WorldWideScience

Sample records for chirped pulse amplification

  1. 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)

  2. Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten;

    2012-01-01

    Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation.......Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

  3. Chirped pulse amplification: Present and future

    International Nuclear Information System (INIS)

    Short pulses with ultrahigh peak powers have been generated in Nd: glass and Alexandrite using the Chirped Pulse Amplification (CPA) technique. This technique has been successful in producing picosecond terawatt pulses with a table-top laser system. In the near future, CPA will be applied to large laser systems such as NOVA to produce petawatt pulses (1 kJ in a 1 ps pulse) with focused intensities exceeding 10/sup /plus/21/ W/cm2. These pulses will be associated with electric fields in excess of 100 e/a/sub o/2 and blackbody energy densities equivalent to 3 /times/ 1010 J/cm3. This petawatt source will have important applications in x-ray laser research and will lead to fundamentally new experiments in atomic, nuclear, solid-state, plasma, and high-energy density physics. A review of present and future designs are discussed. 17 refs., 5 figs

  4. Hyper dispersion pulse compressor for chirped pulse amplification systems

    Science.gov (United States)

    Barty, Christopher P. J.

    2011-11-29

    A grating pulse compressor configuration is introduced for increasing the optical dispersion for a given footprint and to make practical the application for chirped pulse amplification (CPA) to quasi-narrow bandwidth materials, such as Nd:YAG. The grating configurations often use cascaded pairs of gratings to increase angular dispersion an order of magnitude or more. Increased angular dispersion allows for decreased grating separation and a smaller compressor footprint.

  5. Optical parametric chirped pulse amplification based on photonic crystal fibre

    Institute of Scientific and Technical Information of China (English)

    Wang He-Lin; Yang Ai-Jun; Leng Yu-Xin; Wang Cheng; Xu Zhi-Zhan; Hou Lan-Tian

    2011-01-01

    A compact two-stage optical parametric chirped pulse amplifier based on photonic crystal fibre is demonstrated.A 1064-nm soliton pulse is obtained in a home-made photonic crystal fibre(PCF)with femtosecond pulse pumping and then amplified to 2 mJ in an Nd:YAG regenerative amplifier.After the amplified pulses pass through the LBO crystal,the 532-nm double-frequency light with an energy of 0.8 mJ and a duration of over 100 ps at 10-Hz repetition rate is generated as a pump source in the following two-stage optical parametric amplification(OPA).The 850-am chirped signal light gain from the stretcher is 1.5×104in the first-stage OPA while it is 120 in the second-stage OPA.The total signal gain of optical parametric chirped pulse amplification(OPCPA)can reach 1.8×106.

  6. Study on high gain broadband optical parametric chirped pulse amplification

    International Nuclear Information System (INIS)

    Optical parametric chirped pulse amplification has apparent advantages over the current schemes for high energy ultrashort pulse amplification. High gain in a single pass amplification, small B-integral, low heat deposition, high contrast ratio and, especially the extremely broad gain bandwidth with large-size crystals available bring people new hope for over multi-PW level at which the existing Nd:glass systems suffered difficulties. In this paper we present simulation and experimental studies for a high gain optical parametric chirped pulse amplification system which may be used as a preamplifier to replace the current complicated regenerative system or multi-pass Ti:sapphire amplifiers. Investigations on the amplification bandwidth and gain with BBO are performed. Analysis and discussions are also given. (author)

  7. Broadening and Amplification of an Infrared Femtosecond Pulse for Optical Parametric Chirped-Pulse Amplification

    Institute of Scientific and Technical Information of China (English)

    WANG He-Lin; YANG Ai-Jun; LENG Yu-Xin

    2011-01-01

    A high-average-power diode-pumped narrowband regenerative chirped pulse amplifier is developed using the thin-rod Nd:YAG laser architecture for optical parametric chirped-pulse amplification (OPCPA).The effect of the etalons on the amplified pulse in the regenerative cavity is studied experimentally and theoretically.By inserting glass etalons of thickness 1 mm and 5 mm into the regenerative cavity,the pre-stretching pulse from an (O)ffner stretcher is further broadened to above 200ps,which matches the amplification windows of the signal pulses in OPCPA and is suitable for use as a pump source in the OPCPA system.The bandwidth of the amplified pulse is 1.5 nm,and an output energy of 2mJ is achieved at a repetition rate of 10 Hz.Optical parametric chirped pulse amplification (OPCPA)[1-4] has attracted a great deal of attention as the most promising technique for generating ultrashort ultrahigh-peak-power laser pulses because of its very broad gain bandwidth,negligible thermal load on the nonlinear crystal,and extremely high singlepass gain as compared to amplifiers based on laser gain media.For efficient amplification and high fidelity of dispersion compensation in OPCPA,a femtosecond seed pulse is first stretched to several tens of picoseconds with a bulk grating stretcher or a fiber stretcher.%A high-average-power diode-pumped narrowband regenerative chirped pulse amplifier is developed using the thin-rod Nd:YAG laser architecture for optical parametric chirped-pulse amplification (OPCPA). The effect of the etalons on the amplified pulse in the regenerative cavity is studied experimentally and theoretically. By inserting glass etalons of thickness 1 mm and 5 mm into the regenerative cavity, the pre-stretching pulse from an (O)finer stretcher is further broadened to above 200 ps, which matches the amplification windows of the signal pulses in OPCPA and is suitable for use as a pump source in the OPCPA system. The bandwidth of the amplified pulse is 1.5 nm, and an

  8. Control of Brillouin short-pulse seed amplification by chirping the pump pulse

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, G.; Spatschek, K. H. [Institut für Theoretische Physik, Heinrich-Heine-Universität Düsseldorf, D–40225 Düsseldorf (Germany)

    2015-04-15

    Seed amplification via Brillouin backscattering of a long pump pulse is considered. Similar to Raman amplification, several obstructive effects may occur during short-pulse Brillouin amplification. One is the spontaneous Raman backscattering of the pump before interacting with the seed. Preforming the plasma and/or chirping the pump will reduce unwanted pump backscattering. Optimized regions for low-loss pump propagation were proposed already in conjunction with Raman seed amplification. Hence, the influence of the chirp of the pump during Brillouin interaction with the seed becomes important and will be considered here. Both, the linear as well as the nonlinear evolution phases of the seed caused by Brillouin amplification under the action of a chirped pump are investigated. The amplification rate as well as the seed profiles are presented as function of the chirping rate. Also the dependence of superradiant scaling rates on the chirp parameter is discussed.

  9. Fiber Optical Parametric Chirped Pulse Amplification of Sub-Picosecond Pulses

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Da Ros, Francesco;

    2013-01-01

    We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs.......We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs....

  10. Parametric amplification of a chirped pulse in an optical fiber

    International Nuclear Information System (INIS)

    The OPCPA (Optical Parametric Chirped Pulse Amplification) technique is used in the field of powerful lasers for it enables us to get ultra-short pulses with a reduced optical noise. We have shown that we can replace the massive optical non-linear crystals used in this technique by optical silicon fibers. First, we have made a basic demonstration at the wavelength of 1.55 μm in which a picosecond-long pulse has been amplified by 25 decibels without undergoing any spectral changes. The use of micro-structured optical fibers has allowed us to adapt this method to the wavelength of power laser lines. (A.C.)

  11. Chirped pulse Raman amplification in warm plasma: towards controlling saturation.

    Science.gov (United States)

    Yang, X; Vieux, G; Brunetti, E; Ersfeld, B; Farmer, J P; Hur, M S; Issac, R C; Raj, G; Wiggins, S M; Welsh, G H; Yoffe, S R; Jaroszynski, D A

    2015-01-01

    Stimulated Raman backscattering in plasma is potentially an efficient method of amplifying laser pulses to reach exawatt powers because plasma is fully broken down and withstands extremely high electric fields. Plasma also has unique nonlinear optical properties that allow simultaneous compression of optical pulses to ultra-short durations. However, current measured efficiencies are limited to several percent. Here we investigate Raman amplification of short duration seed pulses with different chirp rates using a chirped pump pulse in a preformed plasma waveguide. We identify electron trapping and wavebreaking as the main saturation mechanisms, which lead to spectral broadening and gain saturation when the seed reaches several millijoules for durations of 10's - 100's fs for 250 ps, 800 nm chirped pump pulses. We show that this prevents access to the nonlinear regime and limits the efficiency, and interpret the experimental results using slowly-varying-amplitude, current-averaged particle-in-cell simulations. We also propose methods for achieving higher efficiencies. PMID:26290153

  12. Trends in ultrashort and ultrahigh power laser pulses based on optical parametric chirped pulse amplification

    International Nuclear Information System (INIS)

    Since the proof-of-principle demonstration of optical parametric amplification to efficiently amplify chirped laser pulses in 1992, optical parametric chirped pulse amplification (OPCPA) became the most promising method for the amplification of broadband optical pulses. In the meantime, we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers. The output power and pulse duration of these systems have ranged from a few gigawatts to hundreds of terawatts with a potential of tens of petawatts power level. Meanwhile, the output pulse duration based on optical parametric amplification has entered the range of few-optical-cycle field. In this paper, we overview the basic principles, trends in development, and current state of the ultrashort and laser systems based on OPCPA, respectively. (paper)

  13. Study and comparison on properties of optical parametric chirped pulse amplification of BBO, LBO and KDP

    International Nuclear Information System (INIS)

    This article theoretically studies phase matching, parametric bandwidth, gain property of optical parametric chirped pulse amplification of BBO, LBO and KDP. It compares properties of optical parametric chirped pulse amplification between BBO and LBO in detail. The results show that it is better to use BBO in Ti:sapphire system with 800 nm central wavelength and LBO with 1053 nm central wavelength

  14. 90 mJ parametric chirped pulse amplification of 10 fs pulses.

    Science.gov (United States)

    Tavella, Franz; Marcinkevicius, Andrius; Krausz, Ferenc

    2006-12-25

    We demonstrate the amplification of broadband pulses from a Ti:Sapphire oscillator by non-collinear optical parametric chirped-pulse amplification technique in a type-I BBO crystal to energies of 90 mJ. Partial compression of the amplified pulses is demonstrated down to a 10 fs duration. These parameters come in combination with good spatial quality and focusability of the amplified beam. PMID:19532173

  15. Mismatch characteristics of optical parametric chirped pulse amplification

    Science.gov (United States)

    Novák, O.; Turčičová, H.; Divoký, M.; Huynh, J.; Straka, P.

    2014-02-01

    The stability of an optical parametric chirped pulse amplifier (OPCPA) is influenced by time and the angular matching of the input beams. We derived the Gaussian dependence of the monochromatic signal gain on the small mismatch between the signal and pump beams. Gain characteristics were also calculated for polychromatic amplification and the impact of different beam mismatches and interaction geometries was explained. The asymmetry of the energy gain, and the square root dependence of the phase matched wavelength on beam angles were found. The predicted dependences were verified in a noncollinear OPCPA system with LBO and KDP crystal amplifying pulses of a Ti:sapphire laser around a central wavelength of 800 nm, pumped by the third harmonic frequency of an iodine gas laser at a wavelength of 438 nm. The widths of the gain curves in the dependence on both the pump-signal or the phase matching angles varied from several tenths to a few milliradians. The gain curve widths dependent on the pump-signal pulse delay were about two thirds of the pump pulse width for moderate pumping and about a half of the pump pulse width for pumping on the order of GW cm-2. A stable gain output is achieved if angular and temporal fluctuations are fractions of the measured gain curve widths, and when the signal direction is between the pump and the crystal principal axis (i.e. in the psz geometry).

  16. Mismatch characteristics of optical parametric chirped pulse amplification

    International Nuclear Information System (INIS)

    The stability of an optical parametric chirped pulse amplifier (OPCPA) is influenced by time and the angular matching of the input beams. We derived the Gaussian dependence of the monochromatic signal gain on the small mismatch between the signal and pump beams. Gain characteristics were also calculated for polychromatic amplification and the impact of different beam mismatches and interaction geometries was explained. The asymmetry of the energy gain, and the square root dependence of the phase matched wavelength on beam angles were found. The predicted dependences were verified in a noncollinear OPCPA system with LBO and KDP crystal amplifying pulses of a Ti:sapphire laser around a central wavelength of 800 nm, pumped by the third harmonic frequency of an iodine gas laser at a wavelength of 438 nm. The widths of the gain curves in the dependence on both the pump–signal or the phase matching angles varied from several tenths to a few milliradians. The gain curve widths dependent on the pump–signal pulse delay were about two thirds of the pump pulse width for moderate pumping and about a half of the pump pulse width for pumping on the order of GW cm−2. A stable gain output is achieved if angular and temporal fluctuations are fractions of the measured gain curve widths, and when the signal direction is between the pump and the crystal principal axis (i.e. in the psz geometry). (letter)

  17. Optimization of Pulse Temporal Contrast in Optical Parametric Chirped Pulse Amplification

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Hai; PAN Xue; LI Xue-Chun; LIN Zun-Qi

    2009-01-01

    In optical parametric chirped pulse amplification (OPCPA), the degradation of temporal contrast of the com-pressed signal pulse mainly results from spectral clipping in the grating stretcher with finite size of the optics, parametric fluorescence (PF) and the spectral variations transferred from temporal fluctuation of the pump pulse. The temporal contrast of the recompressed amplified pulse in the OPCPA system is studied numerically and a number of solutions are considered and optimized to achieve the highest temporal contrast.

  18. High gain broadband amplification of ultraviolet pulses in optical parametric chirped pulse amplifier.

    Science.gov (United States)

    Wnuk, Paweł; Stepanenko, Yuriy; Radzewicz, Czesław

    2010-04-12

    We report on a high gain amplification of broadband ultraviolet femtosecond pulses in an optical parametric chirped pulse amplifier. Broadband ultraviolet seed pulses were obtained by an achromatic frequency doubling of the output from a femtosecond Ti:Sapphire oscillator. Stretched seed pulses were amplified in a multipass parametric amplifier with a single BBO crystal pumped by a ns frequency quadrupled Nd:YAG laser. A noncollinear configuration was used for a broadband amplification. The total (after compression) amplification of 2.510(5) was achieved, with compressed pulse energy of 30 microJ and pulse duration of 24 fs. We found that the measured gain was limited by thermal effects induced by the absorption of the pump laser by color centers created in the BBO crystal. PMID:20588633

  19. Flashlamp pumped Ti-sapphire laser for ytterbium glass chirped pulse amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Akihiko; Ohzu, Akira; Sugiyama, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1998-03-01

    A flashlamp pumped Ti:sapphire laser is designed for ytterbium glass chirped pulse amplification. A high quality Ti:sapphire rod and a high energy long pulse discharging power supply are key components. The primary step is to produce the output power of 10 J per pulse at 920 nm. (author)

  20. Dispersion Analysis and Compensation of Collinear Optical Parametric Chirped Pulse Amplification Systems

    Institute of Scientific and Technical Information of China (English)

    WANG Cheng; LENG Yu-Xin; LIANG Xiao-Yan; ZHANG Chun-Mei; ZHAO Bao-Zhen; XU Zhi-Zhan

    2005-01-01

    @@ In an optical parametric chirped pulse amplification (OPCPA) laser system, residual phase dispersion should be compensated as much as possible to shorten the amplified pulses and improve the pulse contrast ratio. Expressions of orders of the induced phases in collinear optical parametric amplification (OPA) processes are presented at the central signal wavelength to depict a clear physics picture and to simplify the design of phase compensation. As examples, we simulate two OPCPA systems to compensate for the phases up to the partial fourth-order terms,and obtain flat phase spectra of 200-nm bandwidth at 1064 nm and 90-nm at 800nm.

  1. A pulse compressor for a chirped-pulse amplification system based on a frequency-doubling crystal and grating

    Science.gov (United States)

    Chen, Ying; Zhou, Yuan; Yuan, Peng; Qian, Liejia

    2016-05-01

    The limited damage threshold of the last compression grating in a general compressor is still an obstruction that limits the output capability of a high-energy laser facility. We propose and theoretically study a novel pulse compressor consisting of a pair of gratings and a nonlinear crystal, which is applied to chirped-pulse amplification (CPA) or optical parametric CPA (OPCPA) systems. The obstruction in the high-energy laser facility is alleviated substantially in our proposed compressor because the nonlinear crystal with a much higher damage threshold can withstand more high energy of the chirped pulse. We prove that, by means of a pair of anti-parallel gratings and noncollinear frequency doubling, it is possible to obtain a compressed second-harmonic pulse without chirp and angular dispersion. A hypothetical example of a 1 μm linear chirped pulse compression is discussed.

  2. Dynamic Characterization of Fiber Optical Chirped Pulse Amplification for Sub-ps Pulses

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard;

    2013-01-01

    We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation.......We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation....

  3. Amplification and focusing of a picosecond chirped pulse to 20TW and 5x1017W/cm2

    International Nuclear Information System (INIS)

    Pulses of 20 TW power have been generated at 1064 nm using the Chirped Pulse Amplification technique coupled to a 90 mm output aperture powerful Nd:silicate glass amplification line. This system delivers 60 J in a chirped pulse of 600 ps duration with a capacity of maintaining 3.5 nm output bandwidth. These chirped pulses have been compressed to 1.2 ps with an energy of 24J using large holographic diffraction gratings. After presenting the results we discuss the expected applications in atomic and plasma physics

  4. High-power chirped-pulse all-fiber amplification system based on large-mode-area fiber gratings

    OpenAIRE

    Broderick, N.G.R.; Richardson, D.J.; Taverner, D.; Caplen, J.E.; Dong, L.; Ibsen, M.

