WorldWideScience

Sample records for laser pulse generation

  1. One laser pulse generates two photoacoustic signals

    CERN Document Server

    Gao, Fei; Zheng, Yuanjin

    2016-01-01

    Photoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying the stress confinement, the dual photoacoustic signals are generated following the positive and negative edges of the long laser pulse. More interestingly, the first expansion-induced photoacoustic signal exhibits positive waveform due to the initial sharp rising of temperature. On the contrary, the second contraction-induced photoacoustic signal exhibits exactly negative waveform due to the falling of temperature, as well as pulse-width-dependent, signal amplitude which is caused by the concurrent heat accumulation and ...

  2. One laser pulse generates two photoacoustic signals

    OpenAIRE

    Gao, Fei; Feng, Xiaohua; Bai, Linyi; Zhang, Ruochong; Liu, Siyu; Ding, Ran; Kishor, Rahul; Zhao, Yanli; Zheng, Yuanjin

    2016-01-01

    Photoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying...

  3. Double nanosecond pulses generation in ytterbium fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Veiko, V. P.; Samokhvalov, A. A., E-mail: samokhvalov.itmo@gmail.com; Yakovlev, E. B.; Zhitenev, I. Yu.; Kliushin, A. N. [Saint-Petersburg State University of Information Technologies, Mechanics and Optics, Kronverksky Pr. 49, Saint Petersburg (Russian Federation); Lednev, V. N. [Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov Str., 38, Moscow (Russian Federation); National University of Science and Technology MISiS, Leninskyave., 4, Moscow (Russian Federation); Pershin, S. M. [Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov Str., 38, Moscow (Russian Federation)

    2016-06-15

    Double pulse generation mode for nanosecond ytterbium fiber laser was developed. Two sequential 60-200 ns laser pulses with variable delay between them were generated by acousto-optic modulator opening with continuous diode pumping. A custom radio frequency generator was developed to produce two sequential “opening” radio pulses with a delay of 0.2–1 μs. It was demonstrated that double pulse generation did not decrease the average laser power while providing the control over the laser pulse power profile. Surprisingly, a greater peak power in the double pulse mode was observed for the second laser pulse. Laser crater studies and plasma emission measurements revealed an improved efficiency of laser ablation in the double pulse mode.

  4. Generation of laser pulse trains for tests of multi-pulse laser wakefield acceleration

    Science.gov (United States)

    Shalloo, R. J.; Corner, L.; Arran, C.; Cowley, J.; Cheung, G.; Thornton, C.; Walczak, R.; Hooker, S. M.

    2016-09-01

    In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150-170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

  5. Generation of laser pulse trains for tests of multi-pulse laser wakefield acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Shalloo, R.J., E-mail: robert.shalloo@physics.ox.ac.uk; Corner, L.; Arran, C.; Cowley, J.; Cheung, G.; Thornton, C.; Walczak, R.; Hooker, S.M.

    2016-09-01

    In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150–170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

  6. Plasma generated during underwater pulsed laser processing

    Science.gov (United States)

    Hoffman, Jacek; Chrzanowska, Justyna; Moscicki, Tomasz; Radziejewska, Joanna; Stobinski, Leszek; Szymanski, Zygmunt

    2017-09-01

    The plasma induced during underwater pulsed laser ablation of graphite is studied both experimentally and theoretically. The results of the experiment show that the maximum plasma temperature of 25000 K is reached 20 ns from the beginning of the laser pulse and decreases to 6500 K after 1000 ns. The observed OH absorption band shows that the plasma plume is surrounded by the thin layer of dissociated water vapour at a temperature around 5500 K. The hydrodynamic model applied shows similar maximum plasma temperature at delay times between 14 ns and 30 ns. The calculations show also that already at 14th ns, the plasma electron density reaches 0.97·1027 m-3, which is the critical density for 1064 nm radiation. At the same time the plasma pressure is 2 GPa, which is consisted with earlier measurements of the peak pressure exerted on a target in similar conditions.

  7. Subpicosecond pulse generation from an all solid-state laser

    Science.gov (United States)

    Keen, S. J.; Ferguson, A. I.

    1989-11-01

    An all-solid-state (holosteric) laser source which produces subpicosecond pulses at 1.4 microns is described. The system consists of a diode laser pumped Nd:YAG laser which is frequency-modulated (FM) mode-locked and Q-switched at 1.32 microns. In continuous wave operation the laser produces pulses of 19 ps while simultaneous Q-switching and mode-locking result in 30 ps pulses being contained in a Q-switched envelope of energy 2.1 microJ. The output of the laser, when passed through a 1 km single-mode optical fiber, produces a spectrally broad Raman signal with its peak at 1.4 microns and the overall conversion efficiency at 12 percent. The pulse duration at 1.4 microns has been measured to be 280 fs. This is the first time that subpicosecond light pulses have been generated by an all-solid-state laser system.

  8. Generation And Measurement Of High Contrast Ultrashort Intense Laser Pulses

    CERN Document Server

    Konoplev, O A

    2000-01-01

    In this thesis, the generation and measurement of high contrast, intense, ultrashort pulses have been studied. Various factors affecting the contrast and pulse shape of ultrashort light pulses from a chirped pulse amplification (CPA) laser system are identified. The level of contrast resulting from influence of these factors is estimated. Methods for improving and controlling the pulse shape and increasing the contrast are discussed. Ultrahigh contrast, 1-ps pulses were generated from a CPA system with no temporal structure up to eleven orders of magnitude. This is eight orders of magnitude higher contrast than the original pulse. This contrast boost was achieved using two techniques. One is the optical pulse cleaning based on the nonlinear birefringence of the chirping fiber and applied to the pulses before amplification. The other is the fast saturable absorber. The fast saturable absorber was placed after amplification and compression of the pulse. The measurements of high-contrast, ultrashort pulse with h...

  9. Synchronous pulse generation in a multicavity fiber laser system

    Science.gov (United States)

    Gómez-Pavón, L. C.; Martí-Panameño, E.; Gómez-de la Fuente, O.; Luis-Ramos, A.

    2006-09-01

    We report the experimental synchronous pulse generation in a multicavity fiber laser system with two Erbium-doped fiber laser cavities. We have demonstrated that through the evanescent fields interaction between one cavity with active modulation and other one in continuous wave it is possible to generate more intense pulses in both cavities. Moreover, the synchronous pulse generation between cavities is achieved with an appropriate selection of pump intensity, modulation frequency and coupling ratio. We found that the pulse intensity is 2.5 times greater and the pulse duration lowers than a single Erbium-doper fiber laser. Furthermore, by means of the synchronous diagram we determined the synchronization strength in temporal pulse emission between cavities.

  10. Dark pulse generation in fiber lasers incorporating carbon nanotubes.

    Science.gov (United States)

    Liu, H H; Chow, K K

    2014-12-01

    We demonstrate the generation of dark pulses from carbon nanotube (CNT) incorporated erbium-doped fiber ring lasers with net anomalous dispersion. A side-polished fiber coated with CNT layer by optically-driven deposition method is embedded into the laser in order to enhance the birefringence and nonlinearity of the laser cavity. The dual-wavelength domain-wall dark pulses are obtained from the developed CNT-incorporated fiber laser at a relatively low pump threshold of 50.6 mW. Dark pulses repeated at the fifth-order harmonic of the fundamental cavity frequency are observed by adjusting the intra-cavity polarization state.

  11. Recent progress in picosecond pulse generation from semiconductor lasers

    Science.gov (United States)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    This paper reviews the recent progress in producing picosecond optical pulses from semiconductor laser diodes. The discussion concentrates on the mode-locking of a semiconductor laser diode in an external resonator. Transform-limited optical pulses ranging from several picoseconds to subpicosecond durations have been observed with active and passive mode-locking. Even though continuing research on the influence of impurities and defects on the mode-locking process is still needed, this technique has good promise for being utilized in fiber-optic communication systems. Alternative methods of direct electrical and optical excitation to produce ultrashort laser pulses are also described. They can generate pulses of similar widths to those obtained by mode-locking. The pulses generated will find applications in laser ranging and detector response measurement.

  12. Generation of Low Jitter Laser Diode Pulse With External Pulse Injection

    Institute of Scientific and Technical Information of China (English)

    Wang Yuncai; Olaf Reimann; Dieter Huhse; Dieter Bimberg

    2003-01-01

    One gain-switched laser diode(LD) was used as external injection seeding source, to reduce the timing jitter of another gain-switched LD, This technique can generate low jitter, frequency-free and wavelength tunable laser pulse.

  13. Short pulse generation by laser slicing at NSLSII

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.; Blednykh, A.; Guo, W.; Krinsky, S.; Li, Y.; Shaftan, T.; Tchoubar, O.; Wang, G.; Willeke, F.; Yang, L.

    2011-03-28

    We discuss an upgrade R&D project for NSLSII to generate sub-pico-second short x-ray pulses using laser slicing. We discuss its basic parameters and present a specific example for a viable design and its performance. Since the installation of the laser slicing system into the storage ring will break the symmetry of the lattice, we demonstrate it is possible to recover the dynamical aperture to the original design goal of the ring. There is a rapid growth of ultrafast user community interested in science using sub-pico-second x-ray pulses. In BNL's Short Pulse Workshop, the discussion from users shows clearly the need for a sub-pico-second pulse source using laser slicing method. In the proposal submitted following this workshop, NSLS team proposed both hard x-ray and soft x-ray beamlines using laser slicing pulses. Hence there is clearly a need to consider the R&D efforts of laser slicing short pulse generation at NSLSII to meet these goals.

  14. Nanosecond pulsed laser generation of holographic structures on metals

    Science.gov (United States)

    Wlodarczyk, Krystian L.; Ardron, Marcus; Weston, Nick J.; Hand, Duncan P.

    2016-03-01

    A laser-based process for the generation of phase holographic structures directly onto the surface of metals is presented. This process uses 35ns long laser pulses of wavelength 355nm to generate optically-smooth surface deformations on a metal. The laser-induced surface deformations (LISDs) are produced by either localized laser melting or the combination of melting and evaporation. The geometry (shape and dimension) of the LISDs depends on the laser processing parameters, in particular the pulse energy, as well as on the chemical composition of a metal. In this paper, we explain the mechanism of the LISDs formation on various metals, such as stainless steel, pure nickel and nickel-chromium Inconel® alloys. In addition, we provide information about the design and fabrication process of the phase holographic structures and demonstrate their use as robust markings for the identification and traceability of high value metal goods.

  15. Pulse generation and preamplification for long pulse beamlines of Orion laser facility.

    Science.gov (United States)

    Hillier, David I; Winter, David N; Hopps, Nicholas W

    2010-06-01

    We describe the pulse generation, shaping, and preamplification system for the nanosecond beamlines of the Orion laser facility. The system generates shaped laser pulses of up to approximately 1 J of 100 ps-5 ns duration with a programmable temporal profile. The laser has a 30th-power supergaussian spatial profile and is diffraction limited. The system is capable of imposing 2D smoothing by spectral dispersion upon the beam, which will produce a nonuniformity of 10% rms at the target.

  16. A Novel Femtosecond Laser System for Attosecond Pulse Generation

    Directory of Open Access Journals (Sweden)

    Jianqiang Zhu

    2012-01-01

    Full Text Available We report a novel ultrabroadband high-energy femtosecond laser to be built in our laboratory. A 7-femtosecond pulse is firstly stretched by an eight-pass offner stretcher with a chirp rate 15 ps/nm, and then energy-amplified by a two-stage optical parametric chirped pulse amplification (OPCPA. The first stage as preamplification with three pieces of BBO crystals provides the majority of the energy gain. At the second stage, a YCOB crystal with the aperture of ~50 mm is used instead of the KDP crystal as the gain medium to ensure the shortest pulse. After the completion, the laser will deliver about 8 J with pulse duration of about 10 femtoseconds, which should be beneficial to the attosecond pulse generation and other ultrafast experiments.

  17. Generation of elliptically polarized nitrogen-ion laser fields using two-color femtosecond laser pulses

    CERN Document Server

    Li, Ziting; Chu, Wei; Xie, Hongqiang; Yao, Jinping; Li, Guihua; Qiao, Lingling; Wang, Zhanshan; Cheng, Ya

    2015-01-01

    We experimentally investigate generation of molecular nitrogen-ion lasers with two femtosecond laser pulses at different wavelengths. The first pulse serves as the pump which ionizes the nitrogen molecules and excites the molecular ions to excited electronic states. The second pulse serves as the probe which leads to stimulated emission from the excited molecular ions. We observe that changing the angle between the polarization directions of the two pulses gives rise to elliptically polarized molecular nitrogen-ion laser fields, which is interpreted as a result of strong birefringence of the gain medium near the wavelengths of the molecular nitrogen-ion laser.

  18. Generation of high harmonics and attosecond pulses with ultrashort laser pulse filaments and conical waves

    Indian Academy of Sciences (India)

    A Couairon; A Lotti; D Faccio; P Di Trapani; D S Steingrube; E Schulz; T Binhammer; U Morgner; M Kovacev; M B Gaarde

    2014-08-01

    Results illustrating the nonlinear dynamics of ultrashort laser pulse filamentation in gases are presented, with particular emphasis on the filament properties useful for developing attosecond light sources. Two aspects of ultrashort pulse filaments are specifically discussed: (i) numerical simulation results on pulse self-compression by filamentation in a gas cell filled with noble gas. Measurements of high harmonics generated by the pulse extracted from the filament allows for the detection of intensity spikes and subcycle pulses generated within the filament. (ii) Simulation results on the spontaneous formation of conical wavepackets during filamentation in gases, which in turn can be used as efficient driving pulses for the generation of high harmonics and isolated attosecond pulses.

  19. High energy protons generation by two sequential laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaofeng; Shen, Baifei, E-mail: bfshen@mail.shcnc.ac.cn, E-mail: zhxm@siom.ac.cn; Zhang, Xiaomei, E-mail: bfshen@mail.shcnc.ac.cn, E-mail: zhxm@siom.ac.cn; Wang, Wenpeng; Xu, Jiancai; Yi, Longqing; Shi, Yin [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2015-04-15

    The sequential proton acceleration by two laser pulses of relativistic intensity is proposed to produce high energy protons. In the scheme, a relativistic super-Gaussian (SG) laser pulse followed by a Laguerre-Gaussian (LG) pulse irradiates dense plasma attached by underdense plasma. A proton beam is produced from the target and accelerated in the radiation pressure regime by the short SG pulse and then trapped and re-accelerated in a special bubble driven by the LG pulse in the underdense plasma. The advantages of radiation pressure acceleration and LG transverse structure are combined to achieve the effective trapping and acceleration of protons. In a two-dimensional particle-in-cell simulation, protons of 6.7 GeV are obtained from a 2 × 10{sup 22 }W/cm{sup 2} SG laser pulse and a LG pulse at a lower peak intensity.

  20. Picosecond lasers: the next generation of short-pulsed lasers.

    Science.gov (United States)

    Freedman, Joshua R; Kaufman, Joely; Metelitsa, Andrea I; Green, Jeremy B

    2014-12-01

    Selective photothermolysis, first discussed in the context of targeted microsurgery in 1983, proposed that the optimal parameters for specific thermal damage rely critically on the duration over which energy is delivered to the tissue. At that time, nonspecific thermal damage had been an intrinsic limitation of all commercially available lasers, despite efforts to mitigate this by a variety of compensatory cooling mechanisms. Fifteen years later, experimental picosecond lasers were first reported in the dermatological literature to demonstrate greater efficacy over their nanosecond predecessors in the context of targeted destruction of tattoo ink. Within the last 4 years, more than a decade after those experiments, the first commercially available cutaneous picosecond laser unit became available (Cynosure, Westford, Massachusetts), and several pilot studies have demonstrated its utility in tattoo removal. An experimental picosecond infrared laser has also recently demonstrated a nonthermal tissue ablative capability in soft tissue, bone, and dentin. In this article, we review the published data pertaining to dermatology on picosecond lasers from their initial reports to the present as well as discuss forthcoming technology.

  1. Generation of Intense THz Pulsed Lasers Pumped Strongly by CO2 Pulsed Lasers

    Institute of Scientific and Technical Information of China (English)

    QI Chun-Chao; CHENG Zu-Hai

    2009-01-01

    A theoretical method dealing with two intense laser fields interacting with a three-level molecular system is proposed.A discussion is presented on the properties of the solutions for time-independent and time-dependent absorption coefficients and gain coemcient on resonance for strong laser fields,based on analytic evaluation of the rate equations for a homogeneously broadened,three-level molecular system.The pump intensity range can be estimated according to the analytic expression of pump saturation intensity.The effects of pulse width,gas pressure and path length on the energy absorbed from pump light are studied theoretically.The results can be applied to the analysis of pulsed,optically pumped terahertz lasers.

  2. Analysis of tunable picosecond pulse generation from a distributed feedback Ti:sapphire laser

    Institute of Scientific and Technical Information of China (English)

    Hong Zhi; Yao Xiao-Ke

    2004-01-01

    A distributed feedback Ti:sapphire laser (DFTL) pumped by a 532nm Q-switched pulse is proposed for the generation of tunable picosecond pulses. With coupled rate equation model, the temporal characteristics of DFTL are obtained. The numerical solutions show that the DFTL pulse with a 50-ps pulse duration and as much as 3.SmJ pulse energy can be obtained under 40-m J, 5-ns pulse pumping. The dependence of output pulse width on the laser crystal's length, pumping pulse duration, and pumping rate is also discussed in detail.

  3. VUV SOURCE FROM PULSED-LASER GENERATED PLASMA

    OpenAIRE

    Laporte, P.; Damany, N.; Damany, H.

    1987-01-01

    We describe a pulsed vacuum ultraviolet (VUV) source consisting of a plasma created by focusing a NdYAG laser beam into rare gases under moderate pressure, and we report on spectral and time properties of that source. Main features are : continuum emission in a large spectral range, with only few lines superimposed, good time characteristics of the pulses, stability, cleanliness, and relatively high repetition rate (20 Hz).

  4. Multiple quantum wells for passive ultra short laser pulse generation

    CERN Document Server

    Quintero-Torres, R; Rodriguez-Rodriguez, E; Stintz, Andreas; Diels, Jean-Claude

    2007-01-01

    Solid state lasers are demanding independent control in the gain media and cavity loss to achieve ultra short laser pulses using passive mode-locking. Recently, laser mode-locking is achieved with a MBE structure with multiple quantum wells, designed to achieve two functions; Bragg mirror and changes in absorption to control the cavity dynamics. The use of an AlGaAs/AlAs Bragg mirror with a 15 nm GaAs saturable absorber used in a Cr:LiSAF tuneable laser proved to be effective to produce femtosecond pulses. The use of saturable absorbers thus far is a trial and error procedure that is changing due to the correlation with more predictive procedures.

  5. Graphene based widely-tunable and singly-polarized pulse generation with random fiber lasers

    CERN Document Server

    Yao, B C; Wang, Z N; Wu, Y; Zhou, J H; Wu, H; Fan, M Q; Cao, X L; Zhang, W L; Chen, Y F; Li, Y R; Churkin, D; Turitsyn, S; Wong, C W

    2015-01-01

    Pulse generation often requires a stabilized cavity and its corresponding mode structure for initial phase-locking. Contrastingly, modeless cavity-free random lasers provide new possibilities for high quantum efficiency lasing that could potentially be widely tunable spectrally and temporally. Pulse generation in random lasers, however, has remained elusive since the discovery of modeless gain lasing. Here we report coherent pulse generation with modeless random lasers based on the unique polarization selectivity and broadband saturable absorption of monolayer graphene. Simultaneous temporal compression of cavity-free pulses are observed with such a polarization modulation, along with a broadly-tunable pulsewidth across two orders of magnitude down to 900 ps, a broadly-tunable repetition rate across three orders of magnitude up to 3 MHz, and a singly-polarized pulse train at 41 dB extinction ratio, about an order of magnitude larger than conventional pulsed fiber lasers. Moreover, our graphene-based pulse for...

  6. Q-switched pulse laser generation from double-cladding Nd:YAG ceramics waveguides.

    Science.gov (United States)

    Tan, Yang; Luan, Qingfang; Liu, Fengqin; Chen, Feng; Vázquez de Aldana, Javier Rodríguez

    2013-08-12

    This work reports on the Q-switched pulsed laser generation from double-cladding Nd:YAG ceramic waveguides. Double-cladding waveguides with different combination of diameters were inscribed into a sample of Nd:YAG ceramic. With an additional semiconductor saturable absorber, stable pulsed laser emission at the wavelength of 1064 nm was achieved with pulses of 21 ns temporal duration and ~14 μJ pulse energy at a repetition rate of 3.65 MHz.

  7. Pulse width tunable subpicosecond pulse generation from an actively modelocked monolithic MQW laser/MQW electroabsorption modulator

    Science.gov (United States)

    Takada, A.; Sato, K.; Saruwatari, M.; Yamamoto, M.

    1994-05-01

    Actively modelocked pulses are generated from a 1.59 micron MQW laser integrated with an MQW electroabsorption modulator driven at the monolithic cavity frequency. The pulse width is controlled from 39 ps to 0.55 ps by changing the inverse bias voltage applied to the electroabsorption modulator and by linear pulse compression using a fiber.

  8. High Harmonic Radiation Generation and Attosecond pulse generation from Intense Laser-Solid Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Alexander Roy [Univ. of Michigan, Ann Arbor, MI (United States); Krushelnick, Karl [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-09-08

    We have studied ion motion effects in high harmonic generation, including shifts to the harmonics which result in degradation of the attosecond pulse train, and how to mitigate them. We have examined the scaling with intensity of harmonic emission. We have also switched the geometry of the interaction to measure, for the first time, harmonics from a normal incidence interaction. This was performed by using a special parabolic reflector with an on axis hole and is to allow measurements of the attosecond pulses using standard techniques. Here is a summary of the findings: First high harmonic generation in laser-solid interactions at 1021 Wcm-2, demonstration of harmonic focusing, study of ion motion effects in high harmonic generation in laser-solid interactions, and demonstration of harmonic amplification.

  9. Generation of energetic, picosecond seed pulses for CO2 laser using Raman shifter

    Science.gov (United States)

    Welch, Eric; Tochitsky, Sergei; Joshi, Chan

    2017-03-01

    We present a new concept for generating 3 ps seed pulses for a high-power CO2 laser amplifier that are multiple orders more energetic than seed pulses generated by slicing from a nanosecond CO2 laser pulse. We propose to send a 1 µm picosecond laser through a C6D6 Raman shifter and mix both the pump and shifted components in a DFG crystal to produce pulses at 10.6 µm. Preliminary results of a proof-of-principle experiment are presented.

  10. Generation of 25-TW Femtosecond Laser Pulses at 515 nm with Extremely High Temporal Contrast

    Directory of Open Access Journals (Sweden)

    Marco Hornung

    2015-12-01

    Full Text Available We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a pulse duration of 120 fs. On the basis of initially ultra-high contrast seed pulses we expect a temporal intensity contrast better 10 17 200 ps before the peak of the main pulse. We analyzed the temporal intensity contrast from milliseconds to femtoseconds with a dynamic range covering more than 20 orders of magnitude. The pulses were focussed with a f/2-focussing parabola resulting in a peak intensity exceeding 10 20 W / cm 2 . The peak power and intensity are to the best of our knowledge the highest values for 515 nm-laser-pulses achieved so far.

  11. Laser-driven electron beam generation for secondary photon sources with few terawatt laser pulses

    Science.gov (United States)

    Bohacek, K.; Chaulagain, U.; Horny, V.; Kozlova, M.; Krus, M.; Nejdl, J.

    2017-05-01

    Relativistic electron beams accelerated by laser wakefield have the ability to serve as sources of collimated, point-like and femtosecond X-ray radiation. Experimental conditions for generation of stable quasi-monoenergetic electron bunches using a femtosecond few-terawatt laser pulse (600 mJ, 50 fs) were investigated as they are crucial for generation of stable betatron radiation and X-ray pulses from inverse Compton scattering. A mixture of helium with argon, and helium with an admixture of synthetic air were tested for this purpose using different backing pressures and the obtained results are compared. The approach to use synthetic air was previously proven to stabilize the energy and energy spread of the generated electron beams at the given laser power. The accelerator was operated in nonlinear regime with forced self-injection and resulted in the generation of stable relativistic electron beams with an energy of tens of MeV and betatron X-ray radiation was generated in the keV range. A razor blade was tested to create a steep density gradient in order to improve the stability of electron injection and to increase the total electron bunch charge. It was proven that the stable electron and X-ray source can be built at small-scale facilities, which readily opens possibilities for various applications due to availability of such few-terawatt laser systems in many laboratories around the world.

  12. Particle Generation by Pulsed Excimer Laser Ablation in Liquid: Hollow Structures and Laser-Induced Reactions

    Science.gov (United States)

    Yan, Zijie

    2011-12-01

    Pulsed laser ablation of solid targets in liquid media is a powerful method to fabricate micro-/nanoparticles, which has attracted much interest in the past decade. It represents a combinatorial library of constituents and interactions, and one can explore disparate regions of parameter space with outcomes that are impossible to envision a priori. In this work, a pulsed excimer laser (wavelength 248 nm, pulse width 30 ns) has been used to ablate targets in liquid media with varying laser fluences, frequencies, ablation times and surfactants. It is observed that hollow particles could be fabricated by excimer laser ablation of Al, Pt, Zn, Mg, Ag, Si, TiO2, and Nb2O5 in water or aqueous solutions. The hollow particles, with sizes from tens of nanometers to micrometers, may have smooth and continuous shells or have morphologies demonstrating that they were assembled from nanoparticles. A new mechanism has been proposed to explain the formation of these novel particle geometries. They were formed on laser-produced bubbles through bubble interface pinning by laser-produced solid species. Considering the bubble dynamics, thermodynamic and kinetic requirements have been discussed in the mechanism that can explain some phenomena associated with the formation of hollow particles, especially (1) larger particles are more likely to be hollow particles; (2) Mg and Al targets have stronger tendency to generate hollow particles; and (3) the 248 nm excimer laser is more beneficial to fabricate hollow particles in water than other lasers with longer wavelengths. The work has also demonstrated the possiblities to fabricate novel nanostructures through laser-induced reactions. Zn(OH)2/dodecyl sulfate flower-like nanostructures, AgCl cubes, and Ag2O cubes, pyramids, triangular plates, pentagonal rods and bars have been obtained via reactions between laser-produced species with water, electrolyes, or surfactant molecules. The underlying mechanisms of forming these structures have been

  13. Generation of Ultra-high Intensity Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    N.J. Fisch; V.M. Malkin

    2003-06-10

    Mainly due to the method of chirped pulse amplification, laser intensities have grown remarkably during recent years. However, the attaining of very much higher powers is limited by the material properties of gratings. These limitations might be overcome through the use of plasma, which is an ideal medium for processing very high power and very high total energy. A plasma can be irradiated by a long pump laser pulse, carrying significant energy, which is then quickly depleted in the plasma by a short counterpropagating pulse. This counterpropagating wave effect has already been employed in Raman amplifiers using gases or plasmas at low laser power. Of particular interest here are the new effects which enter in high power regimes. These new effects can be employed so that one high-energy optical system can be used like a flashlamp in what amounts to pumping the plasma, and a second low-power optical system can be used to extract quickly the energy from the plasma and focus it precisely. The combined system can be very compact. Thus, focused intensities more than 10{sup 25} W/cm{sup 2} can be contemplated using existing optical elements. These intensities are several orders of magnitude higher than what is currently available through chirped pump amplifiers.

  14. Picosecond optical pulse generation at gigahertz rates by direct modulation of a semiconductor laser

    Science.gov (United States)

    Auyeung, J.

    1981-01-01

    We report the generation of picosecond pulses by the direct modulation of a buried heterostructure GaAlAs diode laser. Pulse width of 28 ps is achieved at a repetition frequency of 2.5 GHz. Pulse width dependence on the experimental parameters is described.

  15. A 7 T Pulsed Magnetic Field Generator for Magnetized Laser Plasma Experiments

    Science.gov (United States)

    Hu, Guangyue; Liang, Yihan; Song, Falun; Yuan, Peng; Wang, Yulin; Zhao, Bin; Zheng, Jian

    2015-02-01

    A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast (~230 ns), 55 kA current pulse into a single-turn coil surrounding the laser target, using a capacitor bank of 200 nF, a laser-triggered switch and a low-impedance strip transmission line. A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter. The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam, a femtosecond probing laser beam and an optical Intensified Charge Coupled Device (ICCD) detector. The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.

  16. Peculiarities of Efficient Plasma Generation in Air and Water by Short Duration Laser Pulses

    Science.gov (United States)

    Adamovsky, Grigory; Floyd, Bertram M.

    2017-01-01

    We have conducted experiments to demonstrate an efficient generation of plasma discharges by focused nanosecond pulsed laser beams in air and provided recommendations on the design of optical systems to implement such plasma generation. We have also demonstrated generation of the secondary plasma discharge using the unused energy from the primary one. Focused nanosecond pulsed laser beams have also been utilized to generate plasma in water where we observed self-focusing and filamentation. Furthermore, we applied the laser generated plasma to the decomposition of methylene blue dye diluted in water.

  17. A photonic ultra-wideband pulse generator based on relaxation oscillations of a semiconductor laser

    DEFF Research Database (Denmark)

    Yu, Xianbin; Gibbon, Timothy Braidwood; Pawlik, Michal;

    2009-01-01

    A photonic ultra-wideband (UWB) pulse generator based on relaxation oscillations of a semiconductor laser is proposed and experimentally demonstrated. We numerically simulate the modulation response of a direct modulation laser (DML) and show that due to the relaxation oscillations of the laser...

  18. High energy electron generation by the 15 mJ ultrashort pulse laser

    Energy Technology Data Exchange (ETDEWEB)

    Takano, K; Hotta, E; Nemoto, K [Department of Energy Sciences Tokyo Institute of Technology 4259 Nagatsuta-cho Midori-ku Yokohama 226-8502 (Japan); Nayuki, T; Oishi, Y; Fujii, T; Zhidkov, A [Central Research Institute of Electric Power Industry 2-6-1 Nagasaka, Yokosuka, Kanagawa, 240-0196 (Japan); Todoriki, M; Hasegawa, S [University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8654 (Japan)], E-mail: k-tn@plasma.es.titech.ac.jp

    2008-05-01

    We propose a small size high energy X-ray source utilizing ultrashort pulse lasers, and a new scheme for generating quasi-monoenergetic electrons. In this paper, we developed a compact laser electron generator and performed experiment that generated energetic electrons over 1 MeV electrons with only 15 mJ laser energy. The temperatures of emitted electrons were measured to be 0.2 MeV and 0.25 MeV without and with prepulse, respectively.

  19. Efficient second harmonic generation of picosecond laser pulses.

    Science.gov (United States)

    Rabson, T. A.; Ruiz, H. J.; Shah, P. L.; Tittel, F. K.

    1972-01-01

    Efficient conversion to the second harmonic (SH) using KD2PO4 and CsH2AsO4 crystals inside a folded cavity of a high-power-dye mode-locked neodymium-glass laser is reported. For the first time, frequency-doubled picosecond light pulses have been obtained in CsH2AsO4 with peak powers of the order of 1 GW/sq cm at 0.531 micron for an effective pump power density of 4 GW/sq cm.

  20. Generation of Phase-Locked Pulses from a Seeded Free-Electron Laser.

    Science.gov (United States)

    Gauthier, David; Ribič, Primož Rebernik; De Ninno, Giovanni; Allaria, Enrico; Cinquegrana, Paolo; Danailov, Miltcho Bojanov; Demidovich, Alexander; Ferrari, Eugenio; Giannessi, Luca

    2016-01-15

    In a coherent control experiment, light pulses are used to guide the real-time evolution of a quantum system. This requires the coherence and the control of the pulses' electric-field carrier waves. In this work, we use frequency-domain interferometry to demonstrate the mutual coherence of time-delayed pulses generated by an extreme ultraviolet seeded free-electron laser. Furthermore, we use the driving seed laser to lock and precisely control the relative phase between the two free-electron laser pulses. This new capability opens the way to a multitude of coherent control experiments, which will take advantage of the high intensity, short wavelength, and short duration of the pulses generated by seeded free-electron lasers.

  1. Generation of 7-fs laser pulse directly from a compact Ti:sapphire laser with chirped mirrors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A compact femtosecond Ti:sapphire laser resonator consisting of three chirped mirrors and one output coupler was designed. By accurately balancing the intra- cavity dispersions between Ti:sapphire crystal, air and chirped mirrors, we directly generated the laser pulse shorter than 7 fs at the average power of 340 mW with 3.1 W pump. The repetition rate of the laser oscillator is 173 MHz at the centre wavelength of 791 nm, and the ultrabroaden spectrum covers from 600 nm to 1000 nm. To the best of our knowledge, this is the simplest laser resonator capable of generating sub-10 fs laser pulse.

  2. Generation of 7-fs laser pulse directly from a compact Ti:sapphire laser with chirped mirrors

    Institute of Scientific and Technical Information of China (English)

    ZHAO YanYing; WANG Peng; ZHANG Wei; TIAN JinRong; WEI ZhiYi

    2007-01-01

    A compact femtosecond Ti:sapphire laser resonator consisting of three chirped mirrors and one output coupler was designed. By accurately balancing the intracavity dispersions between Ti:sapphire crystal, air and chirped mirrors, we directly generated the laser pulse shorter than 7 fs at the average power of 340 mW with 3.1 W pump. The repetition rate of the laser oscillator is 173 MHz at the centre wavelength of 791 nm, and the ultrabroaden spectrum covers from 600 nm to 1000 nm. To the best of our knowledge, this is the simplest laser resonator capable of generating sub-10 fs laser pulse.

  3. The effect of laser contrast on generation of highly charged Fe ions by ultra-intense femtosecond laser pulses

    Science.gov (United States)

    Faenov, Anatoly Ya.; Alkhimova, Maria A.; Pikuz, Tatiana A.; Skobelev, Igor Yu.; Nishiuchi, Mamiko; Sakaki, Hironao; Pirozhkov, Alexander S.; Sagisaka, Akito; Dover, Nicholas P.; Kondo, Kotaro; Ogura, Koichi; Fukuda, Yuji; Kiriyama, Hiromitsu; Andreev, Alexander; Nishitani, Keita; Miyahara, Takumi; Watanabe, Yukinobu; Pikuz, Sergey A.; Kando, Masaki; Kodama, Ruosuke; Kondo, Kiminori

    2017-07-01

    Experimental studies on the formation of highly charged ions of medium-Z elements using femtosecond laser pulses with different contrast levels were carried out. Multiply charged Fe ions were generated by laser pulses with 35 fs duration and an intensity exceeding 1021 W/cm2. Using high-resolution X-ray spectroscopic methods, bulk electron temperature of the generated plasma has been identified. It is shown that the presence of a laser pre-pulse at a contrast level of 105-106 with respect to the main pulse drastically decreases the degree of Fe ionization. We conclude that an effective source of energetic, multiply charged moderate and high- Z ions based on femtosecond laser-plasma interactions can be created only using laser pulses of ultra-high contrast.

  4. Powerful 170-attosecond XUV pulses generated with few-cycle laser pulses and broadband multilayer optics

    Energy Technology Data Exchange (ETDEWEB)

    Schultze, M [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermannstrasse 1, D-85748 Garching (Germany); Goulielmakis, E [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermannstrasse 1, D-85748 Garching (Germany); Uiberacker, M [Department fuer Physik, Ludwig-Maximilians-Universitaet, Am Coulombwall 1, D-85748 Garching (Germany); Hofstetter, M [Department fuer Physik, Ludwig-Maximilians-Universitaet, Am Coulombwall 1, D-85748 Garching (Germany); Kim, J [Laser Science Laboratory, Department of Physics, POSTECH, Pohang, Kyungbuk 790-784 (Korea, Republic of); Kim, D [Laser Science Laboratory, Department of Physics, POSTECH, Pohang, Kyungbuk 790-784 (Korea, Republic of); Krausz, F [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermannstrasse 1, D-85748 Garching (Germany); Kleineberg, U [Department fuer Physik, Ludwig-Maximilians-Universitaet, Am Coulombwall 1, D-85748 Garching (Germany)

    2007-07-15

    Single 170-as extreme ultraviolet (XUV) pulses delivering more than 10{sup 6} photons/pulse at {approx}100 eV at a repetition rate of 3 kHz are produced by ionizing neon with waveform-controlled sub-5 fs near-infrared (NIR) laser pulses and spectrally filtering the emerging near-cutoff high-harmonic continuum with a broadband, chirped multilayer molybdenum-silicon (Mo/Si) mirror.

  5. Elongation of plasma channel generated by temporally shaped femtosecond laser pulse

    Science.gov (United States)

    Chen, Anmin; Li, Suyu; Qi, Hongxia; Jiang, Yuanfei; Hu, Zhan; Huang, Xuri; Jin, Mingxing

    2017-01-01

    Temporally shaped femtosecond laser pulse is used to generate the air plasma channel. The length of plasma channel is optimized by a genetic algorithm. Compared with the transform-limited pulse, the temporally shaped femtosecond laser produced by the spatial light modulator with the genetic algorithm can lead to a significant increase in length and brightness of plasma channel in atmosphere. In particular, the length of the plasma channel produced by the optimized shaped pulse can be extended by 50%. This method can be especially advantageous in the context of femtosecond laser-induced plasma channel.

  6. Generation of picosecond laser pulses at 1030 nm with gigahertz range continuously tunable repetition rate.

    Science.gov (United States)

    Aubourg, Adrien; Lhermite, Jérôme; Hocquet, Steve; Cormier, Eric; Santarelli, Giorgio

    2015-12-01

    We report on a watt range laser system generating picosecond pulses using electro-optical modulation of a 1030 nm single frequency low noise laser diode. Its repetition rate is continuously tunable between 11 and 18 GHz. Over this range, output spectra and pulse characteristics are measured and compared with a numerical simulation. Finally, amplitude and residual phase noise measurements of the source are also presented.

  7. Underwater acoustic wave generation by filamentation of terawatt ultrashort laser pulses

    CERN Document Server

    Jukna, Vytautas; Milián, Carles; Brelet, Yohann; Carbonnel, Jérôme; André, Yves-Bernard; Guillermin, Régine; Sessarego, Jean-Pierre; Fattaccioli, Dominique; Mysyrowicz, André; Couairon, Arnaud; Houard, Aurélien

    2016-01-01

    Acoustic signals generated by filamentation of ultrashort TW laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum.

  8. Iron plasma generation using a Nd:YAG laser pulse of several hundred picoseconds

    Science.gov (United States)

    Tamura, Jun; Kumaki, Masafumi; Kondo, Kotaro; Kanesue, Takeshi; Okamura, Masahiro

    2016-02-01

    We investigated the high intensity plasma generated by using a Nd:YAG laser to apply a laser-produced plasma to the direct plasma injection scheme. The capability of the source to generate high charge state ions strongly depends on the power density of the laser irradiation. Therefore, we focused on using a higher power laser with several hundred picoseconds of pulse width. The iron target was irradiated with the pulsed laser, and the ion current of the laser-produced iron plasma was measured using a Faraday cup and the charge state distribution was investigated using an electrostatic ion analyzer. We found that higher charge state iron ions (up to Fe21+) were obtained using a laser pulse of several hundred picoseconds in comparison to those obtained using a laser pulse of several nanoseconds (up to Fe19+). We also found that when the laser irradiation area was relatively large, the laser power was absorbed mainly by the contamination on the target surface.

  9. Erosion resistant anti-ice surfaces generated by ultra short laser pulses

    NARCIS (Netherlands)

    Del Cerro, D.A.; Römer, G.R.B.E.; Huis in't Veld, A.J.

    2010-01-01

    Wetting properties of a wide range of materials can be modified by accurate laser micromachining with ultra short laser pulses. Controlling the surface topography in a micro and sub-micrometer scale allows the generation of water-repellent surfaces, which remain dry and prevent ice accumulation

  10. Erosion resistant anti-ice surfaces generated by ultra short laser pulses

    NARCIS (Netherlands)

    Del Cerro, D.A.; Römer, G.R.B.E.; Huis in't Veld, A.J.

    2010-01-01

    Wetting properties of a wide range of materials can be modified by accurate laser micromachining with ultra short laser pulses. Controlling the surface topography in a micro and sub-micrometer scale allows the generation of water-repellent surfaces, which remain dry and prevent ice accumulation unde

  11. Experimental studies of axial magnetic fields generated in ultrashort-pulse laser-plasma interaction

    Institute of Scientific and Technical Information of China (English)

    李玉同; 张杰; 陈黎明; 赵理曾; 夏江帆; 魏志义; 江文勉

    2000-01-01

    The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obtained with a peak value as high as 170 Tesla. Theory suggests that the axial magnetic field is generated by dynamo effect in laser-plasma interaction.

  12. Generation of bright isolated attosecond soft X-ray pulses driven by multicycle midinfrared lasers.

    Science.gov (United States)

    Chen, Ming-Chang; Mancuso, Christopher; Hernández-García, Carlos; Dollar, Franklin; Galloway, Ben; Popmintchev, Dimitar; Huang, Pei-Chi; Walker, Barry; Plaja, Luis; Jaroń-Becker, Agnieszka A; Becker, Andreas; Murnane, Margaret M; Kapteyn, Henry C; Popmintchev, Tenio

    2014-06-10

    High harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, to date the shortest subfemtosecond (attosecond, 10(-18) s) pulses have been produced only in the extreme UV region of the spectrum below 100 eV, which limits the range of materials and molecular systems that can be explored. Here we experimentally demonstrate a remarkable convergence of physics: when midinfrared lasers are used to drive high harmonic generation, the conditions for optimal bright, soft X-ray generation naturally coincide with the generation of isolated attosecond pulses. The temporal window over which phase matching occurs shrinks rapidly with increasing driving laser wavelength, to the extent that bright isolated attosecond pulses are the norm for 2-µm driving lasers. Harnessing this realization, we experimentally demonstrate the generation of isolated soft X-ray attosecond pulses at photon energies up to 180 eV for the first time, to our knowledge, with a transform limit of 35 attoseconds (as), and a predicted linear chirp of 300 as. Most surprisingly, advanced theory shows that in contrast with as pulse generation in the extreme UV, long-duration, 10-cycle, driving laser pulses are required to generate isolated soft X-ray bursts efficiently, to mitigate group velocity walk-off between the laser and the X-ray fields that otherwise limit the conversion efficiency. Our work demonstrates a clear and straightforward approach for robustly generating bright isolated attosecond pulses of electromagnetic radiation throughout the soft X-ray region of the spectrum.

  13. Generating few-cycle pulses for nanoscale photoemission easily with an erbium-doped fiber laser.

    Science.gov (United States)

    Thomas, Sebastian; Holzwarth, Ronald; Hommelhoff, Peter

    2012-06-18

    We demonstrate a simple setup capable of generating four-cycle pulses at a center wavelength of 1700 nm for nanoscale photoemission. Pulses from an amplified erbium-doped fiber laser are spectrally broadened by propagation through a highly non-linear fiber. Subsequently, we exploit dispersion in two different types of glass to compress the pulses. The pulse length is estimated by measuring an interferometric autocorrelation trace and comparing it to a numerical simulation. We demonstrate highly non-linear photoemission of electrons from a nanometric tungsten tip in a hitherto unexplored pulse parameter range.

  14. Intra-pulse Raman frequency shift versus conventional Stokes generation of diode laser pulses in optical fibers.

    Science.gov (United States)

    Kuzin, Evgeny; Mendoza-Vazquez, Sergio; Gutierrez-Gutierrez, Jaime; Ibarra-Escamilla, Baldemar; Haus, Joseph; Rojas-Laguna, Roberto

    2005-05-02

    We report experimental observations of stimulated Raman scattering in a standard fiber using a directly modulated DFB semiconductor laser amplified by two erbium-doped fibers. The laser pulse width was variably controlled on a nanosecond-scale; the laser emission was separated into two distinct regimes: an initial transient peak regime, followed by a quasi steady-state plateau regime. The transient leading part of the pump pulse containing fast amplitude modulation generated a broadband Raman-induced spectral shift through the modulation instability and subsequent intra-pulse Raman frequency shift. The plateau regime amplified the conventional Stokes shifted emission expected from the peaks of the gain distribution. The output signal spectrum at the end of a 9.13 km length of fiber for the transient part extends from 1550 nm to 1700 nm for a pump pulse peak power of 65 W. We found that the Raman-induced spectral shift is measurable about 8 W for every fiber length examined, 0.6 km, 4.46 km, and 9.13 km. All spectral components of the broadband scattering appear to be generated in the initial kilometer of the fiber span. The Stokes shifted light generation threshold was higher than the threshold for the intra-pulse Raman-induced broadened spectra. This fact enables the nonlinear spectral filtering of pulses from directly modulated semiconductor lasers.

  15. Intra-pulse Raman frequency shift versus conventional Stokes generation of diode laser pulses in optical fibers

    Science.gov (United States)

    Kuzin, Evgeny A.; Mendoza-Vazquez, Sergio; Gutierrez-Gutierrez, Jaime; Ibarra-Escamilla, Baldemar; Haus, Joseph W.; Rojas-Laguna, Roberto

    2005-05-01

    We report experimental observations of stimulated Raman scattering in a standard fiber using a directly modulated DFB semiconductor laser amplified by two erbium-doped fibers. The laser pulse width was variably controlled on a nanosecond-scale; the laser emission was separated into two distinct regimes: an initial transient peak regime, followed by a quasi steady-state plateau regime. The transient leading part of the pump pulse containing fast amplitude modulation generated a broadband Raman-induced spectral shift through the modulation instability and subsequent intra-pulse Raman frequency shift. The plateau regime amplified the conventional Stokes shifted emission expected from the peaks of the gain distribution. The output signal spectrum at the end of a 9.13 km length of fiber for the transient part extends from 1550 nm to 1700 nm for a pump pulse peak power of 65 W. We found that the Raman-induced spectral shift is measurable about 8 W for every fiber length examined, 0.6 km, 4.46 km, and 9.13 km. All spectral components of the broadband scattering appear to be generated in the initial kilometer of the fiber span. The Stokes shifted light generation threshold was higher than the threshold for the intra-pulse Raman-induced broadened spectra. This fact enables the nonlinear spectral filtering of pulses from directly modulated semiconductor lasers.

  16. Ultrafast pulse generation in a mode-locked Erbium chip waveguide laser

    CERN Document Server

    Khurmi, Champak; Zhang, Wen Qi; V., Shahraam Afshar; Chen, George; Genest, Jérôme; Monro, Tanya M; Lancaster, David G

    2016-01-01

    We report mode-locked ~1550 nm output of transform-limited ~180 fs pulses from a large mode-area (diameter ~ 50 {\\mu}m) guided-wave erbium fluorozirconate glass laser. The passively mode-locked oscillator generates pulses with 25 nm bandwidth at 156 MHz repetition rate and peak-power of 260 W. Scalability to higher repetition rate is demonstrated by transform-limited 410 fs pulse output at 1.3 GHz. To understand the origins of the broad spectral output, the laser cavity is simulated by using a numerical solution to the Ginzburg-Landau equation. This paper reports the widest bandwidth and shortest pulses achieved from an ultra-fast laser inscribed waveguide laser.

  17. Single laser pulse generates dual photoacoustic signals for differential contrast photoacoustic imaging.

    Science.gov (United States)

    Gao, Fei; Feng, Xiaohua; Zhang, Ruochong; Liu, Siyu; Ding, Ran; Kishor, Rahul; Zheng, Yuanjin

    2017-04-04

    Photoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying the stress confinement, the dual photoacoustic signals are generated following the positive and negative edges of the long laser pulse. More interestingly, the first expansion-induced photoacoustic signal exhibits positive waveform due to the initial sharp rising of temperature. On the contrary, the second contraction-induced photoacoustic signal exhibits exactly negative waveform due to the falling of temperature, as well as pulse-width-dependent signal amplitude. An analytical model is derived to describe the generation of the dual photoacoustic pulses, incorporating Gruneisen saturation and thermal diffusion effect, which is experimentally proved. Lastly, an alternate of LDPA technique using quasi-CW laser excitation is also introduced and demonstrated for both super-contrast in vitro and in vivo imaging. Compared with existing nonlinear PA techniques, the proposed LDPA nonlinear effect could enable a much broader range of potential applications.

  18. High harmonic generation in underdense plasmas by intense laser pulses with orbital angular momentum

    Energy Technology Data Exchange (ETDEWEB)

    Mendonça, J. T., E-mail: josetitomend@gmail.com [IPFN, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal and Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, SP (Brazil); Vieira, J., E-mail: jorge.vieira@ist.utl.pt [GoLP, IPFN, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2015-12-15

    We study high harmonic generation produced by twisted laser pulses, with orbital angular momentum in the relativistic regime, for pulse propagation in underdense plasma. We consider fast time scale processes associated with an ultra-short pulse, where the ion motion can be neglected. We use both analytical models and numerical simulations using a relativistic particle-in-cell code. The present description is valid for relativistic laser intensities, when the normalized field amplitude is much larger than one, a ≫ 1. We also discuss two distinct processes associated with linear and circular polarization. Using both analytical solutions and particle-in-cell simulations, we are able to show that, for laser pulses in a well defined Laguerre-Gauss mode, angular momentum conservation is observed during the process of harmonic generation. Intensity modulation of the harmonic spectrum is also verified, as imposed by the nonlinear time-scale for energy transfer between different harmonics.

  19. Short-pulse generation in a diode-end-pumped solid-state laser

    CSIR Research Space (South Africa)

    Ngcobo, S

    2010-09-01

    Full Text Available in the picosecond region with a maximum average output power of 2.8W. Passive modelocking of the Nd:YVO4 laser has been demonstrated using a semiconductor saturable absorber mirror (SESAM). THEORETICAL ANALYSIS Ultra-fast solid state lasers are a key component... theoretical PQSML,th of 2.08W. Short-Pulse Generation in a Diode-End-Pumped Solid-State Laser S. Ngcobo1,2, C. Bollig1 and H. Von Bergmann2 1CSIR National Laser Centre, PO Box 395, Pretoria, 0001, South Africa 2Laser Research Center, University...

  20. Third-Order Harmonic Generation in Atmospheric Air with Focused Intense Femtosecond Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    朱长军; 秦元东; 杨宏; 王树峰; 龚旗煌

    2001-01-01

    Generation of third-order harmonics at 800 nm of femtosecond laser pulses is studied in neutral atmospheric air and in plasma of optical breakdown in air. Its efficiency is measured at different fundamental laser intensities. A maximum efficiency is observed at the intensity when optical breakdown in atmospheric air starts. The factors that exhibit the main effects on the harmonic generation, including self-focusing in a neutral air and self-focusing in plasma, are discussed.

  1. Production of quasi ellipsoidal laser pulses for next generation high brightness photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Rublack, T., E-mail: Tino.Rublack@desy.de [DESY, Zeuthen (Germany); Good, J.; Khojoyan, M.; Krasilnikov, M.; Stephan, F. [DESY, Zeuthen (Germany); Hartl, I.; Schreiber, S. [DESY, Hamburg (Germany); Andrianov, A.; Gacheva, E.; Khazanov, E.; Mironov, S.; Potemkin, A.; Zelenogorskii, V.V. [IAP/RAS, Nizhny Novgorod (Russian Federation); Syresin, E. [JINR, Dubna (Russian Federation)

    2016-09-01

    The use of high brightness electron beams in Free Electron Laser (FEL) applications is of increasing importance. One of the most promising methods to generate such beams is the usage of shaped photocathode laser pulses. It has already demonstrated that temporal and transverse flat-top laser pulses can produce very low emittance beams [1]. Nevertheless, based on beam simulations further improvements can be achieved using quasi-ellipsoidal laser pulses, e.g. 30% reduction in transverse projected emittance at 1 nC bunch charge. In a collaboration between DESY, the Institute of Applied Physics of the Russian Academy of Science (IAP RAS) in Nizhny Novgorod and the Joint Institute of Nuclear Research (JINR) in Dubna such a laser system capable of producing trains of laser pulses with a quasi-ellipsoidal distribution, has been developed. The prototype of the system was installed at the Photo Injector Test facility at DESY in Zeuthen (PITZ) and is currently in the commissioning phase. In the following, the laser system will be introduced, the procedure of pulse shaping will be described and the last experimental results will be shown.

  2. High-Power Tunable Laser Pulse Driven Terahertz Generation in Corrugated Plasma Waveguides

    Science.gov (United States)

    Miao, Chenlong; Palastro, John; Antonsen, Thomas

    2016-10-01

    Excitation of terahertz radiation by the interaction of an ultra-short laser pulse and the fields of a miniature, corrugated plasma waveguide is considered. Plasma structures of this type have been realized experimentally and they can support electromagnetic (EM) channel modes with properties that allow for radiation generation. In particular, the mode have subluminal field components, thus allowing phase matching between the generated THz modes and the ponderomotive potential of the laser pulse. Theoretical analysis and full format PIC simulations are conducted. We find THz generated by this slow wave phase matching mechanism is characterized by lateral emission and a coherent, narrow band, tunable spectrum with relatively high power and conversion efficiency. We investigated two different types of channels, and a range of realistic laser pulses and plasma profile parameters are considered with the goal of increasing the conversion of optical energy to THz radiation. We find high laser intensities strongly modify the THz spectrum by exciting higher order channel modes. Enhancement of a specific channel mode can be realized by using an optimum pulse duration and plasma density. As an example, a fixed drive pulse (0.55 J) with spot size of 15 µm and pulse duration of 15 fs excites 37.8 mJ of THz radiation in a 1.5 cm corrugated plasma waveguide with on axis average density of 1.4×1018cm-3, conversion efficiency exceeding 8% is achieved.

  3. Photonic Crystal Fano Laser: Terahertz Modulation and Ultrashort Pulse Generation

    DEFF Research Database (Denmark)

    Mørk, Jesper; Chen, Yaohui; Heuck, Mikkel

    2014-01-01

    We suggest and analyze a laser with a mirror realized by Fano interference between a waveguide and a nanocavity. For small-amplitude modulation of the nanocavity resonance, the laser can be modulated at frequencies exceeding 1 THz, not being limited by carrier dynamics as for conventional lasers....

  4. High-Order Harmonic Generation by Two Non-Collinear Femtosecond Laser Pulses in CO

    Institute of Scientific and Technical Information of China (English)

    WANG Run-Hai; JIANG Hong-Bing; YANG Hong; WU Cheng-Yin; GONG Qi-Huang

    2005-01-01

    @@ We have experimentally studied the high order harmonic generation (HHG) in CO molecules by two femtosecond laser pulses using a pump-probe technique. The delay time between two pulses is longer than the pulse duration, and the pump intensity is about 6.2 × 1014 W/cm2. It is found that the HHG signal is independent of the time delay in the picosecond region, but it is dependent on the distance between the centres of focuses of the two beams. The phase modulation induced by the pump pulse is regarded to be responsible for this.

  5. Intense ultrashort pulse generation using the JAERI far-infrared free electron laser

    CERN Document Server

    Nagai, R; Nishimori, N; Kikuzawa, N; Sawamura, M; Minehara, E J

    2002-01-01

    An intense ultrashort optical pulse has been quasi-continuously generated using a superconducting RF linac-based free-electron laser at a wavelength of 22.5 mu m. The pulse shape and width are measured by second-order optical autocorrelation with a birefringent Te crystal. At synchronism of the optical resonator, the pulse shape is a smooth single pulse with an FWHM width of 255 fs and energy of 74 mu J. A train of subpulses is developed by increasing the desynchronism of the optical resonator. The measured results are in good agreement with numerical simulation.

  6. Sub-50-fs pulse generation from thulium-doped ZBLAN fiber laser oscillator.

    Science.gov (United States)

    Nomura, Yutaka; Fuji, Takao

    2014-05-19

    An ultrafast, passively mode-locked fiber laser oscillator has been realized using thulium-doped ZBLAN fibers. Very low dispersion of ZBLAN glass fibers enabled generation of pulses with broad spectra extending from 1730 nm to 2050 nm. Pulses are obtained with the average power of 13 mW at the repetition rate of 67.5 MHz when the pump power is 140 mW. The output pulses are compressed with a pair of SF10 prisms and their durations are measured with SHG FROG, from which we obtained the pulse duration as short as 45 fs.

