic evolution is critically dependent on the pulse time envelope, indicative of potential optimization schemes.

关键词： carrier plasmas glasses pulse shaping refractive index engineering ultrafast laser excitation