    1999-01-01

    The fabrication of large mode-area single mode fibres are crucial to developing high power all-fibre lasers and amplifiers. We report the amplification of picosecond pulses to microjoule energy levels and pulse peak powers in excess of 500kW in an all fiber Chirped Pulse Amplification (CPA) system based on novel large mode area fiber components.

  5. Chirped-pulse amplification system based on chirp reversal and near-field spatial reversal with common tiled grating pair as stretcher and compressor.

    Science.gov (United States)

    Wang, Xiao; Wei, Xiaofeng; Hu, Yao; Zeng, Xiaoming; Zuo, Yanlei; Hao, Xin; Zhou, Kainan; Xie, Na; Zhang, Ying

    2012-08-10

    Chirped-pulse amplification system based on chirp reversal in optical parametric chirped-pulse amplification is proposed and experimentally demonstrated. The operation of this system can be described as negative stretching-temporal chirp reversal-energy amplification-negative compression, in which the pulse is stretched and compressed with the same gratings. Stand-alone stretcher adopting lenses or concave mirrors with large aperture can be omitted. Simulations showed that this work mode can also increase the cut-off band-pass of the whole system and increase the output energy by 15-17%. In addition, the stability of a tiled-grating compressor can be improved with this work mode. PMID:22885574

  6. Experimental and Theoretical Analysis of Nondegenerate Ultrabroadband Chirped Pulse Optical Parametric Amplification

    Institute of Scientific and Technical Information of China (English)

    刘红军; 赵卫; 陈国夫; 王屹山; 于连君; 阮驰; 卢克清

    2004-01-01

    Experimental investigations of nondegenerate ultrabroadband chirped pulse optical parametric amplification have been carried out. The general mathematical expressions for evaluating parametric bandwidth, gain and gain bandwidth for arbitrary three-wave mixing parametric amplifiers are presented. In our experiments, a type-I noncollinear phase-matched optical parametric amplifier based on lithium triborate, which was pumped by a 5-ns second harmonic pulses from a Q-switched Nd:YAG operating at 10 Hz, seeded by a 14-rs Ti:sapphire laser at 800nm, was presented. The 0.85nJ energy of input chirped signal pulse with 57-FWHM has been amplified to 3.1 μJ at pump intensity 3 G W/cm2, the corresponding parametric gain reached 3.6 × 103, the 53 nm-FWHM gain spectrum bandwidth of output signal has been obtained. The large gain and broad gain bandwidth, which have been confirmed experimentally, provide great potentials to amplify efficiently the broad bandwidth femtosecond light pulses to generate new extremes in power, intensity, and pulse duration using optical parametric chirped pulse amplifiers pumped by powerful nanosecond systems.

  7. Mismatch characteristics of optical parametric chirped pulse amplification

    Czech Academy of Sciences Publication Activity Database

    Novák, Ondřej; Turčičová, Hana; Divoký, Martin; Huynh, Jaroslav; Straka, Petr

    2014-01-01

    Roč. 11, č. 2 (2014), 1-7. ISSN 1612-2011 R&D Projects: GA ČR GA202/06/0814; GA MŠk(CZ) LC528 Institutional support: RVO:68378271 Keywords : phase matching * phase mismatch * beam mismatch * broadband amplification * parametric amplifiers * OPCPA * iodine laser Subject RIV: BH - Optics , Masers, Laser s Impact factor: 2.458, year: 2014

  8. 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

  9. Pump-seed synchronization for MHz repetition rate, high-power optical parametric chirped pulse amplification.

    Science.gov (United States)

    Fattahi, Hanieh; Teisset, Catherine Yuriko; Pronin, Oleg; Sugita, Atsushi; Graf, Roswitha; Pervak, Vladimir; Gu, Xun; Metzger, Thomas; Major, Zsuzsanna; Krausz, Ferenc; Apolonski, Alexander

    2012-04-23

    We report on an active synchronization between two independent mode-locked lasers using a combined electronic-optical feedback. With this scheme, seed pulses at MHz repetition rate were amplified in a non-collinear optical parametric chirped pulse amplifier (OPCPA). The amplifier was seeded with stretched 1.5 nJ pulses from a femtosecond Ti:Sapphire oscillator, while pumped with the 1 ps, 2.9 µJ frequency-doubled output of an Yb:YAG thin-disk oscillator. The residual timing jitter between the two oscillators was suppressed to 120 fs (RMS), allowing for an efficient and broadband amplification at 11.5 MHz to a pulse energy of 700 nJ and an average power of 8 W. First compression experiment with 240 nJ amplified pulse energy resulted in a pulse duration of ~10 fs. PMID:22535076

  10. Spatiotemporal noise characterization for chirped-pulse amplification systems.

    Science.gov (United States)

    Ma, Jingui; Yuan, Peng; Wang, Jing; Wang, Yongzhi; Xie, Guoqiang; Zhu, Heyuan; Qian, Liejia

    2015-01-01

    Optical noise, the core of the pulse-contrast challenge for ultra-high peak power femtosecond lasers, exhibits spatiotemporal (ST) coupling induced by angular dispersion. Full characterization of such ST noise requires two-dimensional measurements in the ST domain. Thus far, all noise measurements have been made only in the temporal domain. Here we report the experimental characterization of the ST noise, which is made feasible by extending cross-correlation from the temporal domain to the ST domain. We experimentally demonstrate that the ST noise originates from the optical surface imperfections in the pulse stretcher/compressor and exhibits a linear ST coupling in the far-field plane. The contrast on the far-field axis, underestimated in the conventional measurements, is further improved by avoiding the far-field optics in the stretcher. These results enhance our understanding of the pulse contrast with respect to its ST-coupling nature and pave the way toward the design of high-contrast ultra-high peak power lasers. PMID:25648187

  11. High-energy infrared femtosecond pulses generated by dual-chirped optical parametric amplification.

    Science.gov (United States)

    Fu, Yuxi; Takahashi, Eiji J; Midorikawa, Katsumi

    2015-11-01

    We demonstrate high-energy infrared femtosecond pulse generation by a dual-chirped optical parametric amplification (DC-OPA) scheme [Opt. Express19, 7190 (2011)]. By employing a 100 mJ pump laser, a signal pulse energy exceeding 20 mJ at a wavelength of 1.4 μm was achieved before dispersion compensation. A total output energy of 33 mJ was recorded. Under a further energy scaling condition, the signal pulse was compressed to an almost transform-limited duration of 27 fs using a fused silica prism compressor. Since the DC-OPA scheme is efficient and energy scalable, design parameters for obtaining 100 mJ level infrared pulses are presented, which are suitable as driver lasers for the energy scaling of high-order harmonic generation with sub-keV photon energy. PMID:26512524

  12. Efficient chirped-pulse amplification of sub-20 fs laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Shinichi; Yamakawa, Koichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    We have developed a model for ultrabroadband and ultrashort pulse amplification including the effects of a pulse shaper for regenerative pulse shaping, gain narrowing and gain saturation in the amplifiers. Thin solid etalons are used to control both gain narrowing and gain saturation during amplification. This model has been used to design an optimized Ti:sapphire amplifier system for producing efficiently pulses of < 20-fs duration with approaching peak and average powers of 100 TW and 20 W. (author)

  13. Conceptual design of sub-exa-watt system by using optical parametric chirped pulse amplification

    Science.gov (United States)

    Kawanaka, J.; Tsubakimoto, K.; Yoshida, H.; Fujioka, K.; Fujimoto, Y.; Tokita, S.; Jitsuno, T.; Miyanaga, N.; Gekko-EXA Design Team

    2016-03-01

    A 50 PW ultrahigh-peak-power laser has been conceptually designed, which is based on optical parametric chirped pulse amplification (OPCPA). A 250 J DPSSL and a flash- lamp-pumped kJ laser are adopted as new repeatable pump source. The existed LFEX-laser with more than ten kilo joules are used in the final amplifier stage and the OPCPA with the 2x2 tiled pump beams in random phase has been proposed with several ten centimeter aperture. A pulse duration of amplified pulses is set at less than 10 fs. A broadband OPCPA with ∼500 nm of the gain spectral width near 1 μm is required. A partially deuterated KDP (p-DKDP) crystal is one of the most promising nonlinear crystals and our numerical calculation ensured such ultra-broad gain width. p-DKDP crystals with several deuteration ratio have been successfully grown.

  14. Precision short-pulse damage test station utilizing optical parametric chirped-pulse amplification

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I; Brown, C; Wattellier, B; Nielsen, N; Molander, W; Stuart, B; Pennington, D; Barty, C J

    2004-03-22

    The next generation of high-energy petawatt (HEPW)-class lasers will utilize multilayer dielectric diffraction gratings for pulse compression, due to their high efficiency and high damage threshold for picosecond pulses. The peak power of HEPW lasers will be determined by the aperture and damage threshold of the final dielectric grating in the pulse compressor and final focusing optics. We have developed a short-pulse damage test station for accurate determination of the damage threshold of the optics used on future HEPW lasers. Our damage test station is based on a highly stable, high-beam-quality optical parametric chirped-pulse amplifier (OPCPA) operating at 1053 nm at a repetition rate of 10 Hz. We present the design of our OPCPA system pumped by a commercial Q-switched pump laser and the results of the full system characterization. Initial short-pulse damage experiments in the far field using our system have been performed.

  15. 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.

  16. Dynamic characterization and amplification of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard;

    2013-01-01

    We show a first-time demonstration of amplification of 400 fs pulses in a fiber optical parametric amplifier. The 400 fs signal is stretched in time, amplified by 26 dB and compressed back to 500 fs. A significant broadening of the pulses is experimentally shown due to dispersion and limited gain...

  17. Yb:YAG Innoslab amplifier: efficient high repetition rate subpicosecond pumping system for optical parametric chirped pulse amplification

    OpenAIRE

    Schulz, M.; Riedel, R; Willner, A.; Mans, T.; Schnitzler, C.; Russbueldt, P.; Dolkemeyer, J.; Seise, E.; Gottschall, T.; Haedrich, S.; Duesterer, S.; Schlarb, H.; Feldhaus, J.; J. Limpert; Faatz, B.

    2011-01-01

    We report on a Yb:YAG Innoslab laser amplifier system for generation of subpicsecond high energy pump pulses for optical parametric chirped pulse amplification (OPCPA) at high repetition rates. Pulse energies of up to 20 mJ (at 12.5 kHz) and repetition rates of up to 100 kHz were attained with pulse durations of 830 fs and average power in excess of 200 W. We further investigate the possibility to use subpicosecond pulses to derive a stable continuum in a YAG crystal for OPCPA seeding.

  18. Yb:YAG Innoslab amplifier: efficient high repetition rate subpicosecond pumping system for optical parametric chirped pulse amplification.

    Science.gov (United States)

    Schulz, M; Riedel, R; Willner, A; Mans, T; Schnitzler, C; Russbueldt, P; Dolkemeyer, J; Seise, E; Gottschall, T; Hädrich, S; Duesterer, S; Schlarb, H; Feldhaus, J; Limpert, J; Faatz, B; Tünnermann, A; Rossbach, J; Drescher, M; Tavella, F

    2011-07-01

    We report on a Yb:YAG Innoslab laser amplifier system for generation of subpicsecond high energy pump pulses for optical parametric chirped pulse amplification (OPCPA) at high repetition rates. Pulse energies of up to 20 mJ (at 12.5 kHz) and repetition rates of up to 100 kHz were attained with pulse durations of 830 fs and average power in excess of 200 W. We further investigate the possibility to use subpicosecond pulses to derive a stable continuum in a YAG crystal for OPCPA seeding. PMID:21725443

  19. Alignment of a tiled-grating compressor in a high-power chirped-pulse amplification laser system.

    Science.gov (United States)

    Hornung, Marco; Bödefeld, Ragnar; Siebold, Mathias; Schnepp, Matthias; Hein, Joachim; Sauerbrey, Roland; Kaluza, Malte C

    2007-10-20

    We present a novel technique to align a tiled grating in all five relevant degrees of freedom utilized in the compressor of the high-power chirped-pulse amplification laser system POLARIS at the Institute for Optics and Quantum Electronics, Jena, Germany. With this technique, alignment errors of the two gratings with respect to each other can be detected with an accuracy of 1 microrad for the rotational and 40 nm for the translational degrees of freedom. This is well sufficient to recompress 1030 nm pulses, which were stretched to 2.2 ns before amplification, to their bandwith limit of 150 fs. PMID:17952178

  20. Optical parametric chirped pulse amplification and spectral shaping of a continuum generated in a photonic band gap fiber.

    Science.gov (United States)

    Hugonnot, E; Somekh, M; Villate, D; Salin, F; Freysz, E

    2004-05-31

    A chirped pulse, spectrally broadened in a photonic bandgap optical fiber by 120 fs Ti:Sapphire laser pulses, is parametrically amplified in a BBO crystal pumped by a frequency doubled nanosecond Nd:YAG laser pulse. Without changing the frequency of the Ti:Sapphire, a spectral tunability of the amplified pulses is demonstrated. The possibility to achieve broader spectral range amplification is confirmed for a non-collinear pump-signal interaction geometry. For optimal non-collinear interaction geometry, the pulse duration of the original and amplified pulse are similar. Finally, we demonstrate that the combination of two BBO crystals makes it possible to spectrally shape the amplified pulses. PMID:19475076

  1. Accurate offline dispersion measurement of Petawatt-class chirped pulse amplification compressor and stretcher systems

    International Nuclear Information System (INIS)

    Complete text of publication follows. The Advanced Radiographic Capability (ARC) on the National Ignition Facility (NIF) is designed to produce energetic x-rays in the range of 10-100 keV for backlighting NIF targets. ARC will convert 4 of the 192 NIF beamlines into 8 split beams, delivering laser pulses with adjustable pulse durations from 1 ps to 50 ps at the kilo-Joule level. Adjustable time delays between the 8 beams enable X-ray 'motion-picture' capture with tens-of-picosecond resolution during the critical phases of an ICF shot. The precise alignment of stretcher-compressor pairs in energetic chirped pulse amplification (CPA) systems is tedious and requires several iterations using advanced temporal diagnostics until the shortest pulse durations and highest peak intensities are achieved. For large, energetic Petawatt laser systems with beam sizes up to 40 cm, diffraction gratings in the compressor reach meter-scale size and are difficult to precisely align. We developed a group delay diagnostic which enables accurate, offline measurements of highly dispersive components such as stretchers or compressors with sub-picosecond accuracy. This diagnostic tool enables us to simply measure each dispersive component offline, and balance the dispersion in each beamline. Furthermore it allows exactly matching the dispersion of ARC's eight, independent four-grating compressors, which is critical for producing eight identical pulses. ARC utilizes a unique, folded compressor design for maximum compactness; two 5.5 m long vacuum vessels house 8 compressors with 91 cm x 45 cm multilayer, dielectric gratings. The group delay diagnostic utilizes the phase-shift technique for measuring the dispersion characteristics of each individual element, e.g. grating stretcher, chirped fiber Bragg grating, grating compressor, material dispersion, or an entire laser system. The system uses an amplitude modulated, highly-stable, single-frequency laser, which is scanned over the spectral

  2. A broadband frequency-tripling scheme for an Nd:glass laser-based chirped-pulse amplification system: an approach for efficiently generating ultraviolet petawatt pulses

    International Nuclear Information System (INIS)

    We propose and numerically demonstrate a broadband frequency-tripling scheme for an Nd:glass laser-based chirped-pulse amplification system at 1053 nm. On the basis of the frequency mixing of a broadband chirped pulse with a narrowband laser pulse, the tripling scheme can support a bandwidth as large as 5 nm by alleviating the effects of the group-velocity mismatch involved, and it can be applied to generate ultraviolet petawatt (PW) pulses from a typical Nd:glass petawatt laser system. Both the energy of the ultraviolet pulse and the tripling efficiency (>80%) are boosted by an additional narrowband fundamental laser. The ultraviolet pulse generated can be compressed to a duration shorter than that of the initial Nd:glass PW pulse and its peak power can be increased to 2.5 times that of the Nd:glass PW pulse

  3. Concepts, performance review, and prospects of table-top, few-cycle optical parametric chirped-pulse amplification

    Science.gov (United States)

    Vaupel, Andreas; Bodnar, Nathan; Webb, Benjamin; Shah, Lawrence; Richardson, Martin

    2014-05-01

    More than 20 years after the first presentation of optical parametric chirped-pulse amplification (OPCPA), the technology has matured as a powerful technique to produce high-intensity, few-cycle, and ultrashort laser pulses. The output characteristics of these systems cover a wide range of center wavelengths, pulse energies, and average powers. The current record performance of table-top, few-cycle OPCPA systems are 16 TW peak power and 22 W average power, which show that OPCPA is able to directly compete with Ti:sapphire chirped-pulse amplification-based systems as source for intense optical pulses. Here, we review the concepts of OPCPA and present the current state-of-the art performance level for several systems reported in the literature. To date, the performance of these systems is most generally limited by the employed pump laser. Thus, we present a comprehensive review on the recent progress in high-energy, high-average-power, picosecond laser systems, which provide improved performance relative to OPCPA pump lasers employed to date. From here, the impact of these novel pump lasers on table-top, few-cycle OPCPA is detailed and the prospects for next-generation OPCPA systems are discussed.