  7. Electromagnetic Pulses Generated From Laser Target Interactions at Shenguang II Laser Facility

    Science.gov (United States)

    Yang, Jinwen; Li, Tingshuai; Yi, Tao; Wang, Chuanke; Yang, Ming; Yang, Weiming; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

    2016-10-01

    Significant electromagnetic pulses (EMP) can be generated by the intensive laser irradiating solid targets in inertial confinement fusion (ICF). To evaluate the EMP intensity and distribution in and outside the laser chamber, we designed and fabricated a discone antenna with ultra-wide bands of over 10 GHz. The return loss (S11 parameter) of this antenna was below -10 dB and could even achieve under -30 dB at 3.1 GHz. The EMP intensity in this study at 80 cm and 40 cm away from the target chamber center (TCC) reached 400 kV/m and 2000 kV/m. The current results are expected to offer preliminary information to study physics regarding laser plasma interactions and will also lay experimental foundation for EMI shielding design to protect various diagnostics. supported by the Fundamental Research Funds for the Central Universities of China (No. ZYGX2015J108) and National Natural Science Foundation of China (Nos. 11575166 and 51581140)

  8. Generation, shaping, compression, characterization and application of intense ultrashort laser pulses

    CERN Document Server

    Cheng, Z

    2001-01-01

    Recently, the development of intense ultrashort laser pulses has attracted much interest because of their significant applications in many fields of science and technology. This thesis contributes to the generation, shaping, compression, characterization and application of intense ultrashort laser pulses as follows: 1. Laser pulses of 17.5-fs with a peak power of 0.1-TW at 1-kHz repetition rate have been generated by a compact single-stage ten-pass Ti:sapphire amplifier system with a high-order-dispersion-mirror compensator and a spectral shaping for the first time. The experimental results are in reasonable agreement with numerical calculations. 2. The first experimental study on arbitrary shaping of intense ultrashort pulses has been conducted in a kHz amplifier system capable of generating 27 fs pulses by using an acousto-optic programmable dispersive filter (AOPDF). 17-fs transform-limited pulses have been achieved and arbitrary shaping of these 17-fs pulses has been demonstrated both in the temporal and ...

  9. Dual-wavelength stable nanosecond pulses generation from cladding-pumped fiber laser

    Institute of Scientific and Technical Information of China (English)

    Shuling Hu; Jing Yu; Chunqing Gao; Guanghui Wei; Fuyun Lü

    2006-01-01

    In this paper, the generation of dual-wavelength stable nanosecond pulses by a laser diode pumped Ybdoped double-clad fiber laser is presented. In the experiment, the fiber laser with two-mirror cavity is approved which operates in a self-Q-switching regime. The Q-switching mechanism is based on stimulatedBrillouin scattering (SBS). When the pump power achieves the SBS threshold, the fiber laser changes from the start resonator to the SBS resonator. With different reflectivities of the second mirror, stable dual-wavelength pulses with the pulse width range from 10 ns to less than 2 ns are obtained. The resultwas explained theoretically by birefringency (including stochastic birefringency and bend birefringency).

  10. Nanosecond pulsed laser induced generation of open macro porosity on sintered ZnO pellet surface

    Energy Technology Data Exchange (ETDEWEB)

    Singh, A.K., E-mail: anilks@barc.gov.in [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai (India); Samanta, Soumen [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai (India); Sinha, Sucharita [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai (India)

    2015-01-15

    Highlights: • Zinc oxide (ZnO) targets have been surface treated using a frequency doubled nanosecond pulsed Nd:YAG laser at laser fluence levels ranging between 2 and 9 J/cm{sup 2}. • Our observations establish that laser irradiation provides an effective technique for generation of surface macro porosity in case of ZnO pellets. • Extent of surface porosity and the mean pore size could be controlled by appropriately varying the incident laser fluence. • Such laser treated ZnO surfaces with enhanced surface porosity and large size pores (mean pore area ∼2–5 μm{sup 2}) can serve as potential candidate for humidity sensors with high sensitivity and fast response time, particularly in high humidity range. - Abstract: Surface porosity and pore size distribution of sensing material greatly influence performance parameters such as sensitivity, reproducibility and response time of sensors. Various approaches have been employed to generate surface porosity having varying pore size distribution. This paper presents our results on pulsed laser irradiation based surface microstructuring of sintered zinc oxide (ZnO) pellets leading to generation of enhanced surface porosity. ZnO targets have been surface treated using a frequency doubled nanosecond pulsed Nd:YAG laser at laser fluence levels ranging between 2 and 9 J/cm{sup 2}. Our observations establish that laser irradiation provides an effective technique for generation of surface macro porosity in case of ZnO pellets. Also, extent of surface porosity and the mean pore size could be controlled by appropriately varying the incident laser fluence. Such laser treated ZnO surfaces with enhanced surface porosity and large size pores can serve as potential candidate for humidity sensors with high sensitivity and fast response time, particularly in high humidity range.

  11. Green and ultraviolet pulse generation with a compact, fiber laser, chirped-pulse amplification system for aerosol fluorescence measurements

    Science.gov (United States)

    Lou, Janet W.; Currie, Marc; Sivaprakasam, Vasanthi; Eversole, Jay D.

    2010-10-01

    We use a compact chirped-pulse amplified system to harmonically generate ultrashort pulses for aerosol fluorescence measurements. The seed laser is a compact, all-normal dispersion, mode-locked Yb-doped fiber laser with a 1050 nm center wavelength operating at 41 MHz. Average powers of more than 1.2 W at 525 nm and 350 mW at 262 nm are generated with biofluorescence measurements as it allows faster sampling rates as well as the higher peak powers as compared to previously demonstrated Q-switched systems while maintaining a pulse period that is longer than the typical fluorescence lifetimes. Thus, the fluorescence excitation can be considered to be quasicontinuous and requires no external synchronization and triggering.

  12. Third Harmonic Generation of a Short Pulse Laser in a Tunnel Ionizing Plasma: Effect of Self-Defocusing

    OpenAIRE

    Niti Kant

    2013-01-01

    Third harmonic generation of a Gaussian short pulse laser in a tunnel ionizing plasma is investigated. A Gaussian short pulse laser propagating through a tunnel ionizing plasma generates third harmonic wave. Inhomogeneity of the electric field along the wavefront of the fundamental laser pulse causes more ionization along the axis of propagation while less ionization off axis, leading to strong density gradient with its maximum on the axis of propagation. The medium acts like a diverging lens...

  13. Next generation ultrashort pulse lasers: Terawatts to Petawatts

    Energy Technology Data Exchange (ETDEWEB)

    Barty, C.P.; Gordon, C.L. III; Korn, G.; Lemoff, B.E.; Raksi, F.; Rose-Petruck, C.; Squier, J.; Wilson, K.R.; Yakovlev, V.V.; Yamakawa, K. [University of California, San Diego, Urey Hall, Mail Code 0339, La Jolla, California 92093-0339 (United States)

    1996-05-01

    Techniques for the control of femtosecond resolution phase and amplitude distortions during the amplification of 10-fs optical pulses to joule-level energies are discussed. {copyright} {ital 1996 American Institute of Physics.}

  14. Wavelength-tunable multicolored femtosecond laser pulse generation in a fused silica glass plate

    Science.gov (United States)

    Kobayashi, Takayoshi; Liu, Jun

    2010-05-01

    We obtained an array of multicolored femtosecond laser pulses with as many as 17 different colors that are spatially isolated. The mechanism of generation was proved to be cascaded four-wave mixing and with the following procedure. The output beam from a femtosecond laser was split into two. One of the two beams was pulse-compressed with a hollow core fiber and the intensity of the other was reduced. The two beams were synchronized and combined with a small crossing angle in a plate of fused silica glass plate. The wavelengths of the sidebands are continuously tunable from near-ultraviolet to near-infrared. The pulse duration, spatial mode, spectrum, and energy stability of the sidebands were studied. As many as fifteen spectral up-shifted pulses and two spectral downshifted pulses were obtained with spectral bandwidths broader than 1.8 octaves. Properties such as pulse energy as high as 1 μmJ, 45 fs pulse duration, smaller than 1.1 times of the diffraction limit Gaussian spatial profile, and better than 2% RMS power stability of the generated sidebands make it can be used in various experiments. The characterization showed that the sidebands have sufficiently good qualities to enable application to for various multicolor femtosecond laser experiments, for example, a multicolor pump-probe experiment.

  15. Tunable high-harmonic generation by chromatic focusing of few-cycle laser pulses

    Science.gov (United States)

    Holgado, W.; Hernández-García, C.; Alonso, B.; Miranda, M.; Silva, F.; Varela, O.; Hernández-Toro, J.; Plaja, L.; Crespo, H.; Sola, I. J.

    2017-06-01

    In this work we study the impact of chromatic focusing of few-cycle laser pulses on high-order-harmonic generation (HHG) through analysis of the emitted extreme ultraviolet (XUV) radiation. Chromatic focusing is usually avoided in the few-cycle regime, as the pulse spatiotemporal structure may be highly distorted by the spatiotemporal aberrations. Here, however, we demonstrate it as an additional control parameter to modify the generated XUV radiation. We present experiments where few-cycle pulses are focused by a singlet lens in a Kr gas jet. The chromatic distribution of focal lengths allows us to tune HHG spectra by changing the relative singlet-target distance. Interestingly, we also show that the degree of chromatic aberration needed for this control does not degrade substantially the harmonic conversion efficiency, still allowing for the generation of supercontinua with the chirped-pulse scheme, demonstrated previously for achromatic focusing. We back up our experiments with theoretical simulations reproducing the experimental HHG results depending on diverse parameters (input pulse spectral phase, pulse duration, and focus position) and proving that, under the considered parameters, the attosecond pulse train remains very similar to the achromatic case, even showing cases of isolated attosecond pulse generation for near-single-cycle driving pulses.

  16. Temperature variation induced by the pulsed-periodic laser pumping under terahertz wave generation

    Science.gov (United States)

    Kitaeva, G. Kh; Moiseenko, E. V.; Shepelev, A. V.

    2017-09-01

    During nonlinear-optical parametric frequency conversion the heat-related effects occur, considerably influencing the conversion process. We develop versatile methods for analytic and numerical calculations of thermo-optical parameters and the temperature distribution inside a non-linear crystal pumped by periodic laser pulses. As an example, numerical results are presented for a number of laser-based schemes actual for the non-linear optical terahertz wave generation and parametric frequency conversion processes.

  17. Second harmonic generation in a centrosymmetric gas medium with spatiotemporally focused intense femtosecond laser pulses

    CERN Document Server

    Li, Guihua; Xie, Hongqiang; Zeng, Bin; Yao, Jinping; Chu, Wei; Zhang, Haisu; Jing, Chenrui; He, Fei; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

    2013-01-01

    We demonstrate unexpectedly strong second harmonic generation (SHG) in Argon gas by use of spatiotemporally focused (SF) femtosecond laser pulses. The resulting SHG by the SF scheme at a 75 cm distance shows a significantly enhanced efficiency than that achieved with conventional focusing scheme, which offers a new promising possibility for standoff applications. Our theoretical calculations reasonably reproduce the experimental observations, which indicate that the observed SHG mainly originates from the gradient of nonuniform plasma dynamically controlled by the SF laser field.

  18. A compact and versatile pulse generation and shaping subsystem for high energy laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Van Wonterghem, B.M.; Speck, D.R.; Norman, M.; Wilcox, R.B.; Karpenko, V.P.; Richards, J.B.

    1993-01-01

    This paper describes the amplifier and beam shaping section of a new pulse generation system that will drive the Beamlet laser at LLNL. The master oscillator and pulse shaping system are described in an accompanying contribution. A modified regenerative amplifier produces a gain of 10[sup 9] to bring the oscillator pulses to the mJ-level. A serrated aperture and birefringent beam shaper produce a flat-topped square beam with high fill factor. A single four-passed Nd:glass rod amplifier provides sufficient gain to generate the desired 12 J output energy in a 3 nsec pulse with very small beam profile, wavefront and pulse shape distortion. We present a description of the system components, followed by a discussion of its performance, based upon over 150 full front end shots being completed since its assembly.

  19. A compact and versatile pulse generation and shaping subsystem for high energy laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Van Wonterghem, B.M.; Speck, D.R.; Norman, M.; Wilcox, R.B.; Karpenko, V.P.; Richards, J.B.

    1993-01-01

    This paper describes the amplifier and beam shaping section of a new pulse generation system that will drive the Beamlet laser at LLNL. The master oscillator and pulse shaping system are described in an accompanying contribution. A modified regenerative amplifier produces a gain of 10{sup 9} to bring the oscillator pulses to the mJ-level. A serrated aperture and birefringent beam shaper produce a flat-topped square beam with high fill factor. A single four-passed Nd:glass rod amplifier provides sufficient gain to generate the desired 12 J output energy in a 3 nsec pulse with very small beam profile, wavefront and pulse shape distortion. We present a description of the system components, followed by a discussion of its performance, based upon over 150 full front end shots being completed since its assembly.

  20. Characteristics of Plasma Shock Waves Generated in the Pulsed Laser Ablation Process

    Institute of Scientific and Technical Information of China (English)

    李智华; 张端明; 郁伯铭; 关丽

    2002-01-01

    We modify the Sedov theory to describe plasma shock waves generated in a pulsed laser ablating process. We also study the propagation characteristics of plasma shock waves during the preparation process of functional thin films deposited by a pulsed laser. In particular, we discuss in detail the temporal behaviour of energy causing the difference of the propagation characteristics between the plasma shock wave and the ideal shock wave in the point explosion model. Under the same experimental conditions, the theoretical results calculated with our modified Sedov theory are in good agreement with the existing experimental data.

  1. Collisionless shocks driven by 800 nm laser pulses generate high-energy carbon ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.; Shen, B. F., E-mail: bfshen@mail.shcnc.ac.cn; Wang, W. P.; Xu, Y.; Liu, Y. Q.; Liang, X. Y.; Leng, Y. X.; Li, R. X., E-mail: ruxinli@mail.shcnc.ac.cn; Xu, Z. Z. [State Key Laboratory of High Filed Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Yan, X. Q.; Chen, J. E. [State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China)

    2015-01-15

    We present experimental studies on ion acceleration from diamond-like carbon (DLC) foils irradiated by 800 nm, linearly polarized laser pulses with peak intensity of 1.7 × 10{sup 19 }W/cm{sup 2} to 3.5 × 10{sup 19 }W/cm{sup 2} at oblique incidence. Diamond-like carbon foils are heated by the prepulse of a high-contrast laser pulse and expand to form plasmas of near-critical density caused by thermal effect before the arrival of the main pulse. It is demonstrated that carbon ions are accelerated by a collisionless shock wave in slightly overdense plasma excited by forward-moving hot electrons generated by the main pulse.

  2. Equal-Amplitude Optical Pulse Generation from a Rational Harmonic Mode-Locked Fibre Laser

    Institute of Scientific and Technical Information of China (English)

    FENG Xin-Huan; YUAN Shu-Zhong; LI Yao; LIU Yan-Ge; KAI Gui-Yun; DONG Xiao-Yi

    2004-01-01

    A simple technique for the generation of equal-amplitude high repetition rate pulses from a rational harmonic mode-locked fibre ring laser is demonstrated. The principle is based on the combination of the nonlinear characteristics of the modulator and the effect of rational harmonic mode-locking. The two sources act on each other and the integrated effect eventually leads to the pulse amplitude-equalization. We obtain amplitude-equalized short pulses up to the fifth-order rational harmonic mode-locking with an optimum bias level and modulation depth of the modulator, which demonstrates the efficiency of this method.

  3. Generation of intense 10-ps, 193-nm pulses using simple distributed feedback dye lasers and an ArF(*) amplifier.

    Science.gov (United States)

    Hatten, D L; Cui, Y; Iii, W T; Mikes, T; Goldhar, J

    1992-11-20

    A pair of holographic distributed feedback dye lasers is used to generate 10-ps pulses at two selected wavelengths that are mixed in a BBO crystal to produce a pulse ~ 10 ps in duration at 193 nm. This seed pulse is subsequently amplified in an ArF(*) excimer laser to an energy of 10-15 mJ with <40 microJ in amplified spontaneous emission. The pulses are nearly transform limited and diffraction limited.

  4. Generation of synchronized signal and pump pulses for an optical parametric chirped pulse amplification based multi-terawatt Nd:glass laser system

    Indian Academy of Sciences (India)

    M Raghuramaiah; R K Patidar; R A Joshi; P A Naik; P D Gupta

    2010-11-01

    Synchronized signal (650 ps) and pump (1.3 ns) pulses were generated using 4-pass geometry in a grating pair based pulse stretcher unit. The pump pulse has been further amplified in a high gain regenerative amplifier. This amplified pulse was used as the pump in an optical parametric chirped pulse amplification based Nd:glass laser system. As the chirped signal pulse and the pump pulse originated from the same oscillator, the time jitter between the pump pulse and the signal pulse can be <50 ps.

  5. A systematic investigation of high harmonic generation using mid-infrared driving laser pulses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We report on a systematic investigation of the influences of gas pressure,focal position and focusing geometry on high harmonic generation by use of mid-infrared femtosecond laser pulses. We also discuss the spatial characteristics of harmonics under different focusing conditions. By optimizing the parameters,we experimentally observed the generation of 1 kHz,low divergence coherent X-ray beams in the water-window region.

  6. Carrier Envelope Phase Controlled High-Order Harmonic Generation in Ultrashort Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    WANG Bing-Bing; CHEN Jing; LIU Jie; LI Xiao-Feng; FU Pan-Ming

    2005-01-01

    @@ We investigate the carrier envelope phase (CEP) effects on high-order harmonic generation (HHG) in ultrashort pulses with the pulse duration 2.5fs when the laser intensity is high enough so that the initial state is ionized effectively during the laser pulse but remains about 20% population at the end of the laser pulse. We find that the ionization process of the initial state is very sensitive to the CEP during the laser pulse. The ionization process of the initial state determines the continuum state population and hence influences dramatically the weights of the classical trajectories that contribute to HHG. In such a case we can not predict the cutoff and the structure of the harmonic spectrum only by the number and the kinetic energy of the classical trajectories. The harmonic spectrum exhibits abundant characters for different CEP cases. As a result, we can control the cutoff frequency and the plateau structure of the harmonic spectrum with CEP by controlling the time behaviour of the ionization of the initial state.

  7. Short optical pulse generated by integrated MQW DBR laser/EA-modulator

    Science.gov (United States)

    Chen, Young-Kai; Tanbun-Ek, Tawee; Logan, Ralph A.; Tate, A. R.; Sergent, A. M.; Wecht, K. W.; Sciortino, Paul F., Jr.; Raybon, Gregory; Froberg, Nan M.; Johnson, Anthony M.

    1994-05-01

    We report on the generation of short optical pulses by utilizing the non-linear absorption characteristics of a multiple quantum well (MQW) electro-absorption modulator, which is monolithically integrated with a MQW wavelength-tunable distributed Bragg reflector (DBR) laser on a single chip. Optical pulses as short as 39 ps and 15 ps have been generated at a repetition rate of 3 GHz and 10 GHz, respectively, with a broad tuning range of 5.4 nm near 1554 nm lasing wavelength.

  8. Generation of the numerator=2 rational harmonic mode-locked pulses in fiber ring lasers

    Institute of Scientific and Technical Information of China (English)

    Pinghe Wang(汪平河); Li Zhan(詹黎); Qinghao Ye(叶庆好); Yuxing Xia(夏宇兴)

    2004-01-01

    In conventional rational harmonic mode-locking, optical pulse trains with the repetition rate of(pn + 1)fc are generated when the modulation frequency of the in-cavity modulator is set at fm=(n + 1/p)fc, where n and p are both integers, fc is the fundamental cavity frequency. In this paper, we report that rational harmonic mode locking phenomenon takes place in the fiber lasers when the modulation frequency is set at fm =(n + 2/p)fc. The pulse generations are experimentally demonstrated when the numerator of the rational corresponds to 2 in 5th and 7th order rational harmonic mode-locking.

  9. Double-pulse induced harmonic generation in laser-produced plasmas

    Science.gov (United States)

    Ganeev, Rashid A.; Suzuki, Masayuki; Yoneya, Shin; Kuroda, Hiroto

    2015-12-01

    We report the studies of the metals, non-metals, powders, and nanoparticles as the targets for laser ablation induced high-order harmonic generation of ultrashort pulses using the double-pulse technique. The proposed technique demonstrates the attractiveness as the method for the studies of the high-order nonlinear optical properties of various materials. The comparative analysis of the harmonic generation using different targets showed that the species allowing easier ablation (powders, nanoparticles) produce stronger harmonic yield in the extreme ultraviolet range.

  10. Generation of efficient THz radiation by optical rectification in DAST crystal using tunable femtosecond laser pulses

    Science.gov (United States)

    Venkatesh, Mottamchetty; Thirupugalmani, K.; Rao, K. S.; Brahadeeswaran, S.; Chaudhary, A. K.

    2017-03-01

    We report the efficient THz generation by optical rectification from an indigenously grown organic DAST crystal using the 140 fs oscillator laser pulses tunable in between 780 and 850 nm. The generated THz pulse profile and powers have been measured using the photoconductive (PC) antennas and pyroelectric detector, respectively. The highest THz peak amplitude and power is obtained at 825 nm central wavelength. We have theoretically explained the enhancement of THz radiation based on the matching of average optical group refractive index and average THz refractive index of the DAST crystal at 825 nm. In addition, the dependence of THz peak amplitude and THz power on laser power have been carried out. The measured quantum conversion efficiency (QCE) of 0.5 and 1.5 THz bands are of the order 3.7 × 10-3, 1.4 × 10-3, respectively. Finally, an attempt has been made to study the effect of polarizations on generated THz signal.

  11. Plasma-Based Generation and Control of a Single Few-Cycle High-Energy Ultrahigh-Intensity Laser Pulse

    Science.gov (United States)

    Tamburini, M.; Di Piazza, A.; Liseykina, T. V.; Keitel, C. H.

    2014-07-01

    A laser-boosted relativistic solid-density paraboloidal foil is known to efficiently reflect and focus a counterpropagating laser pulse. Here we show that in the case of an ultrarelativistic counterpropagating pulse, a high-energy and ultrahigh-intensity reflected pulse can be more effectively generated by a relatively slow and heavy foil than by a fast and light one. This counterintuitive result is explained with the larger reflectivity of a heavy foil, which compensates for its lower relativistic Doppler factor. Moreover, since the counterpropagating pulse is ultrarelativistic, the foil is abruptly dispersed and only the first few cycles of the counterpropagating pulse are reflected. Our multidimensional particle-in-cell simulations show that even few-cycle counterpropagating laser pulses can be further shortened (both temporally and in the number of laser cycles) with pulse amplification. A single few-cycle, multipetawatt laser pulse with several joules of energy and with a peak intensity exceeding 1023 W/cm2 can be generated already employing next-generation high-power laser systems. In addition, the carrier-envelope phase of the generated few-cycle pulse can be tuned provided that the carrier-envelope phase of the initial counterpropagating pulse is controlled.

  12. Infrared nanosecond pulsed laser irradiation of stainless steel: micro iron-oxide zones generation.

    Science.gov (United States)

    Ortiz-Morales, M; Frausto-Reyes, C; Soto-Bernal, J J; Acosta-Ortiz, S E; Gonzalez-Mota, R; Rosales-Candelas, I

    2014-07-15

    Nanosecond-pulsed, infrared (1064 nm) laser irradiation was used to create periodic metal oxide coatings on the surface of two samples of commercial stainless steel at ambient conditions. A pattern of four different metal oxide zones was created using a galvanometer scanning head and a focused laser beam over each sample. This pattern is related to traverse direction of the laser beam scanning. Energy-dispersive X-ray spectroscopy (EDS) was used to find the elemental composition and Raman spectroscopy to characterize each oxide zone. Pulsed laser irradiation modified the composition of the stainless steel samples, affecting the concentration of the main components within each heat affected zone. The Raman spectra of the generated oxides have different intensity profiles, which suggest different oxide phases such as magnetite and maghemite. In addition, these oxides are not sensible to the laser power of the Raman system, as are the iron oxide powders reported in the literature. These experiments show that it is possible to generate periodic patterns of various iron oxide zones by laser irradiation, of stainless steel at ambient conditions, and that Raman spectroscopy is a useful punctual technique for the analysis and inspection of small oxide areas.

  13. Generation of intense attosecond x-ray pulses using ultraviolet laser induced microbunching in electron beams

    Directory of Open Access Journals (Sweden)

    D. Xiang

    2009-06-01

    Full Text Available We propose a scheme that combines the echo-enabled harmonic generation technique with the bunch compression and allows one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of an ultraviolet seed laser. A few-cycle intense laser is used to generate the required energy chirp in the beam for bunch compression and for selection of an attosecond x-ray pulse. Sending this beam through a short undulator results in an intense isolated attosecond x-ray pulse. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power of a few hundred MW and duration as short as 20 attoseconds (FWHM can be generated from a 200 nm ultraviolet seed laser. The proposed scheme may enable the study of electronic dynamics with a resolution beyond the atomic unit of time (∼24 attoseconds and may open a new regime of ultrafast sciences.

  14. NANOSCALE STRUCTURES GENERATION WITHIN THE SURFACE LAYER OF METALS WITH SHORT UV LASER PULSES

    Directory of Open Access Journals (Sweden)

    Dmitry S. Ivanov

    2017-01-01

    Full Text Available We have completed modeling of a laser pulse influence on a gold target. We have applied a hybrid atomistic-continuum model to analyze the physical mechanisms responsible for the process of nanostructuring. The model combines the advantages of Molecular Dynamics and Two Temperature Model. We have carried out a direct comparison of the modeling results and experimental data on nano-modification due to a single ps laser pulse at the energy densities significantly exceeding the melting threshold. The experimental data is obtained due to a laser pulse irradiation at the wavelength of 248 nm and duration of 1.6 ps. The mask projection (diffraction grating creates the sinusoidal intensity distribution on a gold surface with periods of 270 nm, 350 nm, and 500 nm. The experimental data and modeling results have demonstrated a good match subject to complex interrelations between a fast material response to the laser excitation, generation of crystal defects, phase transitions and hydrodynamic motion of matter under condition of strong laser-induced non-equilibrium. The performed work confirms the proposed approach as a powerful tool for revealing the physical mechanisms underlying the process of nanostructuring of metal surfaces. Detailed understanding of the dynamics of these processes gives the possibility for designing the topology of functional surfaces on nano- and micro-scales.

  15. Femtosecond pulse generation from a Topological Insulator mode-locked fiber laser

    CERN Document Server

    Liu, Hao; Liu, Meng; Zhao, Nian; Luo, Ai-Ping; Luo, Zhi-Chao; Xu, Wen-Cheng; Zhang, Han; Zhao, Chu-Jun; Wen, Shuang-Chun

    2014-01-01

    We reported on the generation of femtosecond pulse in an anomalous-dispersion fiber ring laser by using a polyvinyl alcohol (PVA)-based Topological Insulator (TI), Bi2Se3 saturable absorber (SA). The PVA-TI composite has a low saturable optical intensity of 12 MW/cm2 and a modulation depth of ~3.9%. By incorporating the fabricated PVA-TISA into a fiber laser, mode-locking operation could be achieved at a low pump threshold of 25 mW. After an optimization of the cavity parameters, optical pulse with ~660 fs centered at 1557.5 nm wavelength had been generated. The experimental results demonstrate that the PVA could be an excellent host material for fabricating high-performance TISA, and also indicate that the filmy PVA-TISA is indeed a good candidate for ultrafast saturable absorption device.

  16. White-light generation control with crossing beams of femtosecond laser pulses.

    Science.gov (United States)

    Kolomenskii, A A; Strohaber, J; Kaya, N; Kaya, G; Sokolov, A V; Schuessler, H A

    2016-01-11

    We investigated the variations in generated white-light when crossing two femtosecond laser beams in a Kerr medium. By changing the relative delay of two interacting intense femtosecond laser pulses, we show that white-light generation can be enhanced or suppressed. With a decrease of the relative delay an enhancement of the white-light output was observed, which at even smaller delays was reverted to a suppression of white-light generation. Under choosen conditions, the level of suppression resulted in a white-light output lower than the initial level corresponding to large delays, when the pulses do not overlap in time. The enhancement of the white-light generation takes place in the pulse that is lagging. We found that the effect of the interaction of the beams depends on their relative orientation of polarization and increases when the polarizations are changed from perpendicular to parallel. The observed effects are explained by noting that at intermediate delays, the perturbations introduced in the path of the lagging beam lead to a shortening of the length of filament formation and enhancement of the white-light generation, whereas at small delays the stronger interaction and mutual rescattering reduces the intensity in the central part of the beams, suppressing filamentation and white-light generation.

  17. Third Harmonic Generation of a Short Pulse Laser in a Tunnel Ionizing Plasma: Effect of Self-Defocusing

    Directory of Open Access Journals (Sweden)

    Niti Kant

    2013-08-01

    Full Text Available Third harmonic generation of a Gaussian short pulse laser in a tunnel ionizing plasma is investigated. A Gaussian short pulse laser propagating through a tunnel ionizing plasma generates third harmonic wave. Inhomogeneity of the electric field along the wavefront of the fundamental laser pulse causes more ionization along the axis of propagation while less ionization off axis, leading to strong density gradient with its maximum on the axis of propagation. The medium acts like a diverging lens and pulse defocuses strongly. The normalized third harmonic amplitude varies periodically with the distance with successive maxima acquiring lower value. The self-defocusing of the fundamental laser pulse decays the intensity of the third harmonic pulse.

  18. High-Average-Power Diffraction Pulse-Compression Gratings Enabling Next-Generation Ultrafast Laser Systems

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-11-01

    Pulse compressors for ultrafast lasers have been identified as a technology gap in the push towards high peak power systems with high average powers for industrial and scientific applications. Gratings for ultrashort (sub-150fs) pulse compressors are metallic and can absorb a significant percentage of laser energy resulting in up to 40% loss as well as thermal issues which degrade on-target performance. We have developed a next generation gold grating technology which we have scaled to the petawatt-size. This resulted in improvements in efficiency, uniformity and processing as compared to previous substrate etched gratings for high average power. This new design has a deposited dielectric material for the grating ridge rather than etching directly into the glass substrate. It has been observed that average powers as low as 1W in a compressor can cause distortions in the on-target beam. We have developed and tested a method of actively cooling diffraction gratings which, in the case of gold gratings, can support a petawatt peak power laser with up to 600W average power. We demonstrated thermo-mechanical modeling of a grating in its use environment and benchmarked with experimental measurement. Multilayer dielectric (MLD) gratings are not yet used for these high peak power, ultrashort pulse durations due to their design challenges. We have designed and fabricated broad bandwidth, low dispersion MLD gratings suitable for delivering 30 fs pulses at high average power. This new grating design requires the use of a novel Out Of Plane (OOP) compressor, which we have modeled, designed, built and tested. This prototype compressor yielded a transmission of 90% for a pulse with 45 nm bandwidth, and free of spatial and angular chirp. In order to evaluate gratings and compressors built in this project we have commissioned a joule-class ultrafast Ti:Sapphire laser system. Combining the grating cooling and MLD technologies developed here could enable petawatt laser systems to

  19. Optimized plasma high harmonics generation from ultra-intense laser pulses

    CERN Document Server

    Tang, Suo; Keitel, Christoph H

    2016-01-01

    Plasma high harmonics generation from extremely intense short-pulse laser is explored by including the effects of ion motion and radiation reaction force in the plasma dynamics. The laser radiation pressure induces plasma ion motion through the hole-boring effect resulting into the frequency shifting and widening of the harmonic spectra thereby constraining the coherence properties of the harmonics. Radiation reaction force slightly mitigates the effects caused by the ion motion. Based on the analytical estimates and particle-in-cell simulation results, an optimum parameter regime of plasma high-harmonics is presented.

  20. Brilliant petawatt gamma-ray pulse generation in quantum electrodynamic laser-plasma interaction

    Science.gov (United States)

    Chang, H. X.; Qiao, B.; Huang, T. W.; Xu, Z.; Zhou, C. T.; Gu, Y. Q.; Yan, X. Q.; Zepf, M.; He, X. T.

    2017-03-01

    We show a new resonance acceleration scheme for generating ultradense relativistic electron bunches in helical motions and hence emitting brilliant vortical γ-ray pulses in the quantum electrodynamic (QED) regime of circularly-polarized (CP) laser-plasma interactions. Here the combined effects of the radiation reaction recoil force and the self-generated magnetic fields result in not only trapping of a great amount of electrons in laser-produced plasma channel, but also significant broadening of the resonance bandwidth between laser frequency and that of electron betatron oscillation in the channel, which eventually leads to formation of the ultradense electron bunch under resonant helical motion in CP laser fields. Three-dimensional PIC simulations show that a brilliant γ-ray pulse with unprecedented power of 6.7 PW and peak brightness of 1025 photons/s/mm2/mrad2/0.1% BW (at 15 MeV) is emitted at laser intensity of 1.9 × 1023 W/cm2.

  1. Amplification and generation of ultra-intense twisted laser pulses via stimulated Raman scattering

    CERN Document Server

    Vieira, J; Alves, E P; Fonseca, R A; Mendonça, J T; Bingham, R; Norreys, P; Silva, L O

    2016-01-01

    Twisted Laguerre-Gaussian lasers, with orbital angular momentum and characterised by doughnut shaped intensity profiles, provide a transformative set of tools and research directions in a growing range of fields and applications, from super-resolution microcopy and ultra-fast optical communications to quantum computing and astrophysics. The impact of twisted light is widening as recent numerical calculations provided solutions to long-standing challenges in plasma-based acceleration by allowing for high gradient positron acceleration. The production of ultrahigh intensity twisted laser pulses could then also have a broad influence on relativistic laser-matter interactions. Here we show theoretically and with ab-initio three-dimensional particle-in-cell simulations, that stimulated Raman backscattering can generate and amplify twisted lasers to Petawatt intensities in plasmas. This work may open new research directions in non-linear optics and high energy density science, compact plasma based accelerators and ...

  2. Generation of a single attosecond pulse from an overdense plasma surface driven by a laser pulse with time-dependent polarization

    Institute of Scientific and Technical Information of China (English)

    Luo Mu-Hua; Zhang Qiu-Ju

    2011-01-01

    The influence of time-dependent polarization on attosecond pulse generation from an overdense plasma surface driven by laser pulse is discussed analytically and numerically.The results show that the frequency of controlling pulse controls the number and interval of the generated attosecond pulse,that the generation moment of the attosecond pulse is dominated by the phase difference between the controlling and driving pulses,and that the amplitude of the controlling pulse affects the intensity of the attosecond pulse.Using the method of time-dependent polarization,a "single" ultra-strong attosecond pulse with duration τ≈8.6 as and intensity I≈3.08×1020 W·cm-2 can be generated.

  3. Heat generation caused by ablation of dental restorative materials with an ultra short pulse laser (USPL) system

    Science.gov (United States)

    Braun, Andreas; Wehry, Richard; Brede, Olivier; Frentzen, Matthias; Schelle, Florian

    2011-03-01

    The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an Ultra Short Pulse Laser (USPL) system. Specimens of phosphate cement (PC), ceramic (CE) and composite (C) were used. Ablation was performed with an Nd:YVO4 laser at 1064 nm and a pulse length of 8 ps. Heat generation during laser ablation depended on the thickness of the restoration material. A time delay for temperature increase was observed in the PC and C group. Employing the USPL system for removal of restorative materials, heat generation has to be considered.

  4. Ion motion effects on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration

    Institute of Scientific and Technical Information of China (English)

    W.P.Wang; X.M.Zhang; X.F.Wang; X.Y.Zhao; J.C.Xu; Y.H.Yu; L.Q.Yi; Y.Shi; L.G.Zhang; T.J.Xu; C.Liu; Z.K.Pei; B.F.Shen

    2014-01-01

    The effects of ion motion on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration are investigated by analytical modeling and particle-in-cell simulations. Studies show that the rear part of the transmitted pulse modulated by ion motion is sharper compared with the case of the electron shutter only. In this study, the ions further modulate the short-cycle pulses transmitted. A 3.9 fs laser pulse with an intensity of 1.33×1021W cm-2is generated by properly controlling the motions of the electron and ion in the simulations. The short-cycle laser pulse source proposed can be applied in the generation of single attosecond pulses and electron acceleration in a small bubble regime.

  5. Generation of 8-nJ pulses from a dissipative-soliton fiber laser with a nonlinear optical loop mirror

    Science.gov (United States)

    Zhao, L. M.; Bartnik, A. C.; Tai, Q. Q.; Wise, F. W.

    2013-01-01

    Theoretical and experimental investigations of the behavior of normal-dispersion fiber lasers with nonlinear-optical loop mirrors are presented. The use of a loop mirror causes the laser to generate relatively long, flat-topped pulses. The pulse energy can be high, but the pulse duration is limited to greater than 300 fs. Experimentally, 8-nJ pulses that can be dechirped to 340 fs duration are obtained. The laser is a step toward an all-fiber, environmentally-stable design. PMID:23722797

  6. Experimental Research of Fast Proton Generation From Ultra-short Intense Laser Pulses Interaction With Different Thickness Al Foils

    Institute of Scientific and Technical Information of China (English)

    LAN; Xiao-fei; LU; Jian-xin; HUANG; Yong-sheng; WANG; Lei-jian; XI; Xiao-feng; TANG; Xiu-zhang

    2012-01-01

    <正>With the development of laser technology, the generation of fast ions by the interaction of ultra-short ultra-intense laser pulses with matters has recently been attracting considerable attention, especially for acceleration of proton. Before performing experiment, we calibrated the CR39 detector using standard proton beams from conventional accelerator. In the field of proton acceleration driven by ultra-short ultra-intense laser pulses,

  7. Pulsed laser generation of ultrasound in a metal plate between the melting and ablation thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Every, A. G., E-mail: arthur.every@wits.ac.za [School of Physics, University of the Witwatersrand, PO Wits 2050 (South Africa); Utegulov, Z. N., E-mail: zhutegulov@nu.edu.kz [Department of Physics, School of Science and Technology, Nazarbayev University, Astana 010000 (Kazakhstan); Veres, I. A., E-mail: istvan.veres@recendt.at [RECENDT Research Center for Non Destructive Testing GmbH, A-4040 Linz (Austria)

    2015-03-31

    The generation of ultrasound in a metal plate exposed to nanosecond pulsed laser heating, sufficient to cause melting but not ablation, is treated. Consideration is given to the spatial and temporal profiles of the laser pulse, penetration of the laser beam into the sample, the evolution of the melt pool, and thermal conduction in the melt and surrounding solid. The excitation of the ultrasound takes place over a few nanoseconds, and occurs predominantly within the thermal diffusion length of a micron or so beneath the surface. Because of this, the output of the thermal simulations can be represented as axially symmetric transient radial and normal surface force distributions. The epicentral displacement response at the opposite surface to these forces is obtained by two methods, the one based on the elastodynamic Green’s functions for plate geometry determined by the Cagniard generalized ray method, and the other using a finite element numerical method. The two approaches are in very close agreement. Numerical simulations are reported of the epicentral displacement response of a 3.12mm thick tungsten plate irradiated with a 4 ns pulsed laser beam with Gaussian spatial profile, at intensities below and above the melt threshold. Comparison is made between results obtained using available temperature dependent thermophysical data, and room temperature materials constants except near the melting point.

  8. Complicated Laser Pulse Generation With Pulse Stacking for D-D ICF

    Institute of Scientific and Technical Information of China (English)

    GAO; Zhi-xing; WANG; Lei-jian; LU; Ze; ZHANG; Hai-feng

    2012-01-01

    <正>For direct drive fusion, a pre-distorted pulse with the complicated temporal shape is necessary. It is generally accepted that the pulse for shock ignition should begin with a low energy pre-pulse spike (picket) followed by a long (about 10 ns) low intensity foot pulse, which ramps up to an intermediate pedestal (compression pulse) and ends with a short high intensity spike.

  9. Comparison of short pulse generation schemes for a soft x-ray free electron laser

    Science.gov (United States)

    Martin, I. P. S.; Bartolini, R.

    2011-03-01

    In this paper we study the performance of two complementary short pulse generation schemes as applied to a soft x-ray free electron laser. The first scheme, recently proposed by Saldin et al., makes use of a laser pulse consisting of only a few optical cycles to give an energy chirp to a short section of an electron bunch and tapers the main radiator undulator in order to compensate the chirped region. The second scheme investigated takes a low-charge, high brightness electron bunch and compresses it to ˜1fs in order to operate in the so-called “single-spike” regime. We perform start-to-end simulations of both these schemes, assess the sensitivity of each scheme to realistic jitter sources, and provide a direct comparison of the respective strengths and drawbacks.

  10. Comparison of short pulse generation schemes for a soft x-ray free electron laser

    Directory of Open Access Journals (Sweden)

    I. P. S. Martin

    2011-03-01

    Full Text Available In this paper we study the performance of two complementary short pulse generation schemes as applied to a soft x-ray free electron laser. The first scheme, recently proposed by Saldin et al., makes use of a laser pulse consisting of only a few optical cycles to give an energy chirp to a short section of an electron bunch and tapers the main radiator undulator in order to compensate the chirped region. The second scheme investigated takes a low-charge, high brightness electron bunch and compresses it to ∼1  fs in order to operate in the so-called “single-spike” regime. We perform start-to-end simulations of both these schemes, assess the sensitivity of each scheme to realistic jitter sources, and provide a direct comparison of the respective strengths and drawbacks.

  11. Microfiber-based gold nanorods as saturable absorber for femtosecond pulse generation in a fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu-De [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China); School of Physics and Electronic Information, Huaibei Normal University, Huaibei, Anhui 235000 (China); Luo, Zhi-Chao; Liu, Hao; Liu, Meng; Luo, Ai-Ping, E-mail: luoaiping@scnu.edu.cn; Xu, Wen-Cheng, E-mail: xuwch@scnu.edu.cn [Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)

    2014-10-20

    We reported on the femtosecond pulse generation from an erbium-doped fiber (EDF) laser by using microfiber-based gold nanorods (GNRs) as saturable absorber (SA). By virtue of the geometric characteristic of microfiber-based GNRs, the optical damage threshold of GNRs-SA could be greatly enhanced. The microfiber-based GNRs-SA shows a modulation depth of 4.9% and a nonsaturable loss of 21.1%. With the proposed GNRs-SA, the fiber laser emitted a mode-locked pulse train with duration of ∼887 fs. The obtained results demonstrated that the GNRs deposited microfiber could indeed serve as a high-performance SA towards the practical applications in the field of ultrafast photonics.

  12. Low emittance electron beam generation from a laser wakefield accelerator using two laser pulses with different wavelengths

    CERN Document Server

    Xu, X L; Zhang, C J; Li, F; Wan, Y; Hua, J F; Pai, C -H; Lu, W; Yu, P; Joshi, C; Mori, W B

    2014-01-01

    Ionization injection triggered by short wavelength laser pulses inside a nonlinear wakefield driven by a longer wavelength laser is examined via multi-dimensional particle-in-cell simulations. We find that very bright electron beams can be generated through this two-color scheme in either collinear propagating or transverse colliding geometry. For a fixed laser intensity $I$, lasers with longer/shorter wavelength $\\lambda$ have larger/smaller ponderomotive potential ($\\propto I \\lambda^2$). The two color scheme utilizes this property to separate the injection process from the wakefield excitation process. Very strong wakes can be generated at relatively low laser intensities by using a longer wavelength laser driver (e.g. a $10 \\micro\\meter$ CO$_2$ laser) due to its very large ponderomotive potential. On the other hand, short wavelength laser can produce electrons with very small residual momenta ($p_\\perp\\sim a_0\\sim \\sqrt{I}\\lambda$) inside the wake, leading to electron beams with very small normalized emit...

  13. Broadband supercontinuum generation with femtosecond pulse width in erbium-doped fiber laser (EDFL)

    Science.gov (United States)

    Rifin, S. N. M.; Zulkifli, M. Z.; Hassan, S. N. M.; Munajat, Y.; Ahmad, H.

    2016-11-01

    We demonstrate two flat plateaus and the low-noise spectrum of supercontinuum generation (SCG) in a highly nonlinear fiber (HNLF), injected by an amplified picosecond pulse seed of a carbon nanotube-based passively mode locked erbium-doped fiber laser. A broad spectrum of width approximately 1090 nm spanning the range 1130-2220 nm is obtained and the pulse width is compressed to the shorter duration of 70 fs. Variations of the injected peak power up to 33.78 kW into the HNLF are compared and the broad spectrum SCG profiles slightly expand for each of the injected peak powers. This straightforward configuration of SCG offers low output power and ultra-narrow femtosecond pulse width. The results facilitate the development of all fiber time-domain spectroscopy systems based on the photoconductive antenna technique.

  14. High-Order Harmonic Generation by Two Non-collinear Coherent Femtosecond Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    陆伟新; 刘婷婷; 杨宏; 孙騊亨; 龚旗煌

    2003-01-01

    We have studied the high-order harmonic generated by two coherent pulses in argon gas produced by a gas jet. A loop in the relationship of the harmonic intensity versus the absolute values of relative phase difference was observed for non-collinear arrangement. Compared with the collinear arrangement, increase of 10 times of the conversion efficiency for 17th-order harmonic generation at an appropriate relative phase difference was obtained. The calculation of the intensity and phase for the laser field near the focus gives a simple reason for these phenomena.

  15. Analytical description of generation of the residual current density in the plasma produced by a few-cycle laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Silaev, A. A., E-mail: silaev@appl.sci-nnov.ru; Vvedenskii, N. V., E-mail: vved@appl.sci-nnov.ru [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); University of Nizhny Novgorod, Nizhny Novgorod 603950 (Russian Federation)

    2015-05-15

    When a gas is ionized by a few-cycle laser pulse, some residual current density (RCD) of free electrons remains in the produced plasma after the passage of the laser pulse. This quasi-dc RCD is an initial impetus to plasma polarization and excitation of the plasma oscillations which can radiate terahertz (THz) waves. In this work, the analytical model for calculation of RCD excited by a few-cycle laser pulse is developed for the first time. The dependences of the RCD on the carrier-envelope phase (CEP), wavelength, duration, and intensity of the laser pulse are derived. It is shown that maximum RCD corresponding to optimal CEP increases with the laser pulse wavelength, which indicates the prospects of using mid-infrared few-cycle laser pulses in the schemes of generation of high-power THz pulses. Analytical formulas for optimal pulse intensity and maximum efficiency of excitation of the RCD are obtained. Basing on numerical solution of the 3D time-dependent Schrödinger equation for hydrogen atoms, RCD dependence on CEP is calculated in a wide range of wavelengths. High accuracy of analytical formulas is demonstrated at the laser pulse parameters which correspond to the tunneling regime of ionization.

  16. Generation of fluorescent CdSe nanocrystals by short-pulse laser fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Zholudov, Yu. T., E-mail: yurets-z@rambler.ru [Kharkiv National University of Radioelectronics (Ukraine); Sajti, C. L., E-mail: l.sajti@lzh.de [Laser Zentrum Hannover e.V. (Germany); Slipchenko, N. N. [Kharkiv National University of Radioelectronics (Ukraine); Chichkov, B. N. [Laser Zentrum Hannover e.V. (Germany)

    2015-12-15

    A simple liquid-phase laser fragmentation approach, resulting in the rapid transformation of CdSe microcrystals into colloidal quantum dots (QDs), is presented. Laser fragmentation is achieved by irradiating a CdSe suspension in dimethylformamide with intense infrared, picosecond laser pulses followed by surface passivation with oleylamine or different types of phosphines. The generated QDs reveal perfect colloidal stability preventing agglomeration and precipitation, and show characteristic QD absorption and fluorescence characteristics, whereas their emission properties strongly depend on the surface states and applied capping ligands. These QDs show distinct photoemission under 405-nm single-photon and 800-nm multi-photon excitations in the 560- to 610-nm spectral region corresponding to the QDs size of about 1.5–2 nm in diameter which is confirmed by transmission electron microscopy.

  17. Soft x-ray generation in gases with an ultrashort pulse laser

    Energy Technology Data Exchange (ETDEWEB)

    Ditmire, Todd Raymond [Univ. of California, Davis, CA (United States)

    1996-01-08

    An experimental investigation of soft x-ray production resulting from the interaction of intense near infra-red laser radiation with gases is presented in this thesis. Specifically, soft x-ray generation through high order harmonic generation or exploiting intense inverse bremsstrahlung heating is examined. Most of these studies are conducted with femtosecond, terawatt class Cr:LiSrAlF6 (LiSAF) laser, though results derived from studies with other laser systems are presented as well. The majority of this work is devoted to experimental investigations, however, theoretical and computational models are developed to interpret the data. These studies are motivated by the possibility of utilizing the physics of intense laser/matter interactions as a potential compact source of bright x-rays. Consequently, the thrust of many of the experiments conducted is aimed at characterizing the x-rays produced for possible use in applications. In general, the studies of this manuscript fall into three categories. First, a unique 130 fs, 8 TW laser that is based on chirped pulse amplification, is described, and its performance is evaluated. The generation of x-rays through high order harmonics is then discussed with emphasis on characterizing and optimizing harmonic generation. Finally, the generation of strong, incoherent x-ray radiation by the intense irradiation of large (>1,000 atom) clusters in gas jets, is explored. The physics of laser energy absorption by clusters illuminated with intensities of 1015 to 1017 W/cm2 is considered in detail. X-ray spectroscopy of the hot plasmas that result from the irradiation of the clusters is conducted, and energy transport and kinetics issues in these plasmas are discussed.

  18. Supercontinuum generation employing the high-energy wave-breaking-free pulse in a compact all-fiber laser system

    Science.gov (United States)

    Wang, L. R.; Liu, X. M.; Gong, Y. K.; Mao, D.; Duan, L. N.

    2011-10-01

    Supercontinuum (SC) generation is experimentally achieved in a compact all-fiber laser system by using high-energy wave-breaking-free dissipative soliton (DS) pulses. The pulses exhibit Gaussian (rectangular) shape profiles in spectral (temporal) domain, which is even reversed of the typical rectangular-spectrum DSs. With the increase of pump power the pulse duration enlarges dramatically whereas the bandwidth and peak power of the pulse keep almost constant, which enables the pulse to accumulate much higher energy during the pulse-shaping process. When inputting the amplified pulse into the single-mode fiber, SC with excellent flatness is generated with the spectral range from about 1550 to 1700 nm. Broader SC with the bandwidth of even larger than 1000 nm can also be generated by this kind of pulse in the near-zero-dispersion-flattened photonic-crystal fiber through strong nonlinear effects.

  19. Second harmonic pico-second pulse generation with mode-locked 1064nm DBR laser diodes

    Science.gov (United States)

    Klehr, A.; Prziwarka, T.; Jedrzejczyk, D.; Brox, O.; Bugge, F.; Wenzel, H.; Paschke, K.; Erbert, G.; Tränkle, G.

    2014-02-01

    Detailed experimental investigations of the generation of high-energy short infrared and green pulses with a mode-locked multi-section distributed Bragg reflector (DBR) laser in dependence on the lengths of the gain section and the saturableabsorber (SA) section as well the corresponding input currents and reverse voltages, respectively, are presented. The laser under investigation is 3.5 mm long and has a 500 μm long DBR section. The remaining cavity was divided into four 50 μm, four 100 μm, two 200 μm and eight 250 μm long electrically separated segments so that the lengths of the gain and SA sections can be simply varied by bonding. Thus, the dependence of the mode-locking behavior on the lengths of the gain and SA sections can be investigated on the same device. Optimal mode-locking was obtained for absorber lengths between LAbs = 200 μm and 300 μm and absorber voltages between UAbs= -2 V and -3 V. A pulse length of τ ≍ 10 ps, a repetition frequency of 13 GHz and a RF line width of less than 100 kHz were measured. An infrared peak pulse power of 900 mW was reached. The FWHM of the optical spectrum was about 150 pm. With an 11.5 mm long periodically poled MgO doped LiNbO3 crystal having a ridge geometry of 5 μm width and 4 μm height green light pulses were generated. With an infrared pump peak power of 900 mW a green pulse energy of 3.15 pJ was reached. The opto-optical conversion efficiency was about 31%.

  20. High-harmonic generation in benzene with linearly- and circularly-polarised laser pulses

    CERN Document Server

    Wardlow, Abigail

    2015-01-01

    High harmonic generation in benzene is studied using a mixed quantum-classical approach in which the electrons are described using time-dependent density functional theory while the ions move classically. The interaction with both circularly- and linearly-polarised infra-red ($\\lambda = 800$ nm) laser pulses of duration 10 cycles (26.7 fs) is considered. The effect of allowing the ions to move is investigated as is the effect of including self-interaction corrections to the exchange-correlation functional. Our results for circularly-polarised pulses are compared with previous calculations in which the ions were kept fixed and self-interaction corrections were not included while our results for linearly-polarised pulses are compared with both previous calculations and experiment. We find that even for the short duration pulses considered here, the ionic motion greatly influences the harmonic spectra. While ionization and ionic displacements are greatest when linearly-polarised pulses are used, the response to ...

  1. Ultrashort-pulse generation in a YAG:Nd(3+) laser in a scheme with colliding pulses

    Energy Technology Data Exchange (ETDEWEB)

    Prokhorenko, V.I.; Tikhonov, E.A.; Iatskiv, D.IA.; Bushmakin, E.N.

    1987-04-01

    The time, energy, and statistical characteristics of a picosecond mode-locked YAG:Nd(3+) laser with colliding pulses are studied. Under these conditions, no additional pulse shortening occurs as compared to a laser utilizing an absorber which is in contact with the nontransmitting mirror. However, this mode of operation is characterized by a greater reproducibility of the emitted pulse duration. A direct recording of the duration and the spectrum is used. It is shown that spectrally limited pulses are emitted only when the cell with a saturable absorber (dye No. 3274) is located in the center of the antiresonant reflector. 11 references.

  2. Generation of a few femtoseconds pulses in seeded FELs using a seed laser with small transverse size

    Science.gov (United States)

    Li, Heting; Jia, Qika

    2016-09-01

    We propose a simple method to generate a few femtosecond pulses in seeded FELs. We use a longitudinal energy-chirped electron beam passing through a dogleg where transverse dispersion will generate a horizontal energy chirp, then in the modulator, a seed laser with narrow beam radius will only modulate the center portion of the electron beam and then short pulses at high harmonics will be generated in the radiator. Using a representative realistic set of parameters, we show that 30 nm XUV pulse based on the HGHG scheme and 9 nm soft x-ray pulse based on the EEHG scheme with duration of about 8 fs (FWHM) and peak power of GW level can be generated from a 180 nm UV seed laser with beam waist of 75 μm. This new scheme can provide an optional operation mode for the existing seeded FEL facilities to meet the requirement of short-pulse FEL.

  3. Generation of Frequency-Chirped Pulses in the Far-Infrared by Means of a Subpicosecond Free-Electron Laser and an External Pulse Shaper

    NARCIS (Netherlands)

    Knippels, G.M.H.; van der Meer, A. F. G.; Mols, Rfxam; van Amersfoort, P. W.; Vrijen, R. B.; Maas, D. J.; Noordam, L. D.

    1995-01-01

    The generation of frequency-chirped optical pulses in the far-infrared is reported. The pulses are produced by the free-electron laser FELIX. The chirp is induced by means of an external shaping device consisting of a grating and a telescope. The shaper is based on reflective optics to permit operat

  4. Mechanical effects induced by shock waves generated by high energy laser pulses

    Science.gov (United States)

    Fournier, J.; Ballard, P.; Merrien, P.; Barralis, J.; Castex, L.; Fabbro, R.

    1991-09-01

    Specimens made of low alloy and non alloyed medium carbon steels were subjected to high energy laser pulses. Direct ablation and confined plasma procedures were both investigated. An optimum impulse momentum transfer to the material is attained with a pulse duration of 30 ns and a power density of 10 GW .cm^2. Fatigue testing shows that the fatigue strengths of the selected materials are significantly increased. This can be related to the fact that laser shock processing generates an appropriate residual compressive stress field in a sufficiently thick layer and does not alter the initial surface roughness. In addition, the use of cumulative laser impacts and of dual treatment combining thermal and mechanical effects of the laser beam have been investigated and shown to result in an enhanced fatigue strength. Des échantillons d'acier éventuellement faiblement allié sont irradiés par un ou plusieurs pulses laser ayant une intensité comprise entre 1 et 100 GW/cm^2 et une durée d'émission laser de 3 ou 30 ns, les deux configurations d'ablation directe ou de plasma confiné étant utilisées. Les contraintes résiduelles résultant du passage de l'onde de choc sont analysées à l'aide de la technique de diffraction de rayons X. D'après cette étude, il apparaît clairement que les valeurs d'intensité et de durée d'émission laser les plus appropriées sont respectivement 10 GW/cm^2 et 30 ns. Ces valeurs correspondent à l'optimum de transfert d'impulsion. De plus, l'influence du nombre d'impacts laser utilisés est discuté et un essai de fatigue montre que ce traitement mécanique de surface augmente de manière significative la limite d'endurance du matériau étudié.

  5. Measurement of electromagnetic pulses generated during interactions of high power lasers with solid targets

    Science.gov (United States)

    De Marco, M.; Krása, J.; Cikhardt, J.; Pfeifer, M.; Krouský, E.; Margarone, D.; Ahmed, H.; Borghesi, M.; Kar, S.; Giuffrida, L.; Vrana, R.; Velyhan, A.; Limpouch, J.; Korn, G.; Weber, S.; Velardi, L.; Delle Side, D.; Nassisi, V.; Ullschmied, J.