  4. Thermal Properties of Borate Crystals for High Power Optical Parametric Chirped-Pulse Amplification

    OpenAIRE

    Riedel, Robert; Rothhardt, J.; Tünnermann, A.; Prandolini, Mark; Tavella, F.; Beil, K.; Gronloh, B.; Klenke, A.; Höppner, H.; M. Schulz; Teubner, U.; Kraenkel, Christian; Limpert, J.

    2014-01-01

    The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10–100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The line...

  5. Development of the chirped pulse amplification technique for high peak power production with Nd: glass laser system

    International Nuclear Information System (INIS)

    There has been a large amount of development in the field of ultra short pulsed lasers and high peak intensity laser systems. Therefore the objective of this work was to develop the concept of chirped pulse amplification (CPA), that is essential for any high-peak-power laser technology. The design of the CPA system using Nd:glass as the active medium has been developed in this laboratory at B.A.R.C. for the first time. The beginning is with a 100 MHz train of 200fs pulses, that is supported by a 7nm FWHM bandwidth and a central wavelength at 1056nm. A single pulse of 70pJ energy is selected from this train after stretching the pulse to 266ps. The purpose of stretching is to decrease the instantaneous intensity, so that no non-linear effect or damage is introduced in the amplifying medium (Nd:glass) during amplification. This stretched pulse is amplified to about 40mJ and then compressed to a 1.5ps pulse having a bandwidth of 3.8nm. Pulse width expansion and compression is achieved by means of conjugate grating pairs. A real-time autocorrellator set up measures the stretched as well as the compressed pulse. (author)

  6. Generation and Amplification of Cherenkov Superradiance Pulses by Electron Beams with Energy Chirp

    Science.gov (United States)

    Ginzburg, N. S.; Zotova, I. V.; Sergeev, A. S.

    2003-10-01

    We propose a method for increasing the peak power of a superradiance pulse by varying the electron energy along an electron bunch. A one-dimensional time-dependent model describing the evolution of an electromagnetic pulse as well as direct numerical simulations based on the KARAT code show that the power of generated pulses becomes several times greater if the particle energy increases linearly along the bunch. A similar method can be applied to increase the peak power in the case of amplification of a short electromagnetic pulse (and a superradiance pulse generated by an external source) propagated along a quasi-continuous electron beam with a certain particle-energy profile.

  7. Thermal properties of borate crystals for high power optical parametric chirped-pulse amplification.

    Science.gov (United States)

    Riedel, R; Rothhardt, J; Beil, K; Gronloh, B; Klenke, A; Höppner, H; Schulz, M; Teubner, U; Kränkel, C; Limpert, J; Tünnermann, A; Prandolini, M J; Tavella, F

    2014-07-28

    The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10-100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The linear and nonlinear absorption coefficients at 515 nm as well as thermal conductivities were determined for the first time for BiBO. Further, different crystal cooling methods are presented. In addition, the limits to power scaling of OPCPAs are discussed. PMID:25089381

  8. Investigation of two-beam-pumped noncollinear optical parametric chirped-pulse amplification for the generation of few-cycle light pulses.

    Science.gov (United States)

    Herrmann, Daniel; Tautz, Raphael; Tavella, Franz; Krausz, Ferenc; Veisz, Laszlo

    2010-03-01

    We demonstrate a new and compact Phi-plane-pumped noncollinear optical parametric chirped-pulse amplification (NOPCPA) scheme for broadband pulse amplification, which is based on two-beam-pumping (TBP) at 532 nm. We employ type-I phase-matching in a 5 mm long BBO crystal with moderate pump intensities to preserve the temporal pulse contrast. Amplification and compression of the signal pulse from 675 nm - 970 nm is demonstrated, which results in the generation of 7.1-fs light pulses containing 0.35 mJ energy. In this context, we investigate the pump-to-signal energy conversion efficiency for TBP-NOPCPA and outline details for few-cycle pulse characterization. Furthermore, it is verified, that the interference at the intersection of the two pump beams does not degrade the signal beam spatial profile. It is theoretically shown that the accumulated OPA phase partially compensates for wave-vector mismatch and leads to extended broadband amplification. The experimental outcome is supported by numerical split-step simulations of the parametric signal gain, including pump depletion and parametric fluorescence. PMID:20389430

  9. X-ray Chirped Pulse Amplification: towards GW Soft X-ray Lasers

    OpenAIRE

    Marta Fajardo; Pedro Velarde; Lu Li; David Ros; Stéphane Sebban; Eduardo Oliva; Thi Thu Thuy Le; Philippe Zeitoun

    2013-01-01

    Extensive modeling of the seeding of plasma-based soft X-ray lasers is reported in this article. Seminal experiments on amplification in plasmas created from solids have been studied in detail and explained. Using a transient collisional excitation scheme, we show that a 18 µJ, 80 fs fully coherent pulse is achievable by using plasmas pumped by a compact 10 Hz laser. We demonstrate that direct seeding of plasmas created by nanosecond lasers is not efficient. Therefore, we propose and fully st...

  10. High amplified spontaneous emission contrast of 1011 in a Nd:glass laser based on a hybrid double chirped pulse amplification scheme

    International Nuclear Information System (INIS)

    By using a Ti:sapphire-Nd:glass hybrid double chirped pulse amplification scheme and a pulse cleaner based on optical parametric amplification and second harmonic generation, we demonstrate high amplified spontaneous emission (ASE) contrast at 1053 nm. The optimized ASE temporal contrast of the output pulse is about 1011 at about 160 ps before the main peak with an output of 140 mJ/500 fs. And the potential of 10 J level output with high ASE contrast is demonstrated in a laser system with attenuated injection. (paper)

  11. Hybrid master oscillator power amplifier system providing 10 mJ, 32 W, and 50 MW pulses for optical parametric chirped-pulse amplification pumping

    International Nuclear Information System (INIS)

    We present a high-energy, high-average-power picosecond laser system based on a hybrid chain in a master oscillator power amplifier configuration. The chain is seeded by a Ti:sapphire oscillator, followed by a Yb doped fiber preamplifier, a Nd:YAG-based regenerate amplifier, and a Nd:YVO4-based single-pass amplifier. The final diode-pumped, solid-state amplifier is detailed and produces pulses with more than 10 mJ energy at 32 W average power with 207 ps duration, corresponding to 50 MW peak power. The picosecond pulse output is seeded and optically synchronized with the sub-5-fs oscillator for optical parametric chirped-pulse amplification pumping. (authors)

  12. Q-switching operation with a cooled Yb:LiYF4 for diode-pumped chirped-pulse regenerative amplification

    International Nuclear Information System (INIS)

    A diode-pumped regeneration amplifier with a cooled Yb:LiYF4 crystal has been constructed as a booster amplifier in our all solid-state ultrahigh-peak-power laser system. The output energy of 4.5 mJ in a Q-switching operation mode was observed. The small signal gain and cavity loss estimated have been used to calculate output energy of 12 mJ in regenerative amplification of a chirped seed pulse. (author)

  13. Developments of a front-end system for high-intense Nd:glass laser used in optical parametric chirped pulse amplification

    International Nuclear Information System (INIS)

    We have constructed the front-end system using a broadband high-gain OPCPA for chirped pulse amplification. This system can deliver the output energy of 65 mJ with 6-nm spectral width at a 1.053-μm central wavelength. The stability of output energy was substantially improved compared with the Ti:Al2O3 regenerative amplifier. These output parameters are appropriate as a seed of PW-class Nd:glass laser system. (author)

  14. High average power, high energy, femto-second fiber chirped pulse amplification system

    OpenAIRE

    He, F.; Price, J.H.V.; Malinowski, A.; Piper, A.; Ibsen, M.; Richardson, D.J.; Dawson, J. W.; Siders, C.W.; Britten, J.A.; Barty, C. P. J.

    2007-01-01

    We have demonstrated an Yb-fiber laser system incorporating a CFBG stretcher, bandwidth optimised amplifiers and dielectric grating compressor. The system produced 135 W average power with pulse energy of 13.5 µJ. The recompressed pulse duration was 360 fs.

  15. Generation of 287 W, 5.5 ps pulses at 78 MHz repetition rate from a cryogenically cooled Yb:YAG amplifier seeded by a fiber chirped-pulse amplification system.

    Science.gov (United States)

    Hong, Kyung-Han; Siddiqui, Aleem; Moses, Jeffrey; Gopinath, Juliet; Hybl, John; Ilday, F Omer; Fan, Tso Yee; Kärtner, Franz X

    2008-11-01

    We generate linearly polarized, 287 W average-power, 5.5 ps pulses using a cryogenically cooled Yb:YAG amplifier at a repetition rate of 78 MHz. An optical-to-optical efficiency of 41% is obtained at 700 W pump power. A 6 W, 0.4 nm bandwidth picosecond seed source at 1029 nm wavelength is constructed using a chirped-pulse fiber amplification chain based on chirped volume Bragg gratings. The combination of a fiber amplifier system and a cryogenically cooled Yb:YAG amplifier results in good spatial beam quality at large average power. Low nonlinear phase accumulation as small as 5.1 x 10(-3) rad in the bulk Yb:YAG amplifier supports power scalability to a > 10 kW level without being affected by self-phase modulation. This amplification system is well suited for pumping high-power high-repetition-rate optical parametric chirped-pulse amplifiers. PMID:18978891

  16. Development of a front-end system for chirped pulse amplification high-power Nd:glass laser

    International Nuclear Information System (INIS)

    We have developed a front-end system to generate a chirped pulse at a wavelength of 1053 nm for a 100 TW glass laser system. The front-end system consists of a passively mode-locked diode-pumped Nd:glass laser, a pulse stretcher and a Ti:Al2O3 regenerative amplifier. The passive mode-locked diode-pumped Nd:fluorophosphate glass laser produced pulses as short as 150 fs at an average power of 100 mW at 1053 nm-1061 nm at a repetition frequency of 99.98 MHz. The TEM00 Ti:Al2O3 regenerative amplifier exhibited a net gain of over 106 at 1053 nm. At long time operation, the output pulse energy is typically 4 mJ, with a power fluctuation of less than ±5% with temperature and humidity control in cavity. No significant gain narrowing was observed in the cavity, resulting in a 1.6 ns chirped pulse that was synchronized with the RF signal of GEKKO XII laser system within a few ps by controlling the oscillator cavity length with a PZT actuator. (author)

  17. Development of a front-end system for chirped pulse amplification high-power Nd:glass laser

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Hidetsugu; Kodama, Ryosuke; Fujita, Hisanori; Kato, Yoshiaki; Mima, Kunioki [Osaka Univ., Suita (Japan). Inst. of Laser Engineering

    1999-04-01

    We have developed a front-end system to generate a chirped pulse at a wavelength of 1053 nm for a 100 TW glass laser system. The front-end system consists of a passively mode-locked diode-pumped Nd:glass laser, a pulse stretcher and a Ti:Al{sub 2}O{sub 3} regenerative amplifier. The passive mode-locked diode-pumped Nd:fluorophosphate glass laser produced pulses as short as 150 fs at an average power of 100 mW at 1053 nm-1061 nm at a repetition frequency of 99.98 MHz. The TEM{sub 00} Ti:Al{sub 2}O{sub 3} regenerative amplifier exhibited a net gain of over 10{sup 6} at 1053 nm. At long time operation, the output pulse energy is typically 4 mJ, with a power fluctuation of less than {+-}5% with temperature and humidity control in cavity. No significant gain narrowing was observed in the cavity, resulting in a 1.6 ns chirped pulse that was synchronized with the RF signal of GEKKO XII laser system within a few ps by controlling the oscillator cavity length with a PZT actuator. (author)

  18. Amplification of a seed pumped by a chirped laser in the strong coupling Brillouin regime

    Energy Technology Data Exchange (ETDEWEB)

    Schluck, F.; Lehmann, G.; Spatschek, K. H. [Institut für Theoretische Physik, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf (Germany)

    2015-09-15

    Seed amplification via Brillouin backscattering of a long pump laser-pulse is considered. The interaction takes place in the so called strong coupling regime. Pump chirping is applied to mitigate spontaneous Raman backscattering of the pump before interacting with the seed. The strong coupling regime facilitates stronger exponential growth and narrower seeds compared to the so called weak coupling regime, although in the latter the scaling with pump amplitude is stronger. Strong coupling is achieved when the pump laser amplitude exceeds a certain threshold. It is shown how the chirp influences both the linear as well as the nonlinear amplification process. First, linear amplification as well as the seed profiles are determined in dependence of the chirping rate. In contrast to the weak coupling situation, the evolution is not symmetric with respect to the sign of the chirping rate. In the nonlinear stage of the amplification, we find an intrinsic chirp of the seed pulse even for an un-chirped pump. We show that chirping the pump may have a strong influence on the shape of the seed in the nonlinear amplification phase. Also, the influence of pump chirp on the efficiency of Brillouin seed amplification is discussed.

  19. Optimization for high-energy and high-efficiency broadband optical parametric chirped-pulse amplification in LBO near 800  nm.

    Science.gov (United States)

    Yu, Lianghong; Liang, Xiaoyan; Xu, Lu; Li, Wenqi; Peng, Chun; Hu, Zhanggui; Wang, Cheng; Lu, Xiaoming; Chu, Yuxi; Gan, Zebiao; Liu, Xiaodi; Liu, Yanqi; Wang, Xinliang; Lu, Haihe; Yin, Dingjun; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2015-07-15

    In this Letter, we present a study of high-energy and high-conversion-efficiency broadband optical parametric chirped-pulse amplification (OPCPA) system with a 100  mm×100  mm×17  mm LBO crystal near 800 nm. The results showed that the back-conversion was sensitively affected by the pump intensity and the injected signal intensity. It occurred when the injected signal was above 0.82 J with a pump energy of 170 J, and this effect also reshaped the amplified spectrum. After optimization, an amplified energy of 45.3 J was achieved with a conversion efficiency of 26.3% by the OPCPA. The peak power of the hybrid CPA-OPCPA laser system reached 1.02 PW with a compressed duration of 32 fs, which is the first reported OPCPA peak power higher than 1 PW, to the best of our knowledge. PMID:26176482

  20. Ionization of atoms by chirped attosecond pulses

    International Nuclear Information System (INIS)

    We investigate the ionization dynamics of atoms by chirped attosecond pulses using the strong field approximation method. The pulse parameters are carefully chosen in the regime where the strong field approximation method is valid. We analyse the effects of the chirp of attosecond pulses on the energy distributions and the corresponding left-right asymmetry of the ionized electrons. For a single chirped attosecond pulse, the ionized electrons can be redistributed and the left-right asymmetry shows oscillations because of the introduction of the chirp. For time-delayed double attosecond pulses at different intensities with the weaker one chirped, exchanging the order of the two pulses shows a relative shift of the energy spectra, which can be explained by the different effective time delays of different frequency components because of the chirp. (atomic and molecular physics)

  1. Generation of high-contrast millijoule pulses by optical parametric chirped-pulse amplification in periodically poled KTiOPO4

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I; Forget, N; Brown, C G; Ebbers, C A; Blanc, C L; Barty, C J

    2004-10-01

    A new high-contrast, high-gain optical parametric chirped-pulse amplifier (OPCPA) architecture is demonstrated in periodically poled KTiOPO{sub 4} (PPKTP). This architecture overcomes parametric fluorescence contrast limitations of OPCPA in periodically poled materials. The scheme is based on two passes of a single, relay imaged, pump pulse and a free-propagating signal pulse through a 1.5 x 5 x 7.5 mm{sup 3} PPKTP crystal. The output energy of 1.2 mJ is generated at a center wavelength of 1053 nm utilizing 24 mJ of pump energy. Prepulse contrast level of >3 x 10{sup 7} has been measured with >10{sup 6} saturated gain in the amplifier. Amplified pulses were compressed to 200 fs. This simple and versatile concept requires only a modest pump energy from a commercial pump laser and represents a possible high-contrast front end for high-energy Nd:glass-based petawatt-class lasers.

  2. 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.

  3. Optimization and characterization of dual-chirped optical parametric amplification

    International Nuclear Information System (INIS)

    We report optimization and characterization of a dual-chirped optical parametric amplification (DC-OPA) scheme (2011 Opt. Express 19 7190). By increasing a pump pulse energy to 100 mJ, a total (signal + idler) output energy exceeding 30 mJ was recorded with higher than 30% conversion efficiency. The feasibility of further increasing the output energy to a higher scale using the DC-OPA scheme was confirmed by a proof-of-principle experiment, in which 30%–40% conversion efficiency was observed. The signal pulse with the center wavelength of 1.4 μm was compressed to 27 fs (FWHM), which was very close to a transform-limited pulse duration of 25 fs. Since the DC-OPA scheme is efficient for generating high-energy infrared (IR) pulses with excellent scaling ability, the design parameters for obtaining hundred-mJ-level and even joule-level IR pulses are discussed and presented in detail. (invited article)

  4. Pulse distortion in single-mode fibers. 3: Chirped pulses.

    Science.gov (United States)

    Marcuse, D

    1981-10-15

    The theory of pulse distortion in single-mode fibers is extended to include laser sources that suffer a linear wavelength sweep (chirp) during the duration of the pulse. The transmitted pulse is expressed as a Fourier integral whose spectral function is given by an analytical expression in closed form. The rms width of the transmitted pulse is also expressed in closed form. Numerical examples illustrate the influence of the chirp on the shape and rms width of the pulse. A somewhat paradoxical situation exists. A given input pulse can be made arbitrarily short by a sufficiently large amount of chirping, and, after a given fiber length, this chirped pulse returns to its original width. But at this particular distance an unchirped pulse would be only [equiation] times longer. Thus chirping can improve the rate of data transmission by only 40%. PMID:20372221

  5. Chirped-pulse oscillators: a unified standpoint

    OpenAIRE

    Kalashnikov, V. L.; Apolonski, A.