    2016-06-01

    A target irradiated with a high power laser pulse, blows off a large amount of charge and as a consequence the target itself becomes a generator of electromagnetic pulses (EMP) owing to high return current flowing to the ground through the target holder. The first measurement of the magnetic field induced by the neutralizing current reaching a value of a few kA was performed with the use of an inductive target probe at the PALS Laser Facility (Cikhardt et al. Rev. Sci. Instrum. 85 (2014) 103507). A full description of EMP generation should contain information on the spatial distribution and temporal variation of the electromagnetic field inside and outside of the interaction chamber. For this reason, we consider the interaction chamber as a resonant cavity in which different modes of EMP oscillate for hundreds of nanoseconds, until the EMP is transmitted outside through the glass windows and EM waves are attenuated. Since the experimental determination of the electromagnetic field distribution is limited by the number of employed antennas, a mapping of the electromagnetic field has to be integrated with numerical simulations. Thus, this work reports on a detailed numerical mapping of the electromagnetic field inside the interaction chamber at the PALS Laser Facility (covering a frequency spectrum from 100 MHz to 3 GHz) using the commercial code COMSOL Multiphysics 5.2. Moreover we carried out a comparison of the EMP generated in the parallelepiped-like interaction chamber used in the Vulcan Petawatt Laser Facility at the Rutherford Appleton Laboratory, against that produced in the spherical interaction chamber of PALS.

  6. Dynamical studies on the generation of periodic surface structures by femtosecond laser pulses

    Directory of Open Access Journals (Sweden)

    Rosenfeld A.

    2013-11-01

    Full Text Available The dynamics of the formation of laser-induced periodic surface structures (LIPSS on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration, 800 nm center wavelength is studied experimentally using a double pulse experiment with cross polarized pulse sequences and a trans illumination femtosecond time-resolved (0.1 ps – 1 ns pump-probe diffraction approach. The results in both experiments confirm the importance of the ultrafast energy deposition and the laser-induced free-electron plasma in the conduction band of the solids for the formation of LIPSS.

  7. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode

    Science.gov (United States)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  8. Synchronized and timing-stabilized pulse generation from a gain-switched laser diode for stimulated Raman scattering microscopy

    Science.gov (United States)

    Tokunaga, Kyoya; Fang, Yi-Cheng; Yokoyama, Hiroyuki; Ozeki, Yasuyuki

    2016-03-01

    We present a picosecond laser source based on a gain-switched laser diode (GS-LD) that can be applied to stimulated Raman scattering (SRS) microscopy. A 1.06-μm GS-LD was used to generate 14-ps pulses at a repetition rate of 38 MHz. The GS-LD was driven by 200-ps electrical pulses, which were triggered through a toggle flip-flop (T-FF). As a result, the GS-LD pulses were subharmonically synchronized to Ti:sapphire laser (TSL) pulses at a repetition rate of 76 MHz. We investigated the timing jitter of GS-LD pulses and found it to be less than 2.5 ps. We also show that the trigger delay can be less sensitive to the optical power of TSL pulses by controlling the threshold voltage of the T-FF. As a result, GS-LD pulses sufficiently overlapped with TSL pulses even when we scanned the wavelength of the TSL pulses. We demonstrate the SRS imaging of HeLa cells with GS-LD pulses and TSL pulses, proving that GS-LD is readily applicable to SRS microscopy as a compact and stable pulse source.

  9. Multiwavelength picosecond pulse generation with diode-pumped Nd:GAGG and Nd:LGGG lasers

    Science.gov (United States)

    Agnesi, A.; Pirzio, F.; Reali, G.; Arcangeli, A.; Tonelli, M.; Jia, Z.; Tao, X.; Zhang, J.

    2010-05-01

    Laser operation near 1.06 μm by diode-pumped Nd:(LuxGd1-x)3Ga5O12 (Nd:LGGG, with x = 0.1) and Gd3AlxGa5-xO12 (GAGG, with x = 1) disordered crystals has been investigated. Cw oscillation with a slope efficiency as high as 61% and 230 mW output power was achieved with 400 mW absorbed power from a 1-W laser diode in Nd:LGGG. Under the same pumping conditions cw oscillation with a slope efficiency as high as 55% and 255 mW output power was achieved with 500 mW absorbed power in Nd:GAGG. Stable passive mode-locking with single- or multi-wavelength spectrum was obtained with a semiconductor saturable absorber mirror (SAM) and a single-prism, dispersion-compensated cavity with both the samples. Fourier-limited pulses with duration ~ 4-9 ps and output power ~ 40 mW were generated at three well-defined laser transitions in the range 1062-1067 nm with ND:GLGG. Two-color mode-locking regime well described by Fourier-limited synchronized pulses with duration ~ 3.7 and 5.9 ps and output power ~ 65 mW, with wavelength separation of 1.3 nm around 1062 nm was obtained with Nd:GAGG.

  10. High harmonic generation from bulk diamond driven by intense femtosecond laser pulse

    CERN Document Server

    Apostolova, Tzveta

    2016-01-01

    We investigate the high-harmonic generation (HHG) from bulk diamond induced by intense 15 fs laser pulse and photon energy 1.55 eV. For laser intensity in the range $I \\in [1,50]$ TW/cm$^2$, we find that HHG spectra from diamond exhibits two plateaus with high harmonics extending beyond the 50th order. Consistently with experimental observations, we find that the cutoff energy of the two plateaus scales linearly with the field strength. The first plateau is due to recombination of electron-hole pairs near the Brillouin zone center. The appearance of weak second plateau region for high field strength with $F \\sim$ 1 V/$\\AA$ results in emission of highly energetic XUV photons.

  11. Attospiral generation upon interaction of circularly polarized intense laser pulses with cone-like targets

    CERN Document Server

    Lécz, Zsolt

    2015-01-01

    Generation of high intensity attopulses is investigated in cylindrical geometry by using 3D particle-in-cell plasma simulation code. Due to the rotation symmetric target, a circularly polarized laser pulse is considered propagating on the axis of a hollow cone-like target. The large incidence angle and constant ponderomotive pressure leads to nano-bunching of relativistic electrons responsible for the laser-driven synchrotron emission. A numerical method is developed to find the source and direction of the coherent radiation that is responsible for the existence of attopulses. The intensity modulation in the harmonic spectrum is well described by the model of coherent synchrotron emission extended to the regime of higher order \\gamma-spikes. The spatial distribution of the higher harmonics resembles a spiral shape which gets focused into a small volume behind the target.

  12. Classical Dynamics of Harmonic Generation of the Hydrogen Molecular Ion Interacting with Ultrashort Intense Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    LI Chao-Hong; DUAN Yi-Wu; Wing-Ki Liu; Jian-Min Yuan

    2001-01-01

    Within Born-Oppenheimer approximation, by using the classical trajectory theory, a description for the high order harmonic generation of the hydrogen molecular ion interacting with ultrashort laser pulses has been pre sented. The Coulomb singularities have been remedied by the regularization. The action-angle variables have been used to generate the initial inversion symmetry microcanonical distribution. Within a proper intensity range, a harmonic plateau with only odd harmonics appears. For a larger intensity, because of the existence of chaos, the harmonic spectra become noisier. For a large enough intensity, the ionization takes place and the harmonics disappear. So the chaos causes the noises, the ionization suppresses the harmonic generation, and the onset of the ionization follows the onset of chaos.

  13. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  14. Soliton radiation beat analysis of optical pulses generated from two continuous-wave lasers

    Energy Technology Data Exchange (ETDEWEB)

    Zajnulina, M.; Giannone, D.; Haynes, R.; Roth, M. M. [innoFSPEC-VKS, Leibniz Institute for Astrophysics, An der Sternwarte 16, 14482 Potsdam (Germany); Böhm, M. [innoFSPEC-InFaSe, University of Potsdam, Am Mühlenberg 3, 14476 Golm (Germany); Blow, K. [Aston Institute of Photonic Technologies, Aston Triangle, Birmingham B4 7ET (United Kingdom); Rieznik, A. A. [Instituto Tecnologico de Buenos Aires and CONICET, Buenos Aires (Argentina)

    2015-10-15

    We propose a fibre-based approach for generation of optical frequency combs (OFCs) with the aim of calibration of astronomical spectrographs in the low and medium-resolution range. This approach includes two steps: in the first step, an appropriate state of optical pulses is generated and subsequently moulded in the second step delivering the desired OFC. More precisely, the first step is realised by injection of two continuous-wave (CW) lasers into a conventional single-mode fibre, whereas the second step generates a broad OFC by using the optical solitons generated in step one as initial condition. We investigate the conversion of a bichromatic input wave produced by two initial CW lasers into a train of optical solitons, which happens in the fibre used as step one. Especially, we are interested in the soliton content of the pulses created in this fibre. For that, we study different initial conditions (a single cosine-hump, an Akhmediev breather, and a deeply modulated bichromatic wave) by means of soliton radiation beat analysis and compare the results to draw conclusion about the soliton content of the state generated in the first step. In case of a deeply modulated bichromatic wave, we observed the formation of a collective soliton crystal for low input powers and the appearance of separated solitons for high input powers. An intermediate state showing the features of both, the soliton crystal and the separated solitons, turned out to be most suitable for the generation of OFC for the purpose of calibration of astronomical spectrographs.

  15. Ultra short pulse laser generated surface textures for anti-ice applications in aviation

    NARCIS (Netherlands)

    Römer, G.W.; Del Cerro, D.A.; Sipkema, R.C.J.; Groenendijk, M.N.W.; Huis in 't Veld, A.J.

    2009-01-01

    By laser ablation with ultra short laser pulses in the pico- and femto-second range, well controlled dual scaled micro- and nano-scaled surface textures can be obtained. The micro-scale of the texture is mainly determined by the dimensions of the laser spot, whereas the superimposed nano-structure

  16. Ultra short pulse laser generated surface textures for anti-ice applications in aviation

    NARCIS (Netherlands)

    Römer, G.W.; Del Cerro, D.A.; Sipkema, R.C.J.; Groenendijk, M.N.W.; Huis in 't Veld, A.J.

    2009-01-01

    By laser ablation with ultra short laser pulses in the pico- and femto-second range, well controlled dual scaled micro- and nano-scaled surface textures can be obtained. The micro-scale of the texture is mainly determined by the dimensions of the laser spot, whereas the superimposed nano-structure i

  17. High harmonic generation in H$_2^+$ and HD$^+$ by two-colour femtosecond laser pulses

    Indian Academy of Sciences (India)

    Farzana Sharmin; Samir Saha; S S Bhattacharyya

    2013-12-01

    We have theoretically investigated the high harmonic generation (HHG) spectra of H$_2^+$ and HD$^+$ using a time-dependent wave packet approach for the nuclear motion with combined twocolour (1$_L$–3$_L$) pulsed lasers for ωL corresponding to wavelengths 1064 nm and 800 nm. The 1$_L$ and 3$_L$ lasers have peak intensities of $I_1^0 = 5.0 × 10^{13}$ W/cm$^2$ and $I_2^0 = 2.0 × 10^{14}$ W/cm$^2$, respectively. We have taken the pulse duration of $T = 50$ fs for both the fields, and the molecular initial vibrational level 0 = 0. We have argued that for these combinations, the harmonic generation due to transitions in the electronic continuum by tunnelling or multiphoton ionization may be neglected and only the electronic transitions within the two lowest electronic states would be important. Thus, the characteristic features of HHG spectra in the two-colour field are determined, in our model, by the nuclear motions on the two lowest field-coupled electronic states between which interelectronic and intraelectronic (due to the intrinsic dipole moments in case of HD+) radiative transitions can take place. We have studied the role of relative phase ($\\varphi$) of the two fields on the HHG spectra of the molecular ions. In case of HD+, the effect of nonadiabatic (NA) nonradiative interaction between the two lowest Born–Oppenheimer (BO) electronic states (1$s_g$, 2$p_u$) has been taken into account. Our calculations give realistic HHG spectra which are reasonably efficient and extended for both H$_2^+$ and HD$^+$ in the mixed two-colour field without involving the electronic continuum. The use of two-colour (1$_L$–3$_L$) field enables us to generate high harmonics beyond that achievable with a single 1$_L$ or 3$_L$ field of the corresponding intensity, frequency and pulse time.

  18. Forward acceleration and generation of femtosecond, megaelectronvolt electron beams by an ultrafast intense laser pulse

    Institute of Scientific and Technical Information of China (English)

    Xiaofang wang(王晓方); Quandong Wang(汪权东); Baifei Shen(沈百飞)

    2003-01-01

    We present a new mechanism of energy gain of electrons accelerated by a laser pulse. It is shown that when the intensity of an ultrafast intense laser pulse decreases rapidly along the direction of propagation, electrons leaving the pulse experience an action of ponderomotive deceleration at the descending part of a lower-intensity laser field than acceleration at the ascending part of a high-intensity field, thus gain net energy from the pulse and move directly forward. By means of such a mechanism, a megaelectronvolt electron beam with a bunch length shorter than 100 fs could be realized with an ultrafast (≤30 fs),intense (>1019 W/cm2) laser pulse.

  19. Short pulse generation and mode control of broadband terahertz quantum cascade lasers

    CERN Document Server

    Bachmann, Dominic; Süess, Martin J; Beck, Mattias; Unterrainer, Karl; Darmo, Juraj; Faist, Jérôme; Scalari, Giacomo

    2016-01-01

    We report on a waveguide engineering technique that enables the generation of a bandwidth up to 1 THz and record ultra-short pulse length of 2.5 ps in injection seeded terahertz quantum cascade lasers. The reported technique is able to control and fully suppress higher order lateral modes in broadband terahertz quantum cascade lasers by introducing side-absorbers to metal-metal waveguides. The side-absorbers consist of a top metalization set-back with respect to the laser ridge and an additional lossy metal layer. In continuous wave operation the side-absorbers lead to octave spanning laser emission, ranging from 1.63 to 3.37 THz, exhibiting a 725 GHz wide at top within a 10 dB intensity range as well as frequency comb operation with a bandwidth of 442 GHz. Numerical and experimental studies have been performed to optimize the impact of the side-absorbers on the emission properties and to determine the required increase of waveguide losses. Furthermore, these studies have led to a better understanding of the ...

  20. Laser ultrasonic analysis of normal modes generated by a voltage pulse on an AT quartz sensor.

    Science.gov (United States)

    Goossens, Jozefien; Martinez, Loïc; Glorieux, Christ; Wilkie-Chancellier, Nicolas; Ehssein, Chighali Ould; Serfaty, Stéphane

    2006-12-22

    Laser ultrasonic detection is a versatile and highly sensitive tool for the observation of surface waves. In the following study, laser ultrasonic detection is used for the experimental study of spurious normal vibration modes of a disk quartz sensor excited by a voltage pulse. The AT cut crystal (cut of the crystal relative to the the main crystallographic axis is 35.25 degrees) is optimal for generating mainly thickness-shear vibrations (central frequency 6 MHz) on the quartz surface. However, resulting from shear-to-longitudinal and shear-to-surface mode conversion, and from the weak coupling with the other crystallographic axes, other modes (thickness-compressional and bending modes) are always present in the plate response. Since the laser vibrometer is sensitive to normal displacements, the laser investigation shows waves that can be considered as unwanted for the AT quartz used as a shear sensor. The scanned three dimensional (3D) amplitude-space-time signals are carefully analysed using their representation in three dual Fourier domains (space-time, wave number-frequency). Results on the transient analysis of the waves, the normal bending modes and the dispersion curves are shown.

  1. Generation of intense femtosecond optical vortex pulses with blazed-phase grating in chirped-pulse amplification system of Ti:sapphire laser

    Science.gov (United States)

    Lin, Yu-Chieh; Nabekawa, Yasuo; Midorikawa, Katsumi

    2016-11-01

    We demonstrate the generation of an intense femtosecond optical vortex (OV) pulse by employing an OV converter set between two laser amplifiers in a chirped-pulse amplification (CPA) system of a Ti:sapphire laser. The OV converter is composed of a liquid-crystal spatial light modulator (LC-SLM) exhibiting a blazed-phase computer-generated hologram, a concave mirror, and a flat mirror in the 4f setup. Owing to the intrinsic nature of the 4f setup, the OV converter is free from chromatic and topological-charge dispersions, which are always induced in a spiral phase plate conventionally used to convert an intense Gaussian laser pulse to an OV pulse, while we can avoid damage to the LC-SLM by the irradiation of a low-energy pulse before the second amplifier. We have increased the throughput of the OV converter to 42% by systematically investigating the diffraction efficiency of the blazed-phase hologram on the LC-SLM, which relaxes the gain condition required for the second amplifier. The combination of the high-throughput OV converter and the two-stage amplification enables us to generate OV pulses with an energy of 1.63 mJ and a pulse duration of 60 fs at a wavelength of 720 nm, at which the gain of the Ti:sapphire laser is only 60% of the peak gain around 800 nm.

  2. Silver nanoparticles generated by pulsed laser ablation in supercritical CO2 medium

    Science.gov (United States)

    Machmudah, Siti; Sato, Takayuki; Wahyudiono; Sasaki, Mitsuru; Goto, Motonobu

    2012-03-01

    Pulsed laser ablation (PLA) has been widely employed in industrial and biological applications and in other fields. The environmental conditions in which PLA is conducted are important parameters that affect both the solid particle cloud and the deposition produced by the plume. In this work, the generation of nanoparticles (NPs) has been developed by performing PLA of silver (Ag) plates in a supercritical CO2 medium. Ag NPs were successfully generated by allowing the selective generation of clusters. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures and temperatures of CO2 medium. On the basis of the experimental result, both surface of the irradiated Ag plate and structure of Ag NPs were significantly affected by the changes in supercritical CO2 pressure and temperature. With increasing irradiation pressure, plume deposited in the surrounding crater created by the ablation was clearly observed. In Field Emission Scanning Electron Microscopy (FE-SEM) the image of the generated Ag NPs on the silicon wafer and the morphology of Ag particles were basically a sphere-like structure. Ag particles contain NPs with large-varied diameter ranging from 5 nm to 1.2 μm. The bigger Ag NPs melted during the ablation process and then ejected smaller spherical Ag NPs, which formed nanoclusters attached on the molten Ag NPs. The smaller Ag NPs were also formed around the bigger Ag NPs. Based on the results, this new method can also be used to obtain advanced nano-structured materials.

  3. Supercontinuum Generation in Holey Microstructure Fibres with Random Cladding Distribution by Femtosecond Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    李曙光; 侯蓝田; 冀玉领; 周桂耀

    2003-01-01

    It is reported that supercontinuum spectrum from 440 to 1050 nm can be generated in holey microstructure fibres (HMFs) with random cladding distribution by Ti:sapphire femtosecond laser pulses with central wavelength of 800 nm. Based on the method of the effective refractive index and the analogy of step-index fibre, we have calculated the effective mode area and the group velocity dispersion (GVD). It is found that the HMFs have specifically ability of localizing light and controlling GVD. The mechanism of supercontinuum generation in the HMFs with random cladding distribution is that the balance between the GVD and the self-phase modulation in the anomalous dispersion region leads to formation of solitons and fission of high order solitons.

  4. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    Science.gov (United States)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL Z target via bremsstrahlung into low-divergence (Z, the resulting Ne+ /Ne- ratio can approach unity, resulting in a near neutral density plasma jet. These quasi-neutral beams are presumed to retain the short-pulse (τL characteristic of the electron beam, resulting in a high peak density of ne- /e+ ~ 1016 cm-3 , making the source an excellent candidate for laboratory study of astrophysical leptonic jets. Alternatively, the electron beam can be interacted with a counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  5. Development of double-pulse lasers ablation system for generating gold ion source under applying an electric field

    Science.gov (United States)

    Khalil, A. A. I.

    2015-12-01

    Double-pulse lasers ablation (DPLA) technique was developed to generate gold (Au) ion source and produce high current under applying an electric potential in an argon ambient gas environment. Two Q-switched Nd:YAG lasers operating at 1064 and 266 nm wavelengths are combined in an unconventional orthogonal (crossed-beam) double-pulse configuration with 45° angle to focus on a gold target along with a spectrometer for spectral analysis of gold plasma. The properties of gold plasma produced under double-pulse lasers excitation were studied. The velocity distribution function (VDF) of the emitted plasma was studied using a dedicated Faraday-cup ion probe (FCIP) under argon gas discharge. The experimental parameters were optimized to attain the best signal to noise (S/N) ratio. The results depicted that the VDF and current signals depend on the discharge applied voltage, laser intensity, laser wavelength and ambient argon gas pressure. A seven-fold increases in the current signal by increasing the discharge applied voltage and ion velocity under applying double-pulse lasers field. The plasma parameters (electron temperature and density) were also studied and their dependence on the delay (times between the excitation laser pulse and the opening of camera shutter) was investigated as well. This study could provide significant reference data for the optimization and design of DPLA systems engaged in laser induced plasma deposition thin films and facing components diagnostics.

  6. Quasimonoenergetic and low emittance ion bunch generation from ultrathin targets by counterpropagating laser pulses of ultrarelativistic intensities

    CERN Document Server

    Avetissian, H K; Mkrtchian, G F; Sedrakian, Kh V

    2011-01-01

    A new method for generation of quasimonoenergetic and low emittance fast ion/nuclei bunches of solid densities from nanotargets by two counterpropagating laser pulses of ultrarelativistic intensities is proposed, based on the threshold phenomenon of particles "reflection" due to induced nonlinear Compton scattering. Particularly, a setup is considered which provides generation of ion bunches with parameters that are required in hadron therapy.

  7. Short pulse generation in a passively mode-locked photonic crystal semiconductor laser

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Blaaberg, Søren; Mørk, Jesper

    2010-01-01

    We present a new type of passively mode-locked laser with quantum wells embedded in photonic crystal waveguides operating in the slow light regime, which is capable of emitting sub picosecond pulses with widely controllable properties......We present a new type of passively mode-locked laser with quantum wells embedded in photonic crystal waveguides operating in the slow light regime, which is capable of emitting sub picosecond pulses with widely controllable properties...

  8. Plasma-based generation of a single few-cycle, high-energy and ultrahigh intensity laser pulse

    CERN Document Server

    Tamburini, M; Liseykina, T V; Keitel, C H

    2012-01-01

    A laser-boosted relativistic solid-density paraboloidal foil is known to efficiently reflect and focus a counterpropagating laser pulse. We show that in the case of an ultrarelativistic counterpropagating pulse, a high-energy and ultrahigh intensity reflected pulse can be more effectively generated by a relatively slow and heavy foil than by a fast and light one. This counterintuitive feature is explained with the larger reflectivity of a heavy foil, which compensates for the lower relativistic Doppler factor. Moreover, since the counterpropagating pulse is ultrarelativistic, the foil is abruptly dispersed and only the first few cycles of the counterpropagating pulse are reflected. Our three-dimensional particle-in-cell simulations show that a single sub-5-femtosecond, multi-petawatt laser pulse with several joule of energy and with peak intensity exceeding 1024 W cm^{-2} can be generated employing laser pulses with peak intensity of the order of 1022 W cm^{-2}. In addition, the carrier envelope phase of the ...

  9. Generation of Ultrashort Optical Pulses from Chromium - Forsterite and Chromium-Doped Yttrium Aluminum Garnet Tunable Solid-State Lasers.

    Science.gov (United States)

    Sennaroglu, Alphan

    In this thesis, experimental results of ultrashort pulse generation from the Cr:forsterite and Cr:YAG laser systems are presented. Ultrashort pulses from these coherent light sources are potentially important in such technological applications as fiber-optic communications, time-resolved spectroscopy of narrow-bandgap semiconductors, and medical imaging of tissues. Additive-pulse mode-locked operation of a Cr:forsterite laser was first pursued. By using a single-mode optical fiber for pulse shaping, 150-fs pulses were produced at 1.23 μm with 60 mW of average output power. However, pulse-train instabilities, cryogenic operation, and the overall complexity of the experimental setup hindered ready commercialization of this ultrashort pulse source. Regeneratively initiated self-mode-locked operation of the same laser system was then investigated. Regenerative initiation, where synchronization of the rf signal driving the modulator and the pulse repetition rate obviated the need for stringent cavity-length control, gave rise to the formation of a very stable, uninterrupted train of femtosecond pulses. Nearly transform-limited, 48-fs pulses, tunable from 1.21 to 1.27 mum, were produced with useful output powers of 360 mW at 1.23 mum. By employing the high-peak-power pulses generated from the Cr:forsterite laser in external second harmonic generation experiments, red pulses of 116 fs duration, tunable in the wavelength range from 605 to 635 nm, were obtained with power conversion efficiencies approaching 10%. In the next set of experiments, the continuous -wave (cw) power performance of a Cr:YAG laser was characterized as a function of various operating laser parameters. As high as 1.9 W of useful cw output power was obtained at 1.45 μm with a 2% transmitting output coupler when the gain medium was thermoelectrically cooled at 3 ^circC, significantly exceeding the results previously reported in the literature. Self -mode-locked operation of this laser system was also

  10. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    Energy Technology Data Exchange (ETDEWEB)

    Makito, K.; Shin, J.-H. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka (Japan); Zhidkov, A.; Hosokai, T.; Masuda, S. [Photon Pioneers Center, Osaka University, 2-8, Yamadaoka, Suita, Osaka (Japan); Japan Science and Technology Agency (JST), CREST, 2-8 Yamadaoka, Suita, Osaka (Japan); Kodama, R. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka (Japan); Photon Pioneers Center, Osaka University, 2-8, Yamadaoka, Suita, Osaka (Japan); Japan Science and Technology Agency (JST), CREST, 2-8 Yamadaoka, Suita, Osaka (Japan)

    2012-10-15

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of {approx}3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  11. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    Science.gov (United States)

    Makito, K.; Zhidkov, A.; Hosokai, T.; Shin, J.-H.; Masuda, S.; Kodama, R.

    2012-10-01

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of ˜3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  12. Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses.

    Science.gov (United States)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika; Le, Tuan; Stingl, Andreas; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2011-06-20

    For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W of pump power. This corresponds to a reduction in optical conversion efficiencies to 75% of the values achieved with a commercial diode pumped solid-state laser. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser when pumped with our diode laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20 fs can therefore be expected.

  13. Extreme ultraviolet emission from dense plasmas generated with sub-10-fs laser pulses

    CERN Document Server

    Osterholz, J; Cerchez, M; Fischer, T; Hemmers, D; Hidding, B; Pipahl, A; Pretzler, G; Rose, S J; Willi, O

    2008-01-01

    The extreme ultraviolet (XUV) emission from dense plasmas generated with sub-10-fs laser pulses with varying peak intensities up to 3*10^16 W/cm^2 is investigated for different target materials. K shell spectra are obtained from low Z targets (carbon and boron nitride). In the spectra a series limit for the hydrogen and helium like resonance lines is observed indicating that the plasma is at high density and pressure ionization has removed the higher levels. In addition, L shell spectra from titanium targets were obtained. Basic features of the K and L shell spectra are reproduced with computer simulations. The calculations include hydrodynamic simulation of the plasma expansion and collisional radiative calculations of the XUV emission.

  14. Smart Q-switching for single-pulse generation in an erbium-doped fiber laser.

    Science.gov (United States)

    Escalante-Zarate, Luis; Barmenkov, Yuri O; Kolpakov, Stanislav A; Cruz, José L; Andrés, Miguel V

    2012-02-13

    In this paper, we report an active Q-switching of an erbium-doped fiber laser with special modulation functions and novel laser geometry. We experimentally demonstrate that using such a smart Q-switch approach, Q-switch ripple-free pulses with Gaussian-like shape and 17.3 ns width can be easily obtained. The idea behind the smart Q-switch is to suppress one of two laser waves contra-propagating along the fiber cavity, which arises after Q-cell opening, and to eliminate the minor sub-pulses.

  15. Picosecond pulse generation in a hybrid Q-switched laser source by using a microelectromechanical mirror.

    Science.gov (United States)

    Couderc, Vincent; Crunteanu, Aurelian; Fabert, Marc; Doutre, Florent; El Bassri, Farid; Pagnoux, Dominique; Jalocha, Alain

    2012-02-27

    We present a novel Q-switched laser source using a micro-optical-electromechanical mirror (MOEM) designed for short pulse emission. It is based on a hybrid configuration including a passively Q-switched microchip laser coupled to a fiber cavity closed by a cantilever type MOEM acting as an active modulator. This specially designed mirror with a single reflecting gold membrane is switched by low bias voltage ~50 V (peak to peak). This device emits pulses at tunable repetition rates up to 1.6 kHz, with ~564 ps duration and 3.4 kW peak power, which constitutes the shortest pulse duration ever reported with MOEMs based pulsed lasers.

  16. Direct generation of intense extreme ultraviolet supercontinuum with chirped 11-mJ pulses from a femtosecond laser amplifier

    CERN Document Server

    Zeng, Bin; Li, Guihua; Yao, Jinping; Ni, Jielei; Zhang, Haisu; Cheng, Ya; Xu, Zhizhan

    2011-01-01

    We report on the generation of intense extreme ultraviolet (EUV) supercontinuum with photon energies spanning from 35 eV to 50 eV (i. e., supporting an isolated attosecond pulse with a duration of ~271 as) by loosely focusing 11-mJ chirped pulses from a femtosecond laser amplifier into a 10-mm long gas cell filled with krypton gas. We observe that when high-order harmonics are generated with transformed-limited ~35 fs pulses, only discrete harmonics can be produced; whereas for negatively chirped 188 fs pulses, EUV supercontinuum can be observed in single-shot harmonic spectrum. The dramatic change of spectral and temporal properties of the driver pulses after passing through the gas cell indicates that propagation effects play a significant role in promoting the generation of the EUV supercontinuum.

  17. High reliability low jitter pulse generator

    Science.gov (United States)

    Savage, Mark E.; Stoltzfus, Brian S.

    2013-01-01

    A method and concomitant apparatus for generating pulses comprising providing a laser light source, disposing a voltage electrode between ground electrodes, generating laser sparks using the laser light source via laser spark gaps between the voltage electrode and the ground electrodes, and outputting pulses via one or more insulated ground connectors connected to the voltage electrode.

  18. Vector similariton erbium-doped all-fiber laser generating sub-100-fs nJ pulses at 100 MHz.

    Science.gov (United States)

    Olivier, Michel; Piché, Michel

    2016-02-08

    Erbium-doped mode-locked fiber lasers with repetition rates comparable to those of solid-state lasers and generating nJ pulses are required for many applications. Our goal was to design a fiber laser that would meet such requirements, that could be built at relatively low cost and that would be reliable and robust. We thus developed a high-fundamental-repetition-rate erbium-doped all-fiber laser operating in the amplifier similariton regime. Experimental characterization shows that this laser, which is mode-locked by nonlinear polarization evolution, emits 76-fs pulses with an energy of 1.17 nJ at a repetition rate of 100 MHz. Numerical simulations support the interpretation of self-similar evolution of the pulse in the gain fiber. More specifically we introduce the concept of vector similariton in fiber lasers. The coupled x- and y- polarization components of such a pulse have a pulse profile with a linear chirp and their combined power profile evolves self-similarly when the nonlinear asymptotic regime is reached in the gain fiber.

  19. Generation of Bright Isolated Attosecond Soft X-Ray Pulses Driven by Multi-Cycle Mid-Infrared Lasers

    CERN Document Server

    Chen, M -C; Mancuso, C; Dollar, F; Galloway, B; Popmintchev, D; Huang, P -C; Walker, B; Plaja, L; Jaron-Becker, A; Becker, A; Popmintchev, T; Murnane, M M; Kapteyn, H C

    2014-01-01

    High harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, to date the shortest attosecond (as) pulses have been produced only in the extreme ultraviolet (EUV) region of the spectrum below 100 eV, which limits the range of materials and molecular systems that can be explored. Here we use advanced experiment and theory to demonstrate a remarkable convergence of physics: when mid-infrared lasers are used to drive the high harmonic generation process, the conditions for optimal bright soft X-ray generation naturally coincide with the generation of isolated attosecond pulses. The temporal window over which phase matching occurs shrinks rapidly with increasing driving laser wavelength, to the extent that bright isolated attosecond pulses are the norm for 2 \\mu m driving lasers. Harnessing this realization, we demonstrate the generation of isolated soft X-ray attosecond pulses at photon energies up to 180 eV for the first time, that e...

  20. Mode-locked laser realized by selective area growth for short pulse generation and optical clock recovery in TDM systems

    Science.gov (United States)

    Lach, Eugen; Baums, Dieter; Bouayad-Amine, Jamal; Hache, Claudia; Haisch, Hansjorg; Kuhn, Edgar; Satzke, Klaus; Schilling, Michael; Weber, Juergen; Zielinski, Erich

    1996-04-01

    We report on monolithically integrated active/passive coupled cavity mode locked lasers for 1.55 micrometer realized by selective area growth technology of InGaAs(P) quantum wells. Mode locked FP or DBR lasers are fabricated with an integrated cavity comprising up to three different band gaps. The devices emit short light pulses at around 10 GHz repetition rate with pulse width down to 8.7 ps. A time-bandwidth product of 0.5 is achieved for mode locked DBR lasers. Active/passive integrated mode locked laser is used for generation of optical 10 GHz clock signal from optical 10 Gb/s PRBS RZ data stream injected into the laser cavity.

  1. Generation of a Sub-10 fs Laser Pulse by a Ring Oscillator with a High Repetition Rate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing; ZHAO Yan-Ying; WEI Zhi-Yi

    2009-01-01

    @@ A compact femtoescond Ti:sapphire ring oscillator composed of chirped mirrors is designed. By accurately optimizing the intra-cavity dispersion and the mode locking range of the ring configuration, we generate laser pulses as short as 7.7 fs with a repetition rate as high as 745 MHz. The spectrum spans from 660nm to 940nm and the average output power is 480row under the cw pump laser of 7.5 W.

  2. Laser Polarization Effect on Molecular Harmonic and Elliptically Polarized Attosecond Pulse Generation

    Science.gov (United States)

    Feng, Li-Qiang; Li, Wen-Liang; Liu, Hang

    2017-01-01

    Molecular harmonic spectra of {{{H}}}2+ driven by the linearly polarized laser pulses with different polarized angles have been theoretically investigated through solving the two-dimensional time-dependent Schrödinger equation. (i) Below-threshold harmonic spectra show a visible enhanced peak around the 7th harmonic (H7), which produces a red-shift phenomenon as the internuclear distance increased. Theoretical analyses show the red-shift enhanced peak is caused by the laser-induced electron transfer between the ground state and the 1st excited state of {{{H}}}2+. (ii) Due to the two-centre interference phenomenon, the above-threshold harmonic spectra exhibit many maxima and minima. (iii) With the introduction of the polarized angle, the anomalous elliptically polarized harmonics can be found. But, with the introduction of the spatial inhomogeneous effect, not only the ellipticities of the harmonics are equal to a stable value of \\varepsilon ∼ 0.1–0.3, but also the harmonic cutoffs are extended. As a result, four super-bandwidths of 407 eV, 310 eV, 389 eV, and 581 eV can be obtained. Time profiles of the harmonic generations have been shown to explain the harmonic characteristics. Finally, a series of elliptically polarized (\\varepsilon ∼ 0.1–0.3) attosecond X-ray pulses with durations from 18as to 25as can be directly produced through Fourier transformation of the spectral continuum. Supported by National Natural Science Foundation of China under Grant No. 11504151, Doctoral Scientific Research Foundation of Liaoning Province under Grant No. 201501123 and Scientific Research Fund of Liaoning Provincial Education Department under Grant No. L2014242

  3. Electron dynamics from low-order harmonics generated by short laser pulses

    Science.gov (United States)

    Xiong, Wei-Hao; Gong, Qihuang; Peng, Liang-You

    2017-08-01

    Recently, low-order harmonics have gained much attention due to their applications as coherent light sources with a high repetition rate. In addition, the generation process is highly related to the bound electrons and can thus be applied to detect the dynamics of these electrons. In this work, we theoretically investigate the low-order harmonics below the first excited state, produced by a single-cycle optical pulse. We numerically solve the three-dimensional time-dependent Schrödinger equation (TDSE) to calculate the harmonic spectrum. With the help of a perturbation model, we can transparently understand the generation process of the spectrum. The results indicate that the harmonic spectrum can be sensitively influenced by the frequency component of the driving field. We find that the carrier envelope phase (CEP) dependence of low-order-harmonic generation originates from the interference of different harmonic orders. For these harmonics, the CEP effects can only be observed when the spectrum of the driving laser is extremely wide, which corresponds to the very short driving pulse. From the CEP-dependent interference structure, the phase relation of the third and the fifth harmonic can be extracted. The extracted information indicates that the atomic response induces a positive chirp for the emitted low-order harmonics. In addition, we investigated the harmonic phase calculated from the TDSE results. The harmonic phase is different from the phase predicted by the adiabatic model, and this phase difference can be related to the time delay of the electronic response. We extract the time delay from the harmonic phase and explore the CEP and intensity dependence of this time delay.

  4. Generating femtosecond X-ray pulses using an emittance-spoiling foil in free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Y., E-mail: ding@slac.stanford.edu; Coffee, R.; Decker, F.-J.; Emma, P.; Field, C.; Huang, Z.; Krejcik, P.; Krzywinski, J.; Loos, H.; Lutman, A.; Marinelli, A.; Maxwell, T. J.; Turner, J. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Behrens, C. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg (Germany); Helml, W. [Technische Universität München, James-Franck-Straße 1, 85748 Garching (Germany)

    2015-11-09

    Generation of femtosecond to sub-femtosecond pulses is attracting much attention in X-ray free-electron laser user community. One method is to use a slotted, emittance-spoiling foil which was proposed before (P. Emma et al., Phys. Rev. Lett. 92, 074801 (2004)) and has been widely used at the Linac Coherent Light Source. Direct experimental characterization of the slotted-foil performance was previously unfeasible due to a lack of appropriate diagnostics. With a recently installed X-band radio-frequency transverse deflector, we are able to characterize the electron bunch spoiling effect and X-ray pulse when using the slotted foil. We show that few-femtosecond X-ray pulses are generated with flexible control of the single-pulse duration or double-pulse separation with comparison to the theoretical model.

  5. Raman-scattering-assistant broadband noise-like pulse generation in all-normal-dispersion fiber lasers

    CERN Document Server

    Li, Daojing; Li, Lei; Chen, Hao; Tang, Dingyuan; Zhao, Luming

    2015-01-01

    We report on the observation of both stable dissipative solitons and noise-like pulses with the presence of strong Raman scattering in a relatively short all-normal-dispersion Yb-doped fiber laser. We show that Raman scattering can be filtered out by intracavity filter. Furthermore, by appropriate intracavity polarization control, the Raman effect can be utilized to generate broadband noise-like pulses (NLPs) with bandwidth up to 61.4 nm. To the best of our knowledge, this is the broadest NLP achieved in all-normal-dispersion fiber lasers

  6. Hot electrons generated by ultra-short pulse laser interacting with solid targets

    Institute of Scientific and Technical Information of China (English)

    陈黎明; 张杰; 李玉同; 梁天骄; 王龙; 魏志义; 江文勉

    2000-01-01

    Hot electrons produced by ultra-short pulse laser interacting with solid targets were studied systematically. When 800 nm, 8 × 1015 W/cm2 laser pulses interacted with solid targets, hot electron e-mission was found to be collimated in certain directions and the angular distribution of hot electrons depended on the energy absorption. The angular divergence of outgoing hot electrons was inversely proportional to the hot electron energy. The energy spectrum of hot electrons was found to be in a bi-Maxwellian distribution and the maximum energy was over 500 keV.

  7. Hot electrons generated by ultra-short pulse laser interacting with solid targets

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Hot electrons produced by ultra-short pulse laser interacting with solid targets were studied systematically. When 800 nm, 8×1015 W/cm2 laser pulses interacted with solid targets, hot electron emission was found to be collimated in certain directions and the angular distribution of hot electrons depended on the energy absorption. The angular divergence of outgoing hot electrons was inversely proportional to the hot electron energy. The energy spectrum of hot electrons was found to be in a bi-Maxwellian distribution and the maximum energy was over 500 keV.

  8. Interaction of relativistic electrons with an intense laser pulse: High-order harmonic generation based on Thomson scattering

    Energy Technology Data Exchange (ETDEWEB)

    Hack, Szabolcs [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Department of Theoretical Physics, University of Szeged, Tisza L. krt. 84-86, H-6720 Szeged (Hungary); Varró, Sándor [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Wigner Research Center for Physics, SZFI, PO Box 49, H-1525 Budapest (Hungary); Czirják, Attila [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Department of Theoretical Physics, University of Szeged, Tisza L. krt. 84-86, H-6720 Szeged (Hungary)

    2016-02-15

    We investigate nonlinear Thomson scattering as a source of high-order harmonic radiation with the potential to enable attosecond light pulse generation. We present a new analytic solution of the electron’s relativistic equations of motion in the case of a short laser pulse with a sine-squared envelope. Based on the single electron emission, we compute and analyze the radiated amplitude and phase spectrum for a realistic electron bunch, with special attention to the correct initial values. These results show that the radiation spectrum of an electron bunch in head-on collision with a sufficiently strong laser pulse of sine-squared envelope has a smooth frequency dependence to allow for the synthesis of attosecond light pulses.

  9. Pulse generation and propagation in dispersion-managed ultralong erbium-doped fiber lasers mode-locked by carbon nanotubes.

    Science.gov (United States)

    Rosa, H G; Thoroh de Souza, E A

    2012-12-15

    We present a study of pulse generation and propagation in erbium-doped fiber lasers with cavity length varying from 8 m to 3.5 km. We demonstrate that soliton effect determines the pulse stabilization in ultralong cavities, measuring pulses with an average 7.0 ps pulsewidth for cavity lengths between 2.25 and 3.5 km. We also demonstrate that, by filling fundamental soliton requirements, pulsewidth can be determined by length and total dispersion cavity parameters.

  10. White-light emission from solid carbon in aqueous solution during hydrogen generation induced by nanosecond laser pulse irradiation

    Science.gov (United States)

    Akimoto, Ikuko; Yamamoto, Shota; Maeda, Kosuke

    2016-07-01

    We previously discovered a novel method of hydrogen generation from high-grade charcoal in an aqueous solution using nanosecond laser pulse irradiation. In this paper, white-light emission during this reaction is reported: A broad spectrum over the visible range is observed above a threshold excitation energy density. The white-light emission is a simultaneous product of the hydrogen generation reaction and is attributed to blackbody radiation in accordance with Planck's Law at a temperature above 3800 K. Consequently, we propose that hydrogen generation induced by laser irradiation proceeds similarly to classical coal gasification, which features reactions at high pressure and high temperature.

  11. Generation of bright attosecond x-ray pulse trains via Thomson scattering from laser-plasma accelerators.

    Science.gov (United States)

    Luo, W; Yu, T P; Chen, M; Song, Y M; Zhu, Z C; Ma, Y Y; Zhuo, H B

    2014-12-29

    Generation of attosecond x-ray pulse attracts more and more attention within the advanced light source user community due to its potentially wide applications. Here we propose an all-optical scheme to generate bright, attosecond hard x-ray pulse trains by Thomson backscattering of similarly structured electron beams produced in a vacuum channel by a tightly focused laser pulse. Design parameters for a proof-of-concept experiment are presented and demonstrated by using a particle-in-cell code and a four-dimensional laser-Compton scattering simulation code to model both the laser-based electron acceleration and Thomson scattering processes. Trains of 200 attosecond duration hard x-ray pulses holding stable longitudinal spacing with photon energies approaching 50 keV and maximum achievable peak brightness up to 1020 photons/s/mm2/mrad2/0.1%BW for each micro-bunch are observed. The suggested physical scheme for attosecond x-ray pulse trains generation may directly access the fastest time scales relevant to electron dynamics in atoms, molecules and materials.

  12. Millijoule Pulse Energy Second Harmonic Generation With Single-Stage Photonic Bandgap Rod Fiber Laser

    DEFF Research Database (Denmark)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas Tanggaard

    2011-01-01

    In this paper, we demonstrate, for the first time, a single-stage Q-switched single-mode (SM) ytterbium-doped rod fiber laser delivering record breaking pulse energies at visible and UV light. We use a photonic bandgap rod fiber with a mode field diameter of 59μm based on a new distributed...

  13. Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength.

    Science.gov (United States)

    Savochkin, I V; Jäckl, M; Belotelov, V I; Akimov, I A; Kozhaev, M A; Sylgacheva, D A; Chernov, A I; Shaposhnikov, A N; Prokopov, A R; Berzhansky, V N; Yakovlev, D R; Zvezdin, A K; Bayer, M

    2017-07-18

    Currently spin waves are considered for computation and data processing as an alternative to charge currents. Generation of spin waves by ultrashort laser pulses provides several important advances with respect to conventional approaches using microwaves. In particular, focused laser spot works as a point source for spin waves and allows for directional control of spin waves and switching between their different types. For further progress in this direction it is important to manipulate with the spectrum of the optically generated spin waves. Here we tackle this problem by launching spin waves by a sequence of femtosecond laser pulses with pulse interval much shorter than the relaxation time of the magnetization oscillations. This leads to the cumulative phenomenon and allows us to generate magnons in a specific narrow range of wavenumbers. The wavelength of spin waves can be tuned from 15 μm to hundreds of microns by sweeping the external magnetic field by only 10 Oe or by slight variation of the pulse repetition rate. Our findings expand the capabilities of the optical spin pump-probe technique and provide a new method for the spin wave generation and control.

  14. Generation of frequency-chirped pulses in the far-infrared by means of a sub-picosecond free-electron laser and an external pulse shaper

    Science.gov (United States)

    Knippels, G. M. H.; van der Meer, A. F. G.; Mols, R. F. X. A. M.; van Amersfoort, P. W.; Vrijen, R. B.; Maas, D. J.; Noordam, L. D.

    1995-02-01

    The generation of frequency-chirped optical pulses in the far-infrared is reported. The pulses are produced by the free-electron laser FELIX. The chirp is induced by means of an external shaping device consisting of a grating and a telescope. The shaper is based on reflective optics to permit operation in a wide spectral range. The present experiments were made at 8.2 μm wavelength. The fwhm duration of the incident pulse was 0.50 ps, which corresponds to a bandwidth of 2.2%. It has been checked that a linear chirp is produced, for the case that the frequency increases from the leading edge of the pulse to the trailing edge, as well as for the reverse case. This is accompanied by an increase of the fwhm pulse duration which ranges up to 16.5 ps.

  15. XUV generation from the interaction of pico- and nanosecond laser pulses with nanostructured targets

    Science.gov (United States)

    Barte, Ellie Floyd; Lokasani, Ragava; Proska, Jan; Stolcova, Lucie; Maguire, Oisin; Kos, Domagoj; Sheridan, Paul; O'Reilly, Fergal; Sokell, Emma; McCormack, Tom; O'Sullivan, Gerry; Dunne, Padraig; Limpouch, Jiri

    2017-05-01

    Laser-produced plasmas are intense sources of XUV radiation that can be suitable for different applications such as extreme ultraviolet lithography, beyond extreme ultraviolet lithography and water window imaging. In particular, much work has focused on the use of tin plasmas for extreme ultraviolet lithography at 13.5 nm. We have investigated the spectral behavior of the laser produced plasmas formed on closely packed polystyrene microspheres and porous alumina targets covered by a thin tin layer in the spectral region from 2.5 to 16 nm. Nd:YAG lasers delivering pulses of 170 ps (Ekspla SL312P )and 7 ns (Continuum Surelite) duration were focused onto the nanostructured targets coated with tin. The intensity dependence of the recorded spectra was studied; the conversion efficiency (CE) of laser energy into the emission in the 13.5 nm spectral region was estimated. We have observed an increase in CE using high intensity 170 ps Nd:YAG laser pulses as compared with a 7 ns pulse.

  16. Measurement and Generation of Ultra-High Power Fiber Laser Pulses by Coherent Combination

    Science.gov (United States)

    2010-06-01

    through a Michelson interferometer and generated a double pulse as shown in Figure 10. Figure 10. Experimental setup for testing and calibrating...Measuring the Free Spectral Range of the VIPA etalons Using the spectral fringes generated by the Michelson interferometer , we can quantify the spectral...Testing the FROG To test the FROG, we again used use the double pulse from a Michelson interferometer , which yields a FROG trace unlikely to occur by

  17. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude

    2006-01-01

    Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

  18. Generation of an isolated sub-30 attosecond pulse in a two-color laser field and a static electric field

    Institute of Scientific and Technical Information of China (English)

    Zhang Gang-Tai; Bai Ting-Ting; Zhang Mei-Guang

    2012-01-01

    We theoretically investigate high-order harmonic generation(HHG)from a helium ion model in a two-color laser field,which is synthesized by a fundamental pulse and its second harmonic pulse.It is shown that a supercontinuum spectrum can be generated in the two-color field.However,the spectral intensity is very low,limiting the application of the generated attosecond(as)pulse.By adding a static electric field to the synthesized two-color field,not only is the ionization yield of electrons contributing to the harmonic emission remarkably increased,but also the quantum paths of the HHG can be significantly modulated.As a result,the extension and enhancement of the supercontinuum spectrum are achieved,producing an intense isolated 26-as pulse with a bandwidth of about 170.5 eV.In particular,we also analyse the influence of the laser parameters on the ultrabroad supercontinuum spectrum and isolated sub-30-as pulse generation.

  19. Raman spectroscopic analysis of iron chromium oxide microspheres generated by nanosecond pulsed laser irradiation on stainless steel.

    Science.gov (United States)

    Ortiz-Morales, M; Soto-Bernal, J J; Frausto-Reyes, C; Acosta-Ortiz, S E; Gonzalez-Mota, R; Rosales-Candelas, I

    2015-06-15

    Iron chromium oxide microspheres were generated by pulsed laser irradiation on the surface of two commercial samples of stainless steel at room temperature. An Ytterbium pulsed fiber laser was used for this purpose. Raman spectroscopy was used for the characterization of the microspheres, whose size was found to be about 0.2-1.7 μm, as revealed by SEM analysis. The laser irradiation on the surface of the stainless steel modified the composition of the microspheres generated, affecting the concentration of the main elemental components when laser power was increased. Furthermore, the peak ratio of the main bands in the Raman spectra has been associated to the concentration percentage of the main components of the samples, as revealed by Energy-Dispersive X-ray Spectroscopy (EDS) analysis. These experiments showed that it is possible to generate iron chromium oxide microspheres on stainless steel by laser irradiation and that the concentration percentage of their main components is associated with the laser power applied.

  20. Generating Isolated Terawatt-Attosecond X-ray Pulses via a Chirped Laser Enhanced High-Gain Free-electron Laser

    CERN Document Server

    Wang, Zhen; Zhao, Zhentang

    2016-01-01

    A feasible method is proposed to generate isolated attosecond terawatt x-ray radiation pulses in high-gain free-electron lasers. In the proposed scheme, a frequency chirped laser pulse is employed to generate a gradually-varied spacing current enhancement of the electron beam and a series of spatiotemporal shifters are applied between the undulator sections to amplify a chosen ultra-short radiation pulse from self-amplified spontaneous emission. Three-dimensional start-to-end simulations have been carried out and the calculation results demonstrated that 0.15 nm x-ray pulses with peak power over 1TW and duration of several tens of attoseconds could be achieved by using the proposed technique.

  1. Generating isolated terawatt-attosecond x-ray pulses via a chirped-laser-enhanced high-gain free-electron laser

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2017-04-01

    Full Text Available A feasible method is proposed to generate isolated attosecond terawatt x-ray radiation pulses in high-gain free-electron lasers. In the proposed scheme, a frequency chirped laser pulse is employed to generate a gradually varied spacing current enhancement of the electron beam, and a series of spatiotemporal shifters are applied between the undulator sections to amplify a chosen ultrashort radiation pulse from self-amplified spontaneous emission. Three-dimensional start-to-end simulations have been carried out, and the calculation results demonstrated that 0.15 nm x-ray pulses with a peak power over 1 TW and a duration of several tens of attoseconds could be achieved by using the proposed technique.

  2. Double Ion Implantation and Pulsed Laser Melting Processes for Third Generation Solar Cells

    Directory of Open Access Journals (Sweden)

    Eric García-Hemme

    2013-01-01

    Full Text Available In the framework of the third generation of photovoltaic devices, the intermediate band solar cell is one of the possible candidates to reach higher efficiencies with a lower processing cost. In this work, we introduce a novel processing method based on a double ion implantation and, subsequently, a pulsed laser melting (PLM process to obtain thicker layers of Ti supersaturated Si. We perform ab initio theoretical calculations of Si impurified with Ti showing that Ti in Si is a good candidate to theoretically form an intermediate band material in the Ti supersaturated Si. From time-of-flight secondary ion mass spectroscopy measurements, we confirm that we have obtained a Ti implanted and PLM thicker layer of 135 nm. Transmission electron microscopy reveals a single crystalline structure whilst the electrical characterization confirms the transport properties of an intermediate band material/Si substrate junction. High subbandgap absorption has been measured, obtaining an approximate value of 104 cm−1 in the photons energy range from 1.1 to 0.6 eV.

  3. 40 Gb/s Pulse Generation Using Gain Switching of a Commercially Available Laser Module

    DEFF Research Database (Denmark)

    Nørregaard, Jesper; Hanberg, Jesper; Franck, Thorkild

    1999-01-01

    between the microwave substrate and the RF feed-through in the wall of the module. The module is build as a 14 pin butterfly package with the RF feed-through designed as a coplanar 50 ohm impedance port. Included in the module are a built-in optical isolator, a thermistor, a thermo-electric cooler...... to ease RF connection. The laser die is connected to a gold plated AlN microwave substrate that also acts as a heat spreader. The microwave substrate contains an impedance matching resistor for the RF signal as well as a bias-T for the DC bias. 50 ohm Flexguide technology is used for the interconnection......, and a photodiode for optical power monitoring.The RF input port was connected to the driver circuit using a coplanar microwave probe. A DC bias and a large signal modulation at 10 GHz was applied to the module to generate chirped pulses. A linear as well as a non-linear soliton compression was used with optical...

  4. Half-period optical pulse generation using a free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Jaroszynski, D.A.; Chaix, P.; Piovella, N. [Commissariat a l`Energie Atomique, Bruycres-le-Chatel (France)

    1995-12-31

    Recently there has been growth, in interest in non-equilibrium interaction of half-period long optical pulses with matter. To date the optical pulses have been produced by chopping out a half-period long segment from a longer pulse using a semiconductor switch driven by a femtosecond laser. In this paper we present new methods for producing tunable ultra-short optical pulses as short as half an optical period using a free-electron laser driven by electron bunches with a duration a fraction of an optical period. Two different methods relying on the production of coherent spontaneous emission will be described. In the first method we show that when a train of ultra-short optical pulses as short as one half period. We present calculations which show that the small signal gain is unimportant in the early stages of radiation build up in the cavity when the startup process is dominated by coherent spontaneous emission. To support our proposed method we present encouraging experimental results from the FELIX experiment in the Netherlands which show that interference effects between the coherent spontaneous optical pulses at start-up are very important. The second proposed method relies on the fact that coherent spontaneous emission mimics the undulations of electrons as they pass through the undulator. We show that ultra-short optical pulses are produced by coherent spontaneous emission when ultra-short electron bunches pass through an ultra-short undulator. We discuss the interesting case of such undulator radiation in the presence of an optical cavity and show that the optical pulse can be {open_quotes}taylored{close_quotes} by simply adjusting the optical cavity desynchronism. The proposed methods may be realisable using existing rf driven FELs in the far-infrared.

  5. Supercontinuum generation enhanced by conventional Raman amplification at pumping by nanosecond pulses from a directly modulated DFB laser

    Science.gov (United States)

    Rojas-Laguna, Roberto; Gutiérrez-Gutiérrez, Jaime; Kuzin, Evgeny A.; Ibarra-Escamilla, Baldemar; Mendoza-Vázquez, Sergio; Estudillo-Ayala, Julián Moisés; Haus, Joseph W.

    2007-02-01

    We investigated spectral broadening in a standard fiber using a nanosecond directly modulated DFB laser (λ=1549 nm), amplified by a two stage Erbium-doped fiber amplifier. The amplifier provided amplification of 2-mW peak power input pulses to 100-W peak power output pulses. In other hand, the directly modulation of DFB lasers caused transient oscillations at the beginning of pulses. In our case pulses consisted of a 2-ns transient part followed by a steady-state plateau. We used a monochromator to measure the spectrum at the fiber output. A fast photodetector was placed at the monochromator output and pulse shapes were measured for different wavelengths. This technique allowed the separate measurement of different parts in output pulses spectrum. We used the SMF-28 fiber with the standard dispersion of 20 ps/nm-km for our wavelength. We made measurements of the output spectra for three fiber lengths: 0.6-km, 4.46-km and 9.15-km; finding that the initial transient part of a pulse shows supercontinuum generation whereas the plateau results in conventional Raman amplification of this supercontinuum.

  6. Heat-induced structure formation in metal films generated by single ultrashort laser pulses

    Science.gov (United States)

    Koch, Jürgen; Unger, Claudia; Chichkov, Boris N.