    2008-01-01

    A completely analytical and unified approach to the theory of chirped-pulse oscillators is presented. The approach developed is based on the approximate integration of the generalized nonlinear complex Ginzburg-Landau equation and demonstrates that a chirped-pulse oscillator is controlled by only two parameters. It makes it easy to trace spread of the real-world characteristics of both solid-state and fiber oscillators operating in the positive dispersion regime.

  6. Hybrid mid-infrared optical parametric chirped-pulse amplification system with a broadband non-collinear quasi-phase-matched power amplifier

    CERN Document Server

    Mayer, Benedikt W; Gallmann, Lukas; Keller, Ursula

    2014-01-01

    We report a hybrid OPCPA system with the capability of generating broadband mid-infrared idler pulses from a non-collinear quasi-phase-matched power amplifier on the basis of periodically poled MgO:LiNbO3. It is seeded by the idler generated from a two-stage collinear pre-amplifier based on aperiodically poled MgO:LiNbO3. The amplification and pulse compression scheme we use does not require any angular dispersion to be introduced or compensated for on either the seed or the generated idler pulses. The mid-IR idler output has a bandwidth of 800 nm centered at 3.4 $\\mu$m. After compression, we obtain a pulse duration of 43.1 fs (FWHM; 41.4-fs transform limit) and a pulse energy of 17.2 $\\mu$J at a repetition rate of 50 kHz.

  7. Optimizing chirped laser pulse parameters for electron acceleration in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Akhyani, Mina; Jahangiri, Fazel; Niknam, Ali Reza; Massudi, Reza, E-mail: r-massudi@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran 1983969411 (Iran, Islamic Republic of)

    2015-11-14

    Electron dynamics in the field of a chirped linearly polarized laser pulse is investigated. Variations of electron energy gain versus chirp parameter, time duration, and initial phase of laser pulse are studied. Based on maximizing laser pulse asymmetry, a numerical optimization procedure is presented, which leads to the elimination of rapid fluctuations of gain versus the chirp parameter. Instead, a smooth variation is observed that considerably reduces the accuracy required for experimentally adjusting the chirp parameter.

  8. Unexpected Behavior on Nonlinear Tunneling of Chirped Ultrashort Soliton Pulse in Non-Kerr Media with Raman Effect

    Science.gov (United States)

    Rajan, M. S. Mani

    2016-08-01

    In this manuscript, the ultrashort soliton pulse propagation through nonlinear tunneling in cubic quintic media is investigated. The effect of chirping on propagation characteristics of the soliton pulse is analytically investigated using similarity transformation. In particular, we investigate the propagation dynamics of ultrashort soliton pulse through dispersion barrier for both chirp and chirp-free soliton. By investigating the obtained soliton solution, we found that chirping has strong influence on soliton dynamics such as pulse compression with amplification. These two important dynamics of chirped soliton in cubic quintic media open new possibilities to improve the solitonic communication system. Moreover, we surprisingly observe that a dispersion well is formed for the chirped case whereas a barrier is formed for the chirp-free case, which has certain applications in the construction of logic gate devices to achieve ultrafast switching.

  9. Optical parametric chirped pulse amplifier at 1600 nm with all-optical synchronization

    Directory of Open Access Journals (Sweden)

    Leitenstorfer Alfred

    2013-03-01

    Full Text Available We demonstrate the amplification of 1.6 μm pulses by a KTA optical parametric chirped-pulse amplifier based on an all-optical synchronization scheme as a scalable approach to generation of high power tunable mid infrared.

  10. Efficient Formation of Ultracold Molecules with Chirped Nanosecond Pulses

    CERN Document Server

    Carini, J L; Kosloff, R; Gould, P L

    2015-01-01

    We describe experiments and associated quantum simulations involving the production of ultracold $^{87}$Rb$_{2}$ molecules with nanosecond pulses of frequency-chirped light. With appropriate chirp parameters, the formation is dominated by coherent processes. For a positive chirp, excited molecules are produced by photoassociation early in the chirp, then transferred into high vibrational levels of the lowest triplet state by stimulated emission later in the chirp. Generally good agreement is seen between the data and the simulations. Shaping of the chirp can lead to a significant enhancement of the formation rate. Further improvements using higher intensities and different intermediate states are predicted.

  11. Charged particle interaction with a chirped electromagnetic pulse

    OpenAIRE

    Khachatryan, A. G.; Boller, K. -J.; Goor, van, Fred

    2003-01-01

    It is found that a charged particle can get a net energy gain from the interaction with an electromagnetic chirped pulse. Theoretically, the energy gain increases with the pulse amplitude and with the relative frequency variation in the pulse.

  12. Femtosecond pulse amplification in cladding-pumped fibers

    OpenAIRE

    Minelly, J. D.; Galvanauskas, A.; Fermann, M. E.; Harter, D.; Caplen, J.E.; Chen, Z.J.; Payne, D. N.

    1995-01-01

    Femtosecond pulse amplification in a cladding-pumped fiber amplifier is demonstrated for the first time to our knowledge. Using a cladding-pumped erbium-doped fiber power amplifier and a passively mode-locked fiber seed oscillator in conjunction with an all-fiber chirped-pulse amplification system, we obtain 380-fs near-bandwidth-limited pulses with an average power of 260 mW. The pulse repetition rate is varied between 5 and 50 MHz, and pulse energies as high as 20 nJ are generated.

  13. Interplay of the Chirps and Chirped Pulse Compression in a High-gain Seeded Free-electron Laser

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Juhao; /SLAC; Murphy, J.B.; /LBNL, ALS; Emma, P.J.; /SLAC; Wang, X.J.; Watanabe, T.; /LBNL, ALS; Zhong, Xinming; /Beijing Normal U.

    2007-01-03

    In a seeded high-gain Free-electron Laser (FEL), where a coherent laser pulse interacts with an ultra-relativistic electron beam, the seed laser pulse can be frequency chirped, and the electron beam can be energy chirped. Besides these two chirps, the FEL interaction introduces an intrinsic frequency chirp in the FEL even if the above mentioned two chirps are absent. In this paper we examine the interplay of these three chirps. The problem is formulated as an initial value problem, and solved via a Green function approach. Besides the chirp evolution, we also give analytical expressions for the pulse duration and bandwidth of the FEL, which remains fully longitudinally coherent in the high gain exponential growth regime. Because the chirps are normally introduced for a final compression of the FEL pulse, some conceptual issues are discussed. We show that in order to get a short pulse duration, an energy chirp in the electron beam is necessary.

  14. Analysis of radial and longitudinal force of plasma wakefield generated by a chirped pulse laser

    International Nuclear Information System (INIS)

    In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse

  15. Factorization of numbers using chirped pulses

    International Nuclear Information System (INIS)

    Full text: In this work we present a physical system that combines wavepacket dynamics and number theory. It has been shown that Gauss-sums, which involve quadratic phase factors, may be utilized to obtain the prime factor components of a given number N. As the physical system we choose a two-photon transition which is driven by a chirped laser pulse. In addition to a ground and an excited state the underlying level scheme contains a harmonic manifold of intermediate states. Quantum interference of multiple excitation paths is the key mechanism of this factorization scheme. We show how quadratic phase factors enter and present a recipe to encode the number N and reveal its prime components. Refs. 2 (author)

  16. Development of optical parametric chirped-pulse amplifiers and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Nobuhisa

    2006-11-21

    In this work, optical pulse amplification by parametric chirped-pulse amplification (OPCPA) has been applied to the generation of high-energy, few-cycle optical pulses in the near-infrared (NIR) and infrared (IR) spectral regions. Amplification of such pulses is ordinarily difficult to achieve by existing techniques of pulse amplification based on standard laser gain media followed by external compression. Potential applications of few-cycle pulses in the IR have also been demonstrated. The NIR OPCPA system produces 0.5-terawatt (10 fs,5 mJ) pulses by use of noncollinearly phase-matched optical parametric amplification and a down-chirping stretcher and up-chirping compressor pair. An IR OPCPA system was also developed which produces 20-gigawatt (20 fs,350 {mu}J) pulses at 2.1 {mu}m. The IR seed pulse is generated by optical rectification of a broadband pulse and therefore it exhibits a self-stabilized carrier-envelope phase (CEP). In the IR OPCPA a common laser source is used to generate the pump and seed resulting in an inherent sub-picosecond optical synchronization between the two pulses. This was achieved by use of a custom-built Nd:YLF picosecond pump pulse amplifier that is directly seeded with optical pulses from a custom-built ultrabroadband Ti:sapphire oscillator. Synchronization between the pump and seed pulses is critical for efficient and stable amplification. Two spectroscopic applications which utilize these unique sources have been demonstrated. First, the visible supercontinuum was generated in a solid-state media by the infrared optical pulses and through which the carrier-envelope phase (CEP) of the driving pulse was measured with an f-to-3f interferometer. This measurement confirms the self-stabilization mechanism of the CEP in a difference frequency generation process and the preservation of the CEP during optical parametric amplification. Second, high-order harmonics with energies extending beyond 200 eV were generated with the few

  17. Fiber-Optical Parametric Amplification of Sub-Picosecond Pulses for High-Speed Optical Communications

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Cristofori, Valentina; Rottwitt, Karsten;

    2015-01-01

    This article reviews recent results of amplification of short optical pulses using fiber-optical parametric amplifiers. This includes chirped-pulse amplification of 400 fs pulses, error-free amplification of a 640-Gbit/s optical time-division multiplexed signal with less than a 1-dB power penalty......, and all-optical phase-preserving amplitude regeneration of a 640-Gbit/s return-to-zero differential phase-shift keying optical time-division multiplexed signal....

  18. Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Abeysekera, Chamara; Oldham, James; Prozument, Kirill; Joalland, Baptiste; Park, Barratt; Field, Robert W.; Sims, Ian; Suits, Arthur; Zack, Lindsay

    2014-06-01

    We present preliminary results describing the development of a new instrument that combines two powerful techniques: Chirped Pulse-Fourier Transform MicroWave (CP-FTMW) spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates and perform unique spectroscopic, kinetics and dynamics measurements. We have constructed a new high-power K_a-band, 26-40 GHz, chirped pulse spectrometer with sub-MHz resolution, analogous to the revolutionary CP-FTMW spectroscopic technique developed in the Pate group at University of Virginia. In order to study smaller molecules, the E-band, 60-90 GHz, CP capability was added to our spectrometer. A novel strategy for generating uniform supersonic flow through a Laval nozzle is introduced. High throughput pulsed piezo-valve is used to produce cold (30 K) uniform flow with large volumes of 150 cm^3 and densities of 1014 molecules/cm3 with modest pumping facilities. The uniform flow conditions for a variety of noble gases extend as far as 20 cm from the Laval nozzle and a single compound turbo-molecular pump maintains the operating pressure. Two competing design considerations are critical to the performance of the system: a low temperature flow is needed to maximize the population difference between rotational levels, and high gas number densities are needed to ensure rapid cooling to achieve the uniform flow conditions. At the same time, collision times shorter than the chirp duration will give inaccurate intensities and reduced signal levels due to collisional dephasing of free induction decay. Details of the instrument and future directions and challenges will be discussed.

  19. Chirped optical pulse compression using a silicon photonic crystal waveguide

    International Nuclear Information System (INIS)

    We present an integrated pulse compression method for chirped optical pulses based on silicon photonic crystal (PhC) line-defect waveguides. The PhC waveguide structure and dimensions, including the radius of the hole and the thickness of the slab, are carefully designed for effective pulse compression in a short waveguide. In the optimized PhC waveguide, the pulse is effectively compressed and a compression factor, which is defined as the ratio of the output pulse width with respect to the input pulse width, as small as 0.096 is achieved. Analysis shows that the compression effect depends on the initial chirp, the peak power, and the width of the input pulse. In order to realize the best compression, the PhC waveguide length should be carefully chosen to balance the initial chirp, dispersion and nonlinearity of the waveguide. (paper)

  20. Generation of frequency-chirped optical pulses with felix

    Energy Technology Data Exchange (ETDEWEB)

    Knippels, G.M.H.; Meer, A.F.G. van der; Mols, R.F.X.A.M. [FOM-Institute for Plasma Physics, Nieuwegein (Netherlands)] [and others

    1995-12-31

    Frequency-chirped optical pulses have been produced in the picosecond regime by varying the energy of the electron beam on a microsecond time scale. These pulses were then compressed close to their bandwidth limit by an external pulse compressor. The amount of chirp can be controlled by varying the sweep rate on the electron beam energy and by cavity desynchronisation. To examine the generated chirp we used the following diagnostics: a pulse compressor, a crossed beam autocorrelator, a multichannel electron spectrometer and multichannel optical spectrometer. The compressor is build entirely using reflective optics to permit broad band operation. The autocorrelator is currently operating from 6 {mu}m to 30 {mu}m with one single crystal. It has been used to measure pulses as short as 500 fs. All diagnostics are evacuated to prevent pulse shape distortion or pulse lengthening caused by absorption in ambient water vapour. Pulse length measurements and optical spectra will be presented for different electron beam sweep rates, showing the presence of a frequency chirp. Results on the compression of the optical pulses to their bandwidth limit are given for different electron sweep rates. More experimental results showing the dependence of the amount of chirp on cavity desynchronisation will be presented.

  1. Spectral analysis using linearly chirped Gaussian pulse stacking

    International Nuclear Information System (INIS)

    We analyze the spectrum of a stacked pulse with the technique of linearly chirped Gaussian pulse stacking. Our results show that there are modulation structures in the spectrum of the stacked pulse. The modulation frequencies are discussed in detail. By applying spectral analysis, we find that the intensity fluctuation cannot be smoothed by introducing an optical amplitude filter. (authors)

  2. Demonstration of down-chirped and chirp-free pulses from high-repetition-rate passively mode-locked lasers

    OpenAIRE

    Salvatore, Randal A.; Yariv, Amnon

    1995-01-01

    Knowledge and control of the chirp parameters of semiconductor lasers is a prerequisite to obtaining transform-limited pulses and/or to compensate for group velocity dispersion in fiber. Here, we report measurements of the sign and magnitude of chirp in high-repetition-rate mode-locked semiconductor lasers. The chirp of these monolithic lasers is measured in the frequency domain, using filtering and cross-correlation techniques. For different injection currents, a range of different chirp val...

  3. Schwinger Vacuum Pair Production in Chirped Laser Pulses

    CERN Document Server

    Dumlu, Cesim K

    2010-01-01

    The recent developments of high intensity ultra-short laser pulses have raised the hopes of observing Schwinger vacuum pair production which is one of the important non-perturbative phenomena in Quantum electrodynamics (QED). The quantitative analysis of realistic high intensity laser pulses is vital for understanding the effect of the field parameters on the momentum spectrum of the produced particles. In this study, we analyze chirped laser pulses with a sub-cycle structure, and investigate the effects of the chirp parameter on the momentum spectrum of the produced particles. The combined effect of the chirp and carrier phase of the laser pulse is also analyzed. These effects are qualitatively explained by investigating the turning point structure of the potential within the framework of the complex WKB scattering approach to pair production.

  4. High-energy, kHz, picosecond hybrid Yb-doped chirped-pulse amplifier.

    Science.gov (United States)

    Chang, Chun-Lin; Krogen, Peter; Hong, Kyung-Han; Zapata, Luis E; Moses, Jeffrey; Calendron, Anne-Laure; Liang, Houkun; Lai, Chien-Jen; Stein, Gregory J; Keathley, Phillip D; Laurent, Guillaume; Kärtner, Franz X

    2015-04-20

    We report on a diode-pumped, hybrid Yb-doped chirped-pulse amplification (CPA) laser system with a compact pulse stretcher and compressor, consisting of Yb-doped fiber preamplifiers, a room-temperature Yb:KYW regenerative amplifier (RGA), and cryogenic Yb:YAG multi-pass amplifiers. The RGA provides a relatively broad amplification bandwidth and thereby a long pulse duration to mitigate B-integral in the CPA chain. The ~1030-nm laser pulses are amplified up to 70 mJ at 1-kHz repetition rate, currently limited by available optics apertures, and then compressed to ~6 ps with high efficiency. The near-diffraction-limited beam focusing quality is demonstrated with M(x)(2) = 1.1 and M(y)(2) = 1.2. The shot-to-shot energy fluctuation is as low as ~1% (rms), and the long-term energy drift and beam pointing stability for over 8 hours measurement are ~3.5% and <6 μrad (rms), respectively. To the best of our knowledge, this hybrid laser system produces the most energetic picosecond pulses at kHz repetition rates among rod-type laser amplifiers. With an optically synchronized Ti:sapphire seed laser, it provides a versatile platform optimized for pumping optical parametric chirped-pulse amplification systems as well as driving inverse Compton scattered X-rays. PMID:25969056

  5. Optimal control of quantum systems by chirped pulses

    DEFF Research Database (Denmark)

    Amstrup, Bjarne; Doll, J. D.; Sauerbrey, R. A.;

    1993-01-01

    Research on optimal control of quantum systems has been severely restricted by the lack of experimentally feasible control pulses. Here, to overcome this obstacle, optimal control is considered with the help of chirped pulses. Simulated annealing is used as the optimizing procedure. The examples...