    2012-03-01

    Ultrashort pulsed lasers are increasingly used in micromachining applications. Their short pulse lengths lead to well defined thresholds for the onset of material ablation and to the formation of only very small heat affected zones, which can be practically neglected in the majority of cases. Structure sizes down to the sub-micron range are possible in almost all materials - including heat sensitive materials. Ultrashort pulse laser ablation - even though called "cold ablation" - in fact is a heat driven process. Ablation takes place after a strong and fast temperature increase carrying away most of the heat with the ablated particles. This type of heat convection is not possible when reducing the laser fluence slightly below the ablation threshold. In this case temperature decreases slower giving rise to heat-induced material deformations and melt dynamics. After cooling down protruding structures can remain - ablation-free laser surface structuring is possible. Structure formation is boosted on thin metal films and offers best reproducibility and broadest processing windows for metals with high ductility and weak electron phonon coupling strength. All approaches to understand the process formation are currently based only on images of the final structures. The pump-probe imaging investigations presented here lead to a better process understanding.

  7. Ultrafast pulse generation from erbium-doped fiber laser modulated by hybrid organic-inorganic halide perovskites

    Science.gov (United States)

    Jiang, Guobao; Miao, Lili; Yi, Jun; Huang, Bin; Peng, Wei; Zou, Yanhong; Huang, Huihui; Hu, Wei; Zhao, Chujun; Wen, Shuangchun

    2017-04-01

    We report the nonlinear optical responses of organic-inorganic halide perovskite CH3NH3PbI3 and its application in ultrafast pulse generation from an erbium-doped fiber laser in the optical communication band. By adopting the Z-scan technique, the third-order nonlinear optical responses of the organic-inorganic halide perovskites have been characterized. An ultrafast optical pulse with a pulse width of 661 fs centered at a wavelength of 1555 nm has been delivered via the nonlinear optical material introduced into the fiber laser cavity. Our experimental results confirm that the organic-inorganic halide perovskite possesses obvious third-order nonlinear optical responses in the C-band window and manifests its application potential in nonlinear optoelectronic devices.

  8. Thermo-acoustic Sound Generation in the Interaction of Pulsed Proton and Laser Beams with a Water Target

    CERN Document Server

    Lahmann, R; Graf, K; Hößl, J; Kappes, A; Katz, U; Mecke, K; Schwemmer, S

    2015-01-01

    The generation of hydrodynamic radiation in interactions of pulsed proton and laser beams with matter is explored. The beams were directed into a water target and the resulting acoustic signals were recorded with pressure sensitive sensors. Measurements were performed with varying pulse energies, sensor positions, beam diameters and temperatures. The obtained data are matched by simulation results based on the thermo-acoustic model with uncertainties at a level of 10%. The results imply that the primary mechanism for sound generation by the energy deposition of particles propagating in water is the local heating of the medium. The heating results in a fast expansion or contraction and a pressure pulse of bipolar shape is emitted into the surrounding medium. An interesting, widely discussed application of this effect could be the detection of ultra-high energetic cosmic neutrinos in future large-scale acoustic neutrino detectors. For this application a validation of the sound generation mechanism to high accur...

  9. Programmable pulse generator

    CERN Document Server

    Xue Zhi Hua; Duan Xiao Hui

    2002-01-01

    The author introduces the design of programmable pulse generator that is based on a micro-controller and controlled by RS232 interface of personal computer. The whole system has good stability. The pulse generator can produce TTL pulse and analog pulse. The pulse frequency can be selected by EPLD. The voltage amplitude and pulse width of analog pulse can be adjusted by analog switches and digitally-controlled potentiometers. The software development tools of computer is National Instruments LabView5.1. The front panel of this virtual instrumentation is intuitive and easy-to-use. Parameters can be selected and changed conveniently by knob and slide

  10. Excimer Laser Pulse Compress With Pulse Feedback

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>To attain a shorter laser pulse, a compressing technique called pulse feedback was developed from the saturation gain switch applied to the amplification in a discharge pumping excimer laser cavity. It can

  11. Giant electromagnetic vortex and MeV monoenergetic electrons generated by short laser pulses in underdense plasma near quarter critical density region.

    Science.gov (United States)

    Zhidkov, Alexei; Nemoto, Koshichi; Nayuki, Takuya; Oishi, Yuji; Fuji, Takashi

    2007-07-01

    Very efficient generation of monoenergetic, about 1MeV , electrons from underdense plasma with its electron density close to the critical, when irradiated by an intense femtosecond laser pulse, is found via two dimensional particle-in-cell simulation. The stimulated Raman scattering of a laser pulse with frequency omega300 keV .

  12. Generation of 170-fs Laser Pulses at 1053 nm by a Passively Mode-Locked Yb:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bin-Bin; WEI Zhi-Yi; LI De-Hua; TENG Hao; Bourdet G. L

    2009-01-01

    A novel method is developed to obtain 1.05μm laser operation with a Yb:YAG laser. By using a Yb:YAG crystal with proper length and doping concentration, a femtosecond Yb: YAG laser is realized at the central wavelength of 1053nm. The measured pulse duration and spectral bandwidth (FWHM) are 17ors and 7nm; the repetition rate is 80 MHz. Under a power pump of 2 W, an average mode-locking power of 180mW is achieved.

  13. Generation of large-bandwidth x-ray free-electron-laser pulses

    Directory of Open Access Journals (Sweden)

    Angela Saa Hernandez

    2016-09-01

    Full Text Available X-ray free-electron lasers (XFELs are modern research tools in disciplines such as biology, material science, chemistry, and physics. Besides the standard operation that aims at minimizing the bandwidth of the produced XFEL radiation, there is a strong scientific demand to produce large-bandwidth XFEL pulses for several applications such as nanocrystallography, stimulated Raman spectroscopy, and multiwavelength anomalous diffraction. We present a self-consistent method that maximizes the XFEL pulse bandwidth by systematically maximizing the energy chirp of the electron beam at the undulator entrance. This is achieved by optimizing the compression scheme and the electron distribution at the source in an iterative back-and-forward tracking. Start-to-end numerical simulations show that a relative bandwidth of 3.25% full-width can be achieved for the hard x-ray pulses in the SwissFEL case.

  14. Generation of GW radiation pulses from a VUV free-electron laser operating in the femtosecond regime.

    Science.gov (United States)

    Ayvazyan, V; Baboi, N; Bohnet, I; Brinkmann, R; Castellano, M; Castro, P; Catani, L; Choroba, S; Cianchi, A; Dohlus, M; Edwards, H T; Faatz, B; Fateev, A A; Feldhaus, J; Flöttmann, K; Gamp, A; Garvey, T; Genz, H; Gerth, Ch; Gretchko, V; Grigoryan, B; Hahn, U; Hessler, C; Honkavaara, K; Hüning, M; Ischebeck, R; Jablonka, M; Kamps, T; Körfer, M; Krassilnikov, M; Krzywinski, J; Liepe, M; Liero, A; Limberg, T; Loos, H; Luong, M; Magne, C; Menzel, J; Michelato, P; Minty, M; Müller, U-C; Nölle, D; Novokhatski, A; Pagani, C; Peters, F; Pflüger, J; Piot, P; Plucinski, L; Rehlich, K; Reyzl, I; Richter, A; Rossbach, J; Saldin, E L; Sandner, W; Schlarb, H; Schmidt, G; Schmüser, P; Schneider, J R; Schneidmiller, E A; Schreiber, H-J; Schreiber, S; Sertore, D; Setzer, S; Simrock, S; Sobierajski, R; Sonntag, B; Steeg, B; Stephan, F; Sytchev, K P; Tiedtke, K; Tonutti, M; Treusch, R; Trines, D; Türke, D; Verzilov, V; Wanzenberg, R; Weiland, T; Weise, H; Wendt, M; Will, I; Wolff, S; Wittenburg, K; Yurkov, M V; Zapfe, K

    2002-03-11

    Experimental results are presented from vacuum-ultraviolet free-electron laser (FEL) operating in the self-amplified spontaneous emission (SASE) mode. The generation of ultrashort radiation pulses became possible due to specific tailoring of the bunch charge distribution. A complete characterization of the linear and nonlinear modes of the SASE FEL operation was performed. At saturation the FEL produces ultrashort pulses (30-100 fs FWHM) with a peak radiation power in the GW level and with full transverse coherence. The wavelength was tuned in the range of 95-105 nm.

  15. Bremsstrahlung {gamma}-ray generation by electrons from gas jets irradiated by laser pulses for radiographic testing

    Energy Technology Data Exchange (ETDEWEB)

    Oishi, Yuji; Nayuki, Takuya; Zhidkov, Alexei; Fujii, Takashi; Nemoto, Koshichi [Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa 240-0196 (Japan); Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa 240-0196, Japan and Photon Pioneers Center in Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871 (Japan); Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa 240-0196 (Japan)

    2012-07-11

    Electron generation from a gas jet irradiated by low energy femtosecond laser pulses is studied experimentally as a promising source of radiation for radioisotope-free {gamma}-ray imaging systems. The calculated yield of {gamma}-rays in the 0.5-2 MeV range, produced by low-average-power lasers and gas targets, exceeds the yields from solid tape targets up to 60 times. In addition, an effect of quasi-mono energetic electrons on {gamma}-ray imaging is also discussed.

  16. Bremsstrahlung γ-ray generation by electrons from gas jets irradiated by laser pulses for radiographic testing

    Science.gov (United States)

    Oishi, Yuji; Nayuki, Takuya; Zhidkov, Alexei; Fujii, Takashi; Nemoto, Koshichi

    2012-07-01

    Electron generation from a gas jet irradiated by low energy femtosecond laser pulses is studied experimentally as a promising source of radiation for radioisotope-free γ-ray imaging systems. The calculated yield of γ-rays in the 0.5-2 MeV range, produced by low-average-power lasers and gas targets, exceeds the yields from solid tape targets up to 60 times. In addition, an effect of quasi-mono energetic electrons on γ-ray imaging is also discussed.

  17. Generation of Nonlinear Force Driven Blocks from Skin Layer Interaction of Petawatt-Picosecond Laser Pulses for ICF

    Institute of Scientific and Technical Information of China (English)

    Heinrich Hora; K. Jungwirth; B. Kralikova; J. Kraska; L. Laska; Liu Hong; G.H. Miley; P. Parys; Peng Hansheng; M. Pfeifer; K. Rohlena; Cang Yu; J. Skala; Z. Skladanowski; L. Torrisi; J. Ullschmied; J. Wolowski; Zhang Weiyan; He Xiantu; Zhang Jie; F. Osman; J. Badziak; F.P. Boody; S. Gammino; R. H(o)pfl

    2004-01-01

    The discovery of the essential difference of maximum ion energy for TW-ps laser plasma interaction compared with the 100 ns laser pulses [1] led to the theory of a skin layer model [2] where the control of prepulses suppressed the usual relativistic self-focusing. The subsequent generation of two nonlinear force driven blocks has been demonstrated experimentally and in extensive numerical studies where one block moves against the laser light and the other block into the irradiated target. These blocks of nearly solid state density DT plasma correspond to ion beam current densities [3] exceeding 1010 A/cm2 where the ion velocity can be chosen up to highly relativistic values. Using the results of the expected ignition of DT fuel by light ion beams, a selfsustained fusion reaction front may be generated even into uncompressed solid DT fuel similar to the Nuckolls-Wood [4] scheme where 10 kJ laser pulses produce 100 MJ fusion energy. This new and simplified scheme of laser-ICF needs and optimisation of the involved parameters.

  18. Generation of sub-100 fs pulses from mode-locked Nd,Y:SrF2 laser with enhancing SPM

    Science.gov (United States)

    Zhu, Jiangfeng; Wei, Long; Tian, Wenlong; Liu, Jiaxing; Wang, Zhaohua; Su, Liangbi; Xu, Jun; Wei, Zhiyi

    2016-05-01

    A mode-locked laser using Nd,Y:SrF2 crystal as the gain medium is presented in this letter. By special design of the cavity for enhancing the self-phase modulation effect, femtosecond mode-locking with 97 fs pulse duration and 13.2 nm spectral width centered at 1061 nm is obtained at a repetition rate of 96 MHz. The average output power is 102 mW under 925 mW pump power, corresponding to the optical-to-optical efficiency of 11%. To the best of our knowledge, these are the first sub-100 fs pulses generated from a mode-locked Nd doped crystal laser.

  19. Laser-driven plasma wakefield electron acceleration and coherent femtosecond pulse generation in X-ray and gamma ranges

    Science.gov (United States)

    Trunov, V. I.; Lotov, K. V.; Gubin, K. V.; Pestryakov, E. V.; Bagayev, S. N.; Logachev, P. V.

    2017-01-01

    The laser wakefield acceleration (LWFA) of electrons in capillaries and gas jets followed by inverse Compton scattering of high intensity femtosecond laser pulses is discussed. The drive and scattered pulses will be produced by the two-channel multi-terawatt laser system developed in ILP SB RAS.

  20. High-order harmonic generation with a two-color laser pulse

    Institute of Scientific and Technical Information of China (English)

    Luo Lao-Yong; Du Hong-Chuan; Hu Bi-Tao

    2012-01-01

    We theoretically investigate the electron dynamics of the high-order harmonics generation process by combining a near-infrared 800 nm driving pulse with a mid-infrared 2000 nm control field.We also investigate the emission time of harmonics using time-frequency analysis to illustrate the physical mechanisms of high-order harmonic generation.We calculate the ionization rate using the Ammosov-Delone-Krainov model and interpret the variations in harmonic intensity for different control field strengths and delays.We find that the width of the harmonic plateau can be extended when the control electric field is added,and a supercontinuum from 198 to 435 eV is generated,from which an isolated 61-as pulse can be directly obtained.

  1. Computational study of the generation of crystal defects in a bcc metal target irradiated by short laser pulses

    Science.gov (United States)

    Lin, Zhibin; Johnson, Robert A.; Zhigilei, Leonid V.

    2008-06-01

    The generation of crystal defects in a Cr target irradiated by a short, 200 fs, laser pulse is investigated in computer simulations performed with a computational model that combines the classical molecular dynamics method with a continuum description of the laser excitation of conduction band electrons, electron-phonon coupling, and electron heat conduction. Interatomic interactions are described by the embedded atom method (EAM) potential with a parametrization designed for Cr. The potential is tested by comparing the properties of the EAM Cr material with experimental data and predictions of density functional theory calculations. The simulations are performed at laser fluences close to the threshold for surface melting. Fast temperature variation and strong thermoelastic stresses produced by the laser pulse are causing surface melting and epitaxial resolidification, transient appearance of a high density of stacking faults along the {110} planes, and generation of a large number of point defects (vacancies and self-interstitials). The stacking faults appear as a result of internal shifts in the crystal undergoing a rapid uniaxial expansion in the direction normal to the irradiated surface. The stacking faults are unstable and disappear shortly after the laser-induced tensile stress wave leaves the surface region of the target. Thermally activated generation of vacancy-interstitial pairs during the initial temperature spike and quick escape of highly mobile self-interstitials to the melting front or the free surface of the target, along with the formation of vacancies at the solid-liquid interface during the fast resolidification process, result in a high density of vacancies, on the order of 10-3 per lattice site, created in the surface region of the target. The strong supersaturation of vacancies can be related to the incubation effect in multipulse laser ablation/damage and should play an important role in mixing/alloying of multicomponent or composite

  2. Gain engineering for all-optical microwave and high speed pulse generation in mode-locked fiber lasers

    Science.gov (United States)

    Li, Fangxin; Helmy, Amr S.

    2014-03-01

    Pulsed sources based on approaches that employ only photonic components and no RF components will be discussed in this talk. Several technologies have been explored to generate actively mode-locked sources using electronically driven fiber ring cavities. However, for these sources the pulse repetition rate is usually limited by the bandwidth of the intracavity modulator. Filtering of highly-stable low repetition rate optical combs utilizing cavities such as Fabry-Perot etalons can be used to overcome this limitation. This scheme is not flexible as it requires highly precise control of ultrahigh finesse etalons which limits the repetition rate to the free spectral range of the filter. Pulsed sources based on semiconductor devices offer many advantages, including large gain bandwidth, rapid tunability, long-term stability. In this work we introduce a novel, simple method to generate optical clock with wavelength tunability using two continuous wave (CW) lasers. The lasers are injected into a conventional SOAs-based fiber ring laser. The beating signal generated by these two lasers causes the modulation of the SOA gain saturation inside the cavity. Thus, the SOA provides gain and functions as the modulator as well as the gain medium. When the lasing mode inside the cavity is amplified, it also results in gain-induced four wave mixing. The proposed technique is particularly versatile, overcoming the bandwidth limitation of other techniques, which require RF sources. Moreover, this technique provides the possibility for hybrid integration as it is comprised of semiconductor chips that can be heterogeneously integrated on a Si platform.

  3. Research of the elastic waves generated by a pulse laser. Excitation mechanism of elastic waves and application to nondestructive testing; Pulse laser de reikishita danseiha ni kansuru kenkyu. Danseiha reiki no mechanism to hihakai kensa eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Cho, H.; Takemoto, M. [Aoyama Gakuin University, Tokyo (Japan). College of Science and Engineering

    1994-07-20

    A bulk wave is generated when a pulse laser is irradiated to the material, and the characteristics of a Young`s modulus and Poisson`s ratio can be nondestructively estimated from the bulk wave. The generation mechanism of laser ultrasonic waves must be first clarified for such application. In this paper, fundamental research was conducted to study the generation mechanism of the elastic waves excited by a Q-switched Nd-YAG laser, and the generation method and characteristics of Rayleigh waves. The following result was obtained. A bulk wave is generated by the disk-like adiabatic expansion near the surface if the laser power is small when a spot-shape pulse laser was irradiated. A bulk wave is generated by the thin disk-like adiabatic expansion beneath the surface due to the thermal diffusion in the depth direction of a base material when the laser power becomes large. Moreover, a bulk wave is generated by the impact force due to abrasion and plasma when the power becomes still larger. The information on the bulk wave characteristics and Rayleigh wave was also obtained. 25 refs., 15 figs., 1 tab.

  4. Imaging the ultrafast Kerr effect, free carrier generation, relaxation and ablation dynamics of Lithium Niobate irradiated with femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Lechuga, Mario, E-mail: mario@io.cfmac.csic.es; Siegel, Jan, E-mail: j.siegel@io.cfmac.csic.es; Hernandez-Rueda, Javier; Solis, Javier [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain)

    2014-09-21

    The interaction of high-power single 130 femtosecond (fs) laser pulses with the surface of Lithium Niobate is experimentally investigated in this work. The use of fs-resolution time-resolved microscopy allows us to separately observe the instantaneous optical Kerr effect induced by the pulse and the generation of a free electron plasma. The maximum electron density is reached 550 fs after the peak of the Kerr effect, confirming the presence of a delayed carrier generation mechanism. We have also observed the appearance of transient Newton rings during the ablation process, related to optical interference of the probe beam reflected at the front and back surface of the ablating layer. Finally, we have analyzed the dynamics of the photorefractive effect on a much longer time scale by measuring the evolution of the transmittance of the irradiated area for different fluences below the ablation threshold.

  5. Nanofabrication with pulsed lasers.

    Science.gov (United States)

    Kabashin, Av; Delaporte, Ph; Pereira, A; Grojo, D; Torres, R; Sarnet, Th; Sentis, M

    2010-02-24

    An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3), is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser-matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics.

  6. Ultrashort Generation Regimes in the All-Fiber Kerr Mode-Locked Erbium-Doped Fiber Ring Laser for Terahertz Pulsed Spectroscopy

    Directory of Open Access Journals (Sweden)

    V. S. Voropaev

    2015-01-01

    Full Text Available Many femtosecond engineering applications require for a stable generation of ultrashort pulses. Thus, in the terahertz pulsed spectroscopy a measurement error in the refractive index is strongly dependent on the pulse duration stability with allowable variation of few femtoseconds. The aim of this work is to study the ultrashort pulses (USP regimes stability in the all – fiber erbium doped ring laser with Kerr mode-locking. The study was conducted at several different values of the total resonator intra-cavity dispersion. Three laser schemes with the intra-cavity dispersion values from -1.232 ps2 to +0.008 ps2 have been studied. In the experiment there were two regimes of generation observed: the stretched pulse generation and ordinary soliton generation. Main attention is focused on the stability of regimes under study. The most stable regime was that of the stretched pulse generation with a spectrum form of sech2 , possible pulse duration of 490 fs at least, repetition rate of 2.9 MHz, and average output power of 17 mW. It is worth noting, that obtained regimes had characteristics suitable for the successful use in the terahertz pulsed spectroscopy. The results may be useful in the following areas of science and technology: a high-precision spectroscopy, optical frequency standards, super-continuum generation, and terahertz pulsed spectroscopy. The future system development is expected to stabilize duration and repetition rate of the obtained regime of ultra-short pulse generation.

  7. High-power, mid-infrared, picosecond pulses generated by compression of a CO2 laser beat-wave in GaAs

    CERN Document Server

    Pigeon, J J; Joshi, C

    2015-01-01

    We report on the generation of a train of ~ 2 ps, 10 um laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO2 laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  8. High-power, mid-infrared, picosecond pulses generated by compression of a CO₂ laser beat-wave in GaAs.

    Science.gov (United States)

    Pigeon, J J; Tochitsky, S Ya; Joshi, C

    2015-12-15

    We report on the generation of a train of ∼2  ps, 10 μm laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl crystals. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO₂ laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves, we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  9. High-power, mid-infrared, picosecond pulses generated by compression of a CO_2 laser beat-wave in GaAs

    Science.gov (United States)

    Pigeon, J. J.; Tochitsky, S. Ya.; Joshi, C.

    2015-12-01

    We report on the generation of a train of ~ 2 ps, 10 um laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO2 laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  10. Generation of 30  fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO4 laser.

    Science.gov (United States)

    Ma, Jie; Huang, Haitao; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2016-03-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode-locked 8.43 optical-cycle pulses have a spectral bandwidth of ∼50  nm and a pulse repetition frequency of ∼113.5  MHz. To the best of our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique for directly generating few-cycle optical pulses from a laser oscillator.

  11. Generation of 30 fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO_4 laser

    Science.gov (United States)

    Ma, Jie; Huang, Haitao; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2016-03-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode locked 8.43 optical-cycle pulses have a spectral bandwidth of ~ 50 nm and a pulse repetition frequency of ~ 113.5 MHz. To our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique to generate few-cycle optical pulses directly from a laser oscillator.

  12. Generation of 30-fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO4 laser

    CERN Document Server

    Ma, Jie; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2015-01-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode locked 8.43 optical-cycle pulses have a spectral bandwidth of ~ 50 nm and a pulse repetition frequency of ~ 113.5 MHz. To our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique to generate few-cycle optical pulses directly from a laser oscillator.

  13. Solid-like ablation propulsion generation in nanosecond pulsed laser interaction with carbon-doped glycerol

    Science.gov (United States)

    Zheng, Zhi-Yuan; Zhang, Si-Qi; Liang, Tian; Qi, Jing; Tang, Wei-Chong; Xiao, Ke; Gao, Lu; Gao, Hua; Zhang, Zi-Li

    2017-03-01

    A solid-like propellant of carbon-doped glycerol ablated by a nanosecond pulsed laser is investigated. The results show that the specific impulse increases with increasing carbon content, and a maximum value of 228 s is obtained. The high specific impulse is attributed to the low ablated mass loss that occurs at high carbon content. More importantly, with increasing carbon content, the properties of the doped glycerol approach to those of a solid. These results indicate that propulsion at the required coupling coefficient and specific impulse can be realized by doping a liquid propellant with an absorber. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant Nos. 53200859165 and 2562010050).

  14. Nanofabrication with Pulsed Lasers

    Directory of Open Access Journals (Sweden)

    Kabashin AV

    2010-01-01

    Full Text Available Abstract An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3, is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser–matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics.

  15. Broadband coherent anti-Stokes Raman scattering light generation in BBO crystal by using two crossing femtosecond laser pulses.

    Science.gov (United States)

    Liu, Jun; Zhang, Jun; Kobayashi, Takayoshi

    2008-07-01

    As broad as 12000 cm(-1) coherent anti-Stokes Raman scattering (CARS) light from ultraviolet to infrared was generated in a BBO crystal by using two crossing femtosecond laser pulses with 30% conversion efficiency. More than fifteenth-order anti-Stokes and second-order Stokes Raman sidebands were observed with nice Gaussian spatial mode. The effect of the crossing angle between two input beams on the spectrum and emitting angle of the Raman sidebands was studied in detail. Calculation shows that the phase-matching condition determines the frequencies and angles of the sidebands.

  16. Ion Acceleration by Short Chirped Laser Pulses

    Directory of Open Access Journals (Sweden)

    Jian-Xing Li

    2015-02-01

    Full Text Available Direct laser acceleration of ions by short frequency chirped laser pulses is investigated theoretically. We demonstrate that intense beams of ions with a kinetic energy broadening of about 1% can be generated. The chirping of the laser pulse allows the particles to gain kinetic energies of hundreds of MeVs, which is required for hadron cancer therapy, from pulses of energies in the order of 100 J. It is shown that few-cycle chirped pulses can accelerate ions more efficiently than long ones, i.e., higher ion kinetic energies are reached with the same amount of total electromagnetic pulse energy.

  17. Ion Acceleration by Short Chirped Laser Pulses

    CERN Document Server

    Li, Jian-Xing; Keitel, Christoph H; Harman, Zoltán

    2015-01-01

    Direct laser acceleration of ions by short frequency-chirped laser pulses is investigated theoretically. We demonstrate that intense beams of ions with a kinetic energy broadening of about 1 % can be generated. The chirping of the laser pulse allows the particles to gain kinetic energies of hundreds of MeVs, which is required for hadron cancer therapy, from pulses of energies of the order of 100 J. It is shown that few-cycle chirped pulses can accelerate ions more efficiently than long ones, i.e. higher ion kinetic energies are reached with the same amount of total electromagnetic pulse energy.

  18. Novel Scheme for Multiple Channel Pulse Generation from a Single Laser Diodefor 10 Gbit/s Based WDM Systems Using RZ Modulation Format

    Institute of Scientific and Technical Information of China (English)

    H.; C.; Bao; Y.; J.; Wen; H.; F.; Liu

    2003-01-01

    A new technique for the generation of multi-channel optical pulse from a single laser diode (LD) is presented in this paper. 35 channel pulse source with 6.5 GHz repetition rate per channel and 32.5 GHz channel spacing was generated from a subharmonically hybrid mode-locked two section monolithic laser with enhanced amplitude modulation. The obtained pulse source exhibits high extinction ratio (>10 dB) and low level of root mean square (RMS) phase noise (<0.11 rad) over all channels from 1556 nm to 1565...

  19. Novel Scheme for Multiple Channel Pulse Generation from a Single Laser Diodefor 10 Gbit/s Based WDM Systems Using RZ Modulation Format

    Institute of Scientific and Technical Information of China (English)

    H. C. Bao; Y. J. Wen; H. F. Liu

    2003-01-01

    A new technique for the generation of multi-channel optical pulse from a single laser diode (LD) is presented in this paper. 35 channel pulse source with 6.5 GHz repetition rate per channel and 32.5 GHz channel spacing was generated from a subharmonically hybrid mode-locked two section monolithic laser with enhanced amplitude modulation. The obtained pulse source exhibits high extinction ratio (>10 dB) and low level of root mean square (RMS)phase noise (<0.11 rad) over all channels from 1556 nm to 1565 nm.

  20. Ultraviolet absorption spectroscopy in optically dense fireballs using broadband second-harmonic generation of a pulsed modeless dye laser.

    Science.gov (United States)

    Soo, Michael; Glumac, Nick

    2014-01-01

    Broadband frequency doubling of a modeless dye laser pulse is used to enable single-shot absorption spectroscopy in the ultraviolet for optically dense, energetic-materials fireball applications. Band widths of approximately 1-3 nm are generated in the 226 and 268 nm regions using a doubling crystal. Strong focusing of the fundamental beam onto the crystal is found to be sufficient to achieve 1-5% conversion efficiency with a pulse intensity sufficient to saturate the array detector even after 75% attenuation through the fireball. The technique is demonstrated with nitric oxide (NO) absorption in a gas cell and is then used to perform the first detection and temperature fitting of aluminum monofluoride (AlF) and magnesium monofluoride (MgF) in a fireball environment.

  1. Field emission study from an array of hierarchical micro protrusions on stainless steel surface generated by femtosecond pulsed laser irradiation

    Science.gov (United States)

    Singh, A. K.; Suryawanshi, Sachin R.; More, M. A.; Basu, S.; Sinha, Sucharita

    2017-02-01

    This paper reports our results on femtosecond (fs) pulsed laser induced surface micro/nano structuring of stainless steel 304 (SS 304) samples and their characterization in terms of surface morphology, formed material phases on laser irradiation and field emission studies. Our investigations reveal that nearly uniform and dense array of hierarchical micro-protrusions (density: ∼5.6 × 105 protrusions/cm2) is formed upon laser treatment. Typical tip diameters of the generated protrusions are in the range of 2-5 μm and these protrusions are covered with submicron sized features. Grazing incidence X-ray diffraction (GIXRD) analysis of the laser irradiated sample surface has shown formation mainly of iron oxides and cementite (Fe3C) phases in the treated region. These laser micro-structured samples have shown good field emission properties such as low turn on field (∼4.1 V/μm), high macroscopic field enhancement factor (1830) and stable field emission current under ultra high vacuum conditions.

  2. Synchronization and coherent combining of two pulsed fiber lasers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We demonstrate a scalable architecture for coherent combining of pulsed fiber lasers.A new method for generating synchronous pulsed fiber lasers by direct phase modulation is proposed and investigated.It is shown that phase modulated mutually coupled laser array can be a steady synchronous pulsed fiber laser source.The synchronous pulsed fiber lasers are coherently combined with an invariable phase difference of π in adjacent lasers.Neither active phase control nor polarization control is taken in our experiment.

  3. Enhancement of Kα emission through efficient hot electron generation in carbon nanotubes on intense laser pulse irradiation

    Science.gov (United States)

    Chakravarty, U.; Arora, V.; Naik, P. A.; Chakera, J. A.; Srivastava, H.; Srivastava, A.; Varma, G. D.; Kumbhare, S. R.; Gupta, P. D.

    2012-09-01

    Near complete absorption of the energy of intense ultra-short laser pulses (45 fs, intensity ˜1.6 × 1016 to 2.5 × 1017 W/cm2) is observed in carbon nanotubes deposited on a planar molybdenum substrate. The hollow structure of the nanotube plasma facilitates resonant electric field enhancement during its ionization phase. This resonantly enhanced localized field at a density much larger than the critical density nc leads to efficient hot electron generation, which results in enhanced Kα emission of Mo at 17.5 keV. It is observed that for nanotubes, depending on the degree of hollowness, there is an optimum laser intensity for maximum x-ray enhancement compared to a planar uncoated target.

  4. High-intensity, high-contrast laser pulses generated from the fully diode-pumped Yb:glass laser system POLARIS.

    Science.gov (United States)

    Hornung, Marco; Keppler, Sebastian; Bödefeld, Ragnar; Kessler, Alexander; Liebetrau, Hartmut; Körner, Jörg; Hellwing, Marco; Schorcht, Frank; Jäckel, Oliver; Sävert, Alexander; Polz, Jens; Arunachalam, Ajay Kawshik; Hein, Joachim; Kaluza, Malte C

    2013-03-01

    We report on the first generation of high-contrast, 164 fs duration pulses from the laser system POLARIS reaching focused peak intensities in excess of 2×10(20) W/cm2. To our knowledge, this is the highest peak intensity reported so far that has been achieved with a diode-pumped, solid-state laser. Several passive contrast enhancement techniques have been specially developed and implemented, achieving a relative prepulse intensity smaller than 10(-8) at t=-30 ps before the main pulse. Furthermore a closed-loop adaptive-optics system has been installed. Together with angular chirp compensation, this method has led to a significant reduction of the focal spot size and an increase of the peak intensity.

  5. Effect of nuclear motion on high-order harmonic generation of H$_2^+$ in intense ultrashort laser pulses

    CERN Document Server

    Ahmadi, Hamed; Sabzyan, Hassan; Niknam, Ali Reza; Vafaee, Mohsen

    2014-01-01

    High-order harmonic generation is investigated for H$_2^+$ and D$_2^+$ with and without Born-Oppenheimer approximation by numerical solution of full dimensional electronic time-dependent Schr\\"{o}dinger equation under 4-cycle intense laser pulses of 800 nm wavelength and $I$=4, 5, 7, 10 $\\times 10^{14}$ W$/$cm$^2$ intensities. For most harmonic orders, the intensity obtained for D$_2^+$ is higher than that for H$_2^+$, and the yield difference increases as the harmonic order increases. Only at some low harmonic orders, H$_2^+$ generates more intense harmonics compared to D$_2^+$. The results show that nuclear motion, ionization probability and system dimensionality must be simultaneously taken into account to properly explain the isotopic effects on high-order harmonic generation and to justify experimental observations.

  6. Ultrashort optical pulse generation from a chromium(4)- doped yttrium aluminium garnet tunable solid-state laser

    Science.gov (United States)

    Chang, Yongmao

    2000-11-01

    In this thesis, experimental results of ultrashort pulse generation from Cr4+-doped yttrium aluminium garnet (YAG) laser system are presented. The Cr4+:YAG crystal is a vibronically broadened solid state laser gain medium, which lases at room temperature from 1.34 to 1.58 μm and can be pumped by a Nd:YAG laser at 1.06 μm. Ultrashort pulses from this coherent light source are potentially important in technology applications such as ultrafast fiber-optic communications and time-resolved spectroscopy of narrow- bandgap, semiconductors. It is a practical alternative to more conventional cryogenic colour center lasers at this wavelength such as NaCl:OH- or complex optical parametric oscillators synchronously pumped by a Ti:sapphire laser. The cw power performance of a Cr4+:YAG laser was characterized and several unique properties were identified. A broad tuning range of 210 nm, i.e., from 1345 to 1557 nm, was demonstrated by means of one set of mirrors with useful cw output power of as high as 730 mW at 1.46 μm (with a Nd:YAG pump power of 6.5 W). The lasing action was found to be strongly influenced by the temperature of the crystal and the combined effects of thermal lensing and saturable absorption of the pump beam. The excited-state absorption (ESA) at the pump and lasing wavelengths were investigated both experimentally and theoretically. ESA at the lasing wavelength occurs for the transition from the state 3B2(3T2) to 3E(3T1(F)), while the pump ESA comes from the transition from 3A2(3T2 ) to 3E(3T1(P)). The emission ESA cross sections for the free-running modes were estimated from the laser efficiency data by taking into account the pump and cavity parameters. Ultrashort pulse generation with a Cr4+:YAG laser was investigated using passive mode-locking with a semiconductor quantum well saturable absorber. Self-starting of the laser system was demonstrated using a strained GaInAs/InAlAs saturable Bragg reflector (SBR) with a single prism for dispersion

  7. Analysis of picosecond pulsed laser melted graphite

    Energy Technology Data Exchange (ETDEWEB)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M.S.; Huang, C.Y.; Malvezzi, A.M.; Bloembergen, N.

    1986-01-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm/sup -1/ and the disorder-induced mode at 1360 cm/sup -1/, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nonosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  8. Analysis of Picosecond Pulsed Laser Melted Graphite

    Science.gov (United States)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M. S.; Huang, C. Y.; Malvezzi, A. M.; Bloembergen, N.

    1986-12-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm{sup -1} and the disorder-induced mode at 1360 cm{sup -1}, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nanosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  9. Rippled area formed by surface plasmon polaritons upon femtosecond laser double-pulse irradiation of silicon: the role of carrier generation and relaxation processes

    Science.gov (United States)

    Derrien, Thibault J.-Y.; Krüger, Jörg; Itina, Tatiana E.; Höhm, Sandra; Rosenfeld, Arkadi; Bonse, Jörn

    2014-10-01

    The formation of laser-induced periodic surface structures (LIPSS, ripples) upon irradiation of silicon with multiple irradiation sequences consisting of femtosecond laser pulse pairs (pulse duration 150 fs, central wavelength 800 nm) is studied numerically using a rate equation system along with a two-temperature model accounting for one- and two-photon absorption and subsequent carrier diffusion and Auger recombination processes. The temporal delay between the individual equal-energy fs-laser pulses was varied between 0 and ˜4 ps for quantification of the transient carrier densities in the conduction band of the laser-excited silicon. The results of the numerical analysis reveal the importance of carrier generation and relaxation processes in fs-LIPSS formation on silicon and quantitatively explain the two time constants of the delay-dependent decrease of the low spatial frequency LIPSS (LSFL) area observed experimentally. The role of carrier generation, diffusion and recombination is quantified individually.

  10. Comparative investigation of third- and fifth-harmonic generation in atomic and molecular gases driven by midinfrared ultrafast laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Ni Jielei; Yao Jinping; Zeng Bin; Chu Wei; Li Guihua; Zhang Haisu; Jing Chenrui [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Chin, S. L. [Department of Physics, Engineering Physics and Optics, and Center for Optics, Photonics and Laser (COPL), Laval University, Laval, Quebec, G1K 7P4 (Canada); Cheng, Y.; Xu, Z. [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)

    2011-12-15

    We report on the comparative experimental investigation on third- and fifth-harmonic generation (THG and FHG) in atomic and molecular gases driven by midinfrared ultrafast laser pulses at a wavelength of {approx}1500 nm. We observe that the conversion efficiencies of both the THG and FHG processes saturate at similar peak intensities close to {approx}1.5 x 10{sup 14} W/cm{sup 2} for argon, nitrogen, and air, whose ionization potentials are close to each other. Near the saturation intensity, the ratio of yields of the FHG and THG reaches {approx}10{sup -1} for all the gases. Our results show that high-order Kerr effect seems to exist; however, contribution from the fourth-order Kerr refractive index coefficient alone is insufficient to balance the Kerr self-focusing without the assistance of plasma generation.

  11. Generation of ultrashort pulses with minimum duration of 90\\ {\\text{fs}} in a hybrid mode-locked erbium-doped all-fibre ring laser

    Science.gov (United States)

    Dvoretskiy, D. A.; Sazonkin, S. G.; Voropaev, V. S.; Negin, M. A.; Leonov, S. O.; Pnev, A. B.; Karasik, V. E.; Denisov, L. K.; Krylov, A. A.; Davydov, V. A.; Obraztsova, E. D.

    2016-11-01

    Regimes of ultrashort pulse generation in an erbium-doped all-fibre ring laser with hybrid mode locking based on single-wall carbon - boron nitride nanotubes and the nonlinear Kerr effect in fibre waveguides are studied. Stable dechirped ultrashort pulses are obtained with a duration of ˜ 90 {\\text{fs}}, a repetition rate of ˜ 42.2 {\\text{MHz}}, and an average output power of ˜ 16.7 {\\text{mW}}, which corresponds to a pulse energy of ˜ 0.4 {\\text{nJ}} and a peak laser power of ˜ 4.4 {\\text{kW}}.

  12. Generation and Amplification of Tunable Multicolored Femtosecond Laser Pulses by Using Cascaded Four-Wave Mixing in Transparent Bulk Media

    Science.gov (United States)

    Liu, Jun; Kobayashi, Takayoshi

    2010-01-01

    We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM) in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively. The experimental studies showed: (1) as many as fifteen spectral up-shifted and two spectral down-shifted sidebands were obtained simultaneously with spectral bandwidth broader than 1.8 octaves from near ultraviolet (360 nm) to near infrared (1.2 μm); (2) the obtained sidebands were spatially separated well and had extremely high beam quality with M2 factor better than 1.1; (3) the wavelengths of the generated multicolor sidebands could be conveniently tuned by changing the crossing angle or simply replacing with different media; (4) as short as 15-fs negatively chirped or nearly transform limited 20-fs multicolored femtosecond pulses were obtained when one of the two input beams was negatively chirped and the other was positively chirped; (5) the pulse energy of the sideband can reach a μJ level with power stability better than 1% RMS; (6) broadband two-dimensional (2-D) multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate; (7) the obtained sidebands could be simultaneously spectra broadened and power amplified in another bulk medium by using cross-phase modulation (XPM) in conjunction with four-wave optical parametric amplification (FOPA). The characterization showed that this is interesting and the CFWM sidebands generated by this novel method have good enough qualities in terms of power stability, beam quality, and temporal features suited to various experiments such as ultrafast multicolor time-resolved spectroscopy and multicolor-excitation nonlinear microscopy. PMID:22399882

  13. Generation and Amplification of Tunable Multicolored Femtosecond Laser Pulses by Using Cascaded Four-Wave Mixing in Transparent Bulk Media

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2010-04-01

    Full Text Available We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively. The experimental studies showed: (1 as many as fifteen spectral up-shifted and two spectral down-shifted sidebands were obtained simultaneously with spectral bandwidth broader than 1.8 octaves from near ultraviolet (360 nm to near infrared (1.2 μm; (2 the obtained sidebands were spatially separated well and had extremely high beam quality with M2 factor better than 1.1; (3 the wavelengths of the generated multicolor sidebands could be conveniently tuned by changing the crossing angle or simply replacing with different media; (4 as short as 15-fs negatively chirped or nearly transform limited 20-fs multicolored femtosecond pulses were obtained when one of the two input beams was negatively chirped and the other was positively chirped; (5 the pulse energy of the sideband can reach a μJ level with power stability better than 1% RMS; (6 broadband two-dimensional (2-D multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate; (7 the obtained sidebands could be simultaneously spectra broadened and power amplified in another bulk medium by using cross-phase modulation (XPM in conjunction with four-wave optical parametric amplification (FOPA. The characterization showed that this is interesting and the CFWM sidebands generated by this novel method have good enough qualities in terms of power stability, beam quality, and temporal features suited to various experiments such as ultrafast multicolor time-resolved spectroscopy and multicolor-excitation nonlinear microscopy.

  14. Tunable THz Generation by the Interaction of a Super-luminous Laser Pulse with Biased Semiconductor Plasma

    Science.gov (United States)

    Papadopoulos, K.; Zigler, A.

    2006-01-01

    Terahertz (THz) radiation is electromagnetic radiation in the range between several hundred and a few thousand GHz. It covers the gap between fast-wave electronics (millimeter waves) and optics (infrared). This spectral region offers enormous potential for detection of explosives and chemical/biological agents, non-destructive testing of non-metallic structural materials and coatings of aircraft structures, medical imaging, bio-sensing of DNA stretching modes and high-altitude secure communications. The development of these applications has been hindered by the lack of powerful, tunable THz sources with controlled waveform. The need for such sources is accentuated by the strong, but selective absorption of THz radiation during transmission through air with high vapor content. The majority of the current experimental work relies on time-domain spectroscopy using fast electrically biased photoconductive sources in conjunction with femto-second mode-locked Ti:Sapphire lasers. These sources known as Large Aperture Photoconductive Antennas (LAPA) have very limited tunability, relatively low upper bound of power and no bandwidth control. The paper presents a novel source of THz radiation known as Miniature Photoconductive Capacitor Array (MPCA). Experiments demonstrated tunability between .1 - 2 THz, control of the relative bandwidth Δf/f between .5-.01, and controlled pulse length and pulse waveform (temporal shape, chirp, pulse-to-pulse modulation etc.). Direct scaling from the current device indicates efficiency in excess of 30% at 1 THz with 1/f2 scaling at higher frequencies, peak power of 100 kW and average power between .1-1 W. The physics underlying the MPCA is the interaction of a super-luminous ionization front generated by the oblique incidence of a Ti:Sapphire laser pulse on a semiconductor crystal (ZnSe) biased with an alternating electrostatic field, similar to that of a frozen wave generator. It is shown theoretically and experimentally that the

  15. Compact sources for the generation of high-peak power wavelength-stabilized laser pulses in the picoseconds and nanoseconds ranges

    Science.gov (United States)

    Wenzel, H.; Klehr, A.; Schwertfeger, S.; Liero, A.; Hoffmann, Th.; Brox, O.; Thomas, M.; Erbert, G.; Tränkle, G.

    2012-03-01

    Diode lasers are ideally suited for the generation of optical pulses in the nanoseconds and picoseconds ranges by gainswitching, Q-switching or mode-locking. We have developed diode-laser based light sources where the pulses are spectrally stabilized and nearly-diffraction limited as required by many applications. Diffraction limited emission is achieved by a several microns wide ridge waveguide (RW), so that only the fundamental lateral mode should lase. Spectral stabilization is realized with a Bragg grating integrated into the semiconductor chip, resulting in distributed feedback (DFB) or distributed Bragg reflector (DBR) lasers. We obtained a peak power of 3.8W for 4ns long pulses using a gain-switched DFB laser and a peak power of more than 4W for 65ps long pulses using a three-section DBR laser. Higher peak powers of several tens of Watts can be reached by an amplification of the pulses with semiconductor optical amplifiers, which can be either monolithically or hybrid integrated with the master oscillators. We developed compact modules with a footprint of 4×5cm2 combining master oscillator, tapered power amplifier, beam-shaping optical elements and high-frequency electronics. In order to diminish the generation of amplified spontaneous emission between the pulses, the amplifier is modulated with short-pulses of high amplitude, too. Beyond the amplifier, we obtained a peak power of more than 10W for 4ns long pulses, a peak power of about 35W for 80ps long pulses and a peak power of 70W for 10ps long pulses at emission wavelengths around 1064nm.

  16. Laser generation of XeCl exciplex molecules in a longitudinal repetitively pulsed discharge in a Xe – CsCl mixture

    Energy Technology Data Exchange (ETDEWEB)

    Boichenko, A M [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Klenovskii, M S [National Research Tomsk Polytechnic University, Tomsk (Russian Federation)

    2015-12-31

    By using the previously developed kinetic model, we have carried out simulations to study the possibility of laser generation of XeCl exciplex molecules in the working medium based on a mixture of Xe with CsCl vapours, excited by a longitudinal repetitively pulsed discharge. The formation mechanism of exciplex molecules in this mixture is fundamentally different from the formation mechanisms in the traditional mixtures of exciplex lasers. The conditions that make the laser generation possible are discussed. For these conditions, with allowance for available specific experimental conditions of the repetitively pulsed discharge excitation, we have obtained the calculated dependences of the power and efficiency of generation on the reflectivity of mirrors in a laser cavity. (active media)

  17. Generation regimes of bidirectional hybridly mode-locked ultrashort pulse erbium-doped all-fiber ring laser with a distributed polarizer.

    Science.gov (United States)

    Krylov, Alexander A; Chernykh, Dmitriy S; Arutyunyan, Natalia R; Grebenyukov, Vyacheslav V; Pozharov, Anatoly S; Obraztsova, Elena D

    2016-05-20

    We report on the stable picosecond and femtosecond pulse generation from the bidirectional erbium-doped all-fiber ring laser hybridly mode-locked with a coaction of a single-walled carbon nanotube-based saturable absorber and nonlinear polarization evolution that was introduced through the insertion of the short-segment polarizing fiber. Depending on the total intracavity dispersion value, the laser emits conservative solitons, transform-limited Gaussian pulses, or highly chirped stretched pulses with almost 20 nm wide parabolic spectrum in both clockwise (CW) and counterclockwise (CCW) directions of the ring. Owing to the polarizing action in the cavity, we have demonstrated for the first time, to the best of our knowledge, an efficient tuning of soliton pulse characteristics for both CW and CCW channels via an appropriate polarization control. We believe that the bidirectional laser presented may be highly promising for gyroscopic and other dual-channel applications.

  18. High voltage pulse generator

    Science.gov (United States)

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  19. Pulse laser-induced generation of cluster codes from metal nanoparticles for immunoassay applications

    Directory of Open Access Journals (Sweden)

    Chia-Yin Chang

    2017-05-01

    Full Text Available In this work, we have developed an assay for the detection of proteins by functionalized nanomaterials coupled with laser-induced desorption/ionization mass spectrometry (LDI-MS by monitoring the generation of metal cluster ions. We achieved selective detection of three proteins [thrombin, vascular endothelial growth factor-A165 (VEGF-A165, and platelet-derived growth factor-BB (PDGF-BB] by modifying nanoparticles (NPs of three different metals (Au, Ag, and Pt with the corresponding aptamer or antibody in one assay. The Au, Ag, and Pt acted as metal bio-codes for the analysis of thrombin, VEGF-A165, and PDGF-BB, respectively, and a microporous cellulose acetate membrane (CAM served as a medium for an in situ separation of target protein-bound and -unbound NPs. The functionalized metal nanoparticles bound to their specific proteins were subjected to LDI-MS on the CAM. The functional nanoparticles/CAM system can function as a signal transducer and amplifier by transforming the protein concentration into an intense metal cluster ion signal during LDI-MS analysis. This system can selectively detect proteins at picomolar concentrations. Most importantly, the system has great potential for the detection of multiple proteins without any pre-concentration, separation, or purification process because LDI-MS coupled with CAM effectively removes all signals except for those from the metal cluster ions.

  20. Pulse laser-induced generation of cluster codes from metal nanoparticles for immunoassay applications

    Science.gov (United States)

    Chang, Chia-Yin; Chu, Han-Wei; Unnikrishnan, Binesh; Peng, Lung-Hsiang; Cang, Jinshun; Hsu, Pang-Hung; Huang, Chih-Ching

    2017-05-01

    In this work, we have developed an assay for the detection of proteins by functionalized nanomaterials coupled with laser-induced desorption/ionization mass spectrometry (LDI-MS) by monitoring the generation of metal cluster ions. We achieved selective detection of three proteins [thrombin, vascular endothelial growth factor-A165 (VEGF-A165), and platelet-derived growth factor-BB (PDGF-BB)] by modifying nanoparticles (NPs) of three different metals (Au, Ag, and Pt) with the corresponding aptamer or antibody in one assay. The Au, Ag, and Pt acted as metal bio-codes for the analysis of thrombin, VEGF-A165, and PDGF-BB, respectively, and a microporous cellulose acetate membrane (CAM) served as a medium for an in situ separation of target protein-bound and -unbound NPs. The functionalized metal nanoparticles bound to their specific proteins were subjected to LDI-MS on the CAM. The functional nanoparticles/CAM system can function as a signal transducer and amplifier by transforming the protein concentration into an intense metal cluster ion signal during LDI-MS analysis. This system can selectively detect proteins at picomolar concentrations. Most importantly, the system has great potential for the detection of multiple proteins without any pre-concentration, separation, or purification process because LDI-MS coupled with CAM effectively removes all signals except for those from the metal cluster ions.

  1. High-speed pulse-shape generator, pulse multiplexer

    Science.gov (United States)

    Burkhart, Scott C.

    2002-01-01

    The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

  2. Method for Generating a Compressed Optical Pulse

    DEFF Research Database (Denmark)

    2015-01-01

    There is presented a method of for generating a compressed optical pulse (112) comprising emitting from a wavelength tunable microcavity laser system (102), comprising an optical cavity (104) with a mechanically adjustable cavity length (L), a primary optical pulse (111) having a primary temporal...... width (Tl) while adjusting the optical cavity length (L) so that said primary optical pulse comprises temporally separated photons of different wavelengths, and transmitting said pulse through a dispersive medium (114), so as to generate a compressed optical pulse (112) with a secondary temporal width...

  3. Generation of tunable multi-wavelength optical short pulses using self-seeded Fabry-Perot laser diode and tilted multimode fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Tongjian Cai; Yunqi Liu; Xiaobei Zhang; Tingyun Wang

    2011-01-01

    We experimentally demonstrate the simultaneous generation of tunable multi-wavelength picosecond laser pulses using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode (FPLD)with an external cavity formed by a tilted multimode fiber Bragg grating.Dual- and triple-wavelength pulses are obtained and tuned in a flexible manner by changing the temperature of the FPLD.The side mode suppression ratio larger than 25 dB is achieved at different dual- and triple-wavelengths and the typical pulsewidth of the output pulses is ~70 ps.In the experiment, the wavelength separation can be narrowed to 0.57 nm.%@@ We experimentally demonstrate the simultaneous generation of tunable multi-wavelength picosecond laser pulses using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode (FPLD)with an external cavity formed by a tilted multimode fiber Bragg grating.Dual-and triple-wavelength pulses are obtained and tuned in a flexible manner by changing the temperature of the FPLD.The side mode suppression ratio larger than 25 dB is achieved at different dual-and triple-wavelength8 and the typical pulsewidth of the output pulses is~70 ps.In the experiment, the wavelength separation can be narrowed to 0.57 nm.

  4. Generation of soliton and bound soliton pulses in mode-locked erbium-doped fiber laser using graphene film as saturable absorber

    Science.gov (United States)

    Haris, H.; Harun, S. W.; Anyi, C. L.; Muhammad, A. R.; Ahmad, F.; Tan, S. J.; Nor, R. M.; Zulkepely, N. R.; Ali, N. M.; Arof, H.

    2016-04-01

    We report an observation of soliton and bound-state soliton in passive mode-locked fibre laser employing graphene film as a passive saturable absorber (SA). The SA was fabricated from the graphene flakes, which were obtained from electrochemical exfoliation process. The graphene flakes was mixed with polyethylene oxide solution to form a polymer composite, which was then dried at room temperature to produce a film. The film was then integrated in a laser cavity by attaching it to the end of a fibre ferrule with the aid of index matching gel. The fibre laser generated soliton pulses with a 20.7 MHz repetition rate, 0.88 ps pulse width, 0.0158 mW average output power, 0.175 pJ pulse energy and 18.72 W peak power at the wavelength of 1564 nm. A bound soliton with pulse duration of ~1.04 ps was also obtained at the pump power of 110.85 mW by carefully adjusting the polarization of the oscillating laser. The formation of bound soliton is due to the direct pulse to pulse interaction. The results show that the proposed graphene-based SA offers a simple and cost efficient approach of generating soliton and bound soliton in mode-locked EDFL set-up.

  5. Micro pulse laser radar

    Science.gov (United States)

    Spinhirne, James D. (Inventor)

    1993-01-01

    An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

  6. Double pulse laser wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Changbum [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)], E-mail: chbkim@postech.ac.kr; Kim, Jin-Cheol B. [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kim, Kukhee [National Fusion Reserch Center, Daejeon 305-333 (Korea, Republic of); Ko, In Soo [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Suk, Hyyong [Center for Advanced Accelerators, Korea Electrotechnology Research Institute, Changwon 641-120 (Korea, Republic of)

    2007-10-22

    Two-dimensional simulation studies are performed for modified laser wakefield acceleration. After one laser pulse, another identical laser pulse is sent to the plasma to amplify the wake wave resonantly. The simulation results show that the number of injected electrons is bigger than that of the single pulse case and the beam energy is higher as well. In addition, increase of the transverse amplitude is noticed in the wake wave after the second laser pulse. This shows that the transverse motion of the wake wave enhances the wave breaking for strong injection and acceleration of electron beams.

  7. Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser

    Science.gov (United States)

    Li, Chao-yu; Dong, Jun

    2016-08-01

    The incident pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG composite crystal passively Q-switched microchip laser has been investigated experimentally and theoretically by moving the Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction. Highest pulse energy of 0.4 mJ has been generated when the Nd:YAG/Cr4+:YAG composite crystal is moved about 6 mm away from the focused pump beam waist. Laser pulses with pulse width of 1.7 ns and peak power of over 235 kW have been achieved. The theoretically calculated effective laser beam area at different positions of Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction is in good agreement with the experimental results. The highest peak power can be generated by adjusting the pump beam waist incident on the Nd:YAG/Cr4+:YAG composite crystal to optimize the effective laser beam area in passively Q-switched microchip laser.

  8. Superposition of orbital angular momentum of photons by a combined computer-generated hologram fabricated in silica glass with femtosecond laser pulses

    Institute of Scientific and Technical Information of China (English)

    Guo Zhong-Yi; Qu Shi-Liang; Sun Zheng-He; Liu Shu-Tian

    2008-01-01

    This paper introduces a novel method to realize the superposition of orbital angular momentum of photons by combined computer-generated hologram (CCGH) fabricated in silica glass with femtosecond laser pulses.Firstly,the two computer-generated holograms (CGH) of optical vortex were obtained and combined as a CCGH according to the design.Then the CCGH was directly written inside glass by femtosecond laser pulses induced microexplosion without any pre-or post-treatment of the material.The vortex beams with different vortex topological charges (including new topological charges) have been restructured using a collimated He-Ne laser beam incidence to the CCGH normally.A theoretical and experimental explanation has been presented for the generations of the new topological charges.

  9. Implementation of a SVWP-based laser beam shaping technique for generation of 100-mJ-level picosecond pulses.

    Science.gov (United States)

    Adamonis, J; Aleknavičius, A; Michailovas, K; Balickas, S; Petrauskienė, V; Gertus, T; Michailovas, A

    2016-10-01

    We present implementation of the energy-efficient and flexible laser beam shaping technique in a high-power and high-energy laser amplifier system. The beam shaping is based on a spatially variable wave plate (SVWP) fabricated by femtosecond laser nanostructuring of glass. We reshaped the initially Gaussian beam into a super-Gaussian (SG) of the 12th order with efficiency of about 50%. The 12th order of the SG beam provided the best compromise between large fill factor, low diffraction on the edges of the active media, and moderate intensity distribution modification during free-space propagation. We obtained 150 mJ pulses of 532 nm radiation. High-energy, pulse duration of 85 ps and the nearly flat-top spatial profile of the beam make it ideal for pumping optical parametric chirped pulse amplification systems.

  10. Generation of bound states of pulses in a soliton laser with complex relaxation of a saturable absorber

    Energy Technology Data Exchange (ETDEWEB)

    Zolotovskii, I O; Korobko, D A; Okhotnikov, O G [Ulyanovsk State University, Ulyanovsk (Russian Federation); Gumenyuk, R V [Optoelectronics Research Center, Tampere University of Technology, Tampere (Finland)

    2015-01-31

    A numerical model of a soliton fibre laser with a semiconductor saturable absorber mirror (SESAM), characterised by the complex dynamics of absorption relaxation, is considered. It is shown that stationary bound states of pulses can be formed in this laser as a result of their interaction via the dispersion-wave field. The stability of stationary bound states of several pulses is analysed. It is shown that an increase in the number of pulses in a stationary bound state leads eventually to its decay and formation of a random bunch. It is found that the bunch stability is caused by the manifestation of nonlinear self-phase modulation, which attracts pulses to the bunch centre. The simulation results are in qualitative agreement with experimental data. (nonlinear optical phenomena)

  11. Pulsed Artificial Electrojet Generation

    Science.gov (United States)

    Papadopoulos, K.

    2008-12-01

    Traditional techniques for generating low frequency signals in the ULF/ELF range (.1-100 Hz) and rely on ground based Horizontal Electric Dipole (HED) antennas. It is, furthermore, well known that a Vertical Electric Dipole (VED) is by more than 50 dB more efficient than a HED with the same dipole current moment. However, the prohibitively long length of VED antennas in the ELF/ULF range coupled with voltage limitations due to corona discharge in the atmosphere make them totally impracticable. In this paper we discuss a novel concept, inspired by the physics of the equatorial electrojet, that allows for the conversion of a ground based HED to a VED in the E-region of the equatorial ionosphere with current moment comparable to the driving HED. The paper focuses in locations near the dip-equator, where the earth's magnetic is in predominantly in the horizontal direction. The horizontal electric field associated with a pulsed HED drives a large Hall current in the ionospheric E-region, resulting in a vertical current. It is shown that the pulsed vertical current in the altitude range 80-130 km, driven by a horizontal electric field of, approximately, .1 mV/m at 100 km altitude, is of the order of kA. This results in a pulsed VED larger than 106 A-m. Such a pulsed VED will drive ELF/ULF pulses with amplitude in excess of .1 nT at a lateral range larger than few hundred kilometers. This is by three orders of magnitude larger than the one expected by a HED with comparable current moment. The paper will conclude with the description of a sneak-through technique that allows for creating pulsed electric fields in the ionosphere much larger than expected from steady state oscillatory HED antennas.

  12. Up to 400 GHz burst-mode pulse generation from a hybrid harmonic mode-locked Er-doped fibre laser

    Science.gov (United States)

    Wang, Sheng-Min; Lai, Yinchieh

    2017-02-01

    By inserting a birefringence filter with FSR  =  100 GHz inside a hybrid mode-locked Er-doped fibre laser, we successfully generate ps to sub-ps optical burst pulses with the intra-burst pulse rate up to 400 GHz. Multiplication of the intra-burst pulse rate is attributed to a new effect analogous to rational harmonic mode-locking, which occurs due to the relative alignment of the cavity harmonic frequencies, the external phase modulation induced frequencies, and the filter-selected frequencies.

  13. 40 Gb/s Pulse Generation Using Gain Switching of a Commercially Available Laser Module

    DEFF Research Database (Denmark)

    Nørregaard, Jesper; Hanberg, Jesper; Franck, Thorkild

    1999-01-01

    to ease RF connection. The laser die is connected to a gold plated AlN microwave substrate that also acts as a heat spreader. The microwave substrate contains an impedance matching resistor for the RF signal as well as a bias-T for the DC bias. 50 ohm Flexguide technology is used for the interconnection...

  14. Transverse Dynamics and Energy Tuning of Fast Electrons Generated in Sub-Relativistic Intensity Laser Pulse Interaction with Plasmas

    CERN Document Server

    Mori, M; Daito, I; Kotaki, H; Hayashi, Y; Yamazaki, A; Ogura, K; Sagisaka, A; Koga, J; Nakajima, K; Daido, H; Bulanov, S V; Kimura, T

    2006-01-01

    The regimes of quasi-mono-energetic electron beam generation were experimentally studied in the sub-relativistic intensity laser plasma interaction. The observed electron acceleration regime is unfolded with two-dimensional-particle-in-cell simulations of laser-wakefield generation in the self-modulation regime.

  15. Laser system using ultra-short laser pulses

    Science.gov (United States)

    Dantus, Marcos; Lozovoy, Vadim V.; Comstock, Matthew

    2009-10-27

    A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

  16. High-efficiency generation of pulsed Lyman-α radiation by resonant laser wave mixing in low pressure Kr-Ar mixture.

    Science.gov (United States)

    Saito, Norihito; Oishi, Yu; Miyazaki, Koji; Okamura, Kotaro; Nakamura, Jumpei; Louchev, Oleg A; Iwasaki, Masahiko; Wada, Satoshi

    2016-04-04

    We report an experimental generation of ns pulsed 121.568 nm Lyman-α radiation by the resonant nonlinear four-wave mixing of 212.556 nm and 845.015 nm radiation pulses providing a high conversion efficiency 1.7x10-3 with the output pulse energy 3.6 μJ achieved using a low pressure Kr-Ar mixture. Theoretical analysis shows that this efficiency is achieved due to the advantage of using (i) the high input laser intensities in combination with (ii) the low gas pressure allowing us to avoid the onset of full-scale discharge in the laser focus. In particular, under our experimental conditions the main mechanism of photoionization caused by the resonant 2-photon 212.556 nm radiation excitation of Kr atoms followed by the 1-photon ionization leads to ≈17% loss of Kr atoms and efficiency loss only by the end of the pulse. The energy of free electrons, generated by 212.556 nm radiation via (2 + 1)-photon ionization and accelerated mainly by 845.015 nm radiation, remains during the pulse below the level sufficient for the onset of full-scale discharge by the electron avalanche. Our analysis also suggests that ≈30-fold increase of 845.015 nm pulse energy can allow one to scale up the L-α radiation pulse energy towards the level of ≈100 μJ.

  17. High-power pulsed lasers

    Energy Technology Data Exchange (ETDEWEB)

    Holzrichter, J.F.

    1980-04-02

    The ideas that led to the successful construction and operation of large multibeam fusion lasers at the Lawrence Livermore Laboratory are reviewed. These lasers are based on the use of Nd:glass laser materials. However, most of the concepts are applicable to any laser being designed for fusion experimentation. This report is a summary of lectures given by the author at the 20th Scottish University Summer School in Physics, on Laser Plasma Interaction. This report includes basic concepts of the laser plasma system, a discussion of lasers that are useful for short-pulse, high-power operation, laser design constraints, optical diagnostics, and system organization.

  18. Laser-generated micro- and nanoeffects: inactivation of proteins coupled to gold nanoparticles with nano- and picosecond pulses

    Science.gov (United States)

    Radt, Benno; Serbin, Jesper; Lange, Bjoern I.; Birngruber, Reginald; Huettmann, Gereon

    2001-10-01

    Background: Protein denaturation in the fs-ns time regime is of fundamental interest for high precision applications in laser tissue interaction. Conjugates of colloidal gold coupled to proteins are presented as a model system for investigating ultrafast protein denaturation. It is expected that irradiation of such conjugates in tissue using pico- up to nanosecond laser pulses could result in effects with a spatial confinement in the regime of single macromolecules up to organelles. Materials and Methods: Experiments were done with bovine intestinal alkaline phosphatase (aP) coupled to 15 nm colloidal Gold. This complex was irradiated at 527 nm/ 532 nm with a variable number of pico- and nanosecond pulses. The radiant exposure per pulse was varied from 2 to 50 mJ/cm2 in the case of the picosecond pulses and 10 to 500 mJ/cm2 in the case of the nanosecond pulses. Denaturation was detected as a loss of protein function with the help of the uorescence substrate 4MUP. Results and Discussion: Irradiation did result in a steady decrease of the aP activity with increasing radiant exposures and increasing number of pulses. Inactivations up to 80% using 35 ps pulses at 527 nm with 50 mJ/cm2 and a complete inactivation induced by 16 ns pulses at 450 mJ/cm2 are discussed. The induced temperature in the particles and the surrounding water was calculated using Mie's formulas for the absorption of the nanometer gold particles and an analytical solution of the equations for heat diffusion. The calculated temperatures suggest that picosecond pulses heat a molecular scaled area whereas nanosecond pulses could be used for targeting larger cellular compartiments. It is difficult to identify one of the possible damage mechanisms, i.e. thermal denaturation or formation of micro bubbles, from the dependance of the inactivation on pulse energy and number of applied pulses. Therefore experiments are needed to further elucidate the damage mechanisms. The observed inactivation dependencies

  19. Generation of heavy ion beams using high-intensity short pulse lasers

    Science.gov (United States)

    Petrov, George; McGuffey, Chris; Thomas, Alec; Krushelnick, Karl; Beg, Farhat

    2016-10-01

    A theoretical study of ion acceleration from high-Z material irradiated by intense sub-picosecond lasers is presented. The underlying physics of beam formation and acceleration is similar for light and heavy ions, however, nuances of the acceleration process make the heavy ions more challenging. At least four technical hurdles have been identified: low charge-to-mass ratio, limited number of ions amenable to acceleration, delayed acceleration and poor energy coupling due to high reflectivity of the plasma. Using two dimensional particle-in-cell (PIC) simulations, we observed transitions from Radiation Pressure Acceleration (RPA) to the Breakout Afterburner regime (BoA) and to Target Normal Sheath Acceleration (TNSA) akin to light ions. The numerical simulations predict gold ions beams with high directionality (high fluxes (>1011 ions/sr) and energy (>10 MeV/nucleon) from laser systems delivering >20 J of energy on target.

  20. 1.5 GHz picosecond pulse generation from a monolithic waveguide laser with a graphene-film saturable output coupler.

    Science.gov (United States)

    Mary, Rose; Brown, Graeme; Beecher, Stephen J; Torrisi, Felice; Milana, Silvia; Popa, Daniel; Hasan, Tawfique; Sun, Zhipei; Lidorikis, Elefterios; Ohara, Seiki; Ferrari, Andrea C; Kar, Ajoy K

    2013-04-08

    We fabricate a saturable absorber mirror by coating a graphene- film on an output coupler mirror. This is then used to obtain Q-switched mode-locking from a diode-pumped linear cavity channel waveguide laser inscribed in Ytterbium-doped Bismuthate Glass. The laser produces 1.06 ps pulses at ~1039 nm, with a 1.5 GHz repetition rate, 48% slope efficiency and 202 mW average output power. This performance is due to the combination of the graphene saturable absorber and the high quality optical waveguides in the laser glass.

  1. Axial Impulse Generation of Lightcraft Engines with ˜ 1 μs Pulsed TEA CO2 Laser

    Science.gov (United States)

    Kenoyer, D. A.; Salvador, I. I.; Myrabo, L. N.

    2011-11-01

    A twin Lumonics K922M pulsed TEA CO2 laser system (˜50 ns FWHM spike, with selectable 1.5 or 2.5 μs tail—depending upon laser gas mixture) was employed to experimentally measure the axial impulse behavior of a family of lightcraft engine geometries, using a lightweight ballistic pendulum. Axial impulse performance in both airbreathing and solid ablative rocket (SAR) modes was examined as a function of: a) laser pulse energy (˜12 to 40 Joules); b) pulse duration (˜50 ns spike with 1.5 or 2.5 μs tail); and, c) engine geometry. The four engines under investigation were the Lightcraft Types ♯150, ♯200 and ♯250, and a 11 cm parabolic bell. Lightcraft ♯200 axial CM performance reached 250 N/MW, which is sharply higher than the 120 N/MW previously reported for the engine using long pulse (e.g., 10-18 μs) CO2 electric discharge lasers.

  2. The generation of femtosecond light pulses from a laser with combined mode locking with new saturable absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Bondarev, B.V.; Prokhorenko, V.I.; Rodionov, G.D.; Sorokin, V.B.; Slominskii, IU.L.

    1989-01-01

    Combined mode locking was studied experimentally using new 3492-y and 3490-y dyes. In a linear single-stream R6G laser, the 3490-y dye provides for stable mode locking throughout the 576-615 nm tuning range. The pulse duration varies over the tuning range from 180-250 fs, the lasing efficiency amounting to 17 percent. 10 refs.

  3. Noncollinear parametric generation in LiIO(3) and beta-barium borate by frequency-doubled femtosecond Ti:sapphire laser pulses.

    Science.gov (United States)

    Krylov, V; Kalintsev, A; Rebane, A; Erni, D; Wild, U P

    1995-01-15

    In LiIO(3) and BBO crystals the wave-matching conditions for femtosecond noncollinear parametric light generation at lambda = 390 nm pumping wavelength are investigated. In the LiIO(3) crystal simultaneous phase- and group-velocity-matching angles are determined. Parametric generation occurred at 0.45-2.9-mu;m wavelengths by pumping with the second harmonic of 150-fs Ti:sapphire laser pulses and is in qualitative agreement with calculated directions in both crystals.

  4. Optical pulses, lasers, measuring techniques

    CERN Document Server

    Früngel, Frank B A

    1965-01-01

    High Speed Pulse Technology: Volume II: Optical Pulses - Lasers - Measuring Techniques focuses on the theoretical and engineering problems that result from the capacitor discharge technique.This book is organized into three main topics: light flash production from a capacitive energy storage; signal transmission and ranging systems by capacitor discharges and lasers; and impulse measuring technique. This text specifically discusses the air spark under atmospheric conditions, industrial equipment for laser flashing, and claims for light transmitting system. The application of light impulse sign

  5. Molecular wakes for ultrashort laser pulses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The molecular wake-assisted interaction between two collinear femotosecond laser pulses is investigated in air,which leads to the generation of a controllable 1.8 mJ super-continuum pulse with an elongated self-guided channel due to the cross-phase modulation of the impulsively aligned diatomic molecules in air. For two parallel launched femtosecond laser pulses with a certain spatial separation,controllable attraction and repulsion of the pulses are observed due to the counter-balance among molecular wakes,Kerr and plasma effects,where the molecular wakes show a longer interaction distance than the others to control the propagation of the intense ultrashort laser pulses.

  6. Pulse power for lasers II; Proceedings of the Meeting, Los Angeles, CA, Jan. 19, 20, 1989

    Science.gov (United States)

    Burkes, Tom R.; McDuff, Glen

    Various papers on pulse power for lasers are presented. Individual topics addressed include: preionization techniques for discharge lasers, X-ray preionization technology for high-pressure gas-discharge lasers, weight and volume scaling of pulse power for laser systems, method for rapidly terminating the current pulses applied to recombination lasers, high dV/dt spiker pulse generation using magnetic pulse sharpening techniques, multigap thyratrons for future laser applications, high-power thyratron-type switch for laser applications, model for the optically triggered pseudospark thyratron using local field and beam-bulk methods, capacitors for repetitively pulsed laser, fast pulse transformers in laser pulse power circuits, pulsed power topologies for laser applications, pulse power for the CHIRP XeCl laser, line type pulser for gas laser pumping, engineering aspects of long-pulse CO2 lasers using plasma discharge electrodes, high-pressure pulsed radial glow discharge CO2 laser.

  7. Supercontinuum Generation with Output Power of 1.7 W Pumped by a Picosecond Laser Pulse

    Science.gov (United States)

    Pan, Er-Ming; Ruan, Shuang-Chen; Guo, Chun-Yu; Wang, Yun-Cai; Wei, Hui-Feng

    2010-10-01

    By using a photonic crystal fiber, a supercontinuum source with output power up to 1.7W, pumped by a passively mode-locked diode-pumped Nd:YVO4 picosecond laser is obtained. A spectral width of the supercontinuum is 1700 nm (500-2200 nm) with the 5 dB spectral width approximately 1000 nm (1200-2200 nm). This high power wide band supercontinuum source meets the demand of many applications such as optical coherence tomography, frequency metrology and wavelength-division-multiplexing systems. The evolution of the supercontinuum with the increasing pump power is presented and analyzed.

  8. High Repetition-Rate Wakefield Electron Source Generated by Few-millijoule, 30 femtosecond Laser Pulses on a Density Downramp

    CERN Document Server

    He, Z -H; Easter, J H; Krushelnick, K; Nees, J A; Thomas, A G R

    2012-01-01

    We report on an experimental demonstration of laser wakefield electron acceleration using a sub-TW power laser by tightly focusing 30-fs laser pulses with only 8 mJ pulse energy on a 100 \\mu m scale gas target. The experiments are carried out at an unprecedented 0.5 kHz repetition rate, allowing "real time" optimization of accelerator parameters. Well-collimated and stable electron beams with a quasi-monoenergetic peak in excess of 100 keV are measured. Particle-in-cell simulations show excellent agreement with the experimental results and suggest an acceleration mechanism based on electron trapping on the density downramp, due to the time varying phase velocity of the plasma waves.

  9. Generation of Helical and Axial Magnetic Fields by the Relativistic Laser Pulses in Under-dense Plasma: Three-Dimensional Particle-in-Cell Simulation

    Science.gov (United States)

    Zheng, Chun-Yang; Zhu, Shao-Ping; He, Xian-Tu

    2002-07-01

    The quasi-static magnetic fields created in the interaction of relativistic laser pulses with under-dense plasmas have been investigated by three-dimensional particle-in-cell simulation. The relativistic ponderomotive force can drive an intense electron current in the laser propagation direction, which is responsible for the generation of a helical magnetic field. The axial magnetic field results from a difference beat of wave-wave, which drives a solenoidal current. In particular, the physical significance of the kinetic model for the generation of the axial magnetic field is discussed.

  10. Generation of Helical and Axial Magnetic Fields by the Relativistic Laser Pulses in Under-dense Plasma: Three-Dimensional Particle-in-Cell Simulation

    Institute of Scientific and Technical Information of China (English)

    郑春阳; 朱少平; 贺贤土

    2002-01-01

    The quasi-static magnetic fields created in the interaction of relativistic laser pulses with under-dense plasmashave been investigated by three-dimensional particle-in-cell simulation. The relativistic ponderomotive force candrive an intense electron current in the laser propagation direction, which is responsible for the generation ofa helical magnetic field. The axial magnetic field results from a difference beat of wave-wave, which drives asolenoidal current. In particular, the physical significance of the kinetic model for the generation of the axialmagnetic field is discussed.

  11. Laser pulse shaping for high gradient accelerators

    Science.gov (United States)

    Villa, F.; Anania, M. P.; Bellaveglia, M.; Bisesto, F.; Chiadroni, E.; Cianchi, A.; Curcio, A.; Galletti, M.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Gatti, G.; Moreno, M.; Petrarca, M.; Pompili, R.; Vaccarezza, C.

    2016-09-01

    In many high gradient accelerator schemes, i.e. with plasma or dielectric wakefield induced by particles, many electron pulses are required to drive the acceleration of one of them. Those electron bunches, that generally should have very short duration and low emittance, can be generated in photoinjectors driven by a train of laser pulses coming inside the same RF bucket. We present the system used to shape and characterize the laser pulses used in multibunch operations at Sparc_lab. Our system gives us control over the main parameter useful to produce a train of up to five high brightness bunches with tailored intensity and time distribution.

  12. Laser pulse shaping for high gradient accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Villa, F., E-mail: fabio.villa@lnf.infn.it [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Anania, M.P.; Bellaveglia, M. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Bisesto, F. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Università La Sapienza di Roma, Via A. Scarpa 14, Rome (Italy); Chiadroni, E. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Cianchi, A. [INFN-Roma Tor Vergata and Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Curcio, A.; Galletti, M.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Gatti, G. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Moreno, M.; Petrarca, M. [Università La Sapienza di Roma, Via A. Scarpa 14, Rome (Italy); Pompili, R.; Vaccarezza, C. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy)

    2016-09-01

    In many high gradient accelerator schemes, i.e. with plasma or dielectric wakefield induced by particles, many electron pulses are required to drive the acceleration of one of them. Those electron bunches, that generally should have very short duration and low emittance, can be generated in photoinjectors driven by a train of laser pulses coming inside the same RF bucket. We present the system used to shape and characterize the laser pulses used in multibunch operations at Sparc-lab. Our system gives us control over the main parameter useful to produce a train of up to five high brightness bunches with tailored intensity and time distribution.

  13. Generation of ultra-intense and ultra-short laser pulses with high temporal contrast; Generation d'impulsions laser ultra-breves et ultra-intenses a contraste temporel eleve

    Energy Technology Data Exchange (ETDEWEB)

    Julien, A

    2006-03-15

    The topic of this thesis work concerns the design and the characterization of an efficient device devoted to the temporal contrast improvement for ultra-intense femtosecond laser pulses. The contrast is defined as the intensity ratio between the main femtosecond pulse and its nanosecond pedestal. This pedestal is the amplified spontaneous emission (ASE), inherent with laser amplification mechanism. The ASE background has dramatic effects for laser-matter interactions on a solid target. The presented work consists in the theoretical and experimental study of a temporal filter based on a third order nonlinear effect acting on the pulse polarization. We have studied several kinds of nonlinear filters. The selected device is based on the process of cross-polarized wave generation (XPW) in crystals with an anisotropic third-order nonlinear susceptibility. This nonlinear filter has been experimented on various femtosecond systems. It allows a contrast improvement of several orders of magnitude, as demonstrated by temporal profiles measurements on a large intensity dynamic. A device to improve the nonlinear process conversion efficiency, it means the filter transmission, has also been achieved. This method is based on constructive interferences between XPW signals generated in different crystals. This setup has made it possible to reach experimentally the maximum theoretical efficiency ( >20%) and in the same time ensures the system stability. At least, we have demonstrated that the filter preserves, or even improves, spectral and spatial qualities of the laser pulse. These results are thus particularly promising and allow contemplating the implementation of the filter in current femtosecond systems. (author)

  14. Time dependent Doppler shifts in high-order harmonic generation in intense laser interactions with solid density plasma and frequency chirped pulses

    Energy Technology Data Exchange (ETDEWEB)

    Welch, E. C.; Zhang, P.; He, Z.-H. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Dollar, F. [JILA, University of Colorado, Boulder, Colorado 80309 (United States); Krushelnick, K.; Thomas, A. G. R., E-mail: agrt@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States)

    2015-05-15

    High order harmonic generation from solid targets is a compelling route to generating intense attosecond or even zeptosecond pulses. However, the effects of ion motion on the generation of harmonics have only recently started to be considered. Here, we study the effects of ion motion in harmonics production at ultrahigh laser intensities interacting with solid density plasma. Using particle-in-cell simulations, we find that there is an optimum density for harmonic production that depends on laser intensity, which scales linearly with a{sub 0} with no ion motion but with a reduced scaling if ion motion is included. We derive a scaling for this optimum density with ion motion and also find that the background ion motion induces Doppler red-shifts in the harmonic structures of the reflected pulse. The temporal structure of the Doppler shifts is correlated to the envelope of the incident laser pulse. We demonstrate that by introducing a frequency chirp in the incident pulse we are able to eliminate these Doppler shifts almost completely.

  15. Interaction of femtosecond laser pulses with metal photocathode

    Institute of Scientific and Technical Information of China (English)

    Liu Yun-Quan; Zhang Jie; Liang Wen-Xi

    2005-01-01

    The features of interaction of femtosecond laser pulses with photocathode are studied theoretically in this paper.The surface temperature of the metal cathode film while femtosecond laser pulses irradiation is studied with twotemperature model. With a simple photoelectric model we obtain the optimum metal film thickness for the backilluminated photocathode. The generated ultrashort photocurrent pulses are strongly dependent on the temperature of the electron gas and the lattice during the femtosecond laser pulse irradiation on the photocathode.

  16. Pulse-Width Jitter Measurement for Laser Diode Pulses

    Institute of Scientific and Technical Information of China (English)

    TANG Jun-Hua; WANG Yun-Cai

    2006-01-01

    @@ Theoretical analysis and experimental measurement of pulse-width jitter of diode laser pulses are presented. The expression of pulse power spectra with all amplitude jitter, timing jitter and pulse-width jitter is deduced.

  17. Generation of near transform-limited ultrashort laser pulses in kilohertz chirped-pulse amplification system by compensating high order phase distortions

    Institute of Scientific and Technical Information of China (English)

    Yongliang Jiang; Bing Zhou; Yuxin Leng; Xiaowei Chen; Ruxin Li; Zhizhan Xu

    2006-01-01

    The effects of gain narrowing and high order dispersions on the pulse duration in our kilohertz chirpedpulse amplification system have been compensated experimentally. Using an acousto-optic programmable dispersive filter (AOPDF), the spectral full-width at half-maximum (FWHM) is expanded from 30 to50 nm. Stable laser pulses with the duration of 30 fs (FWHM), which is 1.07 times Fourier-transformlimitation, have been acquired by pre-compensating the high order phase distortions using the phase measured by spectral phase interferometry for direct electric-field reconstruction (SPIDER).

  18. High-order harmonic generation driven by chirped laser pulses induced by linear and non linear phenomena

    CERN Document Server

    Neyra, E; Pérez-Hernández, J A; Ciappina, M F; Roso, L; Torchia, G A

    2016-01-01

    We present a theoretical study of high-order harmonic generation (HHG) driven by ultrashort optical pulses with different kind of chirps. The goal of the present work is perform a detailed study to clarify the relevant parameters in the chirped pulses to achieve a noticeable cut-off extensions in HHG. These chirped pulses are generated using both linear and nonlinear dispersive media.The description of the origin of the physical mechanisms responsible of this extension is, however, not usually reported with enough detail in the literature. The study of the behaviour of the harmonic cut-off with these kind of pulses is carried out in the classical context, by the integration of the Newton-Lorentz equation complemented with the quantum approach, based on the integration of the time dependent Schr\\"odinger equation in full dimensions (TDSE-3D), we are able to understand the underlying physics.

  19. Gigahertz repetition rate, sub-femtosecond timing jitter optical pulse train directly generated from a mode-locked Yb:KYW laser

    CERN Document Server

    Yang, Heewon; Shin, Junho; Kim, Chur; Choi, Sun Young; Kim, Guang-Hoon; Rotermund, Fabian; Kim, Jungwon

    2014-01-01

    We show that a 1.13-GHz repetition rate optical pulse train with 0.70 fs high-frequency timing jitter (integration bandwidth of 17.5 kHz - 10 MHz, where the measurement instrument-limited noise floor contributes 0.41 fs in 10 MHz bandwidth) can be directly generated from a free-running, single-mode diode-pumped Yb:KYW laser mode-locked by single-walled carbon nanotube (SWCNT)-coated mirrors. To our knowledge, this is the lowest timing jitter optical pulse train with the GHz repetition rate ever measured. If this pulse train is used for direct sampling of 565-MHz signals (Nyquist frequency of the pulse train), the demonstrated jitter level corresponds to the projected effective-number-of-bit (ENOB) of 17.8, which is much higher than the thermal noise limit of 50-ohm load resistance (~14 bits).

  20. Half-percent terahertz generation efficiency from cryogenically cooled lithium niobate pumped by Ti:sapphire laser pulses

    CERN Document Server

    Wu, Xiaojun; Huang, Wenqian Ronny; Zhou, Chun; Zalden, Peter; Rossi, Giulio M; Cirmi, Giovanni; Muecke, Oliver D; Kaertner, Franz X

    2016-01-01

    We obtained an optical-to-terahertz (THz) energy conversion efficiency of 0.5% using the tilted-pulse-front technique in lithium niobate at a cryogenically cooled temperature of 100 K pumped by amplified Ti:sapphire laser pulses with ~150 fs pulse duration at 800 nm wavelength. Compared with the optimized conversion efficiency of 0.18% achieved at room temperature, we achieved more than 2.5 times enhancement in conversion efficiency upon cryogenically cooling the crystal due to reduction of THz absorption. Further improvements to the conversion efficiency can be made by optimizing the out-coupling of the THz radiation, transportation of pump energy and by further decreasing the THz absorption in the lithium niobate crystal.

  1. Optodynamic analysis of pulsed-laser processing with a Nd:YAG laser

    OpenAIRE

    Strgar, Simon; Možina, Janez

    2015-01-01

    Laser drilling and laser marking of metals with a pulsed Nd:YAG laser are discussed. Some characteristics of pulsed-laser processing and the possibilities of process optodynamic analysis are presented for the laser-drilling of aluminium. The optodynamic analysis is based on observation of generated shock waves, which propagate in the material as well as in the surrounding air during laser processing. For the detection of laser-induced shock waves in the air and for measurements of their chara...

  2. Generation of heavy ion beams using femtosecond laser pulses in the target normal sheath acceleration and radiation pressure acceleration regimes

    Science.gov (United States)

    Petrov, G. M.; McGuffey, C.; Thomas, A. G. R.; Krushelnick, K.; Beg, F. N.

    2016-06-01

    Theoretical study of heavy ion acceleration from sub-micron gold foils irradiated by a short pulse laser is presented. Using two dimensional particle-in-cell simulations, the time history of the laser pulse is examined in order to get insight into the laser energy deposition and ion acceleration process. For laser pulses with intensity 3 × 10 21 W / cm 2 , duration 32 fs, focal spot size 5 μm, and energy 27 J, the calculated reflection, transmission, and coupling coefficients from a 20 nm foil are 80%, 5%, and 15%, respectively. The conversion efficiency into gold ions is 8%. Two highly collimated counter-propagating ion beams have been identified. The forward accelerated gold ions have average and maximum charge-to-mass ratio of 0.25 and 0.3, respectively, maximum normalized energy 25 MeV/nucleon, and flux 2 × 10 11 ions / sr . An analytical model was used to determine a range of foil thicknesses suitable for acceleration of gold ions in the radiation pressure acceleration regime and the onset of the target normal sheath acceleration regime. The numerical simulations and analytical model point to at least four technical challenges hindering the heavy ion acceleration: low charge-to-mass ratio, limited number of ions amenable to acceleration, delayed acceleration, and high reflectivity of the plasma. Finally, a regime suitable for heavy ion acceleration has been identified in an alternative approach by analyzing the energy absorption and distribution among participating species and scaling of conversion efficiency, maximum energy, and flux with laser intensity.

  3. Compact, simple and robust cross polarized wave generation source of few-cycle, high-contrast pulses for seeding petawatt-class laser systems

    OpenAIRE

    Ramirez, Patricia; Papadopoulos, Dimitris N.; Hanna, Marc; Pellegrina, Alain; Friebel, Florence; Georges, Patrick; Druon, Frédéric

    2013-01-01

    International audience; A compact and robust, dual-crystal cross polarized wave generation setup combined with a hollow waveguide filter is implemented to deliver few-cycle, high-contrast laser pulses sourced from a commercial multipass Ti:Sa amplifier. The initial 25-fs pulses with a temporal contrast of 108 are shortened to 10 fs with an improved contrast of at least 10^10. The single nonlinear stage for spectral broadening and contrast enhancement of a commercial amplifier serves as an ide...

  4. Modulated Pulse Generations in a Laser-diode-pumped Passively Q-switched Intracavity-frequency-doubling Nd∶YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    郑加安; 赵圣之; 陈磊

    2002-01-01

    The investigative results of modulated pulse output from an LD end-pumped passively Q-switched intracavity-frequency-doubling Nd∶YVO4/KTP laser with Cr4+∶YAG saturable absorber are presented. The numerical stimulations of these modulated pulses are carried out basing on the rate equations. It indicated that the modulations are attribute to the frequency beating of two eigenstates of the resonant polarized modes. The theoretical calculations are in good agreement with the experimental observations.

  5. Convection roll-driven generation of supra-wavelength periodic surface structures on dielectrics upon irradiation with femtosecond pulsed lasers

    Science.gov (United States)

    Tsibidis, George D.; Skoulas, Evangelos; Papadopoulos, Antonis; Stratakis, Emmanuel

    2016-08-01

    The significance of the magnitude of the Prandtl number of a fluid in the propagation direction of induced convection rolls is elucidated. Specifically, we report on the physical mechanism to account for the formation and orientation of previously unexplored supra-wavelength periodic surface structures in dielectrics, following melting and subsequent capillary effects induced upon irradiation with ultrashort laser pulses. Counterintuitively, it is found that such structures exhibit periodicities, which are markedly, even multiple times, higher than the laser excitation wavelength. It turns out that the extent to which the hydrothermal waves relax depends upon the laser beam energy, produced electron densities upon excitation with femtosecond pulsed lasers, the magnitude of the induced initial local roll disturbances, and the magnitude of the Prandtl number with direct consequences on the orientation and size of the induced structures. It is envisaged that this elucidation may be useful for the interpretation of similar, albeit large-scale periodic or quasiperiodic structures formed in other natural systems due to thermal gradients, while it can also be of great importance for potential applications in biomimetics.

  6. Solid-state Q-switch laser generating pulsed Bessel beam%全固态调Q激光器产生脉冲Bessel光束

    Institute of Scientific and Technical Information of China (English)

    王涛; 杜团结; 庄凤江; 吴逢铁

    2014-01-01

    使用连续式输出的砷化镓半导体激光器泵浦的掺钕钒酸钇激光器作为光源,被动式通过轴棱锥产生Bessel光束。在激光谐振腔内加入Cr4+:YAG晶体调Q产生脉冲Bessel光束。理论模拟了1064 nm波长光束经过轴棱锥之后的三维传播图和截面光强分布。通过实验得到了1064 nm波长脉冲Bessel光束的脉冲宽度和脉冲重复率,并计算得到了单脉冲Bessel光束的能量和峰值功率。利用光束分析仪记录了1064 nm波长Bessel光束的截面光强分布,并测量了中心光斑的直径,得到的数据与理论计算基本吻合。%The laser diode pumped Nd:YVO4 laser was used as light source, Bessel beam was generated by passively passing through axicon. The pulsed Bessel beam was generated by putting the Cr4+:YAG in the laser resonator. The propagation and cross- section distribution of 1 064 nm Bessel beam were simulated. In experiment, the pulse width and pulse repetition rate of 1 064 nm pulse Bessel beam were obtained, the energy and the peak power of pulsed Bessel beam were calculated. The cross- section intensity distribution of Bessel beam was recorded by the laser beam analysis and the diameter of centre spot was measured. The experimental results agrees well with the simulation.

  7. Mechanism of equivalent electric dipole oscillation for high-order harmonic generation from grating-structured solid-surface by femtosecond laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yang; Song, Hai-Ying; Liu, H.Y.; Liu, Shi-Bing, E-mail: sbliu@bjut.edu.cn

    2017-07-12

    Highlights: • Proposed a valid mechanism of high harmonic generation by laser grating target interaction: oscillation of equivalent electric dipole (OEED). • Found that there also exist harmonic emission at large emission angle but not just near-surface direction as the former researches had pointed out. • Show the process of the formation and motion of electron bunches at the grating-target surface irradiating with femtosecond laser pulse. - Abstract: We theoretically study high-order harmonic generation (HHG) from relativistically driven overdense plasma targets with rectangularly grating-structured surfaces by femtosecond laser pulses. Our particle-in-cell (PIC) simulations show that, under the conditions of low laser intensity and plasma density, the harmonics emit principally along small angles deviating from the target surface. Further investigation of the surface electron dynamics reveals that the electron bunches are formed by the interaction between the laser field and the target surface, giving rise to the oscillation of equivalent electric-dipole (OEED), which enhances specific harmonic orders. Our work helps understand the mechanism of harmonic emissions from grating targets and the distinction from the planar harmonic scheme.

  8. Adjusting the properties of the photon generated via an optical parametric oscillator by using a pulse pumped laser

    Institute of Scientific and Technical Information of China (English)

    Chen Song; Shi Bao-Sen; Guo Guang-Can

    2011-01-01

    The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric downconversion almost always utilize continuous wave pump light,but the pulse pumped case is rarely reported. One disadvantage of the continuous wave case is that the photon pair is produced randomly within the coherence time of the pump,which limits its application in the quantum information realm.However,a pulse pump can help to solve this problem.In this paper,we theoretically analyze pulse pumped cavity-enhanced spontaneous parametric downconversion in detail and show how the pump pulse affects the multi-photon interference visibility,two-photon waveform,joint spectrum and spectral brightness.

  9. An investigation of the effects of material anisotropy and heterogeneity on pulsed, laser-generated acoustic signals.

    Science.gov (United States)

    Hurley, D H; Spicer, J B

    1999-01-01

    Point-source and line-source models for the laser ultrasonic source in materials exhibiting transverse isotropy are applied to the specific problem of laser generation and ultrasonic propagation in unidirectional, polymer matrix composite materials. Comparing experiment and theory, it is shown that these composite materials exhibit homogeneous behavior, at the frequencies investigated, for ultrasonic wave propagation perpendicular to the fiber direction. For ultrasonic propagation in the fiber direction, ultrasonic dispersion, resulting from the inhomogeneous nature of the composite, affects the laser ultrasonic signal.

  10. Developing a pulse trigger generator for a three-electrode spark-gap switch in a transversely excited atmospheric CO2 laser

    Science.gov (United States)

    Wang, Jingyuan; Guo, Lihong; Zhang, Xingliang

    2016-04-01

    To improve the probability and stability of breakdown discharge in a three-electrode spark-gap switch for a high-power transversely excited atmospheric CO2 laser and to improve the efficiency of its trigger system, we developed a high-voltage pulse trigger generator based on a two-transistor forward converter topology and a multiple-narrow-pulse trigger method. Our design uses a narrow high-voltage pulse (10 μs) to break down the hyperbaric gas between electrodes of the spark-gap switch; a dry high-voltage transformer is used as a booster; and a sampling and feedback control circuit (mainly consisting of a SG3525 and a CD4098) is designed to monitor the spark-gap switch and control the frequency and the number of output pulses. Our experimental results show that this pulse trigger generator could output high-voltage pulses (number is adjusted) with an amplitude of >38 kV and a width of 10 μs. Compared to a conventional trigger system, our design had a breakdown probability increased by 2.7%, an input power reduced by 1.5 kW, an efficiency increased by 0.12, and a loss reduced by 1.512 kW.

  11. The all-diode-pumped laser system POLARIS——an experimentalist’s tool generating ultra-high contrast pulses with high energy

    Institute of Scientific and Technical Information of China (English)

    Marco; Hornung; Hartmut; Liebetrau; Andreas; Seidel; Sebastian; Keppler; Alexander; Kessler; Jrg; Krner; Marco; Hellwing; Frank; Schorcht; Diethard; Klpfel; Ajay; K.Arunachalam; Georg; A.Becker; Alexander; Svert; Jens; Polz; Joachim; Hein; Malte; C.Kaluza

    2014-01-01

    The development,the underlying technology and the current status of the fully diode-pumped solid-state laser system POLARIS is reviewed.Currently,the POLARIS system delivers 4 J energy,144 fs long laser pulses with an ultra-high temporal contrast of 5 × 1012 for the ASE,which is achieved using a so-called double chirped-pulse amplification scheme and cross-polarized wave generation pulse cleaning.By tightly focusing,the peak intensity exceeds 3.5 × 1020 W cm-2.These parameters predestine POLARIS as a scientific tool well suited for sophisticated experiments,as exemplified by presenting measurements of accelerated proton energies.Recently,an additional amplifier has been added to the laser chain.In the ramp-up phase,pulses from this amplifier are not yet compressed and have not yet reached the anticipated energy.Nevertheless,an output energy of 16.6 J has been achieved so far.

  12. Fast scaling of energetic protons generated in the interaction of linearly polarized femtosecond petawatt laser pulses with ultrathin targets

    Science.gov (United States)

    Kim, I. Jong; Pae, Ki Hong; Kim, Chul Min; Kim, Hyung Taek; Choi, Il Woo; Lee, Chang-Lyoul; Singhal, Himanshu; Sung, Jae Hee; Lee, Seong Ku; Lee, Hwang Woon; Nickles, Peter V.; Jeong, Tae Moon; Nam, Chang Hee

    2015-12-01

    Laser-driven proton/ion acceleration is a rapidly developing research field attractive for both fundamental physics and applications such as hadron therapy, radiography, inertial confinement fusion, and nuclear/particle physics. Laser-driven proton/ion beams, compared to those obtained in conventional accelerators, have outstanding features such as low emittance, small source size, ultra-short duration and huge acceleration gradient of ∼1 MeV μm-1. We report proton acceleration from ultrathin polymer targets irradiated with linearly polarized, 30-fs, 1-PW Ti:sapphire laser pulses. A maximum proton energy of 45 MeV with a broad and modulated profile was obtained when a 10-nm-thick target was irradiated at a laser intensity of 3.3 × 1020 W/cm2. The transition from slow (I1/2) to fast scaling (I) of maximum proton energy with respect to laser intensity I was observed and explained by the hybrid acceleration mechanism including target normal sheath acceleration and radiation pressure acceleration in the acceleration stage and Coulomb-explosion-assisted free expansion in the post acceleration stage.

  13. Third-Harmonic Generated in EH32 Mode of a Gas-Filled Waveguide by fs Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    CHEN Bao-Zhen; HUANG Zu-Qia

    2007-01-01

    In this paper it is reported for the first time that the third harmonic generated in EH32 mode of a gas-filled waveguide by fs pulses has higher generation efficiency. The new finding contrasts with the experiment in [C.G. Durfee Ⅲ, S. Backus, M.M. Murnane, and H.C. Kapteyn, Opt. Lett. 22 (1997) 1565]. Some possible factors, which produce the contradiction, are discussed briefly.

  14. Dynamic parabolic pulse generation using temporal shaping of wavelength to time mapped pulses.

    Science.gov (United States)

    Nguyen, Dat; Piracha, Mohammad Umar; Mandridis, Dimitrios; Delfyett, Peter J

    2011-06-20

    Self-phase modulation in fiber amplifiers can significantly degrade the quality of compressed pulses in chirped pulse amplification systems. Parabolic pulses with linear frequency chirp are suitable for suppressing nonlinearities, and to achieve high peak power pulses after compression. In this paper, we present an active time domain technique to generate parabolic pulses for chirped pulse amplification applications. Pulses from a mode-locked laser are temporally stretched and launched into an amplitude modulator, where the drive voltage is designed using the spectral shape of the input pulse and the transfer function of the modulator, resulting in the generation of parabolic pulses. Experimental results of pulse shaping with a pulse train from a mode-locked laser are presented, with a residual error of less than 5%. Moreover, an extinction ratio of 27 dB is achieved, which is ideal for chirped pulse amplification applications.

  15. Doping management for high-power fiber lasers: 100 W, few-picosecond pulse generation from an all-fiber-integrated amplifier.

    Science.gov (United States)

    Elahi, P; Yılmaz, S; Akçaalan, O; Kalaycıoğlu, H; Oktem, B; Senel, C; Ilday, F Ö; Eken, K

    2012-08-01

    Thermal effects, which limit the average power, can be minimized by using low-doped, longer gain fibers, whereas the presence of nonlinear effects requires use of high-doped, shorter fibers to maximize the peak power. We propose the use of varying doping levels along the gain fiber to circumvent these opposing requirements. By analogy to dispersion management and nonlinearity management, we refer to this scheme as doping management. As a practical first implementation, we report on the development of a fiber laser-amplifier system, the last stage of which has a hybrid gain fiber composed of high-doped and low-doped Yb fibers. The amplifier generates 100 W at 100 MHz with pulse energy of 1 μJ. The seed source is a passively mode-locked fiber oscillator operating in the all-normal-dispersion regime. The amplifier comprises three stages, which are all-fiber-integrated, delivering 13 ps pulses at full power. By optionally placing a grating compressor after the first stage amplifier, chirp of the seed pulses can be controlled, which allows an extra degree of freedom in the interplay between dispersion and self-phase modulation. This way, the laser delivers 4.5 ps pulses with ~200 kW peak power directly from fiber, without using external pulse compression.

  16. Generation of few-cycle terawatt light pulses using optical parametric chirped pulse amplification

    NARCIS (Netherlands)

    Witte, S.; Zinkstok, R.T.; Hogervorst, W.; Eikema, K.S.E.

    2005-01-01

    We demonstrate the generation of 9.8 +/- 0.3 fs laser pulses with a peak power exceeding one terawatt at 30 Hz repetition rate, using optical parametric chirped pulse amplification. The amplifier is pumped by 140 mJ, 60 ps pulses at 532 nm, and amplifies seed pulses from a Ti: Sapphire oscillator to

  17. Pulse shape control in a dual cavity laser: numerical modeling

    Science.gov (United States)

    Yashkir, Yuri

    2006-04-01

    We present a numerical model of the laser system for generating a special shape of the pulse: a steep peak at the beginning followed by a long pulse tail. Laser pulses of this nature are required for various applications (laser material processing, optical breakdown spectroscopy, etc.). The laser system consists of two "overlapped" cavities with different round-trip times. The laser crystal, the Q-switching element, the back mirror, and the output coupler are shared. A shorter pulse is generated in a short cavity. A small fraction of this pulse is injected into the long cavity as a seed. It triggers generation of the longer pulse. The output emission from this hybrid laser produces a required pulse shape. Parameters of the laser pulse (ratios of durations and energies of short- and long- pulse components) can be controlled through cavity length and the output coupler reflection. Modelling of the laser system is based on a set of coupled rate equations for dynamic variables of the system: the inverse population in an active laser media and photon densities in coupled cavities. Numerical experiments were provided with typical parameters of a Nd:YAG laser to study the system behaviour for different combinations of parameters.

  18. Spectral dynamics of THz pulses generated by two-color laser filaments in air: The role of Kerr nonlinearities and pump wavelength

    CERN Document Server

    Nguyen, A; Dechard, J; Thiele, I; Babushkin, I; Skupin, S; Berge, L

    2016-01-01

    We theoretically and numerically study the influence of both instantaneous and Raman-delayed Kerr nonlinearities as well as a long-wavelength pump in the terahertz (THz) emissions produced by two-color femtosecond filaments in air. Although the Raman-delayed nonlinearity induced by air molecules weakens THz generation, four-wave mixing is found to impact the THz spectra accumulated upon propagation via self-, cross-phase modulations and self-steepening. Besides, using the local current theory, we show that the scaling of laser-to-THz conversion efficiency with the fundamental laser wavelength strongly depends on the relative phase between the two colors, the pulse duration and shape, rendering a universal scaling law impossible. Scaling laws in powers of the pump wavelength may only provide a rough estimate of the increase in the THz yield. We confront these results with comprehensive numerical simulations of strongly focused pulses and of filaments propagating over meter-range distances.

  19. Kinetic study on non-thermal volumetric plasma decay in the early afterglow of air discharge generated by a short pulse microwave or laser

    Science.gov (United States)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2016-08-01

    This paper reports a kinetic study on non-thermal plasma decay in the early afterglow of air discharge generated by short pulse microwave or laser. A global self-consistent model is based on the particle balance of complex plasma chemistry, electron energy equation, and gas thermal balance equation. Electron-ion Coulomb collision is included in the steady state Boltzmann equation solver to accurately describe the electron mobility and other transport coefficients. The model is used to simulate the afterglow of microsecond to nanosecond pulse microwave discharge in N2, O2, and air, as well as femtosecond laser filament discharge in dry and humid air. The simulated results for electron density decay are in quantitative agreement with the available measured ones. The evolution of plasma decay under an external electric field is also investigated, and the effect of gas heating is considered. The underlying mechanism of plasma density decay is unveiled through the above kinetic modeling.

  20. Assembly delay line pulse generators

    CERN Document Server

    1971-01-01

    Assembly of six of the ten delay line pulse generators that will power the ten kicker magnet modules. One modulator part contains two pulse generators. Capacitors, inductances, and voltage dividers are in the oil tank on the left. Triggered high-pressure spark gap switches are on the platforms on the right. High voltage pulse cables to the kicker magnet emerge under the spark gaps. In the centre background are the assembled master gaps.

  1. Investigation of Saturable Absorbance Characteristics of Film Composites with SWNT and Graphene for Fiber Laser Pulse Generation

    Science.gov (United States)

    Borodkin, A.; Khudyakov, D.; Lobach, A.; Vartapetov, S.

    Saturable absorption (SA) of film composites based on carboxymethylcellulose (CMC) polymer with single-walled carbon nanotubes (SWNTs) and graphene (GR) was studied by the Z-and P-scan methods with femtosecond probing pulses at a wavelength of 1.06 μm. The values of the saturation intensities for composites GR-CMC and SWNT-CMC were determined. The optical and thermal damage thresholds of the composites were measured. Q-switching stability limits for passive mode locking in fiber laser with SWNT-CMC SA were analyzed.

  2. The Electron Trajectory in a Relativistic Femtosecond Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    He Feng; Yu Wei; Lu Peixiang; Xu Han; Shen Baifei; Li Ruxin; Xu Zhizhan

    2005-01-01

    In this report, we start from Lagrange equation and analyze theoretically the electron dynamics in electromagnetic field. By solving the relativistic government equations of electron,the trajectories of an electron in plane laser pulse, focused laser pulse have been given for different initial conditions. The electron trajectory is determined by its initial momentum, the amplitude,spot size and polarization of the laser pulse. The optimum initial momentum of the electron for LSS (laser synchrotron source) is obtained. Linear polarized laser is more advantaged than circular polarized laser for generating harmonic radiation.

  3. Drop shaping by laser-pulse impact

    CERN Document Server

    Klein, Alexander L; Visser, Claas Willem; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke

    2015-01-01

    We study the hydrodynamic response of a falling drop hit by a laser pulse. Combining high-speed with stroboscopic imaging we report that a millimeter-sized dyed water drop hit by a milli-Joule nanosecond laser-pulse deforms and propels forward at several meters per second, until it eventually fragments. We show that the drop motion results from the recoil momentum imparted at the drop surface by water vaporization. We measure the propulsion speed and the time-deformation law of the drop, complemented by boundary integral simulations. We explain the drop propulsion and shaping in terms of the laser pulse energy and drop surface tension. These findings are crucial for the generation of extreme ultraviolet (EUV) light in lithography machines.

  4. Transform-Limited X-Ray Pulse Generation from a High Brightness Self-Amplified Spontaneous Emission Free-Electron Laser

    CERN Document Server

    McNeil, B W J; Dunning, D J

    2012-01-01

    A method to achieve High-Brightness Self-Amplified Spontaneous Emission (HB-SASE) in the Free Electron Laser (FEL) is described. The method uses repeated non-equal electron beam delays to de-localise the collective FEL interaction and break the radiation coherence length dependence on the FEL cooperation length. The method requires no external seeding or photon optics and so is applicable at any wavelength or repetition rate. It is demonstrated using linear theory and numerical simulations that the radiation coherence length can be increased by approximately two orders of magnitude over SASE with a corresponding increase in spectral brightness. Examples are shown of HB-SASE generating transform-limited FEL pulses in the soft X-ray and near transform-limited pulses in the hard X-ray. Such pulses may greatly benefit existing applications and may also open up new areas of scientific research.

  5. Generation of quasi-monoenergetic protons from a double-species target driven by the radiation pressure of an ultraintense laser pulse

    Science.gov (United States)

    Pae, Ki Hong; Kim, Chul Min; Nam, Chang Hee

    2016-03-01

    In laser-driven proton acceleration, generation of quasi-monoenergetic proton beams has been considered a crucial feature of the radiation pressure acceleration (RPA) scheme, but the required difficult physical conditions have hampered its experimental realization. As a method to generate quasi-monoenergetic protons under experimentally viable conditions, we investigated using double-species targets of controlled composition ratio in order to make protons bunched in the phase space in the RPA scheme. From a modified optimum condition and three-dimensional particle-in-cell simulations, we showed by varying the ion composition ratio of proton and carbon that quasi-monoenergetic protons could be generated from ultrathin plane targets irradiated with a circularly polarized Gaussian laser pulse. The proposed scheme should facilitate the experimental realization of ultrashort quasi-monoenergetic proton beams for unique applications in high field science.

  6. Fs–ns double-pulse Laser Induced Breakdown Spectroscopy of copper-based-alloys: Generation and elemental analysis of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Guarnaccio, A.; Parisi, G.P.; Mollica, D. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); De Bonis, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Teghil, R. [Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Santagata, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy)

    2014-11-01

    Evolution of nanoparticles ejected during ultra-short (250 fs) laser ablation of certified copper alloys and relative calibration plots of a fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration is presented. All work was performed in air at atmospheric pressure using certified copper-based-alloy samples irradiated by a fs laser beam and followed by a delayed perpendicular ns laser pulse. In order to evaluate possible compositional changes of the fs induced nanoparticles, it was necessary to consider, for all samples used, comparable features of the detected species. With this purpose the induced nanoparticles black-body-like emission evolution and their relative temperature decay have been studied. These data were exploited for defining the distance between the target surface and the successive ns laser beam to be used. The consequent calibration plots of minor constituents (i.e. Sn, Pb and Zn) of the certified copper-based-alloy samples have been reported by taking into account self-absorption effects. The resulting linear regression coefficients suggest that the method used, for monitoring and ruling the fs laser induced nanoparticles, could provide a valuable approach for establishing the occurrence of potential compositional changes of the detected species. All experimental data reveal that the fs laser induced nanoparticles can be used for providing a coherent composition of the starting target. In the meantime, the fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration here used can be considered as an efficient technique for compositional determination of the nanoparticles ejected during ultra-short laser ablation processes. - Highlights: • Laser induced NP continuum black-body-like emission was used for T determination. • Invariable composition of generated NPs was assumed in the range of 20 μs. • Fs-ns DP-LIBS was employed for the compositional characterization of NPs. • NPs obtained by fs

  7. Fiber transmission and generation of ultrawideband pulses by direct current modulation of semi-conductor lasers and chirp-to-intensity conversion

    DEFF Research Database (Denmark)

    Company Torres, Victor; Prince, Kamau; Tafur Monroy, Idelfonso

    2008-01-01

    Optical pulses generated by current modulation of semiconductor lasers are strongly frequency chirped. This effect has been considered pernicious for optical communications. We take advantage of this effect for the generation of ultrawideband microwave signals by using an optical filter to achieve...... chirp-to-intensity conversion. We also experimentally achieve propagation through a 20 km nonzero dispersion shifted fiber with no degradation of the signal at the receiver. Our method constitutes a prospective low-cost solution and offers integration capabilities with fiber...

  8. 50-GHz repetition-rate, 280-fs pulse generation at 100-mW average power from a mode-locked laser diode externally compressed in a pedestal-free pulse compressor

    Science.gov (United States)

    Tamura, Kohichi R.; Sato, Kenji

    2002-07-01

    280-fs pedestal-free pulses are generated at average output powers exceeding 100 mW at a repetition rate of 50 GHz by compression of the output of a mode-locked laser diode (MLLD) by use of a pedestal-free pulse compressor (PFPC). The MLLD consists of a monolithically integrated chirped distributed Bragg reflector, a gain section, and an electroabsorption modulator. The PFPC is composed of a dispersion-flattened dispersion-decreasing fiber and a dispersion-flattened dispersion-imbalanced nonlinear optical loop mirror. Frequency modulation for linewidth broadening is used to overcome the power limitation imposed by stimulated Brillouin scattering.

  9. Coiled transmission line pulse generators

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Kenneth Fox (Columbia, MO)

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  10. Picosecond green and deep ultraviolet pulses generated by a high-power 100  kHz thin-disk laser.

    Science.gov (United States)

    Novák, Ondřej; Turčičová, Hana; Smrž, Martin; Miura, Taisuke; Endo, Akira; Mocek, Tomáš

    2016-11-15

    We report on the generation of the second (515 nm) and fourth (257.5 nm) harmonics from a 100 kHz diode-pumped solid-state laser operating at a wavelength of 1030 nm which uses one Yb:YAG thin disk in the regenerative amplifier and delivers 60 W of the average output power in pulses of 4 ps duration. Thirty-five W in green light and 6 W in deep ultraviolet (DUV) were achieved. The sensitivity of the second harmonic generation efficiency toward the lithium triborate crystal temperature is demonstrated in experiment. The overall conversion efficiency from NIR to DUV of 10% was achieved. The β-barium borate and cesium lithium borate crystals were used as green to DUV convertors and compared regarding the efficiency and spectral bandwidths. The achieved output power is unique for DUV picosecond pulses.

  11. Generation of ultra-small InN nanocrystals by pulsed laser ablation of suspension in organic solution

    Energy Technology Data Exchange (ETDEWEB)

    Kursungoez, Canan; Uzcengiz Simsek, Elif; Ortac, Buelend [Bilkent University, Materials Science and Nanotechnology Department, UNAM-National Nanotechnology Research Center, Ankara (Turkey); Bilkent University, Institute of Materials Science and Nanotechnology, Ankara (Turkey); Tuzakli, Refik [Bilkent University, Materials Science and Nanotechnology Department, UNAM-National Nanotechnology Research Center, Ankara (Turkey)

    2017-03-15

    Nanostructures of InN have been extensively investigated since nano-size provides a number of advantages allowing applications in nanoscale electronic and optoelectronic devices. It is quite important to obtain pure InN nanocrystals (InN-NCs) to reveal the characteristic features, which gain interest in the literature. Here, we proposed a new approach for the synthesis of ultra-small hexagonal InN-NCs by using suspension of micron-sized InN powder in ethanol with pulsed laser ablation method. The liquid environment, laser energy and ablation time were optimized and a post-synthesis treatment, centrifugation, was performed to achieve InN-NCs with the smallest size. Besides, the micron-sized InN powder suspension, as a starting material, enabled us to obtain InN-NCs having diameters smaller than 5 nm. We also presented a detailed characterization of InN-NCs and demonstrated that the formation mechanism mainly depends on the fragmentation due to laser irradiation of the suspension. (orig.)