  6. Bloch-Maxwell treatment of amplification of high harmonic seed in soft x-ray laser amplifiers in both direct and chirped amplifications

    Science.gov (United States)

    Zeitoun, Philippe; Oliva, Eduardo; Fajardo, Marta; Ros, David; Sebban, Stéphane; Velarde, Pedro

    2011-12-01

    Seeding plasma-based soft x-ray laser (SXRL) demonstrated diffraction-limited, fully coherent in space and in time beam but with energy not exceeding 1 μJ per pulse. Quasi-steady-state (QSS) plasmas demonstrated to be able to store high amount of energy and then amplify incoherent SXRL up to several mJ. Using 1D time-dependant Bloch-Maxwell model including amplification of noise, we demonstrated that femtosecond HHG cannot be efficiently amplified in QSS plasmas. However, using Chirped Pulse Amplification concept on HHG seed allows to extract most of the stored energy, reaching up to 5 mJ in fully coherent pulses that can be compressed down to 130 fs.

  7. Pulse Compression Of An FM Chirped CO2 Laser

    Science.gov (United States)

    Henderson, D. M.; Halmos, M. J.; Duvall, R. L.

    1989-12-01

    FM chirp/pulse compression has long been used in conventional radar systems [1]. The main advantages of such a technique are: 1. Efficient use of the average power available at the transmitter. 2. Increased system accuracy, both in range and velocity measurements. 3. Reduction of jamming vulnerability. We have explored the use of this technique for laser radar systems and in this paper describe an electro-optically FM modulated CO2 waveguide with post detection pulse compression by a surface acoustic wave (SAW) com-pression filter. The CO2 laser has been FM chirp modulated by a CdTe intracavity modulator. A frequency deviation of 95 MHz in 2.1 psec was attained in this fashion. Following heterodyne detection, the chirped pulse was compressed to 15 nsec using a SAW compression filter. This corresponded to a compression factor of 130. The suppression of unwanted sidelobes with a weighting filter was also demonstrated.

  8. Pulse chirp increasing pulse compression followed by positive resonant radiation in fibers

    CERN Document Server

    McLenaghan, Joanna

    2016-01-01

    Pulse self-compression followed by the generation of resonant radiation is a well known phenomenon in non-linear optics. Resonant radiation is important as it allows for efficient and tunable wavelength conversion. We vary the chirp of the initial pulse and find in simulations and experiments that a small positive chirp enhances the pulse compression and strongly increases the generation of resonant radiation. This result corroborates previously published simulation results indicating an improved degree of pulse compression for a small positive chirp [1]. It also demonstrates how pulse evolution can be studied without cutting back the fiber.

  9. Thomson scattering in high-intensity chirped laser pulses

    International Nuclear Information System (INIS)

    We consider the Thomson scattering of an electron in an ultra-intense laser pulse. It is well known that at high laser intensities, the frequency and brilliance of the emitted radiation will be greatly reduced due to the electron losing energy before it reaches the peak field. In this work, we investigate the use of a small frequency chirp in the laser pulse in order to mitigate this effect of radiation reaction. It is found that the introduction of a negative chirp means the electron enters a high frequency region of the field while it still has a large proportion of its original energy. This results in a significant enhancement of the frequency and intensity of the emitted radiation as compared to the case without chirping

  10. FY07 LDRD Final Report Precision, Split Beam, Chirped-Pulse, Seed Laser Technology

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, J W; Messerly, M J; Phan, H H; Crane, J K; Beach, R J; Siders, C W; Barty, C J

    2009-11-12

    The goal of this LDRD ER was to develop a robust and reliable technology to seed high-energy laser systems with chirped pulses that can be amplified to kilo-Joule energies and recompressed to sub-picosecond pulse widths creating extremely high peak powers suitable for petawatt class physics experiments. This LDRD project focused on the development of optical fiber laser technologies compatible with the current long pulse National Ignition Facility (NIF) seed laser. New technologies developed under this project include, high stability mode-locked fiber lasers, fiber based techniques for reduction of compressed pulse pedestals and prepulses, new compact stretchers based on chirped fiber Bragg gratings (CFBGs), new techniques for manipulation of chirped pulses prior to amplification and new high-energy fiber amplifiers. This project was highly successful and met virtually all of its goals. The National Ignition Campaign has found the results of this work to be very helpful. The LDRD developed system is being employed in experiments to engineer the Advanced Radiographic Capability (ARC) front end and the fully engineered version of the ARC Front End will employ much of the technology and techniques developed here.

  11. Decoherence control in quantum computing with simple chirped pulses

    Indian Academy of Sciences (India)

    Debabrata Goswami

    2002-08-01

    We show how the use of optimally shaped pulses to guide the time evolution of a system (‘coherent control’) can be an effective approach towards quantum computation logic. We demonstrate this with selective control of decoherence for a multilevel system with a simple linearly chirped pulse. We use a multiphoton density-matrix approach to explore the effects of ultrafast shaped pulses for two-level systems that do not have a single photon resonance, and show that many multiphoton results are surprisingly similar to the single-photon results. Finally, we choose two specific chirped pulses: one that always generates inversion and the other that always generates self-induced transparency to demonstrate an ensemble CNOT gate.

  12. Pulse chirp increasing pulse compression followed by positive resonant radiation in fibers

    OpenAIRE

    McLenaghan, Joanna; Koenig, Friedrich

    2016-01-01

    Pulse self-compression followed by the generation of resonant radiation is a well known phenomenon in non-linear optics. Resonant radiation is important as it allows for efficient and tunable wavelength conversion. We vary the chirp of the initial pulse and find in simulations and experiments that a small positive chirp enhances the pulse compression and strongly increases the generation of resonant radiation. This result corroborates previously published simulation results indicating an impr...

  13. Evolution of the frequency chirp of Gaussian pulses and beams when passing through a pulse compressor.

    Science.gov (United States)

    Li, Derong; Lv, Xiaohua; Bowlan, Pamela; Du, Rui; Zeng, Shaoqun; Luo, Qingming

    2009-09-14

    The evolution of the frequency chirp of a laser pulse inside a classical pulse compressor is very different for plane waves and Gaussian beams, although after propagating through the last (4th) dispersive element, the two models give the same results. In this paper, we have analyzed the evolution of the frequency chirp of Gaussian pulses and beams using a method which directly obtains the spectral phase acquired by the compressor. We found the spatiotemporal couplings in the phase to be the fundamental reason for the difference in the frequency chirp acquired by a Gaussian beam and a plane wave. When the Gaussian beam propagates, an additional frequency chirp will be introduced if any spatiotemporal couplings (i.e. angular dispersion, spatial chirp or pulse front tilt) are present. However, if there are no couplings present, the chirp of the Gaussian beam is the same as that of a plane wave. When the Gaussian beam is well collimated, the introduced frequency chirp predicted by the plane wave and Gaussian beam models are in closer agreement. This work improves our understanding of pulse compressors and should be helpful for optimizing dispersion compensation schemes in many applications of femtosecond laser pulses. PMID:19770925

  14. Isolated attosecond pulse generation with the chirped two-color laser field

    Science.gov (United States)

    Tai, Huiqin; Li, Fang; Wang, Zhe

    2016-07-01

    We propose a scheme to generate isolated attosecond pulse using a linearly chirped two-color laser field, which includes a fundamental laser field and a weak infrared control laser field in the multicycle regime. The fundamental laser field consists of one linearly up-chirped and one linearly down-chirped pulses. The control pulse is chirped free. We compare the attosecond pulse generated in the chirped two-color field and the chirp-free field. It is found that an IAP can be generated even without carrier envelop phase stabilization in the chirped two-color laser field with a duration of 40 fs. We also discuss the influence of the relative intensity, relative phase, time delay, and chirping parameters on the generation of IAPs.

  15. Double regenerative amplification of picosecond pulses

    Science.gov (United States)

    Bai, Zhen-ao; Chen, Li-yuan; Bai, Zhen-xu; Chen, Meng; Li, Gang

    2012-04-01

    An double Nd:YAG regenerative amplification picosecond pulse laser is demonstrated under the semiconductor saturable absorption mirror(SESAM) mode-locking technology and regenerative amplification technology, using BBO crystal as PC electro-optic crystal. The laser obtained is 20.71ps pulse width at 10 KHz repetition rate, and the energy power is up to 4W which is much larger than the system without pre-amplification. This result will lay a foundation for the following amplification.

  16. Power scaling of supercontinuum seeded megahertz-repetition rate optical parametric chirped pulse amplifiers.

    Science.gov (United States)

    Riedel, R; Stephanides, A; Prandolini, M J; Gronloh, B; Jungbluth, B; Mans, T; Tavella, F

    2014-03-15

    Optical parametric chirped-pulse amplifiers with high average power are possible with novel high-power Yb:YAG amplifiers with kW-level output powers. We demonstrate a compact wavelength-tunable sub-30-fs amplifier with 11.4 W average power with 20.7% pump-to-signal conversion efficiency. For parametric amplification, a beta-barium borate crystal is pumped by a 140 W, 1 ps Yb:YAG InnoSlab amplifier at 3.25 MHz repetition rate. The broadband seed is generated via supercontinuum generation in a YAG crystal. PMID:24690803

  17. Propagation effects of isolated attosecond pulse generation with a multicycle chirped and chirped-free two-color field

    Energy Technology Data Exchange (ETDEWEB)

    Du Hongchuan; Hu Bitao [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2011-08-15

    We present a theoretical study of isolated attosecond pulse generation with a multicycle chirped and chirped-free two-color field. We show that the bandwidth of the extreme ultraviolet supercontinuum can be extended by combining a multicycle chirped pulse and a multicycle chirped-free pulse. Also, the broadband supercontinuum can still be generated when the macroscopic effects are included. Furthermore, the macroscopic effects can ameliorate the temporal characteristic of the broadband supercontinuum of the single atom, and eliminate the modulations of the broadband supercontinuum. Thus a very smooth broadband supercontinuum and a pure isolated 102-as pulse can be directly obtained. Moreover, the structure of the broadband supercontinuum can be steadily maintained for a relative long distance after a certain distance.

  18. Compression of chirp pulses from a femtosecond fiber based amplifier

    Science.gov (United States)

    Ito, Rumi; Takiuchi, Ken-ichi; Tei, Kazuyoku; Yamaguchi, Shigeru; Enokidani, Jyun; Sumida, Shin

    2015-03-01

    We demonstrate a single mode fiber based master oscillator power amplifier (MOPA) with a single polarization and a fully monolithic design. We have built a passive mode-locked polarization maintaining Yb doped fiber as the master oscillator contains a semiconductor saturable absorber mirror and a chirped fiber Bragg grating for the dispersion management. The net intracavity dispersion was managed to be slightly anomalous. The oscillator generates the 150 fs (sech2) pulses at the center wavelength of 1065 nm, and the repetition rate of 42 MHz. The oscillator output was amplified to 1.4 W from 80 mW in the single stage fiber amplifier which results in pulse shape distortion. The pulse shaping with a band pass filter and a compressor was applied to the amplified pulses. The shaping pulses have the pulse width of 90 fs and the pulse energy of 16 nJ.

  19. 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...

  20. Experimental research of pulsed chirp effect on the small-scale self-focusing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The chirped optical pulses undergoing self-focusing and splitting into multiple filamentation passing through a Kerr medium-carbon disulfide (CS2) are studied experimentally and numerically. At the particular spatial position, modulation growth takes place from the experimental result. The process of modulation growth with different pulsed chirp is analyzed. It is found that with the pulsed chirp in-creasing (equal to the pulse width increasing), modulation growth of chirped opti-cal pulses is delayed and the average input power also increases. The simulation results are in agreement with the experimental results.

  1. Clinical Comparison of Pulse and Chirp Excitation

    DEFF Research Database (Denmark)

    Pedersen, Morten Høgholm; Misaridis, T.; Jensen, Jørgen Arendt

    short pulse excitation to simultaneously produce identical image sequences using both techniques. Nine healthy male volunteers were scanned in abdominal locations. All sequences were evaluated by 3 skilled medical doctors, blinded to each other and to the technique used. They assessed the depth (1) in...

  2. Effects of initial frequency chirp on the linear propagation characteristics of the exponential optical pulse

    Institute of Scientific and Technical Information of China (English)

    Zheng Hong-Jun; Liu Shan-Liang

    2006-01-01

    In this paper, the linear propagation characteristics of the exponential optical pulse with initial linear and nonlinear frequency chirp are numerically studied in a single mode fibre for β2< 0. It can be found that the temporal full width at half maximum and time-bandwidth product of exponential pulse monotonically increase with the increase of propagation distance and decrease with the increase of linear chirp C for C < 0.5, go through an initial decreasing stage near ζ = 1, then increase with the increase of propagation distance and linear chirp C for C ≥ 0.5. The broadening of pulses with negative chirp is faster than that with positive chirp. The exponential pulse with linear chirp gradually evolves into a near-Gaussian pulse. The effect of nonlinear chirp on waveform of the pulse is much greater than that of linear chirp. The temporal waveform breaking of exponential pulse with nonlinear chirp is first observed in linear propagation. Furthermore, the expressions of the spectral width and time-bandwidth product of the exponential optical pulse with the frequency chirp are given by use of the numerical analysis method.

  3. Amplification of Frequency-Modulated Similariton Pulses in Length-Inhomogeneous Active Fibers

    Directory of Open Access Journals (Sweden)

    I. O. Zolotovskii

    2012-01-01

    Full Text Available The possibility of an effective gain of the self-similar frequency-modulated (FM wave packets is studied in the length-inhomogeneous active fibers. The dynamics of parabolic pulses with the constant chirp has been considered. The optimal profile for the change of the group-velocity dispersion corresponding to the optimal similariton pulse amplification has been obtained. It is shown that the use of FM pulses in the active (gain and length-inhomogeneous optical fibers with the normal group-velocity dispersion can provide subpicosecond optical pulse amplification up to the energies higher than 1 nJ.

  4. Plasma absorption evidence via chirped pulse spectral transmission measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jedrkiewicz, Ottavia, E-mail: ottavia.jedrkiewicz@ifn.cnr.it [Istituto di Fotonica e Nanotecnologie, CNR and CNISM UdR Como, Via Valleggio 11, I-22100 Como (Italy); Minardi, Stefano [Institute of Applied Physics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Couairon, Arnaud; Jukna, Vytautas [Centre de Physique Theorique, CNRS, Ecole Polytechnique, F-91128 Palaiseau (France); Selva, Marco; Di Trapani, Paolo [Dipartimento di Scienza e Alta Tecnologia, University of Insubria and CNISM UdR Como, Via Valleggio 11, I-22100 Como (Italy)

    2015-06-08

    This work aims at highlighting the plasma generation dynamics and absorption when a Bessel beam propagates in glass. We developed a simple diagnostics allowing us to retrieve clear indications of the formation of the plasma in the material, thanks to transmission measurements in the angular and wavelength domains. This technique featured by the use of a single chirped pulse having the role of pump and probe simultaneously leads to results showing the plasma nonlinear absorption effect on the trailing part of the pulse, thanks to the spectral-temporal correspondence in the measured signal, which is also confirmed by numerical simulations.

  5. Single quantum path control by a fundamental chirped pulse combined with a subharmonic control pulse

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Liqiang [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Chu, Tianshu, E-mail: tschu008@163.com [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Institute for Computational Sciences and Engineering, Laboratory of New Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer HHG spectra and attosecond pulse generation from a model He atom. Black-Right-Pointing-Pointer Two-color laser field of a chirped fundamental pulse and a subharmonics control pulse. Black-Right-Pointing-Pointer Single quantum path selection by {beta} = 4.55 chirp pulse and the zero-phase 2000 nm control pulse. Black-Right-Pointing-Pointer Formation of 337 eV supercontinuum region and generation of 39 as pulse. -- Abstract: In this paper, we study the issue of single quantum path control and its role in attosecond pulse generation. By carrying out the time-dependent Schroedinger equation analysis for the harmonic emission from a single He atom irradiated by the two-color laser field, consisting of a short 800 fundamental chirped pulse and a subharmonic 800-2400 nm control pulse, we find that the most favorable condition for attosecond generation is at the fundamental chirp parameter {beta} = 4.55 together with the zero-phase 2000 nm control pulse, in which the single quantum path (short quantum path) is selected to contribute to the harmonic spectrum exhibiting an ultrabroad supercontinuum of a 337 eV bandwidth. Finally, an isolated attosecond pulse as short as 39 as is thus generated directly.

  6. A chirped-pulse regenerative-amplifier FEL for the gamma-gamma collider

    International Nuclear Information System (INIS)

    During a Workshop on Gamma-Gamma Colliders in Lawrence Berkeley Laboratory, it was pointed out that an 1-μm laser that can produce 1-J, 1-ps pulses at a few hundred hertz is required. With high-power scalability and ease of formatting, an FEL can be a promising candidate for such a laser. The authors propose an FEL scheme based on chirped-pulsed regenerative amplification to achieve this high peak-power laser. The 1-ps pulse of a solid-state laser will be stretched, amplified, and recompressed to achieve the high peak power. The system is relatively simple and consists of mostly components that have already been demonstrated. This paper will describe the proposal and the important issues of such a scheme

  7. Amplification of high power picosecond laser pulses in multiatmosphere carbon dioxide amplifier

    International Nuclear Information System (INIS)

    High power ultrashort carbon dioxide laser pulses are useful in the study of molecular vibrations: vibrational relaxation, the exchange of vibrational energy between modes and molecules, etc. However multiatmosphere CO2 lasers are studied less than the other amplifying media. This work is devoted to a systematic theoretical investigation of picosecond pulse amplification by high pressure CO2 amplifier. The new features of this process are connected with the discrete structure of CO2 gain spectrum, phase modulation of input pulses as well as with an electron density wave which follows the powerful IR pulse in gas medium of TE CO2 amplifier. At the linear stage of amplification a short input pulse (τ 20 ps) no pulse formation takes place. A nonsteady-state theory has been developed of electron impact ionization of CO2 laser medium by intense IR picosecond pulses. The electron density wave produced by ionization process follows the laser pulse and can result in pulse envelope distortion and phase modulation. In particular it may cause pulse energy limitation and frequency chirping. The influence of phase modulation on the IR short pulse amplification has also been investigated. It is shown that the input pulse chirp may cause a considerable pulse envelope and frequency oscillatory modulation. It may be used for the generation of pulse trains of terahertz repetition rate which is useful for spectroscopic applications. (author)

  8. Anomalous spectral behaviour of diffracted chirped Gaussian pulses in the near field

    Institute of Scientific and Technical Information of China (English)

    Pan Liu-Zhan; L(u) Bai-Da

    2004-01-01

    By using the Fourier transform method, analytical expressions for the axial power spectrum and near-field intensity in the spacetime domain of chirped Gaussian pulses diffracted at an aperture are derived, which permit us to study changes in spectral and temporal profiles of the chirped Gaussian pulses both analytically and numerically. Detailed numerical results and physical analysis show that spectral anomalies take place in the neighbourhood of certain critical distances, and the shifting of maximum and splitting of temporal intensity profiles appear. In particular, for ultrashort chirped pulses, there exists also spectral switch. Besides the truncation parameter, the chirp parameter and pulse duration affect the behaviour of spectral switches.

  9. Simulation of temporal waveform control of laser pulse by frequency chirping

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Yoshinori; Yoshida, Hidetsugu; Fujita, Hisanori; Nakai, Sadao [Osaka Univ., Suita (Japan). Inst. of Laser Engineering

    1998-09-01

    Arbitrary temporal waveform control can be achieved by means of amplifier gain control with a chirped laser pulse. In order to simulate precise waveforms of laser pulses, we developed a multilevel simulation code with transitions between each manifold. Using the developed code, we examined the generation of required temporal waveforms for laser fusion experiment. The maximum amount of chirping decreased considerably at low input intensity and large amplifier gain. In the case of the calculation for a specialized laser system (Gekko XII), a tailored pulse shape can be generated with less than 4 nm chirp, using the current modulation technique. Comparing the amplified pulses with chirping to those without chirping, peak intensity and energy up to peak were 2.34 and 1.41 times higher, while total energy was 0.528 times lower. It was indicated that frequency chirping is one of the most promising methods for generating the tailored pulses for future laser fusion experiments. (author)

  10. Simulation of temporal waveform control of laser pulse by frequency chirping

    International Nuclear Information System (INIS)

    Arbitrary temporal waveform control can be achieved by means of amplifier gain control with a chirped laser pulse. In order to simulate precise waveforms of laser pulses, we developed a multilevel simulation code with transitions between each manifold. Using the developed code, we examined the generation of required temporal waveforms for laser fusion experiment. The maximum amount of chirping decreased considerably at low input intensity and large amplifier gain. In the case of the calculation for a specialized laser system (Gekko XII), a tailored pulse shape can be generated with less than 4 nm chirp, using the current modulation technique. Comparing the amplified pulses with chirping to those without chirping, peak intensity and energy up to peak were 2.34 and 1.41 times higher, while total energy was 0.528 times lower. It was indicated that frequency chirping is one of the most promising methods for generating the tailored pulses for future laser fusion experiments. (author)

  11. Transporting Rydberg Electron Wave Packets with Chirped Trains of Pulses

    International Nuclear Information System (INIS)

    A protocol for steering Rydberg electrons towards targeted final states is realized with the aid of a chirped train of half-cycle pulses (HCPs). Its novel capabilities are demonstrated experimentally by transporting potassium atoms excited to the lowest-lying quasi-one-dimensional states in the ni=350 Stark manifold to a narrow range of much higher-n states. We demonstrate that this coherent state transfer is, to a high degree, reversible. The protocol allows for remarkable selectivity and is highly efficient, with typically over 80% of the parent atoms surviving the HCP sequence

  12. Low frequency Raman gain measurements using chirped pulses.

    Science.gov (United States)

    Dogariu, A; Hagan, D

    1997-08-01

    Two-beam coupling, attributed to Raman gain, is observed in dielectrics using chirped femtosecond pulses. A time resolved pump-probe geometry is used to vary the frequency difference between pulses in the terahertz frequency band. Stimulated Raman scattering couples the pulses transferring energy from the higher to the lower frequency beam, resulting in a dispersion shaped curve as a function of the temporal delay, dependent on the product of the pump and probe irradiances. The observed signal gives the Raman gain in SiO2 and PbF2 for detunings up to 10 THz (approximately 300 cm -1 ) using mm-thick samples. This method may also be sensitive to the electronic motion responsible for bound-electronic nonlinear refractive index, which could yield the optical response time of bound electrons. PMID:19373383

  13. Effect of pulse profile and chirp on a laser wakefield generation

    International Nuclear Information System (INIS)

    A laser wakefield driven by an asymmetric laser pulse with/without chirp is investigated analytically and through two-dimensional particle-in-cell simulations. For a laser pulse with an appropriate pulse length compared with the plasma wavelength, the wakefield amplitude can be enhanced by using an asymmetric un-chirped laser pulse with a fast rise time; however, the growth is small. On the other hand, the wakefield can be greatly enhanced for both positively chirped laser pulse having a fast rise time and negatively chirped laser pulse having a slow rise time. Simulations show that at the early laser-plasma interaction stage, due to the influence of the fast rise time the wakefield driven by the positively chirped laser pulse is more intense than that driven by the negatively chirped laser pulse, which is in good agreement with analytical results. At a later time, since the laser pulse with positive chirp exhibits opposite evolution to the one with negative chirp when propagating in plasma, the wakefield in the latter case grows more intensely. These effects should be useful in laser wakefield acceleration experiments operating at low plasma densities.

  14. Compression and collisions of chirped pulses in a dense two-level medium

    OpenAIRE

    Novitsky, Denis

    2015-01-01

    Using numerical simulations, we study propagation of linearly-chirped optical pulses in a homogeneously broadened two-level medium. We pay attention to the three main topics -- validity of the rotating-wave approximation (RWA), pulse compression, and collisions of counter-propagating pulses. The cases of long and single-cycle pulses are considered and compared with each other. We show that the RWA does not give a correct description of chirped pulse interaction with the medium. The compressio...

  15. Characteristics of filamentation in ZK7 glass by negatively chirped femtosecond laser pulses

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The filamentation characteristics of femtosecond laser pulses in ZK7 glass are in- vestigated experimentally as a function of initial negative chirps. It is found that the filament threshold power grows rapidly and the filament length extends over a long distance with increasing initial temporal chirps. The measurement of supercon- tinuum reveals that the plasma generation process within filamentation becomes weaker as the initial negative chirp increases, leading to a self-guiding long light channel dominated by Kerr nonlinearity. The interference of transverse rings in multifilamentation of the chirped laser pulses is observed as well. Analyses and discussions give an interpretation of this chirp-induced ionization-free filamenta- tion. These results indicate that initial chirps will play a crucial role in the filament formation of ultrashort laser pulses in transparent media.

  16. Effect of Optical Pulse Shape on the Performance of OCDMA in Presence of GVD and Pulse Linear Chirp

    OpenAIRE

    Md. Jahedul Islam; Kalyan Kumar Halder; Md Rafiqul Islam

    2010-01-01

    In this paper, the effect of optical pulse shape on the performance of direct sequence optical code division multiple access in presence of fiber group velocity dispersion (GVD) and pulse linear chirp is analyzed. In our analysis, chirp-Gaussian shape and chirp-Hyperbolic-Secant shape optical orthogonal codes are employed as address sequence. Avalanche photodiode (APD) is used in an optical correlator receiver. The signal to noise power for the proposed system is evaluated on account of APD s...

  17. Effect of Optical Pulse Shape on the Performance of OCDMA in Presence of GVD and Pulse Linear Chirp

    Directory of Open Access Journals (Sweden)

    Md. Jahedul Islam

    2010-07-01

    Full Text Available In this paper, the effect of optical pulse shape on the performance of direct sequence optical code division multiple access in presence of fiber group velocity dispersion (GVD and pulse linear chirp is analyzed. In our analysis, chirp-Gaussian shape and chirp-Hyperbolic-Secant shape optical orthogonal codes are employed as address sequence. Avalanche photodiode (APD is used in an optical correlator receiver. The signal to noise power for the proposed system is evaluated on account of APD short noise, bulk dark current, surface leakage current, thermal noise current, and multiuser access interference noises. The system BER performance is determined as a function of received signal power, number of simultaneous users, fiberlength, pulse linear chirp, and pulse-shape. The power penalty suffered by the system is evaluated at BER of 10-9. The numericalresults show that the BER performance of the proposed system ishighly dependent on the number of simultaneous user, fiber length, pulse linear chirp, and pulse-shape. It is found that, if the effect of GVD is considered, the proposed system performance i.e., BER is degraded. The BER performance of the proposed system also aggravated due to presence of pulse linear chirp. It is also found that the proposed system suffers minimum penalty when chirp-Hyperbolic-Secant shape optical pulse is used instead of chirp-Gaussian shape pulse.

  18. Effect of nonlinear chirped Gaussian laser pulse on plasma wake field generation

    Directory of Open Access Journals (Sweden)

    Saeedeh Afhami

    2014-08-01

    Full Text Available An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wake field which can accelerate charged particles up to GeV energies within a compact space compared to the conventional accelerator devices. In this paper, the effect of different kinds of nonlinear chirped Gaussian laser pulse on wake field generation is investigated. The numerical analysis of our results depicts that the excitation of plasma wave with large and highly amplitude can be accomplished by nonlinear chirped pulses. The maximum amplitude of excited wake in nonlinear chirped pulse is approximately three times more than that of linear chirped pulse. In order to achieve high wake field generation, chirp parameters and functions should be set to optimal values.

  19. Noncollinear SHG with compensation of phase mismatch by controlling frequency chirp and tilted pulse fronts of femtosecond laser pulses

    International Nuclear Information System (INIS)

    In order to achieve efficient second-harmonic generation with femtosecond laser pulses, we studied noncollinear second-harmonic generation with tilted pulse fronts and a suitable frequency chirp of fundamental pulses. We discussed the compensation of a phase-mismatch by controlling the frequency chirp of fundamental pulses and an improvement of the energy conversion efficiency using our method. When the energy conversion efficiency was less than 0.4% under a phase-mismatch condition, we experimentally obtained a 30% energy conversion efficiency with a proper frequency chirp of fundamental pulses. (author)

  20. Perturbation-theory analysis of ionization by a chirped few-cycle attosecond pulse

    Energy Technology Data Exchange (ETDEWEB)

    Pronin, E. A.; Starace, Anthony F.; Peng Liangyou [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588-0299 (United States); State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871 (China)

    2011-07-15

    The angular distribution of electrons ionized from an atom by a chirped few-cycle attosecond pulse is analyzed using perturbation theory (PT), keeping terms in the transition amplitude up to second order in the pulse electric field. The dependence of the asymmetry in the ionized electron distributions on both the chirp and the carrier-envelope phase (CEP) of the pulse are explained using a simple analytical formula that approximates the exact PT result. This approximate formula (in which the chirp dependence is explicit) reproduces reasonably well the chirp-dependent oscillations of the electron angular distribution asymmetries found numerically by Peng et al. [Phys. Rev. A 80, 013407 (2009)]. It can also be used to determine the chirp rate of the attosecond pulse from the measured electron angular distribution asymmetry.

  1. The effect of chirped intense femtosecond laser pulses on the Argon cluster

    CERN Document Server

    Ghaforyan, H; Irani, E

    2016-01-01

    The interaction of intense femtosecond laser pulses with atomic Argon clusters has been investigated by using nano-plasma model. Based on the dynamic simulations, ionization process, heating and expansion of a cluster after irradiation by femtosecond laser pulses at intensities up to 2*1017 Wcm-2 are studied. The analytical calculation provides ionization ratefor different mechanisms and time evolution of the density of electrons for different pulse shapes. In this approach the strong dependence of laser intensity, pulse duration and laser shape on the electron energy, the electron density and the cluster size are presented using the intense chirped laser pulses. Based on the presented theoretical modifications, the effect of chirped laser pulse on the complex dynamical process of the interaction is studied. It is found that the energy of electrons and the radius of cluster for the negatively chirped pulsesare improved up to 20% in comparison to the unchirped and positively chirped pulses.

  2. Coherent population transfer in Rydberg potassium atom by a single frequency-chirped laser pulse

    Institute of Scientific and Technical Information of China (English)

    Zhang Xian-Zhou; Ma Qiao-Zhi; Li Xiao-Hong

    2006-01-01

    By using the time-dependent multilevel approach, we have calculated the coherent population transfer among the quantum states of potassium atom by a single frequency-chirped laser pulse. The results show that the population can be efficiently transferred to a target state and be trapped there by using an ‘intuitive’ or a ‘counter-intuitive’ frequency sweep laser pulse in the case of ‘narrowband’ frequency-chirped laser pulse. It is also found that a pair of sequential ‘broadband’ frequency-chirped laser pulses can efficiently transfer population from one ground state of the A atom to the other one.

  3. Tracking the photodissociation probability of D$_2^+$ induced by linearly chirped laser pulses

    CERN Document Server

    Csehi, András; Cederbaum, Lorenz S; Vibók, Ágnes

    2016-01-01

    In the presence of linearly varying frequency chirped laser pulses the photodissociation dynamics of D$_2^+$ is studied theoretically after ionization of D$_{2}$ . As a completion of our recent work (J. Chem. Phys. 143, 014305 (2015)) a comprehensive dependence on the pulse duration and delay time is presented in terms of total dissociation probabilities. Our numerical analysis carried out in the recently introduced light-induced conical intersection (LICI) framework clearly shows the effects of the changing position of the LICI which is induced by the frequency modulation of the chirped laser pulses. This impact is presented for positively, negatively and zero chirped short pulses.

  4. Spread spectrum compressed sensing MRI using chirp radio frequency pulses

    CERN Document Server

    Qu, Xiaobo; Zhuang, Xiaoxing; Yan, Zhiyu; Guo, Di; Chen, Zhong

    2013-01-01

    Compressed sensing has shown great potential in reducing data acquisition time in magnetic resonance imaging (MRI). Recently, a spread spectrum compressed sensing MRI method modulates an image with a quadratic phase. It performs better than the conventional compressed sensing MRI with variable density sampling, since the coherence between the sensing and sparsity bases are reduced. However, spread spectrum in that method is implemented via a shim coil which limits its modulation intensity and is not convenient to operate. In this letter, we propose to apply chirp (linear frequency-swept) radio frequency pulses to easily control the spread spectrum. To accelerate the image reconstruction, an alternating direction algorithm is modified by exploiting the complex orthogonality of the quadratic phase encoding. Reconstruction on the acquired data demonstrates that more image features are preserved using the proposed approach than those of conventional CS-MRI.

  5. Few-cycle attosecond pulse chirp effects on asymmetries in ionized electron momentum distributions

    International Nuclear Information System (INIS)

    The momentum distributions of electrons ionized from H atoms by chirped few-cycle attosecond pulses are investigated by numerically solving the time-dependent Schroedinger equation. The central carrier frequency of the pulse is chosen to be 25 eV, which is well above the ionization threshold. The asymmetry (or difference) in the yield of electrons ionized along and opposite to the direction of linear laser polarization is found to be very sensitive to the pulse chirp (for pulses with fixed carrier-envelope phase), both for a fixed electron energy and for the energy-integrated yield. In particular, the larger the pulse chirp, the larger the number of times the asymmetry changes sign as a function of ionized electron energy. For a fixed chirp, the ionized electron asymmetry is found to be sensitive also to the carrier-envelope phase of the few-cycle pulse.

  6. Effective temporal resolution in pump-probe spectroscopy with strongly chirped pulses

    International Nuclear Information System (INIS)

    This paper introduces a general theoretical description of femtosecond pump-probe spectroscopy with chirped pulses whose joint spectral and temporal profile is expressed by Wigner spectrograms. We demonstrate that the actual experimental time resolution intimately depends on the pulse-sample interaction and that the commonly used instrumental response function needs to be replaced by a sample-dependent effective response function. We also show that, using the proper configurations in excitation and/or detection, it is possible to overcome the temporal smearing of the measured dynamics due to chirp-induced pulse broadening and recover the temporal resolution that would be afforded by the transform-limited pulses. We verify these predictions with experiments using broadband chirped pump and probe pulses. Our results allow optimization of the temporal resolution in the common case when the chirp of the pump and/or probe pulse is not corrected and may be extended to a broad range of time-resolved experiments.

  7. High-order-harmonic generation driven by pulses with angular spatial chirp

    Science.gov (United States)

    Hernández-García, Carlos; Jaron-Becker, Agnieszka; Hickstein, Daniel D.; Becker, Andreas; Durfee, Charles G.