  12. Ultrafast pulse generation with black phosphorus

    CERN Document Server

    Li, Diao; Karvonen, Lasse; Ye, Guojun; Lipsanen, Harri; Chen, Xianhui; Sun, Zhipei

    2015-01-01

    Black phosphorus has been recently rediscovered as a new and interesting two-dimensional material due to its unique electronic and optical properties. Here, we study the linear and nonlinear optical properties of black phosphorus thin films, indicating that both linear and nonlinear optical properties are anisotropic and can be tuned by the film thickness. Then we employ the nonlinear optical property of black phosphorus for ultrafast (pulse duration down to ~786 fs in mode-locking) and large-energy (pulse energy up to >18 nJ in Q-switching) pulse generation in fiber lasers at the near-infrared telecommunication band ~1.5 {\\mu}m. Our results underscore relatively large optical nonlinearity in black phosphorus and its prospective for ultrafast pulse generation, paving the way to black phosphorus based nonlinear and ultrafast photonics applications (e.g., ultrafast all-optical switches/modulators, frequency converters etc.).

  13. Excitation of H$_{2}^{+}$ with one-cycle laser pulses: Shaped post-laser-field electronic oscillations, generation of higher- and lower-order harmonics

    CERN Document Server

    Paramonov, Guennaddi K; Bandrauk, Andre D

    2016-01-01

    Non Born-Oppenheimer quantum dynamics of H$_{2}^{+}$ excited by shaped one-cycle laser pulses linearly polarized along the molecular axis have been studied by the numerical solution of the time-dependent Schr\\"odinger equation within a %three-body three-dimensional model, including the internuclear separation, $R$, and the electron coordinates $z$ and $\\rho$. Laser carrier frequencies corresponding to the wavelengths $\\lambda_{l}=25$~nm through $\\lambda_{l}=400$~nm were used and the amplitudes of the pulses were chosen such that the energy of H$_{2}^{+}$ was close to its dissociation threshold at the end of any laser pulse applied. It is shown that there exists a characteristic oscillation frequency $\\omega_{\\rm osc} \\simeq 0.2265$~au (corresponding to the period of $\\tau_{\\rm osc} \\simeq 0.671$~fs and the wavelength of $\\lambda_{\\rm osc} \\simeq 200$~nm) that manifests itself as a "carrier" frequency of temporally shaped oscillations of the time-dependent expectation values $\\langle z \\rangle$ and $\\langle \\p...

  14. Generation of shock fronts in the interaction of short pulses of intense laser light in supercritical plasma; Generacion de frentes de choque en la interaccion de pulsos cortos de luz laser intensa en plasmas supercriticos

    Energy Technology Data Exchange (ETDEWEB)

    Lopez V, V.E. [ITESST, 52650 Estado de Mexico (Mexico); Ondarza R, R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    The investigation of the laser interaction with plasma has been carried out mainly in laboratories of Europe, Japan and United States during the last decades. This studies concern the propagation of intense light laser in a non homogeneous plasma, the radiation absorption and the generation of suprathermal electrons, among others. Numerical simulations made by Denavit, for radiation pulses for up of 10{sup 20} W/cm{sup 2} on solid targets, have allowed to observe the generation of ionic crash fronts with high propagation speeds. In this work it is expanded the study of this effect through algorithms of particles simulation. (Author)

  15. Generation of ultra-large-bandwidth X-ray free-electron-laser pulses with a transverse-gradient undulator.

    Science.gov (United States)

    Prat, Eduard; Calvi, Marco; Reiche, Sven

    2016-07-01

    A new and simple method to generate X-ray free-electron-laser radiation with unprecedented spectral bandwidth above the 10% level is presented. The broad bandwidth is achieved by sending a transversely tilted beam through a transverse-gradient undulator. The extent of the bandwidth can easily be controlled by variation of the beam tilt or the undulator gradient. Numerical simulations confirm the validity and feasibility of this method.

  16. Enhanced generation of vacuum-ultraviolet radiation by four-wave mixing in mercury using pulsed laser vaporization

    Science.gov (United States)

    Chénais, S.; Forget, S.; Philippet, L.; Castex, M.-C.

    2007-11-01

    The efficiency of a coherent vacuum ultraviolet (VUV) source at 125 nm, based on two-photon resonant four-wave mixing in mercury vapor, has been enhanced by up to two orders of magnitude. This enhancement was obtained by locally heating a liquid mercury surface with a pulsed excimer laser, resulting in a high-density vapor plume in which the nonlinear interaction occurred. Energies up to 5 μJ (1 kW peak power) have been achieved while keeping the overall mercury cell at room temperature, avoiding the use of a complex heat pipe. We have observed a strong saturation of the VUV yield when peak power densities of the fundamental beams exceeded the GW/cm2 range, as well as a large intensity-dependent broadening (up to ˜ 30 cm-1) of the two-photon resonance. The source has potential applications for high-resolution interference lithography and photochemistry.

  17. Explosive Nucleosynthesis Study Using Laser Driven γ-ray Pulses

    Directory of Open Access Journals (Sweden)

    Takehito Hayakawa

    2017-03-01

    Full Text Available We propose nuclear experiments using γ-ray pulses provided from high field plasma generated by high peak power laser. These γ-ray pulses have the excellent features of extremely short pulse, high intensity, and continuous energy distribution. These features are suitable for the study of explosive nucleosyntheses in novae and supernovae, such as the γ process and ν process. We discuss how to generate suitable γ-ray pulses and the nuclear astrophysics involved.

  18. Nanosecond soliton pulse generation by mode-locked erbium-doped fiber laser using single-walled carbon-nanotube-based saturable absorber.

    Science.gov (United States)

    Ismail, Mohd Afiq; Harun, Sulaiman Wadi; Zulkepely, Nurul Rozullyah; Nor, Roslan Md; Ahmad, Fauzan; Ahmad, Harith

    2012-12-20

    We demonstrate a simple and low cost mode-locked erbium-doped fiber laser (EDFL) operating in the nanosecond region using a single-walled carbon nanotube (SWCNT)-based saturable absorber (SA). A droplet of SWCNT solution is applied on the end of a fiber ferrule, which is then mated to another clean connector ferrule to construct an SA. Then the SA is integrated into a ring EDFL cavity for nanosecond pulse generation. The EDFL operates at around 1570.4 nm, with a soliton-like spectrum with small Kelly sidebands, which confirms the attainment of the anomalous dispersion. It produces a soliton pulse train with a 332 ns width, repetition rate of 909.1 kHz, an average output power of 0.31 mW, and energy of 0.34 nJ at the maximum pump power of 130.8 mW.

  19. Generation of 415 W of p-polarized output power in long pulse operation of Nd:YAG laser using z-fold resonator geometry

    Science.gov (United States)

    Choubey, Ambar; Mondal, Shyamal; Singh, Ravindra; Upadhyaya, B. N.; Datta, P. K.; Oak, S. M.

    2014-08-01

    We report on the generation of high average power linearly p-polarized beam in long pulse operation of dual rod Nd:YAG laser. A z-fold resonator configuration has been designed using simple optical scheme to provide effective birefringence compensation, compactness, and reduction of alignment criticality. Using this geometry, a maximum linearly p-polarized average output power of 415 W and a pulse energy of 150 J was achieved with a slope efficiency of 4.3%, which is on higher side for typical lamp pumped long pulse Nd:YAG lasers. For effective birefringence compensation, an intra-cavity concave mirror based imaging system, a 90° quartz rotator, and a re-entrant feedback mirror has been used. This scheme resulted in an enhancement of p-polarized output power of more than 80% as compared to the p-polarized output power without birefringence compensation. Depolarization loss in the resonator has also been reduced significantly from a value of 35% to a value of ~1.8% after birefringence compensation.

  20. Generation of quasi-monoenergetic heavy ion beams via staged shock wave acceleration driven by intense laser pulses in near-critical plasmas

    Science.gov (United States)

    Zhang, W. L.; Qiao, B.; Shen, X. F.; You, W. Y.; Huang, T. W.; Yan, X. Q.; Wu, S. Z.; Zhou, C. T.; He, X. T.

    2016-09-01

    Laser-driven ion acceleration potentially offers a compact, cost-effective alternative to conventional accelerators for scientific, technological, and health-care applications. A novel scheme for heavy ion acceleration in near-critical plasmas via staged shock waves driven by intense laser pulses is proposed, where, in front of the heavy ion target, a light ion layer is used for launching a high-speed electrostatic shock wave. This shock is enhanced at the interface before it is transmitted into the heavy ion plasmas. Monoenergetic heavy ion beam with much higher energy can be generated by the transmitted shock, comparing to the shock wave acceleration in pure heavy ion target. Two-dimensional particle-in-cell simulations show that quasi-monoenergetic {{{C}}}6+ ion beams with peak energy 168 MeV and considerable particle number 2.1 × {10}11 are obtained by laser pulses at intensity of 1.66 × {10}20 {{W}} {{cm}}-2 in such staged shock wave acceleration scheme. Similarly a high-quality {{Al}}10+ ion beam with a well-defined peak with energy 250 MeV and spread δ E/{E}0=30 % can also be obtained in this scheme.

  1. Ultra-low phase-noise microwave generation using a diode-pumped solid-state laser based frequency comb and a polarization-maintaining pulse interleaver

    CERN Document Server

    Portuondo-Campa, Erwin; Kundermann, Stefan; Balet, Laurent; Lecomte, Steve

    2015-01-01

    We report ultra-low phase-noise microwave generation at a 9.6 GHz carrier frequency from optical frequency combs based on diode-pumped solid-state lasers emitting at telecom wavelength and referenced to a common cavity-stabilized continuous-wave laser. Using a novel fibered polarization-maintaining pulse interleaver, a single-oscillator phase-noise floor of -171 dBc/Hz has been measured with commercial PIN InGaAs photodiodes, constituting a record for this type of detector. Also, a direct optical measurement of the stabilized frequency combs timing jitter was performed using a balanced optical cross correlator, allowing for an identification of the origin of the current phase-noise limitations in the system.

  2. Ultra-low phase-noise microwave generation using a diode-pumped solid-state laser based frequency comb and a polarization-maintaining pulse interleaver.

    Science.gov (United States)

    Portuondo-Campa, Erwin; Buchs, Gilles; Kundermann, Stefan; Balet, Laurent; Lecomte, Steve

    2015-12-14

    We report ultra-low phase-noise microwave generation at a 9.6 GHz carrier frequency from optical frequency combs based on diode-pumped solid-state lasers emitting at telecom wavelength and referenced to a common cavity-stabilized continuous-wave laser. Using a novel fibered polarization-maintaining pulse interleaver, a single-oscillator phase-noise floor of -171 dBc/Hz at 10 MHz offset frequency has been measured with commercial PIN InGaAs photodiodes, constituting a record for this type of detector. Also, a direct optical measurement of the stabilized frequency combs' timing jitter was performed using a balanced optical cross correlator, allowing for an identification of the origin of the phase-noise limitations in the system.

  3. Ablation of boron carbide for high-order harmonic generation of ultrafast pulses in laser-produced plasma

    Science.gov (United States)

    Ganeev, R. A.; Suzuki, M.; Kuroda, H.

    2016-07-01

    We demonstrate the generation of harmonics up to the 27th order (λ=29.9 nm) of 806 nm radiation in the boron carbide plasma. We analyze the advantages and disadvantages of this target compared with the ingredients comprising B4C (solid boron and graphite) by studying the plasma emission and harmonic spectra from three species. We compare different schemes of the two-color pump of B4C plasma, particularly using the second harmonics of 806 nm laser and optical parametric amplifier (1310 nm) as the assistant fields, as well as demonstrate the sum and difference frequency generation using the mixture of the wavelengths of two laser sources. These studies showed the advantages of the two-color pump of B4C plasma leading to the stable harmonic generation and the growth of harmonic conversion efficiency. We also show that the coincidence of harmonic and plasma emission wavelengths in most cases does not cause the enhancement or decrease of the conversion efficiency of this harmonic. Our spatial characterization of harmonics shows their on-axis modification depending on the conditions of frequency conversion.

  4. Generating coherent soft x-ray pulses in the water window with a high-brightness seeded free-electron laser

    CERN Document Server

    Zhou, Kaishang; Deng, Haixiao; Wang, Dong

    2016-01-01

    We propose a new scheme to generate high-brightness and temporal coherent soft x-ray radiation in a seeded free-electron laser. The proposed scheme is based the coherent harmonic generation (CHG) and superradiant principles. A CHG scheme is first used to generate coherent signal at ultra-high harmonics of the seed. This coherent signal is then amplified by a series of chicane-undulator modules via the fresh bunch and superradiant processes in the following radiator. Using a representative of realistic set of parameters, three-dimensional simulations have been carried out and the simulations results demonstrated that 10 GW-level ultra-short coherent radiation pulses in the water window can be achieved by using the proposed technique.

  5. Generating high-brightness and coherent soft x-ray pulses in the water window with a seeded free-electron laser

    Directory of Open Access Journals (Sweden)

    Kaishang Zhou

    2017-01-01

    Full Text Available We propose a new scheme to generate high-brightness and temporal coherent soft x-ray radiation in a seeded free-electron laser. The proposed scheme is based on the coherent harmonic generation (CHG and superradiant principles. A CHG scheme is first used to generate a coherent signal at ultrahigh harmonics of the seed. This coherent signal is then amplified by a series of chicane-undulator modules via the fresh bunch and superradiant processes in the following radiator. Using a representative of a realistic set of parameters, three-dimensional simulations have been carried out and the simulations results demonstrated that 10 GW-level ultrashort (∼20  fs coherent radiation pulses in the water window can be achieved by using a 1.6 GeV electron beam based on the proposed technique.

  6. Sub-nanosecond strong pulse generated by backward Raman scattering

    Institute of Scientific and Technical Information of China (English)

    Zhenhuan Ye(叶震寰); Qihong Lou(楼祺洪); Jingxing Dong(董景星); Yunrong Wei(魏运荣); Lei Ling(凌磊)

    2003-01-01

    Hundreds picosecond strong short-wavelength pulses have been generated by a backward Raman oscillatoramplifier pumped with a 10-J KrF laser from Heaven-1 MOPA system. Not only high power but also highenergy laser pulses have been obtained with an energy conversion efficiency up to 17%. 640-picosecondpulse duration was observed in our experiments by a 1.5-GHz-bandwidth oscilloscope corresponding to 34times of pulse compression rate.

  7. Nonlinear laser pulse response in a crystalline lens.

    Science.gov (United States)

    Sharma, R P; Gupta, Pradeep Kumar; Singh, Ram Kishor; Strickland, D

    2016-04-01

    The propagation characteristics of a spatial Gaussian laser pulse have been studied inside a gradient-index structured crystalline lens with constant-density plasma generated by the laser-tissue interaction. The propagation of the laser pulse is affected by the nonlinearities introduced by the generated plasma inside the crystalline lens. Owing to the movement of plasma species from a higher- to a lower-temperature region, an increase in the refractive index occurs that causes the focusing of the laser pulse. In this study, extended paraxial approximation has been applied to take into account the evolution of the radial profile of the Gaussian laser pulse. To examine the propagation characteristics, variation of the beam width parameter has been observed as a function of the laser power and initial beam radius. The cavitation bubble formation, which plays an important role in the restoration of the elasticity of the crystalline lens, has been investigated.

  8. Bismuth thin films obtained by pulsed laser deposition

    Science.gov (United States)

    Flores, Teresa; Arronte, Miguel; Rodriguez, Eugenio; Ponce, Luis; Alonso, J. C.; Garcia, C.; Fernandez, M.; Haro, E.

    1999-07-01

    In the present work Bi thin films were obtained by Pulsed Laser Deposition, using Nd:YAG lasers. The films were characterized by optical microscopy. Raman spectroscopy and X-rays diffraction. It was accomplished the real time spectral emission characterization of the plasma generated during the laser evaporation process. Highly oriented thin films were obtained.

  9. Generation of Subsurface Voids, Incubation Effect, and Formation of Nanoparticles in Short Pulse Laser Interactions with Bulk Metal Targets in Liquid: Molecular Dynamics Study.

    Science.gov (United States)

    Shih, Cheng-Yu; Shugaev, Maxim V; Wu, Chengping; Zhigilei, Leonid V

    2017-08-03

    The ability of short pulse laser ablation in liquids to produce clean colloidal nanoparticles and unusual surface morphology has been employed in a broad range of practical applications. In this paper, we report the results of large-scale molecular dynamics simulations aimed at revealing the key processes that control the surface morphology and nanoparticle size distributions by pulsed laser ablation in liquids. The simulations of bulk Ag targets irradiated in water are performed with an advanced computational model combining a coarse-grained representation of liquid environment and an atomistic description of laser interaction with metal targets. For the irradiation conditions that correspond to the spallation regime in vacuum, the simulations predict that the water environment can prevent the complete separation of the spalled layer from the target, leading to the formation of large subsurface voids stabilized by rapid cooling and solidification. The subsequent irradiation of the laser-modified surface is found to result in a more efficient ablation and nanoparticle generation, thus suggesting the possibility of the incubation effect in multipulse laser ablation in liquids. The simulations performed at higher laser fluences that correspond to the phase explosion regime in vacuum reveal the accumulation of the ablation plume at the interface with the water environment and the formation of a hot metal layer. The water in contact with the metal layer is brought to the supercritical state and provides an environment suitable for nucleation and growth of small metal nanoparticles from metal atoms emitted from the hot metal layer. The metal layer itself has limited stability and can readily disintegrate into large (tens of nanometers) nanoparticles. The layer disintegration is facilitated by the Rayleigh-Taylor instability of the interface between the higher density metal layer decelerated by the pressure from the lighter supercritical water. The nanoparticles emerging

  10. Spectral compression of single-photon-level laser pulse

    Science.gov (United States)

    Li, Yuanhua; Xiang, Tong; Nie, Yiyou; Sang, Minghuang; Chen, Xianfeng

    2017-01-01

    We experimentally demonstrate that the bandwidth of single photons laser pulse is compressed by a factor of 58 in a periodically poled lithium niobate (PPLN) waveguide chip. A positively chirped single photons laser pulse and a negatively chirped classical laser pulse are employed to produce a narrowband single photon pulse with new frequency through sum-frequency generation. In our experiment, the frequency and bandwidth of single photons at 1550 nm are simultaneously converted. Our results mark a critical step towards the realization of coherent photonic interface between quantum communication at 1550 nm and quantum memory in the near-visible window. PMID:28240245

  11. Dynamics of laser-induced electroconvection pulses.

    Science.gov (United States)

    Giebink, N C; Johnson, E R; Saucedo, S R; Miles, E W; Vardanyan, K K; Spiegel, D R; Allen, C C

    2004-06-01

    We first report that, for planar nematic 4-methoxy-benzilidene-4-butylaniline (MBBA), the electroconvection threshold voltage has a nonmonotonic temperature dependence, with a well-defined minimum, and a slope of about -0.12 V/degrees C near room temperature at 70 Hz. Motivated by this observation, we have designed an experiment in which a weak continuous-wave absorbed laser beam with a diameter comparable to the pattern wavelength generates a locally supercritical region, or pulse, in dye-doped MBBA. Working 10-20 % below the laser-free threshold voltage, we observe a steady-state pulse shaped as an ellipse with the semimajor axis oriented parallel to the nematic director, with a typical size of several wavelengths. The pulse is robust, persisting even when spatially extended rolls develop in the surrounding region, and displays rolls that counterpropagate along the director at frequencies of tenths of Hz, with the rolls on the left (right) side of the ellipse moving to the right (left). Systematic measurements of the sample-voltage dependence of the pulse amplitude, spatial extent, and frequency show a saturation or decrease when the control parameter (evaluated at the center of the pulse) approaches approximately 0.3. We propose that the model for these pulses should be based on the theory of control-parameter ramps, supplemented with new terms to account for the advection of heat away from the pulse when the surrounding state becomes linearly unstable. The advection creates a negative feedback between the pulse size and the efficiency of heat transport, which we argue is responsible for the attenuation of the pulse at larger control-parameter values.

  12. Second-generation dental laser technology

    Science.gov (United States)

    Moretti, Michael

    1993-07-01

    The first generation of dental lasers proved limited to soft tissue applications. Due to the thermal properties of these lasers, drilling of enamel and dentin is harmful to the underlying nerve tissue. As a solution to this problem, more sophisticated solidstate lasers are under commercial development for hard tissue applications. The first of these second generation lasers to emerge is the erbium:YAG now marketed in Europe by KaVo. This system relies on a cumbersome articulated arm delivery device. Other manufacturers have overcome this delivery problem with the introduction of flexible delivery methods. Another hard tissue laser that has been introduced is the short-pulsed Nd:YAG. This laser uses shaped pulses to drill teeth without thermal damage. An overview of these and other second generation dental lasers is presented.

  13. Laser absorption via QED cascades in counter propagating laser pulses

    CERN Document Server

    Grismayer, Thomas; Martins, Joana L; Fonseca, Ricardo A; Silva, Luis O

    2015-01-01

    A model for laser light absorption in electron-positron plasmas self-consistently created via QED cascades is described. The laser energy is mainly absorbed due to hard photon emission via nonlinear Compton scattering. The degree of absorption depends on the laser intensity and the pulse duration. The QED cascades are studied with multi-dimensional particle-in-cell simulations complemented by a QED module and a macro-particle merging algorithm that allows to handle the exponential growth of the number of particles. Results range from moderate-intensity regimes ($\\sim$ 10 PW) where the laser absorption is negligible, to extreme intensities (> 100 PW) where the degree of absorption reaches 80%. Our study demonstrates good agreement between the analytical model and simulations. The expected properties of the hard photon emission and the generated pair-plasma are investigated, and the experimental signatures for near-future laser facilities are discussed.

  14. Nanoplasmonic generation of ultrashort EUV pulses

    Science.gov (United States)

    Choi, Joonhee; Lee, Dong-Hyub; Han, Seunghwoi; Park, In-Yong; Kim, Seungchul; Kim, Seung-Woo

    2012-10-01

    Ultrashort extreme-ultraviolet (EUV) light pulses are an important tool for time-resolved pump-probe spectroscopy to investigate the ultrafast dynamics of electrons in atoms and molecules. Among several methods available to generate ultrashort EUV light pulses, the nonlinear frequency upconversion process of high-harmonic generation (HHG) draws attention as it is capable of producing coherent EUV pulses with precise control of burst timing with respect to the driving near-infrared (NIR) femtosecond laser. In this report, we present and discuss our recent experimental data obtained by the plasmon-driven HHG method that generate EUV radiation by means of plasmonic nano-focusing of NIR femtosecond pulses. For experiment, metallic waveguides having a tapered hole of funnel shape inside were fabricated by adopting the focused-ion-beam process on a micro-cantilever substrate. The plasmonic field formed within the funnelwaveguides being coupled with the incident femtosecond pulse permitted intensity enhancement by a factor of ~350, which creates a hot spot of sub-wavelength size with intensities strong enough for HHG. Experimental results showed that with injection of noble gases into the funnel-waveguides, EUV radiation is generated up to wavelengths of 32 nm and 29.6 nm from Ar and Ne gas atoms, respectively. Further, it was observed that lower-order EUV harmonics are cut off in the HHG spectra by the tiny exit aperture of the funnel-waveguide.

  15. Refurbishment Status of Light Ⅱ-A Pulsed Power Generator

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The Light Ⅱ-A pulsed power generator, formerly used to pump KrF laser, was updated around the year 2000 from the original Light Ⅱ, a pulsed power generator built in 1980s at CIAE. This machine was

  16. Ultrashort-pulse laser calligraphy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Weijia; Kazansky, Peter G. [Optoelectronics Research Centre, University of Southampton, SO17 1BJ (United Kingdom); Shimotsuma, Yasuhiko; Sakakura, Masaaki; Miura, Kiyotaka; Hirao, Kazuyuki [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2008-10-27

    Control of structural modifications inside silica glass by changing the front tilt of an ultrashort pulse is demonstrated, achieving a calligraphic style of laser writing. The phenomena of anisotropic bubble formation at the boundary of an irradiated region and modification transition from microscopic bubbles formation to self-assembled form birefringence are observed, and the physical mechanisms are discussed. The results provide the comprehensive evidence that the light beam with centrosymmetric intensity distribution can produce noncentrosymmetric material modifications.

  17. Ultrashort-pulse laser calligraphy

    Science.gov (United States)

    Yang, Weijia; Kazansky, Peter G.; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Miura, Kiyotaka; Hirao, Kazuyuki

    2008-10-01

    Control of structural modifications inside silica glass by changing the front tilt of an ultrashort pulse is demonstrated, achieving a calligraphic style of laser writing. The phenomena of anisotropic bubble formation at the boundary of an irradiated region and modification transition from microscopic bubbles formation to self-assembled form birefringence are observed, and the physical mechanisms are discussed. The results provide the comprehensive evidence that the light beam with centrosymmetric intensity distribution can produce noncentrosymmetric material modifications.

  18. Optical pulse generation system for the National Ignition Facility (NIF)

    Energy Technology Data Exchange (ETDEWEB)

    Penko, F; Braucht,; Browning, D; Crane, J K; Dane, B; Deadrick, F; Dreifuerst, G; Henesian, M; Jones, B A; Kot, L; Laumann, C; Martinez, M; Moran, B; Rothenberg, J E; Skulina, K; Wilcox, R B

    1998-06-18

    We describe the Optical Pulse Generation (OPG) system for the National Ignition Facility ( NIF ). The OPG system begins with the Master Oscillator Room ( MOR ) where the initial, seed pulse for the entire laser system is produced and properly formatted to enhance ignition in the target. The formatting consists of temporally shaping the pulse and adding additional bandwidth to increase the coupling of the laser generated x-rays to the high density target plasma. The pulse produced in the MOR fans out to 48 identical preamplifier modules where it is amplified by a factor of ten billion and spatially shaped for injection into the 192 main amplifier chai

  19. Comparative investigation of third and fifth harmonic generation in atomic and molecular gases driven by mid-infrared ultrafast laser pulses

    CERN Document Server

    Ni, Jielei; Zeng, Bin; Chu, Wei; Li, Guihua; Zhang, Haisu; Jing, Chenrui; Chin, See Leang; Cheng, Ya; Xu, Zhizhan

    2011-01-01

    We report on the comparative experimental investigation on third and fifth harmonic generation (THG and FHG) in atomic and molecular gases driven by mid-infrared ultrafast laser pulses at a wavelength of ~1500 nm. We observe that the conversion efficiencies of both the THG and FHG processes saturate at similar peak intensities close to ~1.5\\times1014 W/cm2 for argon, nitrogen, and air, whose ionization potentials are close to each other. Near the saturation intensity, the ratio of yields of the FHG and THG reaches ~10-1 for all the gases. Our results show that high-order Kerr effects do exist, whereas they are insufficient to balance the Kerr self-focusing without the assistance of plasma generation.

  20. Isolated sub-10 attosecond pulse generation by a 6-fs driving pulse and a 5-fs subharmonic controlling pulse

    Directory of Open Access Journals (Sweden)

    Yunhui Wang

    2012-06-01

    Full Text Available We theoretically study high-order harmonic generation by quantum path control in a special two-color laser field, which is synthesized by a 6 fs/800 nm fundamental pulse and a weaker 5 fs/1600 nm subharmonic controlling pulse. Single quantum path is selected without optimizing any carrier phase, which not only broadens the harmonic bandwidth to 400 eV, but also enhances the harmonic conversion efficiency in comparison with the short-plus-long scheme, which is based on 5 fs/800 nm driving pulse and 6 fs/1600 nm control pulse. An isolated 8-attosecond pulse is produced with currently available ultrafast laser sources.

  1. Laser-driven hydrothermal process studied with excimer laser pulses

    Science.gov (United States)

    Mariella, Raymond; Rubenchik, Alexander; Fong, Erika; Norton, Mary; Hollingsworth, William; Clarkson, James; Johnsen, Howard; Osborn, David L.

    2017-08-01

    Previously, we discovered [Mariella et al., J. Appl. Phys. 114, 014904 (2013)] that modest-fluence/modest-intensity 351-nm laser pulses, with insufficient fluence/intensity to ablate rock, mineral, or concrete samples via surface vaporization, still removed the surface material from water-submerged target samples with confinement of the removed material, and then dispersed at least some of the removed material into the water as a long-lived suspension of nanoparticles. We called this new process, which appears to include the generation of larger colorless particles, "laser-driven hydrothermal processing" (LDHP) [Mariella et al., J. Appl. Phys. 114, 014904 (2013)]. We, now, report that we have studied this process using 248-nm and 193-nm laser light on submerged concrete, quartzite, and obsidian, and, even though light at these wavelengths is more strongly absorbed than at 351 nm, we found that the overall efficiency of LDHP, in terms of the mass of the target removed per Joule of laser-pulse energy, is lower with 248-nm and 193-nm laser pulses than with 351-nm laser pulses. Given that stronger absorption creates higher peak surface temperatures for comparable laser fluence and intensity, it was surprising to observe reduced efficiencies for material removal. We also measured the nascent particle-size distributions that LDHP creates in the submerging water and found that they do not display the long tail towards larger particle sizes that we had observed when there had been a multi-week delay between experiments and the date of measuring the size distributions. This is consistent with transient dissolution of the solid surface, followed by diffusion-limited kinetics of nucleation and growth of particles from the resulting thin layer of supersaturated solution at the sample surface.

  2. Progress in time transfer by laser pulses

    Science.gov (United States)

    Li, Xin; Yang, Fu-Min

    2004-03-01

    Time transfer by laser pulses is based on the propagation of light pulses between satellite and ground clocks or between remote clocks on earth. It will realize the synchronization of these clocks with high accuracy and stability. Several experiments of the time transfer by laser pulses had been successfully carried out in some countries. These experiments validate the feasibility of the synchronization of clocks by laser pulses. The paper describes the results of these experiments. The time comparison by laser pulses between atomic clocks on aircraft and ground ones in the United States, and the LASSO and T2L2 projects in France are introduced in detail.

  3. Phase Noise and Intensity Noise of the Pulse Train Generated from Mode-locked Lasers in the Demodulation Measurement

    OpenAIRE

    Kan WU; Shum, Ping

    2010-01-01

    The phase noise and intensity noise of a pulse train are theoretically analyzed in the demodulation measurement. The effect of pulse asymmetry is discussed for the first time using Fourier series. Experimentally, photodetectors with different bandwidth and incident power levels are compared to achieve minimum pulse distortion.

  4. Ultrashort Laser Pulses in Biology and Medicine

    CERN Document Server

    Braun, Markus; Zinth, Wolfgang

    2008-01-01

    Sources of ultrashort laser pulses are nowadays commercially available and have entered many areas of research and development. This book gives an overview of biological and medical applications of these laser pulses. The briefness of these laser pulses permits the tracing of the fastest processes in photo-active bio-systems, which is one focus of the book. The other focus is applications that rely on the high peak intensity of ultrashort laser pulses. Examples covered span non-linear imaging techniques, optical tomography, and laser surgery.

  5. High harmonic generation in H$_{2}^{+}$ and HD+ by intense femtosecond laser pulses: A wave packet approach with nonadiabatic interaction in HD+

    Indian Academy of Sciences (India)

    Farzana Sharmin; Samir Saha; S S Bhattacharyya

    2013-06-01

    We have theoretically investigated the high harmonic generation (HHG) spectra of H$_{2}^{+}$ and HD+ using a time-dependent wave packet approach for the nuclear motion with pulsed lasers of peak intensities (0) of 3.5 × 1014 and 4.5 × 1014 W/cm2, wavelengths (L) of 800 and 1064 nm, and pulse durations () of 40 and 50 fs, for initial vibrational levels 0 = 0 and 1. We have argued that for these conditions the harmonic generation due to the transitions in the electronic continuum by tunnelling or multiphoton ionization will not be important. Thus, the characteristic features of HHG spectra in our model arise only due to the nuclear motions on the two lowest field-coupled electronic states between which both interelectronic and intraelectronic (due to intrinsic dipole moments, for HD+) radiative transitions can take place. For HD+, the effect of nonadiabatic (NA) interaction between the two lowest Born–Oppenheimer (BO) electronic states has been taken into account and comparison has been made with the HHG spectra of HD+ obtained in the BO approximation. Even harmonics and a second plateau in the HHG spectra of HD+ with the NA interaction and hyper-Raman lines in the spectra of both H$_{2}^{+}$ and HD+ for 0 = 1 have been observed for higher value of 0 or L. Our calculations indicate reasonable efficiencies of harmonic generation even without involving the electronic continuum.

  6. Optimization and control of electron beams from laser wakefield accelerations using asymmetric laser pulses

    Science.gov (United States)

    Gopal, K.; Gupta, D. N.

    2017-10-01

    Optimization and control of electron beam quality in laser wakefield acceleration are explored by using a temporally asymmetric laser pulse of the sharp rising front portion. The temporally asymmetric laser pulse imparts stronger ponderomotive force on the ambient plasma electrons. The stronger ponderomotive force associated with the asymmetric pulse significantly affects the injection of electrons into the wakefield and consequently the quality of the injected bunch in terms of injected charge, mean energy, and emittance. Based on particle-in-cell simulations, we report to generate a monoenergetic electron beam with reduced emittance and enhanced charge in laser wakefield acceleration using an asymmetric pulse of duration 30 fs.

  7. Pulsed laser deposition: metal versus oxide ablation

    NARCIS (Netherlands)

    Doeswijk, L.M.; Rijnders, G.; Blank, D.H.A.

    2004-01-01

    We present experimental results of pulsed laser interaction with metal (Ni, Fe, Nb) and oxide (TiO2, SrTiO3, BaTiO3) targets. The influence of the laser fluence and the number of laser pulses on the resulting target morphology are discussed. Although different responses for metal and oxide targets t

  8. Generation of high energy square-wave pulses in all anomalous dispersion Er:Yb passive mode locked fiber ring laser.

    Science.gov (United States)

    Semaan, Georges; Ben Braham, Fatma; Salhi, Mohamed; Meng, Yichang; Bahloul, Faouzi; Sanchez, François

    2016-04-18

    We have experimentally demonstrated square pulses emission from a co-doped Er:Yb double-clad fiber laser operating in anomalous dispersion DSR regime using the nonlinear polarization evolution technique. Stable mode-locked pulses have a repetition rate of 373 kHz with 2.27 µJ energy per pulse under a pumping power of 30 W in cavity. With the increase of pump power, both the duration and the energy of the output square pulses broaden. The experimental results demonstrate that the passively mode-locked fiber laser operating in the anomalous regime can also realize a high-energy pulse, which is different from the conventional low-energy soliton pulse.

  9. Generation of nanosecond soft X-ray pulsed as a result of interaction of laser radiation with gas puff target; Wplyw nanosekundowych impulsow miekkiego promieniowania rentgenowskiego w wyniku oddzialywania promieniowania laserowego z impulsowa tarcza gazowa

    Energy Technology Data Exchange (ETDEWEB)

    Fiedorowicz, H.; Patron, Z.; Bartnik, A.; Parys, P. [Wojskowa Akademia Techniczna, Warsaw (Poland)

    1995-10-01

    A new method of generation of nanosecond soft x-ray pulsed with a photon energy around 1 keV is presented. X-rays are generated in a high-temperature plasma, which is created as a result of interaction of Nd:glass laser radiation with a gas puff target. The target was obtained by puffing a small amount of gas, through the nozzle, into the vacuum chamber, by means of a pressure electromagnetic valve. The pulses of laser radiation with the pulse duration of 1 ns and energy up to 15 J, generated in the system of a high-power Nd:glass laser, were for the target heating. Spatial, spectral and temporal measurements of X-ray emission have shown that the high-intensity soft X-ray are generated as a result of the interaction of nanosecond pulses of Nd:glass laser radiation with the gas puff target. High efficiency of X-ray generation is suggested to be related to the effect of condensation of the gas, outflowing from the valve nozzle and, in effect, to the interaction of laser radiation with matter in a form of aerosol. (author). 55 refs, 5 figs.

  10. Generation of few-cycle laser pulses:Comparison between atomic and molecular gases in a hollow-core fiber

    Institute of Scientific and Technical Information of China (English)

    黄志远; 戴晔; 赵睿睿; 王丁; 冷雨欣

    2016-01-01

    We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber. From the perspective of self-phase modulation (SPM), we give the extensive study of the SPM infl uence on a probe pulse with molecular phase modulation (MPM) effect. By comparing the two compression methods, we summarize their advan-tages and drawbacks to obtain the few-cycle pulses with micro-or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values.

  11. Characteristics of the evolution of a plasma generated by radiation from CW and repetitively pulsed CO2 lasers in different gases

    Science.gov (United States)

    Kanevskii, M. F.; Stepanova, M. A.

    1990-06-01

    The interaction between high-power CW and repetitively pulsed CO2 laser radiation and a low-threshold optical-breakdown plasma near a metal surface is investigated. The characteristics of the breakdown plasma are examined as functions of the experimental conditions. A qualitative analysis of the results obtained was performed using a simple one-dimensional model for laser combustion waves.

  12. Over 0.5 MW green laser from sub-nanosecond giant pulsed microchip laser

    Science.gov (United States)

    Zheng, Lihe; Taira, Takunori

    2016-03-01

    A sub-nanosecond green laser with laser head sized 35 × 35 × 35 mm3 was developed from a giant pulsed microchip laser for laser processing on organic superconducting transistor with a flexible substrate. A composite monolithic Y3Al5O12 (YAG) /Nd:YAG/Cr4+:YAG/YAG crystal was designed for generating giant pulsed 1064 nm laser. A fibercoupled 30 W laser diode centered at 808 nm was used with pump pulse duration of 245 μs. The 532 nm green laser was obtained from a LiB3O5 (LBO) crystal with output energy of 150 μJ and pulse duration of 268 ps. The sub-nanosecond green laser is interesting for 2-D ablation patterns.

  13. Subthreshold pair production in short laser pulses

    OpenAIRE

    Nousch, T.; Seipt, D.; Kampfer, B.; Titov, A. I.

    2012-01-01

    The $e^+e^-$ pair production by a probe photon traversing a linearly polarized laser pulse is treated as generalized nonlinear Breit-Wheeler process. For short laser pulses with very few oscillations of the electromagnetic field we find below the perturbative weak-field threshold $\\sqrt{s} = 2m$ a similar enhancement of the pair production rate as for circular polarization. The strong subthreshold enhancement is traced back to the finite bandwidth of the laser pulse. A folding model is develo...

  14. Concave pulse shaping of a circularly polarized laser pulse from non-uniform overdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Min Sup [School of Natural Science, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Kulagin, Victor V. [Sternberg Astronomical Institute, Moscow State University, Universitetsky prosp. 13, Moscow, 119992 (Russian Federation); Suk, Hyyong, E-mail: hysuk@gist.ac.kr [Department of Physics and Photon Science, GIST, 123 Cheomdan-gwangiro, Buk-gu, Gwangju, 500-712 (Korea, Republic of)

    2015-03-20

    Pulse shaping of circularly polarized laser pulses in nonuniform overdense plasmas are investigated numerically. Specifically we show by two-dimensional particle-in-cell simulations the generation of a concave pulse front of a circularly polarized, a few tens of petawatt laser pulse from a density-tapered, overdense plasma slab. The concept used for the transverse-directional shaping is the differential transmittance depending on the plasma density, and the laser intensity. For suitable selection of the slab parameters for the concave pulse shaping, we studied numerically the pulse transmittance, which can be used for further parameter design of the pulse shaping. The concavely shaped circularly polarized pulse is expected to add more freedom in controlling the ion-beam characteristics in the RPDA regime. - Highlights: • Laser pulse shaping for a concave front by non-uniform overdense plasma was studied. • Particle-in-cell (PIC) simulations were used for the investigation. • A laser pulse can be shaped by a density-tapered overdense plasma. • The concave and sharp pulse front are useful in many laser–plasma applications. • They are important for ion acceleration, especially in the radiation pressure dominant regime.

  15. Generation of nanocrystalline surface layer in short pulse laser processing of metal targets under conditions of spatial confinement by solid or liquid overlayer

    Science.gov (United States)

    Shugaev, Maxim V.; Shih, Cheng-Yu; Karim, Eaman T.; Wu, Chengping; Zhigilei, Leonid V.

    2017-09-01

    The effect of spatial confinement by a solid or liquid overlayer on short pulse laser-induced surface microstructure modification is investigated in a series of large-scale atomistic simulations performed for Ag targets irradiated in the regime of melting and resolidification, below the thresholds for laser spallation and ablation. For Ag targets with free surfaces, the formation of a nanocrystalline region with random crystallographic grain orientation is observed under irradiation conditions leading to the generation of numerous sub-surface voids that slow down the solidification process. When no voids are generated, the resolidification produces grains misoriented with respect to the bulk of the target by just several degrees and separated from each other by low angle grain boundaries or dislocation walls. The presence of a liquid or solid overlayer suppresses nucleation of sub-surface voids, provides an additional pathway for cooling through the heat conduction to the overlayer, and facilitates the formation of nanocrystalline structure in a region of the metal target adjacent to the overlayer. Moreover, the stabilizing effect of the solid overlayer may result in an incomplete melting of metal in the vicinity of the interface, making it possible for grains growing from the interface to retain ;memory; of the target orientation and to produce nanocrystalline interfacial region with small misorientation of grains with respect to the bulk of the target. In all simulations, the nanocrystalline layers generated by laser processing of single crystal Ag targets are characterized by a high density of stacking faults, twin boundaries, and point defects produced in the course of the rapid resolidification.

  16. Generation of few-cycle terawatt light pulses using optical parametric chirped pulse amplification.

    Science.gov (United States)

    Witte, S; Zinkstok, R; Hogervorst, W; Eikema, K

    2005-06-27

    We demonstrate the generation of 9.8+/-0.3 fs laser pulses with a peak power exceeding one terawatt at 30 Hz repetition rate, using optical parametric chirped pulse amplification. The amplifier is pumped by 140 mJ, 60 ps pulses at 532 nm, and amplifies seed pulses from a Ti:Sapphire oscillator to 23 mJ/pulse, resulting in 10.5 mJ/pulse after compression while amplified fluorescence is kept below 1%. We employ grating-based stretching and compression in combination with an LCD phase-shaper, allowing compression close to the Fourier limit of 9.3 fs.

  17. Generation of a quasi-monoenergetic high energy proton beam from a vacuum-sandwiched double layer target irradiated by an ultraintense laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Nam Kim, Kyung; Lee, Kitae, E-mail: klee@kaeri.re.kr; Hee Park, Seong; Young Lee, Ji; Uk Jeong, Young; Vinokurov, Nikolay [Center for Quantum-Beam-based Radiation Research, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Gi Kim, Yong [Department of Physics, Kongju National University, Kongju (Korea, Republic of)

    2014-04-15

    An acceleration mechanism to generate a high energy proton beam with a narrow energy spread in the laser-induced plasma acceleration of a proton beam is proposed; this mechanism employs two thin foils separated by a narrow vacuum gap. Instead of a thin sheath field at the plasma surfaces, it utilizes an electrostatic field formed in the bulk of the plasma. From a one-dimensional fluid analysis, it has been found that with an appropriate target thickness, protons on the front surface of the second layer can be fed into the plasma, in which the protons are accelerated by an electrostatic field built into the bulk of the plasma. This leads to a proton beam with higher energy and a narrower energy spread than those accelerated at the rear surface of the second layer. The acceleration mechanism is also verified by a two-dimensional particle-in-cell simulation. With a 27-fs long and 2×10{sup 19} W/cm{sup 2} intense laser pulse, a proton beam with an 18-MeV peak energy and a 35% energy spread is generated. The peak energy is higher than that from the rear surface of the second layer by a factor of 3.

  18. Generation of 10 GHz transform-limited pulse train from dual-pump mode-locking erbium-doped fiber laser

    Science.gov (United States)

    He, Li; Yang, Bojun; Zhang, Xiaoguang; Yu, Li

    2006-09-01

    A dual-pump 10 GHz mode-locking erbium-doped fiber laser was demonstrated. With 10-GHz signal modulation of the modulator, less than 12 ps mode-locked pulse at 10 GHz repetition rate with 1.097 mW average output power was obtained. The corresponding spectrum width is 0.277 nm, which is centered at 1561 nm. The corresponding product of time and bandwidth is Δv*Δt which equals 0.433. Gaussian pulse shape is assumed, the output pulse is almost transform limited. Compared with single-pump fiber ring laser, the dual-pump fiber ring laser is helpful for suppression of supermode noise, which make this kind of fiber ring laser more stable.

  19. Interaction of nanosecond laser pulse with tetramethyl silane (Si(CH34 clusters: Generation of multiply charged silicon and carbon ions

    Directory of Open Access Journals (Sweden)

    Purav M. Badani

    2011-12-01

    Full Text Available Present work reports significantly high levels of ionization, eventually leading to Coulomb explosion of Tetramethyl silane (TMS clusters, on interaction with laser pulses of intensity ∼109 W/cm2. Tetramethyl silane clusters, prepared by supersonic expansion were photoionized at 266, 355 or 532 nm and the resultant ions were detected using time-of-flight mass spectrometer. It is observed that wavelength of irradiation and the size of the cluster are crucial parameters which drastically affect the nature of charge species generated upon photoionization of cluster. The results show that clusters absorb significantly higher energy from the laser field at longer wavelengths (532 nm and generate multiply charged silicon and carbon ions which have large kinetic energies. Further, laser-cluster interaction at different wavelengths has been quantified and charge densities at 266, 355 and 532 nm are found to be 4x 1010, 5x 1010 and 5x 1011 charges/cm3 respectively. These unusual results have been rationalized based on dominance of secondary ionization processes at 532 nm ultimately leading to Coulomb explosion of clusters. In another set of experiments, multiply charged ions of Ar (up to +5 state and Kr (up to +6 state were observed when TMS doped inert gas clusters were photoionized at 532 and 355 nm. The extent of energy absorption at these two wavelengths is clearly manifested from the charge state of the atomic ions generated upon Coulomb disintegration of the doped cluster. These experiments thus demonstrate a novel method for generation of multiply charged atomic ions of inert gases at laser intensity of ∼ 109 W/cm2. The average size of the cluster exhibiting Coulomb explosion phenomena under giga watt intensity conditions has been estimated to be ∼ 6 nm. Experimental results obtained in the present work agree qualitatively with the model proposed earlier [D. Niu, H. Li, F. Liang, L. Wen, X. Luo, B. Wang, and H. Qu, J. Chem. Phys. 122, 151103

  20. Laser diode structures with a saturable absorber for high-energy picosecond optical pulse generation by combined gain-and Q-switching

    Science.gov (United States)

    Ryvkin, B. S.; Avrutin, E. A.; Kostamovaara, J. E. K.; Kostamovaara, J. T.

    2017-02-01

    The performance of gain-switched Fabry-Perot asymmetric-waveguide semiconductor lasers with a large equivalent spot size and an intracavity saturable absorber was investigated experimentally and theoretically. The laser with a short (˜20 μm) absorber emitted high-energy afterpulse-free optical pulses in a broad range of injection current pulse amplitudes; optical pulses with a peak power of about 35 W and a duration of about 80 ps at half maximum were achieved with a current pulse with an amplitude of just 8 A and a duration of 1.5 ns. Good quality pulsations were observed in a broad range of elevated temperatures. The introduction of a substantially longer absorber section leads to strong spectral broadening of the output without a significant improvement to pulse energy and peak power.

  1. Laser pulse spectral shaping based on electro-optic modulation

    Institute of Scientific and Technical Information of China (English)

    Yanhai Wang; Jiangfeng Wang; You'en Jiang; Yan Bao; Xuechun Li; Zunqi Lin

    2008-01-01

    A new spectrum shaping method, based on electro-optic modulation, to alleviate gain narrowing in chirped pulse amplification (CPA) system, is described and numerically simulated. Near-Fourier transform-limited seed laser pulse is chirped linearly through optical stretcher. Then the chirped laser pulse is coupled into integrated waveguide electro-optic modulator driven by an aperture-coupled-stripline (ACSL) electricalwaveform generator, and the pulse shape and amplitude are shaped in time domain. Because of the directrelationship between frequency interval and time interval of the linearly chirped pulse, the laser pulse spectrum is shaped correspondingly. Spectrum-shaping examples are modeled numerically to determine the spectral resolution of this technique. The phase error introduced in this method is also discussed.

  2. Generation of few-cycle laser pulses: Comparison between atomic and molecular gases in a hollow-core fiber

    Science.gov (United States)

    Zhi-Yuan, Huang; Ye, Dai; Rui-Rui, Zhao; Ding, Wang; Yu-Xin, Leng

    2016-07-01

    We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber. From the perspective of self-phase modulation (SPM), we give the extensive study of the SPM influence on a probe pulse with molecular phase modulation (MPM) effect. By comparing the two compression methods, we summarize their advantages and drawbacks to obtain the few-cycle pulses with micro- or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204328, 61221064, 61078037, 11127901, 11134010, and 61205208), the National Basic Research Program of China (Grant No. 2011CB808101), and the Natural Science Foundation of Shanghai, China (Grant No. 13ZR1414800).

  3. Features of femtosecond laser pulses interaction with laser nanoceramics

    Science.gov (United States)

    Pestryakov, E. V.; Petrov, V. V.; Trunov, V. I.; Kirpichnikov, A. V.; Merzliakov, M. A.; Laptev, A. V.

    2007-06-01

    In this work we have performed the experimental researches of features for the generation of supercontinuum in laser materials with identical chemical composition: Yb:YAG crystal and Yb:YAG laser nanoceramics. Dependence of width of supercontinuum spectrum in 515-1100 nm spectral range on femtosecond radiation intensity was investigated. At laser intensity ~1.2•10 14 W/cm2 the short-wave wing of a spectrum for nanoceramics has greater intensity and more flat shape in comparison with crystal. Experiments were made at lens focusing of the Ti:Sapphire femtosecond laser system radiation with energy up to 0.5 mJ in explored sample that was inside of integrating optical sphere. Also we investigated the interaction of femtosecond laser pulses and the generation of supercontinuum in Nd:Y IIO 3 nanoceramics. The maximum value of laser intensity in experiments was restricted by optical breakdown on target output surface, i.e. was below threshold of ablation of sample substance.

  4. Pulsed Laser Centre (CLPU). The Salamanca peta watt laser; Centro de Laseres Pulsados (CLPU). El laser de Petavatio de Salamanca

    Energy Technology Data Exchange (ETDEWEB)

    Franco, L. R.

    2016-08-01

    With pulses lasting 30 photo seconds, the CLPU VEGA laser is capable of generating a peak power level of one peta watt, this making it one of the worlds most powerful lasers. When focussed it can reach extreme intensities. The way in which a pulse of this nature interacts with an atom or what its applications might be are among the questions answered by this article. (Author)

  5. Three-dimensional polymer nanostructures for applications in cell biology generated by high-repetition rate sub-15 fs near-infrared laser pulses

    Science.gov (United States)

    Licht, Martin; Straub, Martin; König, Karsten; Afshar, Maziar; Feili, Dara; Seidel, Helmut

    2011-03-01

    In recent years two-photon photopolymerization has emerged as a novel and extremely powerful technique of three-dimensional nanostructure formation. Complex-shaped structures can be generated using appropriate beam steering or nanopositioning systems. Here, we report on the fabrication of three-dimensional arrangements made of biocompatible polymer material, which can be used as templates for cell growth. Using three-dimensional cell cages as cell culture substrates is advantageous, as cells may develop in a more natural environment as compared to conventional planar growth methods. The two-photon fabrication experiments were carried out on a commercial microscope setup. Sub-15 fs pulsed Ti:Sapphire laser light (centre wavelength 800 nm, bandwidth 120 nm, repetition rate 85 MHz) was focused into the polymer material by a high-numerical aperture oil immersion objective. Due to the high peak intensities picojoule pulse energies in the focal spot are sufficient to polymerize the material at sub-100 nm structural element dimensions. Therefore, cell cages of sophisticated architecture can be constructed involving very fine features which take into account the specific needs of various types of cells. Ultimately, our research aims at three-dimensional assemblies of photopolymerized structural elements involving sub-100 nm features, which provide cell culture substrates far superior to those currently existing.

  6. Generation of pulsed ion beams by an inductive storage pulsed power generator

    Science.gov (United States)

    Katsuki, Sunao; Akiyama, Hidenori; Maeda, Sadao

    1990-10-01

    A pulsed power generator by an inductive energy storage system is extremely compact and light in comparison with a conventional pulsed power generator, which consists of a Marx bank and a water pulse forming line. A compact and light pulse power generator is applied to the generation of pulsed ion beams. A thin copper fuse is used an an opening switch, which is necessary in the inductive storage pulsed power generator. A magnetically insulated diode is used for the generation of ion beams. The pulsed ion beams are successfully generated by the inductive storage pulsed power generator for the first time.

  7. Parabolic similariton Yb-fiber laser with triangular pulse evolution

    Science.gov (United States)

    Wang, Sijia; Wang, Lei

    2016-04-01

    We propose a novel mode-locked fiber laser design which features a passive nonlinear triangular pulse formation and self-similar parabolic pulse amplification intra cavity. Attribute to the nonlinear reshaping progress in the passive fiber, a triangular-profiled pulse with negative-chirp is generated and paved the way for rapid and efficient self-similar parabolic evolution in a following short-length high-gain fiber. In the meanwhile, the accompanied significantly compressed narrow spectrum from this passive nonlinear reshaping also gives the promise of pulse stabilization and gain-shaping robustness without strong filtering. The resulting short average intra-cavity pulse duration, low amplified spontaneous emission (ASE) and low intra-cavity power loss are essential for the low-noise operation. Simulations predict this modelocked fiber laser allows for high-energy ultra-short transform-limited pulse generation exceeding the gain bandwidth. The output pulse has a de-chirped duration (full-width at half maximum, FWHM) of 27 fs. In addition to the ultrafast laser applications, the proposed fiber laser scheme can support low-noise parabolic and triangular pulse trains at the same time, which are also attractive in optical pulse shaping, all-optical signal processing and high-speed communication applications.

  8. Efficient broadband 400  nm noncollinear second-harmonic generation of chirped femtosecond laser pulses in BBO and LBO.

    Science.gov (United States)

    Gobert, O; Mennerat, G; Maksimenka, R; Fedorov, N; Perdrix, M; Guillaumet, D; Ramond, C; Habib, J; Prigent, C; Vernhet, D; Oksenhendler, T; Comte, M

    2014-04-20

    We report on 400 nm broadband type I frequency doubling in a noncollinear geometry with pulse-front-tilted and chirped femtosecond pulses (λ =800  nm; Fourier transform limited pulse duration, 45 fs). With moderate power densities (2 to 10  GW/cm2) thus avoiding higher-order nonlinear phenomena, the energy conversion efficiency was up to 65%. Second-harmonic pulses of Fourier transform limited pulse duration shorter than the fundamental wave were generated, exhibiting good beam quality and no pulse-front tilt. High energy (20 mJ/pulse) was produced in a 40 mm diameter and 6 mm thick LBO crystal. To the best of our knowledge, this is the first demonstration of this optical configuration with sub-100-fs pulses. Good agreement between experimental results and simulations is obtained.

  9. Ultrashort pulse laser technology laser sources and applications

    CERN Document Server

    Schrempel, Frank; Dausinger, Friedrich

    2016-01-01

    Ultrashort laser pulses with durations in the femtosecond range up to a few picoseconds provide a unique method for precise materials processing or medical applications. Paired with the recent developments in ultrashort pulse lasers, this technology is finding its way into various application fields. The book gives a comprehensive overview of the principles and applications of ultrashort pulse lasers, especially applied to medicine and production technology. Recent advances in laser technology are discussed in detail. This covers the development of reliable and cheap low power laser sources as well as high average power ultrashort pulse lasers for large scale manufacturing. The fundamentals of laser-matter-interaction as well as processing strategies and the required system technology are discussed for these laser sources with respect to precise materials processing. Finally, different applications within medicine, measurement technology or materials processing are highlighted.

  10. Subthreshold pair production in short laser pulses

    CERN Document Server

    Nousch, T; Kampfer, B; Titov, A I

    2012-01-01

    The $e^+e^-$ pair production by a probe photon traversing a linearly polarized laser pulse is treated as generalized nonlinear Breit-Wheeler process. For short laser pulses with very few oscillations of the electromagnetic field we find below the perturbative weak-field threshold $\\sqrt{s} = 2m$ a similar enhancement of the pair production rate as for circular polarization. The strong subthreshold enhancement is traced back to the finite bandwidth of the laser pulse. A folding model is developed which accounts for the interplay of the frequency spectrum and the intensity distribution in the course of the pulse.