    2016-02-01

    We present and analyze a technique to drive high-order harmonics by laser pulses with an angular spatial chirp. Results of our numerical simulations show that each harmonic is emitted with an angular chirp which scales inversely with the harmonic order and leads to additional control of the spatial and temporal resolution of the spectrum. In particular, the use of angular chirp leads to separation of the harmonics in two dimensions where (i) high spectral resolution can be achieved and (ii) the temporal periodicity of the harmonic pulse trains can be controlled. We show that this technique does not require carrier-envelope-phase stabilization when using few-cycle laser pulses.

  8. Control of two-photon double ionization of helium with intense chirped attosecond laser pulses

    Science.gov (United States)

    Barmaki, S.; Lanteigne, P.; Laulan, S.

    2014-06-01

    We study the two-photon double-ionization process of the helium atom by solving numerically the nonrelativistic, time-dependent Schrödinger equation in its full dimensionality. We investigate with intense chirped attosecond laser pulses of 23.5-nm wavelength the two-photon absorption near and above the sequential threshold. We show how it is possible by adjusting the chirp parameter to control the electronic transitions inside the atom, thereby reinforcing or weakening the ionization process. Attosecond chirped laser pulses offer a promising way to probe and control the two-photon double ionization of helium when compared with attosecond transform-limited pulses.

  9. From Chirps to Random-FM Excitations in Pulse Compression Ultrasound Systems

    CERN Document Server

    Callegari, Sergio; Caporale, Salvatore; Monticelli, Marcello; Eroli, Massimiliano; Senni, Luca; Rovatti, Riccardo; Setti, Gianluca; Burrascano, Pietro

    2013-01-01

    Pulse compression is often practiced in ultrasound Non Destructive Testing (NDT) systems using chirps. However, chirps are inadequate for setups where multiple probes need to operate concurrently in Multiple Input Multiple Output (MIMO) arrangements. Conversely, many coded excitation systems designed for MIMO miss some chirp advantages (constant envelope excitation, easiness of bandwidth control, etc.) and may not be easily implemented on hardware originally conceived for chirp excitations. Here, we propose a system based on random-FM excitations, capable of enabling MIMO with minimal changes with respect to a chirp-based setup. Following recent results, we show that random-FM excitations retain many advantages of chirps and provide the ability to frequency-shape the excitations matching the transducers features.

  10. Multi-GeV electron acceleration by a periodic frequency chirped radially polarized laser pulse in vacuum

    Science.gov (United States)

    Singh Ghotra, Harjit; Kant, Niti

    2016-06-01

    Linear and periodic effects of frequency chirp on electron acceleration by radially polarized (RP) laser pulse in vacuum have been investigated. A frequency chirp influences the electron dynamics, betatron resonance, and energy gain by electron during interaction with the RP laser pulse and ensures effective electron acceleration with high energy gain (~GeV). The electron energy gain with a periodic frequency chirped laser pulse is about twice as high as with a linear chirp. Our observations reveal electron energy gain of about 10.5 GeV with a periodic chirped RP petawatt laser pulse in vacuum.

  11. Generation of an isolated sub-40-as pulse using two-color laser pulses: Combined chirp effects

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Liqiang [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China); Chu, Tianshu [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China); Institute for Computational Sciences and Engineering, Laboratory of New Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao, 266071 (China)

    2011-11-15

    In this paper, we theoretically discuss the combined chirp effects on the isolated attosecond generation when a model Ar is exposed to an intense 5-fs, 800-nm fundamental chirped pulse combined with a weak 10-fs, 1200-nm controlling chirped pulse. It shows that for the case of the chirp parameters {beta}{sub 1} = 6.1 (corresponding to the 800-nm field) and {beta}{sub 2} = 4.0 (corresponding to the 1200-nm field), both the harmonic cutoff energy and the supercontinuum can be remarkably extended resulting in a 663-eV bandwidth. Moreover, due to the introduction of the chirps, the short quantum path is selected to contribute to the harmonic spectrum. Finally, by superposing a properly selected harmonic spectrum in the supercontinuum region, an isolated pulse as short as 31 as (5 as) is generated without (with) phase compensation.

  12. The chirped-pulse free-electron laser: Final technical report, September 1987--October 1988

    International Nuclear Information System (INIS)

    This is the final report of a theoretical and numerical investigation into the operation of pulsed free-electron lasers in which the electron energy depends on the time of injection into the wiggler. Such energy ''chirping'' over each of a train of electron micropulses injected into an FEL oscillator is expected to give rise to a laser pulse inside the optical resonator with a chirped carrier frequency ω/sub s/(/tau/)

  13. Control of optical properties of hybrid materials with chirped femtosecond laser pulses under strong coupling conditions

    CERN Document Server

    Sukharev, Maxim

    2014-01-01

    The interaction of chirped femtosecond laser pulses with hybrid materials - materials comprised of plasmon sustaining structures and resonant molecules - is scrutinized using a self-consistent model of coupled Maxwell-Bloch equations. The optical properties of such systems are examined with the example of periodic sinusoidal gratings. It is shown that under strong coupling conditions one can control light transmission using chirped pulses in a spatiotemporal manner. The temporal origin of control relies on chirps non-symmetric in time while the space control is achieved via spatial localization of electromagnetic energy due to plasmon resonances.

  14. Factorization of numbers with Gauss sums: II. Suggestions for implementations with chirped laser pulses

    OpenAIRE

    Merkel, W.; Wölk, S.; Schleich, W. P.; Averbukh, I.Sh.; Girard, B; Paulus, G. G.

    2012-01-01

    We propose three implementations of the Gauss sum factorization schemes discussed in part I of this series: (i) a two-photon transition in a multi-level ladder system induced by a chirped laser pulse, (ii) a chirped one-photon transition in a two-level atom with a periodically modulated excited state, and (iii) a linearly chirped one-photon transition driven by a sequence of ultrashort pulses. For each of these quantum systems we show that the excitation probability amplitude is given by an a...

  15. Generation of orthogonal UWB shaping pulses based on compressed chirp signal

    Institute of Scientific and Technical Information of China (English)

    CHE Shu-liang; ZHANG Hong-xin; LU Ying-hua; HE Peng-fei

    2007-01-01

    This study investigates a novel method to numerically generate orthogonal ultrawide band (UWB) shaping pulses based on compressed chirp signal. First, a pulse template with less than 1 ns duration time, which is used to construct a Hermitian matrix, is produced with a compressed chirp pulse. Sub-nanosecond orthogonal pulses are then generated for UWB by using the Hermitian matrix eigenvectors. The simulation results show that the power spectral density distribution of the UWB shaping pulses met the constraint of Federal communications commissions (FCC) spectral mask. The shaping pulses not only have higher spectrum utilization ratio and very short time duration but also have excellent autocorrelation and cross-correlation properties, which is an advantage to reduce the interference between multiusers. Especially, a method to produce sub-nanosecond orthogonal UWB shaping pulses by using a relatively longer duration chirp signal is presented.

  16. Numerical simulation of extremely chirped pulse formation with an optical fiber

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Tamitake; Nishimura, Akihiko; Tei, Kazuyoku; Matoba, Tohru; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Yamashita, Mikio; Morita, Ryuji

    1998-03-01

    A nonlinear propagation code which used a symmetric split-step Fourier method as an algorithm was improved to simulate a propagation behavior of extremely chirped pulse in a long fiber. The performances of pulse propagation in noble gases cored hollow fibers and a pulse stretcher using a nonlinear and normal silicate fibers have been simulated by the code. The calculation results in the case of the hollow fiber are consistent with their experimental results. We estimated that this pulse stretcher could give a extremely chirped pulse whose spectral width was 84.2 nm and temporal duration was 1.5 ns. (author)

  17. Quasi-phase-matching high-harmonic radiation using chirped THz pulses

    CERN Document Server

    Kovács, Katalin; Hebling, János; Tosa, Valer; Varjú, Katalin

    2014-01-01

    High-order harmonic generation in the presence of a chirped THz pulse is investigated numerically with a complete 3D non-adiabatic model. The assisting THz pulse illuminates the HHG gas cell laterally inducing quasi-phase-matching. We demonstrate that it is possible to compensate the phase mismatch during propagation and extend the macroscopic cutoff of a propagated strong IR pulse to the single-dipole cutoff. We obtain two orders of magnitude increase in the harmonic efficiency of cutoff harmonics ($\\approx$170 eV) using a THz pulse of constant wavelength, and a further factor of 3 enhancement when a chirped THz pulse is used.

  18. Propagation characteristics of nanometer-level broadband chirped pulse in high power laser system

    International Nuclear Information System (INIS)

    High frequency spatial modulation induced by Fresnel diffraction of broadband nanosecond chirped laser pulse were studied. It shows that the hundreds-nm broadband pulse has some effects of Fresnel diffraction, while the tens-nm one has hardly any. Moreover, three B-integral expressions and the fast gain frequency of tens-nm broadband nanosecond chirped laser pulse were studied, and compared with the nonlinear experiments of narrowband pulse and chirped pulse stacking on prototype facility. The results reveal that, the maximal B-integral or the weighted average B-integral can better reflect the nonlinear self-focusing phenomenon, and there are no distinct differences between the narrowband and the tens-nm broadband nanosecond laser pulses with respect to the fast gain frequency. (authors)

  19. Dynamic wavelength switching of a remote nitrogen or air laser with chirped femtosecond laser pulses

    International Nuclear Information System (INIS)

    We experimentally investigate the influence of the chirp of 800 nm Ti:sapphire pump laser pulses on the lasing behaviors of N2+ ions for the transitions between the excited electronic B2∑u+ state (v′ = 0) and the ground X2∑g+ state (v = 0,1) at wavelengths of 391 and 428 nm. We found that as the chirp of the pump laser pulses varies from negative to positive, the intensities of the lasing signals at 391 and 428 nm show different chirp-dependent behaviors. Namely, the coherent emission at 391 nm reaches the maximum when the chirp of the pump pulse is transform-limited; whereas the 428 nm emission becomes strongest when the pump pulse is negatively chirped. This observation is ascribed to different self-generated seed sources produced in the plasma channel, which is verified by introducing an external seed for a pump–probe measurement. Our finding enables switching of wavelengths of remote lasing emissions of N2+ by manipulating the chirp of the pump laser pulses. (letter)

  20. Attosecond chirp compensation over broadband high-order harmonics to generate near transform-limited 63 as pulses

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Dong Hyuk; Kim, Kyung Taec; Park, Juyun; Lee, Jae-hwan; Nam, Chang Hee, E-mail: chnam@kaist.ac.k [Department of Physics and Coherent X-ray Research Center, KAIST, Daejeon 305-701 (Korea, Republic of)

    2010-06-15

    By generating broadband high-harmonic pulses from neon and compensating for attosecond chirp by the material dispersion of argon, the generation of near transform-limited 63 as pulses was achieved. The spectral phase analysis showed that, without proper compensation, the attosecond chirp of the broadband harmonics caused splitting of attosecond high-harmonic pulses in addition to pulse broadening. Although it was attained only within a limited spectral range, the attosecond chirp compensation was successful in bringing out pulse compression over broad harmonics, which signifies the effectiveness of the attosecond chirp compensation by material dispersion.

  1. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    International Nuclear Information System (INIS)

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system

  2. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    Energy Technology Data Exchange (ETDEWEB)

    Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C. [Departament de Física i Enginyeria Nuclear, Universitat Politècnica Catalunya, Terrassa 08222 (Spain); Sola, I. [Grupo de Investigación en Óptica Extrema (GIOE), Departamento de Física Aplicada, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Krolikowski, W. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Science Program, Texas A and M University at Qatar, Doha (Qatar); Sheng, Y. [Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2015-06-01

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.

  3. Single Ultrashort Attosecond Pulse Generation via Combination of Chirped Fundamental Laser and an Ultraviolet Controlling Pulse

    International Nuclear Information System (INIS)

    We theoretically study the high-order harmonic generation (HHG) from a hydrogen atom in an intense few-cycle chirped fundamental laser in combination with an ultraviolet (uv) controlling pulse. The high-order harmonic spectrum is calculated by solving the time-dependent Schroedinger equation using the split-operator method. In our calculation, we present the difference of the high-order harmonic spectrum from one-dimensional (1D) model hydrogen atom and three-dimensional (3D) real hydrogen atom. We found that the plateau of the high-order harmonic generation from the 1D case and 3D case are all extended effectively to Ip + 35Up due to the presence of the chirped laser pulse and the HHG supercontinuum spectrum is generated by adding an ultraviolet controlling pulse at a proper time, but the efficiency of the HHG for 3D case is more higher at the near cut-off region than the 1D case. Therefore, the generation of the attosecond pulse by synthesizing the harmonics near cut-off region have some slight differences between 1D and 3D simulations. As a real 3D case study, we show that an isolated 18 as pulse with a bandwidth of 232.5 eV is generated directly by optmizing the combination laser fields. (atomic and molecular physics)

  4. SASE FEL with energy-chirped electron beam and its application for generation of attosecond pulses

    International Nuclear Information System (INIS)

    Influence of a linear energy chirp in the electron beam on a SASE FEL operation is studied analytically and numerically using 1-D model. Explicit expressions for Green's functions and for output power of a SASE FEL are obtained for high-gain linear regime in the limits of small and large energy chirp parameter. Saturation length and power versus energy chirp parameter are calculated numerically. It is shown that the effect of linear energy chirp on FEL gain is equivalent to the linear undulator tapering (or linear energy variation along the undulator). A consequence of this fact is a possibility to perfectly compensate FEL gain degradation, caused by the energy chirp, by means of the undulator tapering independently of the value of the energy chirp parameter. An application of this effect for generation of attosecond pulses from a hard X-ray FEL is proposed. Strong energy modulation within a short slice of an electron bunch is produced by few-cycle optical laser pulse in a short undulator, placed in front of the main undulator. Gain degradation within this slice is compensated by an appropriate undulator taper while the rest of the bunch suffers from this taper and does not lase. Three-dimensional simulations predict that short (200 attoseconds) high-power (up to 100 GW) pulses can be produced in Angstroem wavelength range with a high degree of contrast. A possibility to reduce pulse duration to sub-100 attosecond scale is discussed. (Orig.)

  5. Nonlinear chirped-pulse propagation and supercontinuum generation in photonic crystal fibers.

    Science.gov (United States)

    Hu, Xiaohong; Wang, Yishan; Zhao, Wei; Yang, Zhi; Zhang, Wei; Li, Cheng; Wang, Hushan

    2010-09-10

    Based on the generalized nonlinear Schrödinger equation and waveguiding properties typical of the photonic crystal fiber structure, nonlinear chirped-pulse propagation and supercontinua generation in the femtosecond and picosecond regimes are investigated numerically. The simulation results indicate that an input chirp parameter mainly affects the initial stage of spectral broadening caused by the self-phase modulation (SPM) effect. In the femtosecond regime where the SPM effect plays an important role in the process of spectral broadening, an input positive chirp can enhance the supercontinuum bandwidth through a modified pulse compression phase and a decreased propagation distance required by soliton fission. In the picosecond regime, where the SPM effect contributes less to the continuum bandwidth and four-wave mixing process or modulational instability dominates the initial stage of spectral and temporal evolution, the output spectral shape and bandwidths are less sensitive to the input chirp parameters. PMID:20830188

  6. Generation of a synchronized pulse of extraordinary precision using chirped pulse laser

    International Nuclear Information System (INIS)

    We have developed the generation system of synchronized pulses of high precision using chirped pulse laser. The PW laser is synchronized to Gekko XII beams within 10 picosecond by injecting part of the PW laser into the Gekko XII laser system. A part of the 3 ns/6 nm (pulse width/spectral width) output from the front end is stretched to 5.5 ns/5 nm and is then sliced to 1.1 ns/nm width and injected into Gekko XII system. We have obtained 2.5-kJ output energy at a 532-nm wavelength from 12 semi-Gaussian beams. The pulse width is 1.1 ± 0.1 ns (FWHM) and the conversion efficiency from 1 to 0.5 mm was 43%. (author)

  7. Spectral property of ultrashort chirped pulsed Gaussian beams diffracted by Gaussian aperture in dispersive media

    Science.gov (United States)

    Zou, Qihui; Hu, Qianhuan; Guo, Jie; Duan, Xi; Tong, Shihong

    2015-10-01

    Based on the Fresnel-Kirchhoff diffraction integral and Fourier transform, the propagation equation and its Fourier spectrum for ultra-short chirped pulsed Gaussian beams diffracted by Gaussian aperture are derived in dispersive medium, and the frequency-domain analytical electric field are presented. The effects of relative aperture, transmission distance and chirp parameter on the axial spectral properties are illustrated with numerical calculation results, and the variations of off-axis power spectrum with relative aperture, transmission distance and off-axis radius are given. It is found that the axial power spectrum of ultra-short chirped pulsed Gaussian increases with increasing relative aperture, the axial spectral blue-shift increases and approaches an asymptotic value associated with chirp parameter and propagation distance. The axial spectra of ultra-short chirped pulsed Gaussian become broadened with increasing the absolute value of the chirp parameter. With increasing off-axis radius, the off-axis power spectrum reduce rapidly, and the distribution of spectra shifts to the left. The off-axis spectral redshift increases with increasing off-axis radius.

  8. Shock-Accelerated Flying Foil Diagnostic with a Chirped Pulse Spectral Interferometry

    Institute of Scientific and Technical Information of China (English)

    陈建平; 李儒新; 曾志男; 王兴涛; 程传福; 徐至展

    2003-01-01

    A shock-accelerated flying foil is diagnosed with a chirped pulse spectral interferometry. The shock is pumped by a 1.2ps chirped laser pulse with a power of~1014 W/cm2 at 785nm irradiating on a 500nm aluminium film and detected by a probe pulse split from the pump based on a Michelson spectral interferometry. A flying foil of~5.595×10-6 g in~400 μm diameter was accelerated to~165 nm away from the initial target rear surface at~1.83 km/s before ablation.