  11. Generation of pulsed light in the visible spectral region based on non-linear cavity dumping

    DEFF Research Database (Denmark)

    Johansson, Sandra; Andersen, Martin; Tidemand-Lichtenberg, Peter

    We propose a novel generic approach for generation of pulsed light in the visible spectrum based on sum-frequency generation between the high circulating intra-cavity power of a high finesse CW laser and a single-passed pulsed laser. For demonstration, we used a CW 1342 nm laser mixed with a pass...

  12. The Use of Ultrashort Picosecond Laser Pulses to Generate Quantum Optical Properties of Single Molecules in Biophysics

    Science.gov (United States)

    Ly, Sonny

    Generation of quantum optical states from ultrashort laser-molecule interactions have led to fascinating discoveries in physics and chemistry. In recent years, these interactions have been extended to probe phenomena in single molecule biophysics. Photons emitted from a single fluorescent molecule contains important properties about how the molecule behave and function in that particular environment. Analysis of the second order coherence function through fluorescence correlation spectroscopy plays a pivotal role in quantum optics. At very short nanosecond timescales, the coherence function predicts photon antibunching, a purely quantum optical phenomena which states that a single molecule can only emit one photon at a time. Photon antibunching is the only direct proof of single molecule emission. From the nanosecond to microsecond timescale, the coherence function gives information about rotational diffusion coefficients, and at longer millisecond timescales, gives information regarding the translational diffusion coefficients. In addition, energy transfer between molecules from dipole-dipole interaction results in FRET, a highly sensitive method to probe conformational dynamics at nanometer distances. Here I apply the quantum optical techniques of photon antibunching, fluorescence correlation spectroscopy and FRET to probe how lipid nanodiscs form and function at the single molecule level. Lipid nanodiscs are particles that contain two apolipoprotein (apo) A-I circumventing a lipid bilayer in a belt conformation. From a technological point of view, nanodiscs mimics a patch of cell membrane that have recently been used to reconstitute a variety of membrane proteins including cytochrome P450 and bacteriorhodopsin. They are also potential drug transport vehicles due to its small and stable 10nm diameter size. Biologically, nanodiscs resemble to high degree, high density lipoproteins (HDL) in our body and provides a model platform to study lipid-protein interactions

  13. Complex Spectra Structure of an Attosecond Pulse Train Driven by Sub-5-fs Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    YUN Chen-Xia; TENG Hao; ZHANG Wei; WANG Li-Feng; ZHAN Min-Jie; HE Xin-Kui; WANG Bing-Bing; WEI Zhi-Yi

    2011-01-01

    We present the observation of the additional spectral components between the odd order harmonics in the harmonic spectrum generated from argon gas driven by sub-5-fs laser pulses.The theoretical analysis shows that the asymmetric laser field in both spatial and temporal domains leads to this complicated spectrum structure of high order harmonics.

  14. Picosecond Pulse Laser Microstructuring of silicon

    Institute of Scientific and Technical Information of China (English)

    赵明; 尹钢; 朱京涛; 赵利

    2003-01-01

    We report the experimental results of picosecond pulse laser microstructuring (pulse duration 35ps, wavelength 1.06μm, repetition rate 10Hz) of silicon using the direct focusing technique. Arrays of sharp conical spikes located below the initial surface have been formed by cumulative picosecond pulsed laser irradiation of silicon in SF6. Irradiation of silicon surface in air, N2, or vacuum creates ripple-like patterns, but does not create the sharp conical spikes.

  15. Pulse properties of external cavity mode locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Kroh, Marcel; Mørk, Jesper

    2006-01-01

    The performance of an external-cavity mode-locked semiconductor laser is investigated both theoretically and experimentally. The optimization analysis focuses on the regimes of stable mode locking and the generation of sub-picosecond optical pulses. We demonstrate stable output pulses down to one...... picosecond duration with more than 30 dB trailing pulse suppression. The limiting factors to the device performance are investigated on the basis of a fully-distributed time-domain model.We find that ultrafast gain dynamics effectively reduce the pulse-shaping strength and inhibit the generation...

  16. Repetitively pulsed TEA CO{sub 2} laser and its application for second harmonic generation in ZnGeP{sub 2} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Koval' chuk, L V; Grezev, A N; Niz' ev, V G; Yakunin, V P [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation); Mezhevov, V S [Kaluga Laser Innovation and Technology Centre, Obninsk, Kaluga region (Russian Federation); Goryachkin, D A [Russian State Scientific Center for Robotics and Technical Cybernetics, St. Petersburg (Russian Federation); Sergeev, V V; Kalintsev, A G [Open Joint Stock Company S.I.Vavilov State Optical Institute, St. Petersburg (Russian Federation)

    2015-10-31

    Experimental results are presented on the development of a radiation source emitting at a wavelength of 4.775 μm with a pulse energy up to 50 mJ and an average power up to several watts in short pulse trains. A TEA CO{sub 2} laser and a nonlinear converter based on a ZnGeP{sub 2} crystal, which are specially designed for these experiments, are described. The main limitations of nonlinear conversion and possible ways to overcome these limitations are considered. (lasers)

  17. Cavity Optical Pulse Extraction: ultra-short pulse generation as seeded Hawking radiation.

    Science.gov (United States)

    Eilenberger, Falk; Kabakova, Irina V; de Sterke, C Martijn; Eggleton, Benjamin J; Pertsch, Thomas

    2013-01-01

    We show that light trapped in an optical cavity can be extracted from that cavity in an ultrashort burst by means of a trigger pulse. We find a simple analytic description of this process and show that while the extracted pulse inherits its pulse length from that of the trigger pulse, its wavelength can be completely different. Cavity Optical Pulse Extraction is thus well suited for the development of ultrashort laser sources in new wavelength ranges. We discuss similarities between this process and the generation of Hawking radiation at the optical analogue of an event horizon with extremely high Hawking temperature. Our analytic predictions are confirmed by thorough numerical simulations.

  18. Laser Pulsing in Linear Compton Scattering

    CERN Document Server

    Krafft, Geoffrey; Deitrick, Kirsten; Terzic, Balsa; Kelmar, R; Hodges, Todd; Melnitchouk, W; Delayen, Jean

    2016-01-01

    Previous work on calculating energy spectra from Compton scattering events has either neglected considering the pulsed structure of the incident laser beam, or has calculated these effects in an approximate way subject to criticism. In this paper, this problem has been reconsidered within a linear plane wave model for the incident laser beam. By performing the proper Lorentz transformation of the Klein-Nishina scattering cross section, a spectrum calculation can be created which allows the electron beam energy spread and emittance effects on the spectrum to be accurately calculated, essentially by summing over the emission of each individual electron. Such an approach has the obvious advantage that it is easily integrated with a particle distribution generated by particle tracking, allowing precise calculations of spectra for realistic particle distributions in collision. The method is used to predict the energy spectrum of radiation passing through an aperture for the proposed Old Dominion University inverse...

  19. Pulse radiolysis of liquid water using picosecond electron pulses produced by a table-top terawatt laser system

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Ned [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Flippo, Kirk [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Nemoto, Koshichi [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Umstadter, Donald [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Crowell, Robert A. [Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Jonah, Charles D. [Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Trifunac, Alexander D. [Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2000-06-01

    A laser based electron generator is shown, for the first time, to produce sufficient charge to conduct time resolved investigations of radiation induced chemical events. Electron pulses generated by focussing terawatt laser pulses into a supersonic helium gas jet are used to ionize liquid water. The decay of the hydrated electrons produced by the ionizing electron pulses is monitored with 0.3 {mu}s time resolution. Hydrated electron concentrations as high as 22 {mu}M were generated. The results show that terawatt lasers offer both an alternative to linear accelerators and a means to achieve subpicosecond time resolution for pulse radiolysis studies. (c) 2000 American Institute of Physics.

  20. High-Precision Pulse Generator

    Science.gov (United States)

    Katz, Richard; Kleyner, Igor

    2011-01-01

    A document discusses a pulse generator with subnanosecond resolution implemented with a low-cost field-programmable gate array (FPGA) at low power levels. The method used exploits the fast carry chains of certain FPGAs. Prototypes have been built and tested in both Actel AX and Xilinx Virtex 4 technologies. In-flight calibration or control can be performed by using a similar and related technique as a time interval measurement circuit by measuring a period of the stable oscillator, as the delays through the fast carry chains will vary as a result of manufacturing variances as well as the result of environmental conditions (voltage, aging, temperature, and radiation).

  1. Short pulse laser systems for biomedical applications

    CERN Document Server

    Mitra, Kunal

    2017-01-01

    This book presents practical information on the clinical applications of short pulse laser systems and the techniques for optimizing these applications in a manner that will be relevant to a broad audience, including engineering and medical students as well as researchers, clinicians, and technicians. Short pulse laser systems are useful for both subsurface tissue imaging and laser induced thermal therapy (LITT), which hold great promise in cancer diagnostics and treatment. Such laser systems may be used alone or in combination with optically active nanoparticles specifically administered to the tissues of interest for enhanced contrast in imaging and precise heating during LITT. Mathematical and computational models of short pulse laser-tissue interactions that consider the transient radiative transport equation coupled with a bio-heat equation considering the initial transients of laser heating were developed to analyze the laser-tissue interaction during imaging and therapy. Experiments were first performe...

  2. Pulsed pumping of semiconductor disk lasers.

    Science.gov (United States)

    Hempler, Nils; Hopkins, John-Mark; Kemp, Alan J; Schulz, Nico; Rattunde, Marcel; Wagner, Joachim; Dawson, Martin D; Burns, David

    2007-03-19

    Efficient operation of semiconductor disk lasers is demonstrated using uncooled and inexpensive 905nm high-power pulsed semiconductor pump lasers. Laser emission, with a peak power of 1.7W, is obtained from a 2.3mum semiconductor disk laser. This is seven times the power achieved under continuous pumping. Analysis of the time-dependent spectral characteristics of the laser demonstrate that significant device heating occurs over the 100-200ns duration of the pumping pulse - finite element modelling of the thermal processes is undertaken in support of these data. Spectral narrowing to below 0.8nm is obtained by using an intra-cavity birefringent filter.

  3. a Portable Pulsed Neutron Generator

    Science.gov (United States)

    Skoulakis, A.; Androulakis, G. C.; Clark, E. L.; Hassan, S. M.; Lee, P.; Chatzakis, J.; Bakarezos, M.; Dimitriou, V.; Petridis, C.; Papadogiannis, N. A.; Tatarakis, M.

    2014-02-01

    The design and construction of a pulsed plasma focus device to be used as a portable neutron source for material analysis such as explosive detection using gamma spectroscopy is presented. The device is capable of operating at a repetitive rate of a few Hz. When deuterium gas is used, up to 105 neutrons per shot are expected to be produced with a temporal pulse width of a few tens of nanoseconds. The pulsed operation of the device and its portable size are its main advantage in comparison with the existing continuous neutron sources. Parts of the device include the electrical charging unit, the capacitor bank, the spark switch (spark gap), the trigger unit and the vacuum-fuel chamber / anode-cathode. Numerical simulations are used for the simulation of the electrical characteristics of the device including the scaling of the capacitor bank energies with total current, the pinch current, and the scaling of neutron yields with energies and currents. The MCNPX code is used to simulate the moderation of the produced neutrons in a simplified geometry and subsequently, the interaction of thermal neutrons with a test target and the corresponding prompt γ-ray generation.

  4. Exawatt-Zettawatt Pulse Generation and Applications

    OpenAIRE

    Mourou, G. A.; Fisch, N. J.; Malkin, V. M.; Toroker, Z.; Khazanov, E. A.; Sergeev, A. M.; TAJIMA, T.

    2011-01-01

    A new amplification method, weaving the three basic compression techniques, Chirped Pulse Amplification (CPA), Optical Parametric Chirped Pulse Amplification (OPCPA) and Plasma Compression by Backward Raman Amplification (BRA) in plasma, is proposed. It is called C3 for Cascaded Conversion Compression. It has the capability to compress with good efficiency kilojoule to megajoule, nanosecond laser pulses into femtosecond pulses, to produce exawatt and beyond peak power. In the future, C3 could...

  5. Supression of laser breakdown by pulsed nonequilibrium ns discharge

    Science.gov (United States)

    Starikovskiy, A. Y.; Semenov, I. E.; Shneider, M. N.

    2016-10-01

    The avalanche ionization induced by infrared laser pulses was investigated in a pre-ionized argon gas. Pre-ionization was created by a high-voltage pulsed nanosecond discharge developed in the form of a fast ionization wave. Then, behind the front of ionization wave additional avalanche ionization was initiated by the focused Nd-YAG laser pulse. It was shown that the gas pre-ionization inhibits the laser spark generation. It was demonstrated that the suppression of laser spark development in the case of strong gas pre-ionization is because of fast electron energy transfer from the laser beam focal region. The main mechanism of this energy transfer is free electrons diffusion.

  6. High Power Picosecond Laser Pulse Recirculation

    Energy Technology Data Exchange (ETDEWEB)

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

    2010-04-12

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  7. High-power picosecond laser pulse recirculation.

    Science.gov (United States)

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P J

    2010-07-01

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high-power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering-based light sources. We demonstrate up to 40x average power enhancement of frequency-doubled submillijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  8. Exawatt-Zettawatt Pulse Generation and Applications

    CERN Document Server

    Mourou, G A; Malkin, V M; Toroker, Z; Khazanov, E A; Sergeev, A M; Tajima, T

    2011-01-01

    A new amplification method, weaving the three basic compression techniques, Chirped Pulse Amplification (CPA), Optical Parametric Chirped Pulse Amplification (OPCPA) and Plasma Compression by Backward Raman Amplification (BRA) in plasma, is proposed. It is called C3 for Cascaded Conversion Compression. It has the capability to compress with good efficiency kilojoule to megajoule, nanosecond laser pulses into femtosecond pulses, to produce exawatt and beyond peak power. In the future, C3 could be used at large-scale facilities such as the National Ignition Facility (NIF) or the Laser Megajoule (LMJ) and open the way to zettawatt level pulses. The beam will be focused to a wavelength spot size with a f#1. The very small beam size, i.e. few centimeters, along with the low laser repetition rate laser system will make possible the use of inexpensive, precision, disposable optics. The resulting intensity will approach the Schwinger value, thus opening up new possibilities in fundamental physics.

  9. Tunable CO2 laser system with subnanosecond-pulse-train output

    Science.gov (United States)

    Kimura, W. D.

    2017-02-01

    A CO2 laser system has been demonstrated that generates a train of subnanosecond pulses tunable over the P and R branches of the CO2 laser spectrum at 9-11 μm. It utilizes optical free induction decay to generate a single 100-ps laser pulse from a tunable transverse-excited-atmospheric CO2 laser. This laser pulse is injection-seeded into a high-pressure CO2 oscillator whose output consists of a train of amplified 100-ps pulses with maximum pulse energy of 30 mJ, corresponding to a peak power of 300 MW. The 100-ps, tunable, infrared laser pulses are needed for a new technique to remotely detect atmospheric gaseous molecules, which relies on the train of CO2 laser pulses selectively exciting the target molecules whose presence is then revealed using a separate terahertz probe beam.

  10. Propagating Characteristics of Pulsed Laser in Rain

    Directory of Open Access Journals (Sweden)

    Jing Guo

    2015-01-01

    Full Text Available To understand the performance of laser ranging system under the rain weather condition, we need to know the propagating characteristics of laser pulse in rain. In this paper, the absorption and attenuation coefficients were calculated based on the scattering theories in discrete stochastic media, and the propagating characteristics of laser pulse in rain were simulated and analyzed using Monte-Carlo method. Some simulation results were verified by experiments, and the simulation results are well matched with the experimental data, with the maximal deviation not less than 7.5%. The results indicated that the propagating laser beam would be attenuated and distorted due to the scattering and absorption of raindrops, and the energy attenuation and pulse shape distortion strongly depended on the laser pulse widths.

  11. Laser sclerostomy by pulsed-dye laser and goniolens

    Energy Technology Data Exchange (ETDEWEB)

    Latina, M.A.; Dobrogowski, M.; March, W.F.; Birngruber, R. (Massachusetts General Hospital, Boston (USA))

    1990-12-01

    We describe an ab-interno laser sclerostomy procedure using the method termed dye-enhanced ablation with a slit-lamp delivery system and special goniolens such that only the laser light beam penetrates the anterior chamber. The procedure uses a microsecond-pulsed-dye laser emitting at 666 nm and iontophoresis of methylene blue dye (absorption of 668 nm) into the sclera at the limbus to enhance the absorption of the laser light. We compared the number of pulses needed to perforate excised human sclera at pulse durations of 1.5, 20, and 300 microseconds. Pulse durations of 1.5 and 20 microseconds required 20 pulses or fewer to perforate excised human sclera with pulse energies of 75 to 100 mJ. The ab-interno laser sclerostomy procedure was performed in 54 eyes of Dutch-belted rabbits with pulse durations of 1.5 or 20 microseconds and a 100- or 200-microns incident spot diameter delivered using a CGF goniolens. Full-thickness fistulas were successfully created at both pulse durations in approximately 80% of eyes treated. A range of three to 25 pulses was required to perforate sclera with slightly fewer pulses and lower pulse energies at 1.5 microseconds compared with 20 microseconds. There were no significant complications from the procedure. This technique could permit filtration surgery to be performed on an outpatient basis.

  12. Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

    Science.gov (United States)

    Hu, Wenqian; Shin, Yung C.; King, Galen B.

    2012-01-01

    Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11. Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps). Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators. PMID:22806170

  13. Direct generation of 2  W average-power and 232  nJ picosecond pulses from an ultra-simple Yb-doped double-clad fiber laser.

    Science.gov (United States)

    Huang, Yizhong; Luo, Zhengqian; Xiong, Fengfu; Li, Yingyue; Zhong, Min; Cai, Zhiping; Xu, Huiying; Fu, Hongyan

    2015-03-15

    We report the generation of 2.06 W average-power and 232 nJ picosecond mode-locked pulses directly from an ultra-simple Yb-doped fiber laser. A section of Yb-doped double-clad fiber pumped by a 976 nm laser diode provides the large gain, and the linear cavity is simply formed by a 1064 nm highly reflective fiber Bragg grating and a fiber loop mirror (FLM) using a 5/95 optical coupler. The asymmetric FLM not only acts as the output mirror for providing ∼20% optical feedback, but also equivalently behaves as a nonlinear optical loop mirror (NOLM) to initiate the mode-locking operation in this cavity. Stable mode-locking is therefore achieved over a pump power of 3.76 W. The mode-locked pulses show the dissipative soliton resonance (DSR), which has the pulse duration of 695 ps to ∼1  ns, and the almost unchanged peak power of ∼200  W as increasing the pump power. In particular, this laser can emit 232 nJ high-energy DSR pulses with an average output power of >2  W. This is, to the best of our knowledge, the first demonstration of such an ultra-simple, mode-locked fiber laser that enables watt-level, high energy, picosecond DSR pulses.

  14. Hybrid mode-locking in pulsed ytterbium fiber laser with carbon nanotube saturable absorber

    Science.gov (United States)

    Khudyakov, Dmitry V.; Borodkin, Andrey A.; Lobach, Anatoly S.; Vartapetov, Sergey K.

    2015-10-01

    Ultrafast pulse generation in all-normal dispersion Yb-doped fiber laser on 1.04 μm have been reported. Stable self-starting pulse generation in output of the ring fiber laser have been investigated where nonlinear polarization rotation interacted with contribution from the single walled carbon nanotube saturable absorber. Laser pulses with 0.7 nJ pulse energy and 1.7 ps pulse width at 35.6 MHz repetition rate were achieved. The output pulse could be externally compressed to width of 180 fs by pair of gratings.

  15. Pulse power for lasers; Proceedings of the Meeting, Los Angeles, CA, Jan. 13, 14, 1987

    Science.gov (United States)

    Burkes, Tommy R.

    Papers are presented on high energy lasers which use advanced thyratron switches; pulsed power for repetitively pulsed high power discharge lasers; Nova pulse power design and operation; the power oscillator circuit modeling and redesign of the particle beam fusion accelerator II switch trigger laser; and a compact, efficient, solid-state flashlamp modulator. Topics discussed include the effects of laser discharge impedance on circuit designs; pulsed power for high power electron-beam pumped lasers; a pulse forming network of low inductance and large energy storage density; an integrated high efficiency switched mode laser power supply; and a parallel thyratron pulser with magnetic sharpening for large NgBr lasers. Consideration is given to the gating of thyristors; high repetition rate pseudospark switches for laser applications; the use of the molecular photoelectron-detachment and photodissociation process to switch electron conduction current; electron beam and optical control of bulk semiconductor switches; and scaling pulse generators for lasers.

  16. High-harmonic generation: Ultrafast lasers yield X-rays

    NARCIS (Netherlands)

    McKinnie, Iain; Kapteyn, Henry

    2010-01-01

    Table-top sources that generate both extreme ultraviolet light and soft X-rays through high-harmonic generation of ultrafast infrared laser pulses look set to perform tasks previously accessible using only large-scale synchrotrons.

  17. The interaction of intense subpicosecond laser pulses with underdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Coverdale, C.A.

    1995-05-11

    Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 10{sup 16} W/cm{sup 2} laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by L{sub plasma} {ge} 2L{sub Rayleigh} > c{tau}. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (n{sub o} {le} 0.05n{sub cr}). Specifically, the parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in {omega}-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

  18. The interaction of intense subpicosecond laser pulses with underdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Coverdale, Christine Ann [Univ. of California, Davis, CA (United States)

    1995-05-11

    Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 1016 W/cm2 laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by Lplasma ≥ 2LRayleigh > cτ. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (no ≤ 0.05ncr). Specifically, the parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in ω-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

  19. Short pulse generation and high speed communication system

    Science.gov (United States)

    Fan, Honglei

    Ultrahigh-speed optical time-division-multiplexing (TDM) transmission technologies are essential to construct ultrahigh-speed all-optical networks needed in the multimedia era. In order to realize high-speed optical TDM systems, ultra-short pulses should be generated. In this dissertation, the gain switching and mode locking techniques have been analyzed and used to produce ultra- short pulses. Gain-switched pulses with a width of ~18ps have been obtained. The theoretical analysis on gain-switching phenomena has been carried out. A new approach for the simulation of the spectrum of a gain- switched laser has been developed. The principle of mode locking has been discussed. ~6.5ps, pulses have been obtained from a monolithic mode-locked distributed Bragg reflector (DBR) laser, which are the shortest pulses from the actively mode- locked DBR lasers as we know. ~1.1ps pulses have been achieved from a colliding-pulse mode-locked (CPM) laser. The operation principle of CPM lasers has been discussed. Pulse compression using dispersion-compensating fiber has been applied in order to get shorter pulses. The semiconductor optical amplifier (SOA) plays a very important role in TDM systems. The cross gain modulation (XGM) measurements on a 2-section SOA, using both cw and pulsed pump and probe beams, have been performed. A theoretical analysis has been carried out. Wavelength conversion and fiber transmission experiments have been achieved at different bit rates. The basic idea of TDM system has been discussed. Multiplexing has been achieved using fibers. Demulitplexing has been demonstrated using XGM in SOA, four-wave mixing (FWM) in SOA, and cascaded modulators. The operation principles have been discussed in detail. The FWM experiments between two optical pulses have been performed.

  20. Pulsed Laser Cladding of Ni Based Powder

    Science.gov (United States)

    Pascu, A.; Stanciu, E. M.; Croitoru, C.; Roata, I. C.; Tierean, M. H.

    2017-06-01

    The aim of this paper is to optimize the operational parameters and quality of one step Metco Inconel 718 atomized powder laser cladded tracks, deposited on AISI 316 stainless steel substrate by means of a 1064 nm high power pulsed laser, together with a Precitec cladding head manipulated by a CLOOS 7 axes robot. The optimization of parameters and cladding quality has been assessed through Taguchi interaction matrix and graphical output. The study demonstrates that very good cladded layers with low dilution and increased mechanical proprieties could be fabricated using low laser energy density by involving a pulsed laser.

  1. Measurement of pulse lengthening with pulse energy increase in picosecond Nd:YAG laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Cutolo, A.; Zeni, L.; Berardi, V.; Bruzzese, R.; Solimeno, S.; Spinelli, N.

    1989-03-15

    Taking advantage of a new technique, we have monitored the relative variations of time duration and mode size as a function of the pulse energy for 30-ps-long Nd:YAG laser pulses. In particular, by carrying out a statistical analysis, we have observed that the pulse time duration is an increasing function of the pulse energy, according to the theoretical modeling of passively mode-locked lasers. The measurements can be easily extended to the femtosecond regime.

  2. Components for monolithic fiber chirped pulse amplification laser systems

    Science.gov (United States)

    Swan, Michael Craig

    The first portion of this work develops techniques for generating femtosecond-pulses from conventional fabry-perot laser diodes using nonlinear-spectral-broadening techniques in Yb-doped positive dispersion fiber ampliers. The approach employed an injection-locked fabry-perot laser diode followed by two stages of nonlinear-spectral-broadening to generate sub-200fs pulses. This thesis demonstrated that a 60ps gain-switched fabry-perot laser-diode can be injection-locked to generate a single-longitudinal-mode pulse and compressed by nonlinear spectral broadening to 4ps. Two problems have been identified that must be resolved before moving forward with this approach. First, gain-switched pulses from a standard diode-laser have a number of characteristics not well suited for producing clean self-phase-modulation-broadened pulses, such as an asymmetric temporal shape, which has a long pulse tail. Second, though parabolic pulse formation occurs for any arbitrary temporal input pulse profile, deviation from the optimum parabolic input results in extensively spectrally modulated self-phase-modulation-broadened pulses. In conclusion, the approach of generating self-phase-modulation-broadened pulses from pulsed laser diodes has to be modified from the initial approach explored in this thesis. The first Yb-doped chirally-coupled-core ber based systems are demonstrated and characterized in the second portion of this work. Robust single-mode performance independent of excitation or any other external mode management techniques have been demonstrated in Yb-doped chirally-coupled-core fibers. Gain and power efficiency characteristics are not compromised in any way in this novel fiber structure up to the 87W maximum power achieved. Both the small signal gain at 1064nm of 30.3dB, and the wavelength dependence of the small signal gain were comparable to currently deployed large-mode-area-fiber technology. The efficiencies of the laser and amplifier were measured to be 75% and 54

  3. Effects of cavity-dispersion noncoaxiality on the generation of ultrabroadband femtosecond pulses

    Institute of Scientific and Technical Information of China (English)

    JIAO ZhongXing; LEI Liang; HUANG ZhiLing; WEN JinHui; LAI Tianshu; LIN WeiZhu

    2008-01-01

    The effects of cavity-dispersion noncoaxiality (CDN) on the generation of ultrabroadband femtosecond pulses in KLM Ti:sapphire laser were investigated theoretically and experimentally. It was predicted that when the laser sub-cavity works near the coaxial operation point, the limitation of CDN on the bandwidth broadening is minimum, which is favorable for ultrabroadband pulse generation. On the basis of this prediction, femtosecond pulses with bandwidth of 650 to 1000 nm were directly generated from a home built KLM Ti:sapphire laser. To our knowledge, they are the broadest bandwidth pulses produced from KLM Ti:sapphire laser with similar oscillator configuration and gain crystal length of 3 mm.

  4. Intense ultrashort terahertz pulses: generation and applications

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Matthias C [Max Planck Research Department for Structural Dynamics, University of Hamburg, CFEL, 22607 Hamburg (Germany); Fueloep, Jozsef Andras, E-mail: matthias.c.hoffmann@mpsd.cfel.de, E-mail: fulop@fizika.ttk.pte.hu [Department of Experimental Physics, University of Pecs, Ifjusag u. 6, 7624 Pecs (Hungary)

    2011-03-02

    Ultrashort terahertz pulses derived from femtosecond table-top sources have become a valuable tool for time-resolved spectroscopy during the last two decades. Until recently, the pulse energies and field strengths of these pulses have been generally too low to allow for the use as pump pulses or the study of nonlinear effects in the terahertz range. In this review article we will describe methods of generation of intense single cycle terahertz pulses with emphasis on optical rectification using the tilted-pulse-front pumping technique. We will also discuss some applications of these intense pulses in the emerging field of nonlinear terahertz spectroscopy. (topical review)

  5. Evolution Strategies for Laser Pulse Compression

    NARCIS (Netherlands)

    Monmarché, Nicolas; Fanciulli, Riccardo; Willmes, Lars; Talbi, El-Ghazali; Savolainen, Janne; Collet, Pierre; Schoenauer, Marc; van der Walle, P.; Lutton, Evelyne; Back, Thomas; Herek, Jennifer Lynn

    2008-01-01

    This study describes first steps taken to bring evolutionary optimization technology from computer simulations to real world experimentation in physics laboratories. The approach taken considers a well understood Laser Pulse Compression problem accessible both to simulation and laboratory experiment

  6. High peak-power picosecond pulse generation at 1.26 µm using a quantum-dot-based external-cavity mode-locked laser and tapered optical amplifier.

    Science.gov (United States)

    Ding, Y; Aviles-Espinosa, R; Cataluna, M A; Nikitichev, D; Ruiz, M; Tran, M; Robert, Y; Kapsalis, A; Simos, H; Mesaritakis, C; Xu, T; Bardella, P; Rossetti, M; Krestnikov, I; Livshits, D; Montrosset, Ivo; Syvridis, D; Krakowski, M; Loza-Alvarez, P; Rafailov, E

    2012-06-18

    In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetition-rate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chirped volume Bragg grating which was used as an external cavity output coupler. An average power of 208.2 mW, pulse energy of 321 pJ, and peak power of 30.3 W were achieved. Preliminary nonlinear imaging investigations indicate that this system is promising as a high peak-power pulsed light source for nonlinear bio-imaging applications across the 1.0 μm - 1.3 μm spectral range.

  7. Some features of generation of spoke-shaped neodyminum lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dzhibladze, M.I.; Lazarev, L.E.

    1982-08-01

    Experimental results are presented on the generation properties of spoke-shaped neodymium lasers in the periodic giant pulse regime. In lasers with polished end-faces, two types of pulses were observed, corresponding to longitudinal and circular types of oscillation. It is shown that the energetic characteristics of generation in spoke-shaped neodymium lasers improve greatly when circular types of oscillation are suppressed.

  8. Generation of NiO nanoparticles via pulsed laser ablation in deionised water and their antibacterial activity

    Science.gov (United States)

    Khashan, Khawla S.; Sulaiman, Ghassan M.; Hamad, Abubaker H.; Abdulameer, Farah A.; Hadi, Assel

    2017-03-01

    Nickel oxide (NiO) nanoparticles were synthesised by nanosecond laser ablation in deionised water. Spherical NiO nanoparticles with sizes ranging from 2 to 21 nm were produced. The optical absorption spectra of the nanoparticles were measured using UV-VIS spectroscopy, and their size distribution was characterised using transmission electron microscopy (TEM). The crystalline material structures were investigated using X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FTIR) was used to obtain infrared spectra of the samples. The results show that crystalline NiO nanoparticles were produced. The antibacterial activity of the nanoparticles against Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and Staphylococcus aureus bacteria was then examined. It was found that the NiO nanoparticles have a synergistic effect on inhibiting E. coli and S. aureus growth; this effect was also tested using the well-diffusion method. In this method, NiO nanoparticles at a concentration of 1000 µg ml-1 along with amoxicillin yielded an inhibition zone against E. coli of 14.3 ± 1.15 mm; this zone was 12.6 ± 0.57 mm against S. aureus. Therefore, from the present findings, it can be concluded that the efficiency of inhibiting bacterial growth could be improved by the addition of metal-oxide nanoparticles to amoxicillin in comparison with either pure amoxicillin or pure metal-oxide nanoparticles.

  9. Pulsed lasers in dentistry: sense or nonsense?

    Science.gov (United States)

    Koort, Hans J.; Frentzen, Matthias

    1991-05-01

    The great interest in the field of laser applications in dentistry provokes the question, if all these new techniques may really fulfill advantages, which are expected after initial in-vitro studies. Whereas laser surgery of soft oral tissues has been developed to a standard method, laser treatment of dental hard tissues and the bone are attended with many unsolved problems. Different laser types, especially pulsed lasers in a wide spectrum of wavelengths have been proofed for dental use. Today neither the excimer lasers, emitting in the far uv-range from 193 to 351 nm, nor the mid-infrared lasers like Nd:YAG (1,064 μm), Ho:YAG (2,1 μm) and Er:YAG (2,96 μm) or the C02-laser (10,6 μm) show mechanism of interaction more carefully and faster than a preparation of teeth with diamond drillers. The laser type with the most precise and considerate treatment effects in the moment is the short pulsed (15 ns) ArF-excimer laser with a wavelength of 193 nm. However this laser type has not yet the effectivity of mechanical instruments and it needs a mirror system to deliver the radiation. Histological results point out, that this laser shows no significant pathological alterations in the adjacent tissues. Another interesting excimer laser, filled with XeCI and emitting at a wavelength of 308 nm has the advantage to be good to deliver through quartz fibers. A little more thermal influence is to be seen according to the longer wavelength. Yet the energy density, necessary to cut dental hard tissues will not be reached with the laser systems available now. Both the pulsed Er:YAG- (2,94 μm, pulse duration 250 s) and the Ho:YAG -laser (2,1 μm, pulse duration 250 μs) have an effective coupling of the laser energy to hydrogeneous tissues, but they do not work sufficient on healthy enamel and dentine. The influence to adjacent healthy tissue is not tolerable, especially in regard of the thermal damage dentine and pulp tissues. Moreover, like the 193 nm ArF-excimer laser

  10. Phosphate Nd:glass materials for femtosecond pulse generation

    Science.gov (United States)

    Agnesi, Antonio; Carrà, Luca; Reali, Giancarlo

    2008-08-01

    Two different phosphate Nd-doped glasses have been investigated in a diode-pumped femtosecond laser. To our knowledge, only Schott's phosphate glasses were previously used in femtosecond oscillators. A slightly different behaviour was observed in our experiments, with respect to earlier reports: clean sech 2-pulses with duration <400 fs were routinely generated with wavelength corresponding to the fluorescence peak ≈1054 nm, whereas shorter pulses occurred at red-shifted wavelengths near 1067 nm. With a single 1-W pump diode (broad area emitter), cw slope efficiency as high as 32% and 139-fs pulse generation were demonstrated.

  11. Laser generating metallic components

    Science.gov (United States)

    McLean, Marc A.; Shannon, G. J.; Steen, William M.

    1997-04-01

    Recent developments in rapid prototyping have led to the concept of laser generating, the first additive manufacturing technology. This paper presents an innovative process of depositing multi-layer tracks, by fusing successive powder tracks, to generate three dimensional components, thereby offering an alternative to casting for small metal component manufacture. A coaxial nozzle assembly has been designed and manufactured enabling consistent omni-directional multi-layer deposition. In conjunction with this the software route from a CAD drawing to machine code generation has been established. The part is manufactured on a six axes machining center incorporating a 1.8 kW carbon-dioxide laser, providing an integrated opto-mechanical workstation. The part build-up program is controlled by a P150 host computer, linked directly to the DNC machining center. The direct manufacturing route is shown, including initial examples of simple objects (primitives -- cube, cylinder, cone) leading to more complex turbine blade generation, incorporating build-up techniques and the associated mechanical properties.

  12. Evolution of laser pulse shape in a parabolic plasma channel

    Science.gov (United States)

    Kaur, M.; Gupta, D. N.; Suk, H.

    2017-01-01

    During high-intensity laser propagation in a plasma, the group velocity of a laser pulse is subjected to change with the laser intensity due to alteration in refractive index associated with the variation of the nonlinear plasma density. The pulse front sharpened while the back of the pulse broadened due to difference in the group velocity at different parts of the laser pulse. Thus the distortion in the shape of the laser pulse is expected. We present 2D particle-in-cell simulations demonstrating the controlling the shape distortion of a Gaussian laser pulse using a parabolic plasma channel. We show the results of the intensity distribution of laser pulse in a plasma with and without a plasma channel. It has been observed that the plasma channel helps in controlling the laser pulse shape distortion. The understanding of evolution of laser pulse shape may be crucial while applying the parabolic plasma channel for guiding the laser pulse in plasma based accelerators.

  13. Synchronization of Sub-Picosecond Electron and Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, J.B.; Le Sage G.P.

    2000-08-15

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is subpicosecond, with tens of femtosecond synchronization implied for next-generation experiments. Typically, an RF electron accelerator is synchronized to a short pulse laser system by detecting the repetition signal of a laser oscillator, adjusted to an exact subharmonic of the linac RF frequency, and multiplying or phase locking this signal to produce the master RF clock. Pulse-to-pulse jitter characteristic of self-mode-locked laser oscillators represents a direct contribution to the ultimate timing jitter between a high intensity laser focus and electron beam at the interaction point, or a photocathode drive laser in an RF photoinjector. This timing jitter problem has been addressed most seriously in the context of the RF photoinjector, where the electron beam properties are sensitive functions of relative timing jitter. The timing jitter achieved in synchronized photocathode drive laser systems is near, or slightly below one picosecond. The ultimate time of arrival jitter of the beam at the photoinjector exit is typically a bit smaller than the photocathode drive-laser jitter due to velocity compression effects in the first RF cell of the gun. This tendency of the timing of the electron beam arrival at a given spatial point to lock to the RF lock is strongly reinforced by use of magnetic compression.

  14. Methods of Attosecond X-Ray Pulse Generation

    CERN Document Server

    Zholents, Alexander

    2005-01-01

    Our attitude towards attosecond x-ray pulses has changed dramatically over the past several years. Not long ago x-ray pulses with a duration of a few hundred attoseconds were just science fiction for most of us, but they are already a tool for some researchers in present days. Breakthrough progress in the generation of solitary soft x-ray pulses of attosecond duration has been made by the laser community. Following this lead, people in the free electron laser community have begun to develop new ideas on how to generate attosecond x-ray pulses in the hard x-ray energy range. In this report I will review some of these ideas.

  15. Cluster-assisted generation of multi-charged ions in nanosecond laser ionization of pulsed hydrogen sulfide beam at 1064 and 532 nm

    Institute of Scientific and Technical Information of China (English)

    Niu Dong-Mei; Li Hai-Yang; Luo Xiao-Lin; Liang Feng; Cheng Shuang; Li An-Lin

    2006-01-01

    The multi-charged sulfur ions of Sq+ (q ≤ 6) have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532 nm with an intensity of 1010 ~ 1012W·cm-2. S6+ is the dominant multicharged species at 1064 nm, while S4+, S3+ and S2+ ions are the main multi-charged species at 532 nm. A three-step model (i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing) is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to λ2, λ being the laser wavelength.

  16. Efficient multi-keV x-ray generation from a high-Z target irradiated with a clean ultra-short laser pulse.

    Science.gov (United States)

    Zhang, Z; Nishikino, M; Nishimura, H; Kawachi, T; Pirozhkov, A S; Sagisaka, A; Orimo, S; Ogura, K; Yogo, A; Okano, Y; Ohshima, S; Fujioka, S; Kiriyama, H; Kondo, K; Shimomura, T; Kanazawa, S

    2011-02-28

    Kα line emissions from Mo and Ag plates were experimentally studied using clean, ultrahigh-intensity femtosecond laser pulses. The absolute yields of Kα x-rays at 17 keV from Mo and 22 keV from Ag were measured as a function of the laser pulse contrast ratio and irradiation intensity. Significantly enhanced Kα yields were obtained for both Mo and Ag by employing high contrast ratios and irradiances. Conversion efficiencies of 4.28×10⁻⁵/sr for Mo and 4.84×10⁻⁵/sr for Ag, the highest values obtained to date, were demonstrated with contrast ratios in the range 10⁻¹⁰ to 10⁻¹¹.

  17. Method for Third Harmonic Generation of Double Wavelength and Double Pulse Laser%双波长双脉冲激光三次谐波的产生方法

    Institute of Scientific and Technical Information of China (English)

    谢建平; 陈长水; 王佩琳; 吴云霞; 孙晓红; 明海

    2001-01-01

    The method for third harmonic generation of double wavelength and double pulse laser is proposed. Two pulsed laser beams with different wavelengths are reflected to make them near close and passing through two BBO crystals. Two wavelength second harmonics (SH) of laser pulses are generated after two times passing through the BBO of SHG. SHs and laser fundamental waves pass through the BBO of third harmonic generation (THG) to obtain two wavelength THGs, and couple out by 45° output mirror. The four phase matching conditions are analyzed to be satisfied in SHG and THG. This method can be used to intracavity THG of double wavelength and double pulse laser. The corresponding experimental results are given.%提出双波长双脉冲激光产生三次谐波的方法。波长不同的两脉冲激光束由反射使它们合拢后通过两块非线性的BBO晶体,激光脉冲第一次通过BBO晶体产生两波长的二次谐波(SHG),它们由各自的反射镜反射再次通过BBO又产生了二次谐波,这两次产生的二次谐波和基波通过用于产生三次谐波的BBO晶体可产生双波长的三次谐波,它们由45°斜置的耦合镜输出。文中分析了满足二次谐波和三次谐波的四个相位匹配的条件,该方法也可用于腔内双波长双脉冲的三次谐波激光的产生,给出了相应的实验结果。

  18. Cross-correlation frequency-resolved optical gating of white-light continuum (500-900 nm) generated in bulk media by 1053 nm laser pulses

    Science.gov (United States)

    Imran, T.; Hussain, M.; Figueira, G.

    2016-06-01

    We have efficiently characterized the white-light continuum (WLC) generation covering 500-900 nm in a bulk sapphire plate using 280 fs pulse duration, 1053 nm center-wavelength seed laser pulses. We have acquired the well-optimized smoother region of the WLC spectrum successfully by using an FGS-900 color glass filter (Edmund Optics, Inc.). We have suppressed the spectral components below 500 nm and over 900 nm including an intense 1053 nm residual seed laser peak of the WLC spectrum. The experimental artifacts have been avoided by suppressing the intense 1053 nm seed laser. We employed the sum frequency generation cross-correlation frequency-resolved optical gating (SFG-XFROG) technique for characterization. The XFROG measurement was carried out by introducing the crystal dithering method up to 10° in 2° intervals to obtain the phase matching effectively over the filtered and smoother region of the WLC spectrum. This well-optimized WLC region covering 500-900 nm has significant importance for use as a seed pulse in an optical parametric chirped pulse amplification (OPCPA) system.

  19. Generation of Stable Picosecond Chirp-Free Pulses at 10 GHz from a Nonpolarization Maintaining Regeneratively Mode-Locked Fibre Laser

    Institute of Scientific and Technical Information of China (English)

    TAN Bin; LI Zhi-Yong; WANG Zhao-Ying; GE Chun-Feng; JIA Dong-Fang; NI Wen-Jun; LI Shi-Chen

    2004-01-01

    @@ A 10 GHz regeneratively mode-lockedfibre laser (RMLFL) at 1550nm constructed with commercially available radio frequency components is presented. Chirp-free hyperbolic secant pulses with duration from 4.4ps to 8ps and output reaching 3.6 mW are acquired. Without any cavity length or polarization maintaining mechanism,the error-free operation of this RMLFL can be carried out in room temperature.

  20. Drop Shaping by Laser-Pulse Impact

    NARCIS (Netherlands)

    Klein, A.L.; Bouwhuis, W.; Visser, C.W.; Lhuissier, H.E.; Sun, C.; Snoeijer, J.H.; Villermaux, E.; Lohse, D.; Gelderblom, H.

    2015-01-01

    We show how the deposition of laser energy induces propulsion and strong deformation of an absorbing liquid body. Combining high speed with stroboscopic imaging, we observe that a millimeter-sized dyed water drop hit by a millijoule nanosecond laser pulse propels forward at several meters per second

  1. Beamlet pulse-generation and wavefront-control system

    Energy Technology Data Exchange (ETDEWEB)

    Van Wonterghem, B.M.; Salmon, J.T.; Wilcox, R.W.

    1996-06-01

    The Beamlet pulse-generation system (or {open_quotes}front end{close_quotes}) refers to the laser hardware that generates the spatially and temporally shaped pulse that is injected into the main laser cavity. All large ICF lasers have pulse-generation systems that typically consist of a narrow-band oscillator, elector-optic modulators for temporal and bandwidth shaping, and one or more preamplifiers. Temporal shaping is used to provide the desired laser output pulse shape and also to compensate for gain saturation effects in the large-aperture amplifiers. Bandwidth is applied to fulfill specific target irradiation requirements and to avoid stimulated Brillouin scattering (SBS) in large-aperture laser components. Usually the sharp edge of the beam`s spatial intensity profile is apodized before injection in the main amplifier beam line. This prevents large-amplitude ripples on the intensity profile. Here the authors briefly review the front-end design and discuss improvements to the oscillator and modulator systems. Their main focus, however, is to describe Beamlet`s novel beam-shaping and wavefront-control systems that have recently been fully activated and tested.

  2. Lipase biofilm deposited by Matrix Assisted Pulsed Laser Evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Aronne, Antonio [Department of Chemical Engineering, Materials and Industrial Production, University of Naples “Federico II”, Napoli (Italy); Bloisi, Francesco, E-mail: bloisi@na.infn.it [SPIN – CNR, Naples (Italy); Department of Physics, University of Naples “Federico II”, Napoli (Italy); Calabria, Raffaela; Califano, Valeria [Istituto Motori – CNR, Naples (Italy); Depero, Laura E. [Department of Mechanical and Industrial Engineering, University of Brescia, Brescia (Italy); Fanelli, Esther [Department of Chemical Engineering, Materials and Industrial Production, University of Naples “Federico II”, Napoli (Italy); Federici, Stefania [Department of Mechanical and Industrial Engineering, University of Brescia, Brescia (Italy); Massoli, Patrizio [Istituto Motori – CNR, Naples (Italy); Vicari, Luciano R.M. [SPIN – CNR, Naples (Italy); Department of Physics, University of Naples “Federico II”, Napoli (Italy)

    2015-05-01

    Highlights: • A lipase film was deposited with Matrix Assisted Pulsed Laser Evaporation technique. • FTIR spectra show that laser irradiation do not damage lipase molecule. • Laser fluence controls the characteristics of complex structure generated by MAPLE. - Abstract: Lipase is an enzyme that finds application in biodiesel production and for detection of esters and triglycerides in biosensors. Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique derived from Pulsed Laser Deposition (PLD) for deposition of undamaged biomolecules or polymers, is characterized by the use of a frozen target obtained from a solution/suspension of the guest material (to be deposited) in a volatile matrix (solvent). The presence of the solvent avoids or at least reduces the potential damage of guest molecules by laser radiation but only the guest material reaches the substrate in an essentially solvent-free deposition. MAPLE can be used for enzymes immobilization, essential for industrial application, allowing the development of continuous processes, an easier separation of products, the reuse of the catalyst and, in some cases, enhancing enzyme properties (pH, temperature stability, etc.) and catalytic activity in non-aqueous media. Here we show that MAPLE technique can be used to deposit undamaged lipase and that the complex structure (due to droplets generated during extraction from target) of the deposited material can be controlled by changing the laser beam fluence.

  3. Generation of dual-wavelength square pulse in a figure-eight erbium-doped fiber laser with ultra-large net-anomalous dispersion.

    Science.gov (United States)

    Shao, Zhihua; Qiao, Xueguang; Rong, Qiangzhou; Su, Dan

    2015-08-01

    A type of wave-breaking-free mode-locked dual-wavelength square pulse was experimentally observed in a figure-eight erbium-doped fiber laser with ultra-large net-anomalous dispersion. A 2.7 km long single-mode fiber (SMF) was incorporated as a nonlinear optical loop mirror (NOLM) and provided largely nonlinear phase accumulation and anomalous dispersion, which enhanced the four-wave-mixing effect to improve the stability of the dual-wavelength operation. In the NOLM, the long SMF with small birefringence supported the Sagnac interference as a filter to manage the dual-wavelength lasing. The dual-wavelength operation was made switchable by adjusting the intra-cavity polarization loss and phase delay corresponding to two square pulses. When the pump power was increased, the duration of the square pulse increased continuously while the peak pulse power gradually decreased. This square-type pulse can potentially be utilized for signal transmission and sensing.

  4. Thrust Measurement of Laser Detonation Thruster with a Pulsed Glass Laser

    Science.gov (United States)

    Wang, Bin; Han, Taro; Michigami, Keisuke; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2011-11-01

    Experimental studies were carried out for measuring the laser propulsion thrust with using of a Q-switched Nd:Glass laser. In the tests, a laser beam with 33 ns FWHM pulse width was focused to generate breakdown in the cone-shaped nozzle of aluminum thrusters which were fixed at the end of a ballistic pendulum. The pulse energy used was 1.0 J and the focusing number is 6.27, which gave the highest energy conversion efficiency from laser energy to that of induced blast wave as found in previous research. The momentum coupling coefficient Cm dependency on nozzle apex angles, 30°, 45° and 60°, were investigated with carefully controlling of the laser ignition positions. Results show that, solid-state laser could be a candidate to suffice laser propulsion missions in term of Cm it can achieve.

  5. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement.

    Science.gov (United States)

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-11-01

    A compact multifunctional optical correlator system for pulse width measurement of ultrashort ultraviolet (UV) pulses has been designed and experimentally demonstrated. Both autocorrelation and cross-correlation functions are measured using a single nonlinear crystal, and the switching between two measurements requires no adjustment of phase matching and detector. The system can measure UV pulse widths from sub-picoseconds to 100 ps, and it involves no auxiliary pulse in the measurement. The measurement results on a burst-mode picosecond UV laser show a high-quality performance on speed, accuracy, resolution, and dynamic range. The proposed correlator can be applied to measure any ultrashort UV pulses produced through sum-frequency generation or second-harmonic generation.

  6. Supercontinuum generation in standard telecom fiber using picoseconds pulses

    Science.gov (United States)

    Estudillo-Ayala, J. M.; Rojas-Laguna, R.; Hernandez-Garcia, J. C.; Pottiez, O.; Mata-Chavez, R. I.; Trejo-Duran, M.; Jauregui-Vazquez, D.; Sierra-Hernandez, J. M.; Andrade-Lucio, J. A.

    2012-02-01

    We reported Supercontinuum (SC) generation in standard telecom fiber using picosecond pulses of microchip laser. The pulses width is 700 ps at 1064 nm, using 57 m long of standard fiber, and the spectra extend from 700 to above 1700 nm, some 100 nm further into the visible. The physical processes leading to the formation of the continuum spectrum were studied by monitoring the growth of the SC while increasing the input power. The coupling efficiency of ours experimental setup between the microchip laser and the telecom fiber helped us to obtain this wide spectrum.

  7. Design of efficient single stage chirped pulse difference frequency generation at 7 {\\mu}m driven by a dual wavelength Ti:sapphire laser

    CERN Document Server

    Erny, Christian

    2013-01-01

    We present a design for a high-energy single stage mid-IR difference frequency generation adapted to a two-color Ti:sapphire amplifier system. The optimized mixing process is based on chirped pulse difference frequency generation (CP-DFG), allowing for a higher conversion efficiency, larger bandwidth and reduced two photon absorption losses. The numerical start-to-end simulations include stretching, chirped pulse difference frequency generation and pulse compression. Realistic design parameters for commercially available non linear crystals (GaSe, AgGaS2, LiInSe2, LiGaSe2) are considered. Compared to conventional un-chirped DFG directly pumped by Ti:sapphire technology we report a threefold increase of the quantum efficiency. Our CP-DFG scheme provides up to 340 {\\mu}J pulse energy directly at 7.2 {\\mu}m when pumped with 3 mJ and supports a bandwidth of up to 350 nm. The resulting 240 fs mid-IR pulses are inherently phase stable.

  8. Absorption of a laser light pulse in a dense plasma.

    Science.gov (United States)

    Mehlman-Balloffet, G.

    1973-01-01

    An experimental study of the absorption of a laser light pulse in a transient, high-density, high-temperature plasma is presented. The plasma is generated around a metallic anode tip by a fast capacitive discharge occurring in vacuum. The amount of transmitted light is measured for plasmas made of different metallic ions in the regions of the discharge of high electronic density. Variation of the transmission during the laser pulse is also recorded. Plasma electrons are considered responsible for the very high absorption observed.

  9. Synchronization and Coherent Combining of Two Pulsed Fiber Ring Lasers Based on Direct Phase Modulation

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Lin; ZHOU Pu; MA Hao-Tong; CHEN Zi-Lun; LI Xiao; XU Xiao-Jun; LIU Ze-Jin

    2009-01-01

    We demonstrate a scalable architecture for coherent combining of pulsed fiber ring lasers based on mutual injection and direct phase modulation. By direct phase modulation in the common arm of two ring lasers, synchronous pulsed lasers can be generated and coherent combining of the two synchronous lasers is obtained. Two pulsed fiber ring lasers are coherently combined with 0.55 μJ pulse energy and 10μs pulse duration at a repetition rate of 27.5 kHz. Experimental results show that the two fiber ring lasers are phase locked with an invariable phase difference of π and have good temporal synchronization and spatial coherence. The combining efficiency of the two pulsed fiber laser reaches 90% and the fringe contrast is larger than 40%. Neither active phase control nor polarization control is used in our experiment and this method can be extended to combine more beams and higher repetition rate scaling up to higher power.

  10. Ultra-short pulse laser proton acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Zeil, Karl; Kraft, Stephan; Bussmann, Michael; Cowan, Thomas; Kluge, Thomas; Metzkes, Josefine; Richter, Tom; Schramm, Ulrich [Forschungszentrum Dresden-Rossendorf, Dresden (Germany)

    2010-07-01

    We present a systematic investigation of ultra-short pulse laser acceleration of protons yielding unprecedented maximum proton energies of 17 MeV using the Ti:Sapphire lased high power laser of 100 TW Draco at the Research Centre Dresden-Rossendorf. For plain few micron thick foil targets a linear scaling of the maximum proton energy with laser power is observed and attributed to the short acceleration period close to the target rear surface. Although excellent laser pulse contrast was available slight deformations of the target rear were found to lead to a predictable shift of the direction of the energetic proton emission away from target normal towards the laser direction. The change of the emission characteristics are compared to analytical modelling and 2D PIC simulations.

  11. High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I; Shverdin, M; Gibson, D; Brown, C

    2007-04-17

    Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.

  12. Energy deposition from focused terawatt laser pulses in air

    CERN Document Server

    Point, Guillaume; Mysyrowicz, André; Houard, Aurélien

    2015-01-01

    Laser filamentation is responsible for the deposition of a significant part of the laser pulse energy in the propagation medium. We found that using terawatt laser pulses and relatively tight focusing conditions in air, resulting in a bundle of co-propagating multifilaments, more than 50 % of the pulses energy is transferred to the medium, eventually degrading into heat. This results in a strong hydrodynamic reaction of air with the generation of shock waves and associated underdense channels for each short-scale filament. In the focal zone, where filaments are close to each other, these discrete channels eventually merge to form a single cylindrical low-density tube over a $\\sim 1~ \\mu\\mathrm{s}$ timescale. We measured the maximum lineic deposited energy to be more than 1 J/m.

  13. Spectrotemporal shaping of seeded free-electron laser pulses.

    Science.gov (United States)

    Gauthier, David; Ribič, Primož Rebernik; De Ninno, Giovanni; Allaria, Enrico; Cinquegrana, Paolo; Danailov, Miltcho Bojanov; Demidovich, Alexander; Ferrari, Eugenio; Giannessi, Luca; Mahieu, Benoît; Penco, Giuseppe

    2015-09-11

    We demonstrate the ability to control and shape the spectrotemporal content of extreme-ultraviolet (XUV) pulses produced by a seeded free-electron laser (FEL). The control over the spectrotemporal properties of XUV light was achieved by precisely manipulating the linear frequency chirp of the seed laser. Our results agree with existing theory, which allows us to retrieve the temporal properties (amplitude and phase) of the FEL pulse from measurements of the spectra as a function of the FEL operating parameters. Furthermore, we show the first direct evidence of the full temporal coherence of FEL light and generate Fourier limited pulses by fine-tuning the FEL temporal phase. The possibility of tailoring the spectrotemporal content of intense short-wavelength pulses represents the first step towards efficient nonlinear optics in the XUV to x-ray spectral region and will enable precise manipulation of core-electron excitations using the methods of coherent quantum control.

  14. Long-pulse-width narrow-bandwidth solid state laser

    Science.gov (United States)

    Dane, C.B.; Hackel, L.A.

    1997-11-18

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications. 5 figs.

  15. Circularly Polarized MHOHG with Bichromatic Circularly Polarized Laser Pulses

    Science.gov (United States)

    Bandrauk, Andre D.; Mauger, Francois; Uzer, Turgay

    2016-05-01

    Circularly polarized MHOHG-Molecular High Order Harmonic Generation is shown to occur efficiently with intense ultrashort bichromatic circularly polarized pulses due to frequent electron-parent -ion recollision with co-or counter-rotating incident circular pulses as predicted in 1995. We show in this context that molecules offer a very robust and efficient frameworkfor the production of circularly polarized harmonics for the generation of single circularly polarized ``attosecond'' pulses. The efficiency of such new MHOHG is shown to depend on the compatibility of the symmetry of the molecular medium with the net electric field generated by the combination of the laser pulses.Using a time-dependent symmetry analysis with concrete examples such as H 2 + vs H 3 + we show how all the features(harmonic order and ∧ polarization) of MHOHG can be explained and predicted.

  16. Pulsed Raman fiber laser and multispectral imaging in three dimensions

    DEFF Research Database (Denmark)

    Andersen, Joachim F.; Busck, Jens; Heiselberg, Henning

    2006-01-01

    Raman scattering in single-mode optical fibers is exploited to generate multispectral light from a green nanolaser with high pulse repetition rate. Each pulse triggers a picosecond camera and measures the distance by time-of-flight in each of the 0.5 Mpixels. Three-dimensional images are then con......Raman scattering in single-mode optical fibers is exploited to generate multispectral light from a green nanolaser with high pulse repetition rate. Each pulse triggers a picosecond camera and measures the distance by time-of-flight in each of the 0.5 Mpixels. Three-dimensional images...... are then constructed with submillimeter accuracy for all visible colors. The generation of a series of Stokes peaks by Raman scattering in a Si fiber is discussed in detail and the laser radar technique is demonstrated. The data recording takes only a few seconds, and the high accuracy 3D color imaging works at ranges...

  17. Digital Communication Using Chaotic Pulse Generators

    CERN Document Server

    Rulkov, N F; Tsimring, L S; Volkovskii, A R; Abarbanel, Henry D I; Larson, L; Yao, K

    1999-01-01

    Utilization of chaotic signals for covert communications remains a very promising practical application. Multiple studies indicated that the major shortcoming of recently proposed chaos-based communication schemes is their susceptibility to noise and distortions in communication channels. In this talk we discuss a new approach to communication with chaotic signals, which demonstrates good performance in the presence of channel distortions. This communication scheme is based upon chaotic signals in the form of pulse trains where intervals between the pulses are determined by chaotic dynamics of a pulse generator. The pulse train with chaotic interpulse intervals is used as a carrier. Binary information is modulated onto this carrier by the pulse position modulation method, such that each pulse is either left unchanged or delayed by a certain time, depending on whether ``0'' or ``1'' is transmitted. By synchronizing the receiver to the chaotic pulse train we can anticipate the timing of pulses corresponding to ...

  18. Free space optical communication based on pulsed lasers

    Science.gov (United States)

    Drozd, Tadeusz; Mierczyk, Zygmunt; Zygmunt, Marek; Wojtanowski, Jacek

    2016-12-01

    Most of the current optical data transmission systems are based on continuous wave (cw) lasers. It results from the tendency to increase data transmission speed, and from the simplicity in implementation (straightforward modulation). Pulsed lasers, which find many applications in a variety of industrial, medical and military systems, in this field are not common. Depending on the type, pulsed lasers can generate instantaneous power which is many times greater when compared with cw lasers. As such, they seem to be very attractive to be used in data transmission technology, especially due to the potentially larger ranges of transmission, or in adverse atmospheric conditions where low power cw-lasersbased transmission is no longer feasible. It is also a very practical idea to implement data transmission capability in the pulsed laser devices that have been around and already used, increasing the functionality of this type of equipment. At the Institute of Optoelectronics at Military University of Technology, a unique method of data transmission based on pulsed laser radiation has been developed. This method is discussed in the paper in terms of both data transmission speed and transmission range. Additionally, in order to verify the theoretical assumptions, modules for voice and data transmission were developed and practically tested which is also reported, including the measurements of Bit Error Rate (BER) and performance vs. range analysis.

  19. Robust Short-Pulse, High-Peak-Power Laser Transmitter for Optical Communications

    Science.gov (United States)

    Wright, Malcolm W.

    2009-01-01

    We report on a pulsed fiber based master oscillator power amplifier laser at 1550 nm to support moderate data rates with high peak powers in a compact package suitable for interplanetary optical communications. To accommodate pulse position modulation, the polarization maintaining laser transmitter generates pulses from 0.1 to 1 ns with variable duty cycle over a pulse repetition frequency range of 10 to 100 MHz.

  20. Coupled Optoelectronic Oscillators:. Application to Low-Jitter Pulse Generation

    Science.gov (United States)

    Yu, N.; Tu, M.; Maleki, L.

    2002-04-01

    Actively mode-locked Erbium-doped fiber lasers (EDFL) have been studied for generating stable ultra-fast pulses ( 5 GHz) [1,2]. These devices can be compact and environmentally stable, quite suitable for fiber-based high-data-rate communications and optical ultra-fast analog-to-digital conversions (ADC) [3]. The pulse-to-pulse jitter of an EDFL-based pulse generator will be ultimately limited by the phase noise of the mode-locking microwave source (typically electronic frequency synthesizers). On the other hand, opto-electronic oscillators (OEO) using fibers have been demonstrated to generate ultra-low phase noise microwaves at 10 GHz and higher [4]. The overall phase noise of an OEO can be much lower than commercially available synthesizers at the offset-frequency range above 100 Hz. Clearly, ultra-low jitter pulses can be generated by taking advantage of the low phase noise of OEOs. In this paper, we report the progress in developing a new low-jitter pulse generator by combing the two technologies. In our approach, the optical oscillator (mode-locked EDFL) and the microwave oscillator (OEO) are coupled through a common Mach-Zehnder (MZ) modulator, thus named coupled opto-electronic oscillator (COEO) [5]. Based on the results of previous OEO study, we can expect a 10 GHz pulse train with jitters less than 10 fs.

  1. Laser pulsing in linear Compton scattering

    Science.gov (United States)

    Krafft, G. A.; Johnson, E.; Deitrick, K.; Terzić, B.; Kelmar, R.; Hodges, T.; Melnitchouk, W.; Delayen, J. R.

    2016-12-01

    Previous work on calculating energy spectra from Compton scattering events has either neglected considering the pulsed structure of the incident laser beam, or has calculated these effects in an approximate way subject to criticism. In this paper, this problem has been reconsidered within a linear plane wave model for the incident laser beam. By performing the proper Lorentz transformation of the Klein-Nishina scattering cross section, a spectrum calculation can be created which allows the electron beam energy spread and emittance effects on the spectrum to be accurately calculated, essentially by summing over the emission of each individual electron. Such an approach has the obvious advantage that it is easily integrated with a particle distribution generated by particle tracking, allowing precise calculations of spectra for realistic particle distributions "in collision." The method is used to predict the energy spectrum of radiation passing through an aperture for the proposed Old Dominion University inverse Compton source. Many of the results allow easy scaling estimates to be made of the expected spectrum.

  2. Next generation Chirped Pulse Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nees, J.; Biswal, S.; Mourou, G. [Univ. Michigan, Center for Ultrafast Optical Science, Ann Arbor, MI (United States); Nishimura, Akihiko; Takuma, Hiroshi

    1998-03-01

    The limiting factors of Chirped Pulse Amplification (CPA) are discussed and experimental results of CPA in Yb:glass regenerative amplifier are given. Scaling of Yb:glass to the petawatt level is briefly discussed. (author)

  3. The Mercury Laser Advances Laser Technology for Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Ebbers, C A; Caird, J; Moses, E

    2009-01-21

    The National Ignition Facility (NIF) at Lawrence Livermore Laboratory is on target to demonstrate 'breakeven' - creating as much fusion-energy output as laser-energy input. NIF will compress a tiny sphere of hydrogen isotopes with 1.8 MJ of laser light in a 20-ns pulse, packing the isotopes so tightly that they fuse together, producing helium nuclei and releasing energy in the form of energetic particles. The achievement of breakeven will culminate an enormous effort by thousands of scientists and engineers, not only at Livermore but around the world, during the past several decades. But what about the day after NIF achieves breakeven? NIF is a world-class engineering research facility, but if laser fusion is ever to generate power for civilian consumption, the laser will have to deliver pulses nearly 100,000 times faster than NIF - a rate of perhaps 10 shots per second as opposed to NIF's several shots a day. The Mercury laser (named after the Roman messenger god) is intended to lead the way to a 10-shots-per-second, electrically-efficient, driver laser for commercial laser fusion. While the Mercury laser will generate only a small fraction of the peak power of NIF (1/30,000), Mercury operates at higher average power. The design of Mercury takes full advantage of the technology advances manifest in its behemoth cousin (Table 1). One significant difference is that, unlike the flashlamp-pumped NIF, Mercury is pumped by highly efficient laser diodes. Mercury is a prototype laser capable of scaling in aperture and energy to a NIF-like beamline, with greater electrical efficiency, while still running at a repetition rate 100,000 times greater.

  4. Pulsed laser illumination of photovoltaic cells

    Science.gov (United States)

    Yater, Jane A.; Lowe, Roland A.; Jenkins, Phillip P.; Landis, Geoffrey A.

    1995-01-01

    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic receivers to provide remote power. Both the radio-frequency (RF) and induction FEL produce pulsed rather than continuous output. In this work we investigate cell response to pulsed laser light which simulates the RF FEL format. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced compared to constant illumination at the same wavelength. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments indicates that the RF FEL pulse format yields more efficient photovoltaic conversion than does an induction FEL format.

  5. Demonstration of a self-pulsing photonic crystal Fano laser

    CERN Document Server

    Yu, Yi; Semenova, Elizaveta; Yvind, Kresten; Mork, Jesper

    2016-01-01

    Semiconductor lasers in use today rely on mirrors based on the reflection at a cleaved facet or Bragg reflection from a periodic stack of layers. Here, we demonstrate an ultra-small laser with a mirror based on the Fano resonance between a continuum of waveguide modes and the discrete resonance of a nanocavity. The Fano resonance leads to unique laser characteristics. Since the Fano mirror is very narrow-band compared to conventional lasers, the laser is single-mode and in particular, it can be modulated via the mirror. We show, experimentally and theoretically, that nonlinearities in the mirror may even promote the generation of a self-sustained train of pulses at gigahertz frequencies, an effect that was previously only observed in macroscopic lasers. Such a source is of interest for a number of applications within integrated photonics.

  6. Tandem electroabsorption modulators integrated with DFB laser by ultra-low-pressure selective-area-growth MOCVD for 10 GHz optical short pulse generation

    Science.gov (United States)

    Zhao, Q.; Pan, J. Q.; Zhang, J.; Zhou, G. T.; Wu, J.; Wang, L. F.; Wang, W.

    2005-08-01

    A novel device of tandem MQW EAMs monolithically integrated with a DFB laser is fabricated by an ultra-low-pressure (22 mbar) selective area growth MOCVD technique. Experimental results exhibit superior device characteristics with low threshold of 19 mA, output light power of 4.5 mW, and over 20 dB extinction ratio when coupled to a single mode fibre. Moreover, over 10 GHz modulation bandwidth is developed with a driving voltage of 2 V. Using this sinusoidal voltage driven integrated device, 10 GHz repetition rate pulse with an actual width of 13.7 ps without any compression elements is obtained.

  7. Tandem electro-absorption modulators integrated with DFB laser by ultra-low-pressure selective-area-growth MOCVD for 10 GHz optical short-pulse generation

    Science.gov (United States)

    Zhao, Q.; Pan, J. Q.; Zhang, J.; Zhou, G. T.; Wu, J.; Wang, L. F.; Wang, W.

    2005-11-01

    A novel device of tandem multiple quantum wells (MQWs) electroabsorption modulators (EAMs) monolithically integrated with DFB laser is fabricated by ultra-low-pressure (22 mbar) selective area growth (SAG) MOCVD technique. Experimental results exhibit superior device characteristics with low threshold of 19 mA, output light power of 4.5 mW, and over 20 dB extinction ratio when coupled into a single mode fiber. Moreover, over 10 GHz modulation bandwidth is developed with a driving voltage of 2 V. Using this sinusoidal voltage driven integrated device, 10GHz repetition rate pulse with a width of 13.7 ps without any compression elements is obtained.

  8. Controllable generation of partially coherent light pulses with direct space-to-time pulse shaper.

    Science.gov (United States)

    Torres-Company, Víctor; Mínguez-Vega, Gladys; Lancis, Jesús; Friberg, Ari T

    2007-06-15

    We demonstrate the possibility of creating user-defined partially coherent light pulses by means of a slight modification of the direct space-to-time pulse shaper. Specifically, we generate a mutual coherence function that corresponds to the independent-elementary-pulse representation model. The theoretical limits in the parameter of global coherence and the efficiency of the system are studied. Our result opens the door to a new way of quantum control in laser-assisted chemical reactions, namely, control by partial coherence.

  9. Generator of ultrashort megavolt voltage pulses

    CERN Document Server

    Zheltov, K A; Shalimanov, V F

    2002-01-01

    Paper describes approx 3 ns duration and > 1 MW amplitude voltage pulse generator under high-ohmic (approx 450 Ohm) load. Generator comprises pulse transformer with magnetized core, as well as, resonance tuned circuit of high-voltage solenoid and accumulating spaces of a shaping line containing, moreover, spark gap to switch charge in transmitting line. Paper contains the results of voltage measuring in generator basic units

  10. Ceramic dentures manufactured with ultrashort laser pulses

    Science.gov (United States)

    Werelius, Kristian; Weigl, Paul

    2004-06-01

    Conventional manufacturing of individual ceramic dental prosthesis implies a handmade metallic framework, which is then veneered with ceramic layers. In order to manufacture all-ceramic dental prosthesis a CAD/CAM system is necessary due to the three dimensional shaping of high strength ceramics. Most CAD/CAM systems presently grind blocks of ceramic after the construction process in order to create the prosthesis. Using high-strength ceramics, such as Hot Isostatic Pressed (HIP)-zirconia, this is limited to copings. Anatomically shaped fixed dentures have a sculptured surface with small details, which can't be created by existing grinding tools. This procedure is also time consuming and subject to significant loss in mechanical strength and thus reduced survival rate once inserted. Ultra-short laser pulses offer a possibility in machining highly complex sculptured surfaces out of high-strength ceramic with negligible damage to the surface and bulk of the ceramic. In order to determine efficiency, quality and damage, several laser ablation parameters such as pulse duration, pulse energy and ablation strategies were studied. The maximum ablation rate was found using 400 fs at high pulse energies. High pulse energies such as 200μJ were used with low damage in mechanical strength compared to grinding. Due to the limitation of available laser systems in pulse repetition rates and power, the use of special ablation strategies provide a possibility to manufacture fully ceramic dental prosthesis efficiently.

  11. Development of all solid-state, high average power ultra-short pulse laser for X-ray generation. High average power CPA system and wavefront control of ultra short laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Harayama, Sayaka; Akaoka, Katsuaki; Tei, Kazuyoku; Kato, Masaaki; Niwa, Yoshito; Maruyama, Yoichiro; Matoba, Toru; Arisawa, Takashi; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    We developed a prototype CPA laser system which is pumped by a all solid-state Nd:YAG laser. In a preliminary experiment, the output energy of 52mJ before compression was obtained when the pumping energy was 250mJ. To compensate the wavefront distortion, an adaptive optics has been developed. By using this wavefront control system, the laser beam with the distortion of 0.15{lambda} was obtained. (author)

  12. Ionization of Atoms by Intense Laser Pulses

    CERN Document Server

    Froehlich, Juerg; Schlein, Benjamin

    2010-01-01

    The process of ionization of a hydrogen atom by a short infrared laser pulse is studied in the regime of very large pulse intensity, in the dipole approximation. Let $A$ denote the integral of the electric field of the pulse over time at the location of the atomic nucleus. It is shown that, in the limit where $|A| \\to \\infty$, the ionization probability approaches unity and the electron is ejected into a cone opening in the direction of $-A$ and of arbitrarily small opening angle. Asymptotics of various physical quantities in $|A|^{-1}$ is studied carefully. Our results are in qualitative agreement with experimental data reported in \\cite{1,2}.

  13. Cooling of relativistic electron beams in chirped laser pulses

    CERN Document Server

    Yoffe, Samuel R; Kravets, Yevgen; Jaroszynski, Dino A

    2015-01-01

    The next few years will see next-generation high-power laser facilities (such as the Extreme Light Infrastructure) become operational, for which it is important to understand how interaction with intense laser pulses affects the bulk properties of a relativistic electron beam. At such high field intensities, we expect both radiation reaction and quantum effects to play a significant role in the beam dynamics. The resulting reduction in relative energy spread (beam cooling) at the expense of mean beam energy predicted by classical theories of radiation reaction depends only on the energy of the laser pulse. Quantum effects suppress this cooling, with the dynamics additionally sensitive to the distribution of energy within the pulse. Since chirps occur in both the production of high-intensity pulses (CPA) and the propagation of pulses in media, the effect of using chirps to modify the pulse shape has been investigated using a semi-classical extension to the Landau--Lifshitz theory. Results indicate that even la...

  14. Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Chen, L. M., E-mail: lmchen@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, D. Z. [Institute of High Energy Physics, CAS, Beijing 100049 (China); Chen, Z. Y. [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621999 (China); Sheng, Z. M. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Zhang, J. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-08-15

    By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

  15. Generation of Single-Cycle Light Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, B C; Jovanovic, I; Armstrong, J P; Pyke, B; Crane, J K; Shuttlesworth, R

    2004-02-13

    Most optical pulses, even at the 10-femtosecond timescale, consist of several oscillations of the electric field. By producing and amplifying an ultra-broadband continuum, single cycle (e 3 fs) or shorter optical pulses may be generated. This requires a very challenging pulse-compression with sub-femtosecond accuracy. Production of these single-cycle pulses will lead to new generations of experiments in the areas of coherent control of chemical excitations and reactions, 0.1-fs high-order harmonic (XUV) generation for probing of materials and fast processes, and selective 3-D micron-scale material removal and modification. We activated the first stage of a planned three-stage optical parametric amplifier (OPA) that would ultimately produce sub-3 fs pulses. Active control with a learning algorithm was implemented to optimize the continuum generated in an argon-filled capillary and to control and optimize the final compressed pulse temporal shape. A collaboration was initiated to coherently control the population of different states upon dissociation of Rb{sub 2}. Except for one final optic, a pulse compressor and diagnostics were constructed to produce and characterize pulses in the 5-fs range from the first OPA stage.

  16. In vivo photoacoustic imaging of blood vessels with a pulsed laser diode

    NARCIS (Netherlands)

    Kolkman, R.G.M.; Steenbergen, Wiendelt; van Leeuwen, Ton

    2006-01-01

    Photoacoustic imaging is a hybrid imaging modality that is based on the detection of acoustic waves generated by absorption of pulsed light by tissue chromophores such as hemoglobin in blood. For this technique, usually large and costly Q-switched Nd:YAG lasers are used. These lasers provide a pulse

  17. Lasers and Intense Pulsed Light Hidradenitis Suppurativa.

    Science.gov (United States)

    Saunte, Ditte M; Lapins, Jan

    2016-01-01

    Lasers and intense pulsed light (IPL) treatment are useful for the treatment of hidradenitis suppurativa (HS). Carbon dioxide lasers are used for cutting or vaporization of the affected area. It is a effective therapy for the management of severe and recalcitrant HS with persistent sinus tract and scarring, and can be performed under local anesthesia. HS has a follicular pathogenesis. Lasers and IPL targeting the hair have been found useful in treating HS by reducing the numbers of hairs in areas with HS. The methods have few side effects, but the studies are preliminary and need to be repeated.

  18. Modulated Pulsed Laser Sources for Imaging Lidars

    Science.gov (United States)

    2007-10-01

    manufactured by QPC. This C-mount device has a monolithic semiconductor amplifier allowing the package to output up to 1.5 Watts at 1064 nm with linewidths ɘ.1...pulsed driver based on the avalanche transistor circuit being used for gain switching, a 1064 nm DFB laser manufactured by QPC and a DBR -style laser...available now that may provide the needed power. An example of such a laser is the QPC C-mount monolithic oscillator/amplifier which can output 1.5

  19. Pulsed Lasers: Pulsed Lasers Employing Solution-Processed Plasmonic Cu3- x P Colloidal Nanocrystals (Adv. Mater. 18/2016).

    Science.gov (United States)

    Liu, Zeke; Mu, Haoran; Xiao, Si; Wang, Rongbin; Wang, Zhiteng; Wang, Weiwei; Wang, Yongjie; Zhu, Xiangxiang; Lu, Kunyuan; Zhang, Han; Lee, Shuit-Tong; Bao, Qiaoliang; Ma, Wanli

    2016-05-01

    Q. Bao, W. Ma and co-workers demonstrate the usage of plasmonic Cu3-x P colloidal nanocrystals as a new type of tunable saturable absorber for the generation of high-energy pulses in a fiber laser. As described on page 3535, these low-cost, solution-processed, next-generation nonlinear optical materials can be harnessed for applications in signal processing and optical communication. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. X-ray generation by the interaction of laser pulses of GW and high repetition rate, with solid targets of Al, Cu, Cd and Au; Generacion de rayos X por interaccion de pulsos laser de GW y alta tasa de repeticion, con blancos solidos de Al, Cu, Cd, Au

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca Cuenca, C.; Rodriguez Entem, D.; Mendez Valverde, C.; Roso Franco, L.; Fernandez Gonzalez, F.

    2011-07-01

    In the present study we characterized the Bremsstrahlung radiation and X-ray emission associated with the radiation emitted during the interaction of laser pulses incident on solid targets of different material and discusses the radiation risk generated by the nature of this interaction.

  1. Electron photodetachment by short laser pulse

    NARCIS (Netherlands)

    Golovinski, P. A.; Drobyshev, A. A.

    2012-01-01

    Expressions are derived for calculations of the total probabilities and electron spectra for the photodetachment of electrons from negative ions with filled valence s shells by ultrashort laser pulses. Particular calculations have been performed for two negative ions (H- and Li-) and titanium-sapphi

  2. Electron photodetachment by short laser pulse

    NARCIS (Netherlands)

    Golovinski, P. A.; Drobyshev, A. A.

    2012-01-01

    Expressions are derived for calculations of the total probabilities and electron spectra for the photodetachment of electrons from negative ions with filled valence s shells by ultrashort laser pulses. Particular calculations have been performed for two negative ions (H- and Li-) and titanium-sapphi

  3. Ultrashort Pulse (USP) Laser-Matter Interactions

    Science.gov (United States)

    2013-03-05

    unlimited 2D electron wavepacket quantum simulation Source: Luis Plaja, U Salamanca 31 Direct Frequency Comb Spectroscopy in the Extreme...intensity short pulse laser interacting with structured targets yields an enhancement in the number and energy of hot electron. • Monte Carlo

  4. Pulsed laser deposition: Prospects for commercial deposition of epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Muenchausen, R.E.

    1999-03-01

    Pulsed laser deposition (PLD) is a physical vapor deposition (PVD) technique for the deposition of thin films. The vapor source is induced by the flash evaporation that occurs when a laser pulse of sufficient intensity (about 100 MW/cm{sup 2}) is absorbed by a target. In this paper the author briefly defines pulsed laser deposition, current applications, research directed at gaining a better understanding of the pulsed laser deposition process, and suggests some future directions to enable commercial applications.

  5. Temporal laser pulse manipulation using multiple optical ring-cavities

    Science.gov (United States)

    Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor)

    2010-01-01

    An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities. The optical pulse stretcher system can also function as a high-repetition-rate (MHz) laser pulse generator, making it suitable for use as a stroboscopic light source for high speed ballistic projectile imaging studies, or it can be used for high speed flow diagnostics using a laser light sheet with digital particle imaging velocimetry. The optical pulse stretcher system can also be implemented using fiber optic components to realize a rugged and compact optical system that is alignment free and easy to use.

  6. Spatially modulated laser pulses for printing electronics.

    Science.gov (United States)

    Auyeung, Raymond C Y; Kim, Heungsoo; Mathews, Scott; Piqué, Alberto

    2015-11-01

    The use of a digital micromirror device (DMD) in laser-induced forward transfer (LIFT) is reviewed. Combining this technique with high-viscosity donor ink (silver nanopaste) results in laser-printed features that are highly congruent in shape and size to the incident laser beam spatial profile. The DMD empowers LIFT to become a highly parallel, rapidly reconfigurable direct-write technology. By adapting half-toning techniques to the DMD bitmap image, the laser transfer threshold fluence for 10 μm features can be reduced using an edge-enhanced beam profile. The integration of LIFT with this beam-shaping technique allows the printing of complex large-area patterns with a single laser pulse.

  7. High power parallel ultrashort pulse laser processing

    Science.gov (United States)

    Gillner, Arnold; Gretzki, Patrick; Büsing, Lasse

    2016-03-01

    The class of ultra-short-pulse (USP) laser sources are used, whenever high precession and high quality material processing is demanded. These laser sources deliver pulse duration in the range of ps to fs and are characterized with high peak intensities leading to a direct vaporization of the material with a minimum thermal damage. With the availability of industrial laser source with an average power of up to 1000W, the main challenge consist of the effective energy distribution and disposition. Using lasers with high repetition rates in the MHz region can cause thermal issues like overheating, melt production and low ablation quality. In this paper, we will discuss different approaches for multibeam processing for utilization of high pulse energies. The combination of diffractive optics and conventional galvometer scanner can be used for high throughput laser ablation, but are limited in the optical qualities. We will show which applications can benefit from this hybrid optic and which improvements in productivity are expected. In addition, the optical limitations of the system will be compiled, in order to evaluate the suitability of this approach for any given application.

  8. Multiple THz pulse generation with variable energy ratio and delay

    Science.gov (United States)

    Ungureanu, R. G.; Grigore, O. V.; Dinca, M. P.; Cojocaru, G. V.; Ursescu, D.; Dascalu, T.

    2015-04-01

    Two methods for multiple high energetic THz pulse generation by two-color filamentation in air with controllable energy ratio and delay ranging from one to hundreds of ps were investigated. In the first method the laser pulse is split into two inside the optical stretcher of a CPA laser system, the resulting consecutive filaments occur in the same region and allows the study of the influence of the first plasma filament on the THz emission of the delayed filament. Based on a polarization sensitive thin film beam splitter placed in front of a 45° mirror, the second method produces multiple parallel consecutive filaments. Above a certain total pump level the THz energy delivered by multiple pulses exceeds the value given by a single filament for the same pump energy, thereby overcoming the THz emission saturation of the single filament.

  9. Group velocity and pulse lengthening of mismatched laser pulses in plasma channels

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; van Tilborg, Jeroen; Leemans, Wim

    2011-07-07

    Analytic solutions are presented to the non-paraxial wave equation describing an ultra-short, low-power, laser pulse propagating in aplasma channel. Expressions for the laser pulse centroid motion and laser group velocity are derived, valid for matched and mismatchedpropagation in a parabolic plasma channel, as well as in vacuum, for an arbitrary Laguerre-Gaussian laser mode. The group velocity of amismatched laser pulse, for which the laser spot size is strongly oscillating, is found to be independent of propagation distance andsignificantly less than that of a matched pulse. Laser pulse lengthening of a mismatched pulse owing to laser mode slippage isexamined and found to dominate over that due to dispersive pulse spreading for sufficiently long pulses. Analytic results are shown tobe in excellent agreement with numerical solutions of the full Maxwell equations coupled to the plasma response. Implications for plasmachannel diagnostics are discussed.

  10. A frequency-doubled, pulsed laser system for rubidium manipulation

    CERN Document Server

    Dingjan, J; Beugnon, J; Jones, M P A; Bergamini, S; Messin, G; Browaeys, A; Grangier, P

    2005-01-01

    We have constructed a pulsed laser system for the manipulation of cold Rb atoms. The system combines optical telecommunications components and frequency doubling to generate light at 780 nm. Using a fast, fibre-coupled intensity modulator, output from a continuous laser diode is sliced into pulses with a length between 1.3 and 6.1 ns and a repetition frequency of 5 MHz. These pulses are amplified using an erbium-doped fibre amplifier, and frequency-doubled in a periodically poled lithium niobate crystal, yielding a peak power up to 12 W. Using the resulting light at 780 nm, we demonstrate Rabi oscillations on the F = 2 F=3-transition of a single 87Rb atom.

  11. Supercontinuum generation from dispersion-flattened photonic crystal fiber using picosecond pulses

    Institute of Scientific and Technical Information of China (English)

    Li He; Bojun Yang; Xiaoguang Zhang; Li Yu

    2006-01-01

    We present the all-fiber system for supercontiuum (SC) generation with picosecond pulses. By launching1.6-ps pulses from pulsed erbium-doped fiber laser (EDFL) into a section of photonic crystal fiber (PCF),the spectral broadening is observed. The bandwidth of 237 nm (at 20 dB level) is achieved.

  12. Phase Noise Comparision of Short Pulse Laser Systems

    Energy Technology Data Exchange (ETDEWEB)

    S. Zhang; S. V. Benson; J. Hansknecht; D. Hardy; G. Neil; Michelle D. Shinn

    2006-12-01

    This paper describes the phase noise measurement on several different mode-locked laser systems that have completely different gain media and configurations including a multi-kW free-electron laser. We will focus on the state of the art short pulse lasers, especially the drive lasers for photocathode injectors. A comparison between the phase noise of the drive laser pulses, electron bunches and FEL pulses will also be presented.

  13. Theoretical analysis of pulse modulation of semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Xu Baoxi; Zhan Yushu; Guo Siji

    1987-05-01

    Rate equations of Gaussian shape pulse modulated semiconductor lasers are solved by Runge--Kutta method, and the results are analyzed. The formulae for calculating the delay time, pulse width of laser pulse and maximum bit-rate of Gaussian shape pulse modulation are derived. The experimental results of modulation pattern effects are given.

  14. Insights in the laser-induced breakdown spectroscopy signal generation underwater using dual pulse excitation — Part I: Vapor bubble, shockwaves and plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lazic, V., E-mail: violeta.lazic@enea.it [ENEA (UTAPRAD-DIM), Via. E. Fermi 45, 00044 Frascati (RM) (Italy); Laserna, J.J. [Dept. of Analytical Chemistry, Faculty of Sciences, University of Málaga, Málaga (Spain); Jovicevic, S. [Institute of Physics, University of Belgrade, Belgrade (Serbia)

    2013-04-01

    Plasma and vapor bubble formation and evolution after a nanosecond laser pulse delivered to aluminum targets inside water were studied by fast photography. This technique was also applied to monitor the plasma produced by a second laser pulse and for different interpulse delays. The bubble growth was evident only after 3 μs from the first laser pulse and the bubble shape changed during expansion and collapse cycles. The evolution and propagation of the initial shockwave and its reflections both from the back sample surface and cell walls were detected by Schlieren photography. The primary plasma develops in two phases: violent particle expulsion and ionization during the first μs, followed by slow plasma growth from the ablation crater into the evolving vapor bubble. The shape of the secondary plasma strongly depends on the inner bubble pressure whereas the particle expulsion into the expanded bubble is much less evident. Both the primary and secondary plasma have similar duration of about 30 μs. Detection efficiency of the secondary plasma is much reduced by light refraction at the curved bubble–water interface, which behaves as a negative lens; this leads to an apparent reduction of the plasma dimensions. Defocusing power of the bubble lens increases with its expansion due to the lowering of the vapor's refraction index with respect to that of the surrounding liquid (Lazic et al., 2012 [1]). Smell's reflections of secondary plasma radiation at the expanded bubble wall redistribute the detected intensity on a wavelength-dependent way and allow gathering of the emission also from the external plasma layer that otherwise, would not enter into the optical system. - Highlights: ► Primary plasma during the first μs is irregular due to particle expulsion. ► Later the plasma grows into the evolving bubble, its emission lasts more than 30 μs. ► The initial shockwave and its echoes alter locally the refraction index. ► Defocusing by the bubble

  15. Gain dynamics of a free-space nitrogen laser pumped by circularly polarized femtosecond laser pulses

    CERN Document Server

    Yao, Jinping; Zeng, Bin; Chu, Wei; Li, Guihua; Ni, Jielei; Zhang, Haisu; Jing, Chenrui; Zhang, Chaojin; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

    2015-01-01

    We experimentally demonstrate ultrafast dynamic of generation of a strong 337-nm nitrogen laser by injecting an external seed pulse into a femtosecond laser filament pumped by a circularly polarized laser pulse. In the pump-probe scheme, it is revealed that the population inversion between the excited and ground states of N2 for the free-space 337-nm laser is firstly built up on the timescale of several picoseconds, followed by a relatively slow decay on the timescale of tens of picoseconds, depending on the nitrogen gas pressure. By measuring the intensities of 337-nm signal from nitrogen gas mixed with different concentrations of oxygen gas, it is also found that oxygen molecules have a significant quenching effect on the nitrogen laser signal. Our experimental observations agree with the picture of electron-impact excitation.

  16. Laboratory Transferability of Optimally Shaped Laser Pulses for Quantum Control

    CERN Document Server

    Tibbetts, Katharine Moore; Rabitz, Herschel

    2013-01-01

    Optimal control experiments can readily identify effective shaped laser pulses, or "photonic reagents", that achieve a wide variety of objectives. For many practical applications, an important criterion is that a particular photonic reagent prescription still produce a good, if not optimal, target objective yield when transferred to a different system or laboratory, {even if the same shaped pulse profile cannot be reproduced exactly. As a specific example, we assess the potential for transferring optimal photonic reagents for the objective of optimizing a ratio of photoproduct ions from a family of halomethanes through three related experiments.} First, applying the same set of photonic reagents with systematically varying second- and third-order chirp on both laser systems generated similar shapes of the associated control landscape (i.e., relation between the objective yield and the variables describing the photonic reagents). Second, optimal photonic reagents obtained from the first laser system were found...

  17. Development of a 1 J short pulse tunable TEA CO2 laser with high energy stability

    Science.gov (United States)

    Kumar, Manoj; Reghu, T.; Biswas, A. K.; Bhargav, Pankaj; Pakhare, J. S.; Kumar, Shailesh; Verma, Abrat; Mandloi, Vagesh; Kukreja, L. M.

    2014-12-01

    The design, development and operational characteristics of a 1 J, repetitively pulsed, line tunable TEA CO2 laser producing nearly tail free short pulses (~170 ns) suitable for laser isotope separation is discussed. Tail free short laser pulses were generated by employing a nitrogen lean gaseous active medium. Use of an indigenously developed stable pulsed power supply, uniform and intense UV spark pre-ionization and optimum gas purging with catalytic regeneration to control the deleterious oxygen accumulation helps generate laser pulses with high energy stability. Integration of a sensitive arc detection system allows long term arc-free operation of the laser and protects it from catastrophic failure. Laser pulses in more than 90 lines in 10.6 μm and 9.6 μm bands of CO2 laser spectrum with energy about 1 J in as many as 50 lines could be generated with a typical efficiency of about 4%. A typical pulse to pulse energy stability of ±1.4% was obtained during one hour of continuous operation of the TEA CO2 laser at 75 Hz.

  18. Pulsed Power for Solid-State Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Gagnon, W; Albrecht, G; Trenholme, J; Newton, M

    2007-04-19

    Beginning in the early 1970s, a number of research and development efforts were undertaken at U.S. National Laboratories with a goal of developing high power lasers whose characteristics were suitable for investigating the feasibility of laser-driven fusion. A number of different laser systems were developed and tested at ever larger scale in pursuit of the optimum driver for laser fusion experiments. Each of these systems had associated with it a unique pulsed power option. A considerable amount of original and innovative engineering was carried out in support of these options. Ultimately, the Solid-state Laser approach was selected as the optimum driver for the application. Following this, the Laser Program at the Lawrence Livermore National Laboratory and the University of Rochester undertook aggressive efforts directed at developing the technology. In particular, at Lawrence Livermore National Laboratory, a series of laser systems beginning with the Cyclops laser and culminating in the present with the National Ignition Facility were developed and tested. As a result, a large amount of design information for solid-state laser pulsed power systems has been documented. Some of it is in the form of published papers, but most of it is buried in internal memoranda, engineering reports and LLNL annual reports. One of the goals of this book is to gather this information into a single useable format, such that it is easily accessed and understood by other engineers and physicists for use with future designs. It can also serve as a primer, which when seriously studied, makes the subsequent reading of original work and follow-up references considerably easier. While this book deals only with the solid-state laser pulsed power systems, in the bibliography we have included a representative cross section of papers and references from much of the very fine work carried out at other institutions in support of different laser approaches. Finally, in recent years, there has

  19. Selective laser melting of copper using ultrashort laser pulses

    Science.gov (United States)

    Kaden, Lisa; Matthäus, Gabor; Ullsperger, Tobias; Engelhardt, Hannes; Rettenmayr, Markus; Tünnermann, Andreas; Nolte, Stefan

    2017-09-01

    Within the field of laser-assisted additive manufacturing, the application of ultrashort pulse lasers for selective laser melting came into focus recently. In contrast to conventional lasers, these systems provide extremely high peak power at ultrashort interaction times and offer the potential to control the thermal impact at the vicinity of the processed region by tailoring the pulse repetition rate. Consequently, materials with extremely high melting points such as tungsten or special composites such as AlSi40 can be processed. In this paper, we present the selective laser melting of copper using 500 fs laser pulses at MHz repetition rates emitted at a center wavelength of about 1030 nm. To identify an appropriate processing window, a detailed parameter study was performed. We demonstrate the fabrication of bulk copper parts as well as the realization of thin-wall structures featuring thicknesses below 100 {μ }m. With respect to the extraordinary high thermal conductivity of copper which in general prevents the additive manufacturing of elements with micrometer resolution, this work demonstrates the potential for sophisticated copper products that can be applied in a wide field of applications extending from microelectronics functionality to complex cooling structures.

  20. High Efficiency Pulse Acetone Liquid Raman Laser Using DCM Fluorescent Dye as the Enhancement Medium

    Institute of Scientific and Technical Information of China (English)

    CHENG Andrew Yuk-Sun; YANG Jing-Guo; CHAN Mau-Hing

    2006-01-01

    Pumped by a frequency-doubled Nd:YAG laser, 10-Hz repetition rate, 320-mJ pump energy, and 5.1-ns pulse width, a liquid Raman laser using acetone as the Raman shifting medium has been established. The residual pump laser pulse and the generated Stokes pulse are directed to a DCM dye cell for energy enhancement of the Stokes pulse. The Raman laser system is capable to produce a laser pulse at wavelength 630 nm, with single pulse energy of 120 mJ, peak power of 70 MW and an average power of 1200 mW. The energy conversion efficiency is 37.5%, or equivalently a quantum efficiency of 44.5%.

  1. Electromagnetic pulses produced by expanding laser-produced Au plasma

    Directory of Open Access Journals (Sweden)

    De Marco Massimo

    2015-06-01

    Full Text Available The interaction of an intense laser pulse with a solid target produces large number of fast free electrons. This emission gives rise to two distinct sources of the electromagnetic pulse (EMP: the pulsed return current through the holder of the target and the outflow of electrons into the vacuum. A relation between the characteristics of laser-produced plasma, the target return current and the EMP emission are presented in the case of a massive Au target irradiated with the intensity of up to 3 × 1016 W/cm2. The emission of the EMP was recorded using a 12 cm diameter Moebius loop antennas, and the target return current was measured using a new type of inductive target probe (T-probe. The simultaneous use of the inductive target probe and the Moebius loop antenna represents a new useful way of diagnosing the laser–matter interaction, which was employed to distinguish between laser-generated ion sources driven by low and high contrast laser pulses.

  2. Nanosecond Square Pulse Fiber Laser based on the Nonlinear Amplifying Loop Mirror

    Institute of Scientific and Technical Information of China (English)

    陈国梁; 顾春; 许立新; 王安廷; 明海

    2011-01-01

    We propose and demonstrate a nanosecond square pulse ytterbium doped fiber laser in the 1060 nm band. The laser is based on the figure-8 structure and has a tunable pulse bandwidth from 3 ns to beyond 100 ns, showing excellent temporal tuning ability. The experimental results show that a steady square pulse can be generated when the parameters of the cavity are chosen appropriately.%We propose and demonstrate a nanosecond square pulse ytterbium doped fiber laser in the 1060nm band.The laser is based on the figure-8 structure and has a tunable pulse bandwidth from 3ns to beyond 100ns,showing excellent temporal tuning ability.The experimental results show that a steady square pulse can be generated when the parameters of the cavity are chosen appropriately.

  3. Repetition rate tunable ultra-short optical pulse generation based on electrical pattern generator

    Institute of Scientific and Technical Information of China (English)

    Xin Fu; Hongming Zhang; Meng Yan; Minyu Yao

    2009-01-01

    @@ An actively mode-locked laser with tunable repetition rate is proposed and experimentally demonstrated based on a programmable electrical pattern generator.By changing the repetition rate of the electrical patterns applied on the in-cavity modulator, the repetition rate of the output optical pulse sequences changes accordingly while the pulse width of the optical pulse train remains almost constant.In other words, the output ultra-short pulse train has a tunable duty cycle.In a proof-of-principle experiment, optical pulses with repetition rates of 10, 5, 2.5 and 1.25 GHz are obtained by adjusting the electrical pattern applied on the in-cavity modulator while their pulse widths remain almost unchanged.

  4. Two-Color Laser High-Harmonic Generation in Cavitated Plasma Wakefields

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2016-10-03

    A method is proposed for producing coherent x-rays via high-harmonic generation using a laser interacting with highly-stripped ions in cavitated plasma wakefields. Two laser pulses of different colors are employed: a long-wavelength pulse for cavitation and a short-wavelength pulse for harmonic generation. This method enables efficient laser harmonic generation in the sub-nm wavelength regime.

  5. Laser-Material Interaction of Powerful Ultrashort Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, A

    2003-01-06

    Laser-material interaction of powerful (up to a terawatt) ultrashort (several picoseconds or shorter) laser pulses and laser-induced effects were investigated theoretically in this dissertation. Since the ultrashort laser pulse (USLP) duration time is much smaller than the characteristic time of the hydrodynamic expansion and thermal diffusion, the interaction occurs at a solid-like material density with most of the light energy absorbed in a thin surface layer. Powerful USLP creates hot, high-pressure plasma, which is quickly ejected without significant energy diffusion into the bulk of the material, Thus collateral damage is reduced. These and other features make USLPs attractive for a variety of applications. The purpose of this dissertation was development of the physical models and numerical tools for improvement of our understanding of the process and as an aid in optimization of the USLP applications. The study is concentrated on two types of materials - simple metals (materials like aluminum or copper) and wide-bandgap dielectrics (fused silica, water). First, key physical phenomena of the ultrashort light interaction with metals and the models needed to describe it are presented. Then, employing one-dimensional plasma hydrodynamics code enhanced with models for laser energy deposition and material properties at low and moderate temperatures, light absorption was self-consistently simulated as a function of laser wavelength, pulse energy and length, angle of incidence and polarization. Next, material response on time scales much longer than the pulse duration was studied using the hydrocode and analytical models. These studies include examination of evolution of the pressure pulses, effects of the shock waves, material ablation and removal and three-dimensional dynamics of the ablation plume. Investigation of the interaction with wide-bandgap dielectrics was stimulated by the experimental studies of the USLP surface ablation of water (water is a model of

  6. Atmospheric propagation of two CO2 laser pulses

    Science.gov (United States)

    Autric, M.; Caressa, J.-P.; Dufresne, D.; Bournot, Ph.

    1984-01-01

    At the intensity and fluence levels reached in an experimental investigation of high-energy laser beam propagation, air breakdown occurs through the interaction of the intense radiation with aerosol particles naturally suspended in the path of the beam. The air plasma created is found to expand rapidly and have a detrimental effect on energy propagation. It is determined that the energy transmitted through the breakdown plasma as a function of the incident average energy density is less than 15 percent for fluences greater than 300 J/sq cm, and that incident energy transmission may be increased through the generation of a precursor pulse as a function of double pulse separation times ranging from a few microsec to 0.1 sec. Maximum effects have been obtained at pulse separation intervals of 100-200 microsec, and these are ascribed to the vaporization of aerosol particles by the first pulse.

  7. Precision resection of intestine using ultrashort laser pulses

    Science.gov (United States)

    Beck, Rainer J.; Gora, Wojciech S.; Jayne, David; Hand, Duncan P.; Shephard, Jonathan D.

    2016-03-01

    Endoscopic resection of early colorectal neoplasms typically employs electrocautery tools, which lack precision and run the risk of full thickness thermal injury to the bowel wall with subsequent perforation. We present a means of endoluminal colonic ablation using picosecond laser pulses as a potential alternative to mitigate these limitations. High intensity ultrashort laser pulses enable nonlinear absorption processes, plasma generation, and as a consequence a predominantly non-thermal ablation regimen. Robust process parameters for the laser resection are demonstrated using fresh ex vivo pig intestine samples. Square cavities with comparable thickness to early colorectal neoplasms are removed for a wavelength of 1030 nm and 515 nm using a picosecond laser system. The corresponding histology sections exhibit in both cases only minimal collateral damage to the surrounding tissue. The ablation depth can be controlled precisely by means of the pulse energy. Overall, the application of ultrafast lasers for the resection of intestine enables significantly improved precision and reduced thermal damage to the surrounding tissue compared to conventional electrocautery.

  8. Pulse Sequences for Efficient Multi-Cycle Terahertz Generation in Periodically Poled Lithium Niobate

    CERN Document Server

    Ravi, Koustuban; Kärtner, Franz X

    2016-01-01

    The use of laser pulse sequences to drive the cascaded difference frequency generation of high energy, high peak-power and multi-cycle terahertz pulses in cryogenically cooled periodically poled lithium niobate is proposed. Detailed simulations considering the coupled nonlinear interaction of terahertz and optical waves show that unprecedented optical-to-terahertz energy conversion efficiencies > 5%, peak electric fields of hundred(s) of Mega volts/meter at terahertz pulse durations of hundred(s) of picoseconds can be achieved. The proposed methods are shown to circumvent laser-induced damage at Joule-level pumping by 1$\\mu$m lasers to enable multi-cycle terahertz sources with pulse energies >> 10 milli-joules. Various pulse sequence formats are proposed and analyzed. Numerical calculations for periodically poled structures accounting for cascaded difference frequency generation, self-phase-modulation, cascaded second harmonic generation and laser induced damage are introduced. Unprecedented studies of the ph...

  9. On the Role of Laser Pulses on Spallation of Granite

    Science.gov (United States)

    Ndeda, Rehema; Sebusang, Sebusang E. M.; Marumo, Rapelang; Ogur, Erich O.

    2017-06-01

    Laser spallation is one of the thermal methods under study as an alternative to mechanical drilling mainly due to high power capabilities and non-contact nature. Spallation has been attributed to stress generated on the rock due to large temperature gradient and thermal expansion of the rock. It is necessary to determine the effect of pulsing of the laser as well as convective cooling on spallation, in a bid to increase the efficiency of laser spallation. In this paper, analysis of thermal stresses during pulsed laser spallation of granite is carried out. The effect of convective cooling at the end of the heating period on stress and crack propagation is also examined. A two dimensional finite element model is developed. It is observed that on cooling, tensile stresses generated during heating are inverted to compressive stresses, increasing the rate of spallation. Results also indicate that residual stresses on the rock due to pulsing are much higher. Finally, increased rate of crack propagation is observed when the rock is subjected to sudden cooling.

  10. Accordion effect in a laser wakefield accelerator: Generating comb-like electron beams for a tunable pulsed source of polychromatic gamma-rays

    Science.gov (United States)

    Kalmykov, Serge; Davoine, Xavier; Ghebregziabher, Isaac; Shadwick, Bradley

    2016-10-01

    Trains of synchronized, fs-length GeV-scale electron bunches with a sub-micron normalized transverse emittance, brightness up to 1017 A/m2, and controlled energy spacing may be purposely produced in both plasma channels and uniform plasmas. A cavity of electron density, driven by an optimally designed multi-color stack of 10-TW-scale laser pulses, experiences expansions and contractions, periodically injecting electrons from the ambient dense plasma, accelerating them without compromising the beam quality. This periodic injection is naturally achieved in a plasma channel. The channel, however, is not a prerequisite to this effect. The number of comb components, as well as their charge and energy spacing, can be controlled in a uniform plasma by independently varying focal spots of the laser stack components. Inverse Thomson scattering from these comb-like beams produces synchronized sequences of quasi-monochromatic, fs-length gamma-ray flashes, which may become an asset to pump-probe experiments in dense plasmas. NSF Grant PHY-1535678.

  11. Ultra-Short Optical Pulse Generation with Single-Layer Graphene

    CERN Document Server

    Lee, C -C; Bunch, J S; Schibli, T R

    2010-01-01

    Pulses as short as 260 fs have been generated in a diode-pumped low-gain Er:Yb:glass laser by exploiting the nonlinear optical response of single-layer graphene. The application of this novel material to solid-state bulk lasers opens up a way to compact and robust lasers with ultrahigh repetition rates.

  12. A high current, high gradient, laser excited, pulsed electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, K.; Farrell, J.P.; Dudnikova, G. [Brookhaven Technology Group, Inc., Stony Brook, NY (United States); Ben-Zvi, I.; Srinivasan-Rao, T.; Smedley, J.; Yakimenko, V. [Brookhaven National Lab., Upton, NY (United States)

    1998-06-01

    This paper describes a pulsed electron gun that can be used as an FEL, as an injector for electron linear accelerators or for rf power generation. It comprises a 1 to 5 MeV, 1 to 2 ns pulsed power supply feeding a single diode, photoexcited acceleration gap. Beam quality of a {approximately}1nC charge in {approximately}1 GV/m field was studied. Computations of the beam parameters as a function of electrode configuration and peak electron current are presented together with descriptions of the power supply, laser and beam diagnostics systems.

  13. High speed sampling circuit design for pulse laser ranging

    Science.gov (United States)

    Qian, Rui-hai; Gao, Xuan-yi; Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; Guo, Xiao-kang; He, Shi-jie

    2016-10-01

    In recent years, with the rapid development of digital chip, high speed sampling rate analog to digital conversion chip can be used to sample narrow laser pulse echo. Moreover, high speed processor is widely applied to achieve digital laser echo signal processing algorithm. The development of digital chip greatly improved the laser ranging detection accuracy. High speed sampling and processing circuit used in the laser ranging detection system has gradually been a research hotspot. In this paper, a pulse laser echo data logging and digital signal processing circuit system is studied based on the high speed sampling. This circuit consists of two parts: the pulse laser echo data processing circuit and the data transmission circuit. The pulse laser echo data processing circuit includes a laser diode, a laser detector and a high sample rate data logging circuit. The data transmission circuit receives the processed data from the pulse laser echo data processing circuit. The sample data is transmitted to the computer through USB2.0 interface. Finally, a PC interface is designed using C# language, in which the sampling laser pulse echo signal is demonstrated and the processed laser pulse is plotted. Finally, the laser ranging experiment is carried out to test the pulse laser echo data logging and digital signal processing circuit system. The experiment result demonstrates that the laser ranging hardware system achieved high speed data logging, high speed processing and high speed sampling data transmission.

  14. Strong and superstrong pulsed magnetic fields generation

    CERN Document Server

    Shneerson, German A; Krivosheev, Sergey I

    2014-01-01

    Strong pulsed magnetic fields are important for several fields in physics and engineering, such as power generation and accelerator facilities. Basic aspects of the generation of strong and superstrong pulsed magnetic fields technique are given, including the physics and hydrodynamics of the conductors interacting with the field as well as an account of the significant progress in generation of strong magnetic fields using the magnetic accumulation technique. Results of computer simulations as well as a survey of available field technology are completing the volume.

  15. Fast magnetic field annihilation driven by two laser pulses in underdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y. J.; Kumar, D.; Weber, S.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); Klimo, O. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); FNSPE, Czech Technical University in Prague, 11519 Prague (Czech Republic); Bulanov, S. V.; Esirkepov, T. Zh. [Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215 (Japan)

    2015-10-15

    Fast magnetic annihilation is investigated by using 2.5-dimensional particle-in-cell simulations of two parallel ultra-short petawatt laser pulses co-propagating in underdense plasma. The magnetic field generated by the laser pulses annihilates in a current sheet formed between the pulses. Magnetic field energy is converted to an inductive longitudinal electric field, which efficiently accelerates the electrons of the current sheet. This new regime of collisionless relativistic magnetic field annihilation with a timescale of tens of femtoseconds can be extended to near-critical and overdense plasma with the ultra-high intensity femtosecond laser pulses.

  16. LIGHT SOURCE: Terahertz emission in tenuous gases irradiated by ultrashort laser pulses

    Science.gov (United States)

    Wang, Wei-Min; Sheng, Zheng-Ming; Wit, Hui-Chun; Chen, Min; Li, Chun; Zhang, Jie; Mima, K.

    2009-06-01

    Mechanism of terahertz (THz) pulse generation in gases irradiated by ultrashort laser pulses is investigated theoretically. Quasi-static transverse currents produced by laser field ionization of gases and the longitudinal modulation in formed plasmas are responsible for the THz emission at the electron plasma frequency, as demonstrated by particle-in-cell simulations including field ionization. The THz field amplitude scaling with the laser amplitude within a large range is also discussed.

  17. Short-Pulse Laser-Matter Computational Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Town, R; Tabak, M

    2004-11-02

    For three days at the end of August 2004, 55 plasma scientists met at the Four Points by Sheraton in Pleasanton to discuss some of the critical issues associated with the computational aspects of the interaction of short-pulse high-intensity lasers with matter. The workshop was organized around the following six key areas: (1) Laser propagation/interaction through various density plasmas: micro scale; (2) Anomalous electron transport effects: From micro to meso scale; (3) Electron transport through plasmas: From meso to macro scale; (4) Ion beam generation, transport, and focusing; (5) ''Atomic-scale'' electron and proton stopping powers; and (6) K{alpha} diagnostics.

  18. Laser Pulse Heating of Spherical Metal Particles

    Science.gov (United States)

    Tribelsky, Michael I.; Miroshnichenko, Andrey E.; Kivshar, Yuri S.; Luk'Yanchuk, Boris S.; Khokhlov, Alexei R.

    2011-10-01

    We consider the general problem of laser pulse heating of spherical metal particles with the sizes ranging from nanometers to millimeters. We employ the exact Mie solution of the diffraction problem and solve the heat-transfer equation to determine the maximum temperature rise at the particle surface as a function of optical and thermometric parameters of the problem. Primary attention is paid to the case when the thermal diffusivity of the particle is much larger than that of the environment, as it is in the case of metal particles in fluids. We show that, in this case, for any given duration of the laser pulse, the maximum temperature rise as a function of the particle size reaches a maximum at a certain finite size of the particle. We suggest simple approximate analytical expressions for this dependence, which cover the entire parameter range of the problem and agree well with direct numerical simulations.

  19. A second-order autocorrelator for single-shot measurement of femtosecond laser pulse durations

    Indian Academy of Sciences (India)

    M Raghuramaiah; A K Sharma; P A Naik; P D Gupta; R A Ganeev

    2001-12-01

    A second-order autocorrelator for single-shot measurement of ultrashort laser pulse durations has been set up. It is based on recording the spatial profile of non-collinear phase-matched second harmonic generation in a KDP crystal using a CCD camera-framegrabber combination. Performance of the system is described from measurement of 250 femtosecond transform-limited laser pulses from a passively mode-locked, diode pumped Nd:glass laser. It can also be used for measurement of picosecond laser pulses in the multi-shot scanning mode.

  20. Generation of shock fronts in the interaction of the short pulses of intense laser light in supercritical plasma; Generacion de frentes de choque en la interaccion de pulsos cortos de luz laser intensa en plasmas supercriticos

    Energy Technology Data Exchange (ETDEWEB)

    Lopez V, V.E

    2004-07-01

    The plasma is the state of the matter but diffused in the nature. The sun and the stars big heaps of hot plasma can be considered. The external surface of the terrestrial atmosphere this recovered by a layer of plasma. All gassy discharge (lightning spark arch etc.) this related with the formation of plasma. This way, 99 percent of our environment this formed almost of plasma. It is denominated plasma to the ionized gas in the one which all or most of the atoms have lost one or several of the electrons that belonged him, becoming positive ions and free electrons. In the plasma certain physical characteristics exist as for their behavior like they are the collective movements the quasi neutrality, the Debye length, the uncertainty etc. All these behaviors make that the study of the plasma is complex. For this they exist technical of numeric simulation joined to the technological advance of big computers of more capacity and prosecution speed. The simulation techniques of particles are those where a numeric code is built based on a model or theory of a system that it is wanted to investigate. This way through the simulation the results are compared with those theoretical predictions based on an analytic model. The applications of the physics of the plasma are multiple however we focus ourselves in the interaction laser-plasma. Both finish decades of investigation in the interaction of lasers with plasma they have been carried out in laboratories of Europe, Japan, United States. This studies concern the propagation of intense light laser in dense plasma homogeneous, the radiation absorption in cold plasma and problems related with the generation of suprathermal electrons among others. Other areas of the physics of the plasma-laser interaction that it has been considerable attention is the broadly well-known field as parametric uncertainties induced instabilities by the light and that they include the dispersions for example stimulated Raman and Brillouin being able to