  9. Transform-limited 100 microJ, 340 MW pulses from a nonlinear-fiber chirped-pulse amplifier using a mismatched grating stretcher-compressor.

    Science.gov (United States)

    Zaouter, Y; Boullet, J; Mottay, E; Cormier, E

    2008-07-01

    We report on a compact double-stage ytterbium-doped-fiber chirped-pulse amplifier system delivering high temporal quality 270 fs pulses of 100 microJ energy at a repetition rate of 300 kHz resulting in a peak power of 340 MW. The recompression down to 1.1 times the Fourier limit is based on the exploitation of nonlinear phase shifts associated with mismatched stretcher-compressor units. A 1-m-long ytterbium-doped 80 mum core diameter photonic crystal fiber is implemented as the power amplifier and allows the production of 143 microJ pulses before compression with an accumulated B integral of 17 rad throughout the amplification stages. PMID:18594687

  10. Control of the two-Photon Double Ionization of Helium with Intense Chirped Attosecond Laser Pulses

    Science.gov (United States)

    Barmaki, Samira; Laulan, Stephane

    2014-05-01

    We study the two-photon double ionization process of the helium atom by solving numerically the nonrelativistic time-dependent Schrödinger equation in its full dimensionality. We investigate with an intense chirped attosecond laser pulse of central carrier frequency that corresponds to the 29th harmonic of a Ti-sapphire laser the direct and sequential processes in helium. We show how it is possible by adjusting the chirp parameter to control the dominance of one process over the other within the atom. Attosecond chirped laser pulses offer a promising way to probe and control the two-photon double ionization of helium when compared with attosecond transform-limited pulses.

  11. Pulse-To-Pulse Spectra of a Picosecond Optical Parametric Oscillator Based on Chirped Quasi-Phase Matching

    OpenAIRE

    Descloux, D.; Laporte, C.; Dherbecourt, J.B.; Melkonian, J.M.; Raybaut, M.; Drag, C.; Godard, A.

    2014-01-01

    The pulse-to-pulse evolution of the spectrum emitted by a picoseconds synchronously-pumped optical parametric oscillator based on chirped quasi-phase matching is measured, enabling to study the spectro-temporal dynamics upon the buildup of the oscillation.

  12. An analysis of As2S3 chirped fiber grating formed by two-photon absorption effect

    Institute of Scientific and Technical Information of China (English)

    Huaisheng Wang(王淮生); Zhigang Zhang(张志刚); Lu Chai(柴路); Qingyue Wang(王清月)

    2003-01-01

    When femtosecond laser pulses interfere with chirped femtosecond laser pulses in As2S3 fiber, a chirped fiber grating is formed. An analytical expression is given to describe the chirped grating, and its Bragg reflectivity is calculated. Because of the high photosensitive effect of As2S3 material, the chirped fiber grating has a wide Bragg reflective spectrum and high reflectivity by choosing proper parameters. This indicates that the chirped fiber grating can be used as a stretcher in the femtosecond chirped pulse amplification (CPA) system.

  13. Chirped pulse reflectivity and frequency domain interferometry in laser driven shock experiments.

    Science.gov (United States)

    Benuzzi-Mounaix, A; Koenig, M; Boudenne, J M; Hall, T A; Batani, D; Scianitti, F; Masini, A; Di Santo, D

    1999-09-01

    We show the simultaneous applicability of the frequency domain interferometry and the chirped pulse reflectometry techniques to measure shock parameters. The experiment has been realized with the laser at the Laboratoire pour l'Utilisation des Lasers Intenses (LULI) with a 550-ps pulse duration and an intensity on target approximately 5 x 10(13) W/cm(2) to produce a shock in a layered aluminum-fused silica target. A second low energy, partially compressed chirped probe beam was used to irradiate the target rear side and the reflected light has been analyzed with a spectrometer, achieving a temporal resolution of the order of 1 ps. PMID:11970183

  14. Chirped pulse reflectivity and frequency domain interferometry in laser driven shock experiments

    Science.gov (United States)

    Benuzzi-Mounaix, A.; Koenig, M.; Boudenne, J. M.; Hall, T. A.; Batani, D.; Scianitti, F.; Masini, A.; di Santo, D.

    1999-09-01

    We show the simultaneous applicability of the frequency domain interferometry and the chirped pulse reflectometry techniques to measure shock parameters. The experiment has been realized with the laser at the Laboratoire pour l'Utilisation des Lasers Intenses (LULI) with a 550-ps pulse duration and an intensity on target ~5×1013 W/cm2 to produce a shock in a layered aluminum-fused silica target. A second low energy, partially compressed chirped probe beam was used to irradiate the target rear side and the reflected light has been analyzed with a spectrometer, achieving a temporal resolution of the order of 1 ps.

  15. Broadband excitation by chirped pulses: application to single electron spins in diamond

    International Nuclear Information System (INIS)

    Pulsed excitation of broad spectra requires very high field strengths if monochromatic pulses are used. If the corresponding high power is not available or not desirable, the pulses can be replaced by suitable low-power pulses that distribute the power over a wider bandwidth. As a simple case, we use microwave pulses with a linear frequency chirp. We use these pulses to excite spectra of single nitrogen–vacancy centres in a Ramsey experiment. Compared to the conventional Ramsey experiment, our approach increases the bandwidth by at least an order of magnitude. Compared to the conventional continuous wave-ODMR experiment, the chirped Ramsey experiment does not suffer from power broadening and increases the resolution by at least an order of magnitude. As an additional benefit, the chirped Ramsey spectrum contains not only ‘allowed’ single quantum transitions, but also ‘forbidden’ zero- and double quantum transitions, which can be distinguished from the single quantum transitions by phase-shifting the readout pulse with respect to the excitation pulse or by variation of the external magnetic field strength. (paper)

  16. Subpicosecond fiber optical parametric chirped pulse amplifier based on highly-nonlinear fiber

    OpenAIRE

    Chui, PC; Wong, KKY; Zhou, Y.; Q. Li; Cheung, KKY; Yang, S.

    2010-01-01

    We experimentally demonstrate a fiber optical parametric chirped pulse amplifier. A 750-fs signal is stretched to 40 ps, amplified with a gain of 30 dB through parametric process and then compressed to 808 fs. 2010 Optical Society of America. © 2010 IEEE.

  17. Single sub-50-attosecond pulse generation from chirp-compensated harmonic radiation using material dispersion

    International Nuclear Information System (INIS)

    A method for obtaining a single sub-50-attosecond pulse using harmonic radiation is proposed. For the generation of broad harmonic radiation during a single half-optical cycle, atoms are driven by a femtosecond laser pulse with intensity above the saturation intensity for optical field ionization and hence experience a large nonadiabatic increase of the laser electric field between optical cycles. Although the chirped structure of the harmonic radiation imposes a limit on the minimum achievable pulse duration, we demonstrate that its positive chirp can be compensated by the negative group delay dispersion of an appropriately selected x-ray filter material, used also for the spectral selection, resulting in a single attosecond pulse with a duration less than 50 as

  18. Single sub-50-attosecond pulse generation from chirp-compensated harmonic radiation using material dispersion

    International Nuclear Information System (INIS)

    A method for obtaining a single sub-50-attosecond pulse using harmonic radiation is proposed. For the generation of broad harmonic radiation during a single half-optical cycle, atoms are driven by a femtosecond laser pulse with intensity above the saturation intensity for optical field ionization, experiencing large nonadiabatic increase of the laser electric field between optical cycles. Although the chirped structure of the harmonic radiation imposes a limit on the minimum achievable pulse duration, we demonstrate that its positive chirp can be compensated by the negative group delay dispersion of an appropriately selected x-ray filter material, used also for the spectral selection, resulting in a single attosecond pulse with the duration less than 50 as.

  19. Spatial chirp control of high-intensity 4D pulse focusing for laser-matter interactions

    Directory of Open Access Journals (Sweden)

    Durfee C.

    2013-11-01

    Full Text Available Spatial chirp can be manipulated to control the focusing conditions for materials processing. Our double-ABCD nonparaxial analysis helps to understand and exploit the mechanisms for intensity localization, pulse front tilt, and grating formation, and includes initial spectral phase and detuning of the wavelength crossing plane. We also present a novel method for creating high density, high intensity interference patterns with crossed beams that have no relative pulse front tilt.

  20. Simultaneous compression and characterization of ultrashort laser pulses using chirped mirrors and glass wedges

    OpenAIRE

    Miranda, Miguel; Fordell, Thomas; Arnold, Cord,; L’Huillier, Anne; Crespo, Helder

    2011-01-01

    We present a simple and robust technique to retrieve the phase of ultrashort laser pulses, based on a chirped mirror and glass wedges compressor. It uses the compression system itself as a diagnostic tool, thereby making unnecessary the use of complementary diagnostic tools. We used this technique to compress and characterize 7.1 fs laser pulses from an ultrafast laser oscillator. (C)2011 Optical Society of America

  1. Population Transfer between Two Quantum States by Piecewise Chirping of Femtosecond Pulses: Theory and Experiment

    International Nuclear Information System (INIS)

    We propose and experimentally demonstrate the method of population transfer by piecewise adiabatic passage between two quantum states. Coherent excitation of a two-level system with a train of ultrashort laser pulses is shown to reproduce the effect of an adiabatic passage, conventionally achieved with a single frequency-chirped pulse. By properly adjusting the amplitudes and phases of the pulses in the excitation pulse train, we achieve complete and robust population transfer to the target state. The piecewise nature of the process suggests a possibility for the selective population transfer in complex quantum systems

  2. Divided-pulse amplification to the joule level.

    Science.gov (United States)

    Webb, Benjamin; Azim, Ahmad; Bodnar, Nathan; Chini, Michael; Shah, Lawrence; Richardson, Martin

    2016-07-01

    Divided-pulse amplification (DPA) has proven to be a valuable tool in scaling the peak power of diode-pumped ytterbium-doped amplifiers to beyond the single-pulse threshold for parasitic nonlinear effects. DPA enables the amplification of picosecond pulses in solid-state amplifiers with limited bandwidth beyond the single-pulse damage threshold. In this Letter, we demonstrate DPA of picosecond pulses in a flashlamp-pumped Nd:YAG amplifier for the first time, to the best of our knowledge, yielding a combined pulse energy of 167 mJ. PMID:27367113

  3. 24-mJ diode-pumped chirped-pulse regenerative amplifier with a cooled Yb:LiYF4

    International Nuclear Information System (INIS)

    A 24-mJ diode-pumped chirped-pulse regenerative amplifier with a cooled Yb:LiYF4 crystal has been developed. A 10-mJ pulse energy with sub-ps pulse duration was obtained with a 660 fs pulse duration after compression. (author)

  4. Spatially and spectrally resolved quantum path interference with chirped driving pulses

    CERN Document Server

    Preclíková, Jana; Lorek, Eleonora; Larsen, Esben Witting; Heyl, Christoph M; Paleček, David; Zigmantas, Donatas; Schafer, Kenneth J; Gaarde, Mette B; Mauritsson, Johan

    2016-01-01

    We measure spectrally and spatially resolved high-order harmonics generated in argon using chirped multi-cycle laser pulses. Using a very stable, high-repetition rate laser we are able to clearly observe the interference between light emitted from the two shortest trajectories and study this interference structure systematically. The interference structure is clearly observed over a large range of harmonic orders, ranging from harmonic 11, which is below the ionization threshold of argon, to harmonic 25. The interference pattern contains more information than just the relative phase of the light from the two trajectories, since it is both spatially and spectrally resolved. We can access this additional information by changing the chirp of the driving laser pulses which affects both the spatial and the spectral phases of the two trajectories differently, allowing us to reconstruct the dipole phase parameters for the short ($\\alpha_s$) and long ($\\alpha_l$) trajectories from the data. The reconstruction is done...

  5. Propagation of intrinsic chirped sub-cycle and single-cycle pulses in a silica fiber

    Science.gov (United States)

    Cai, Xunming; Zhao, Jingyun; Lin, Qiang; Luo, Jiaolian; Yang, Yang

    2016-05-01

    The propagation of Gaussian sub-cycle and single-cycle pulses in a nonlinear media is studied using the analytical expression of pulses. The analytical expression is a modified version of the vector potential definition model of sub-cycle pulse. The intrinsic characteristics of sub-cycle and single-cycle pulses, such as the intrinsic chirp and the self-induced blue-shift of the central frequency of spectrum are found to have an important effect on the propagation of pulses in the nonlinear media. The initial 0.28-cycle pulse evolves into a primary multi-cycle pulse and a single-cycle precursor pulse during the propagation. The single-cycle precursor pulse is formed by the carrier frequency modulation on the leading side of pulse. During the propagation of the sub-cycle pulse, the self-steepening effect and the amplitude of the precursor pulse are more significant due to the shorter pulse duration. The reason can be attributed to the intrinsic characteristics of sub-cycle pulse.

  6. Short-Pulse Amplification by Strongly-Coupled Brillouin Scattering

    CERN Document Server

    Edwards, Matthew R; Mikhailova, Julia M; Fisch, Nathaniel J

    2016-01-01

    We examine the feasibility of strongly-coupled stimulated Brillouin scattering as a mechanism for the plasma-based amplification of sub-picosecond pulses. In particular, we use fluid theory and particle-in-cell simulations to compare the relative advantages of Raman and Brillouin amplification over a broad range of achievable parameters.

  7. Chirped-beam two-stage free-electron laser for high-power femtosecond x-ray pulse generation

    International Nuclear Information System (INIS)

    A method for generating femtosecond-duration x-ray pulses with a free-electron laser is presented. This method uses an energy-chirped electron beam propagating through an undulator to produce a frequency-chirped x-ray pulse by self-amplified spontaneous emission. A short temporal pulse is created by use of a monochromator to select a narrow radiation bandwidth. A second undulator is used to amplify the short-duration radiation. The radiation characteristics produced by a chirped-beam two-stage free-electron laser are calculated, and the performance of the chirped-beam two-stage option for the Linac Coherent Light Source is considered

  8. Micro-joule sub-10-fs VUV pulse generation by MW pump pulse using highly efficient chirped-four-wave mixing in hollow-core photonic crystal fibers

    OpenAIRE

    Im, Song-Jin

    2013-01-01

    We theoretically study chirped four-wave mixing for VUV pulse generation in hollow-core photonic crystal fibers. We predict the generation of sub-10-fs VUV pulses with energy of up to hundreds of microjoule by broad-band chirped idler pulses at 830 nm and MW pump pulses with narrow-band at 277 nm. MW pump could be desirable to reduce the complexity of the laser system or use a high repetition rate-laser system. The energy conversion efficiency from pump pulse to VUV pulse reaches to 30%. This...

  9. Divided-pulse nonlinear amplification and simultaneous compression

    International Nuclear Information System (INIS)

    We report on a fiber laser system delivering 122 fs pulse duration and 600 mW average power at 1560 nm by the interplay between divided pulse amplification and nonlinear pulse compression. A small-core double-clad erbium-doped fiber with anomalous dispersion carries out the pulse amplification and simultaneously compresses the laser pulses such that a separate compressor is no longer necessary. A numeric simulation reveals the existence of an optimum fiber length for producing transform-limited pulses. Furthermore, frequency doubling to 780 nm with 240 mW average power and 98 fs pulse duration is achieved by using a periodically poled lithium niobate crystal at room temperature

  10. X-band photoinjector for a chirped-pulse FEL

    Energy Technology Data Exchange (ETDEWEB)

    Luhmann, Jr., N. C.; Alvis, R. M.; Baldis, H. A.; Hartemann, F. V; Heritage, J. P.; Ho, C. H.; Landahl, E. C.; Li, K.; Troha,A. L.; White, W. E.

    1998-12-15

    The phase noise and jitter characteristics of the laser and rf systems of a high gradient X-band photoinjector have been measured experimentally. When > 100 coherently phased 5 MeV electron bunches are produced in bursts, the photoinjector should be an ideal electron source for a pulsed, pre-bunched free-electron laser (FEL) operating at 100 GHz. The laser oscillator is a self-modelocked Titanium:Sapphire system operating at the 108th subharmonic of the rf gun. The X-band signal is produced from the laser by a phase-locked dielectric resonance oscillator, and amplified by a pulsed TWT and klystron. A comparison between the klystron and TWT amplifier phase noise and the fields excited in the rf gun demonstrates the filtering effect of the high Q structure, thus indicating that the rf gun can be used as a master oscillator, and could be energized by either a rf oscillator such as a magnetron or a compact source such as a cross-field amplifier. In particular, the rf gun can play the role of a pulsed rf clock to synchronize the photocathode laser system: direct drive of a synchronously mode-locked AlGaAs quantum well laser has been achieved using the X0-band gun rf fields. This novel, GHz repetition rate, sub-picosecond laser system is being developed to replace the more conventional femtosecond Ti: Al2O3 system. Some advantages include pumping this laser with a stabilized current source instead of a costly, low efficiency pump laser. Finally, dark current measurements and initial photoelectron measurements are reported.

  11. X-band photoinjector for a chirped-pulse FEL

    International Nuclear Information System (INIS)

    The phase noise and jitter characteristics of the laser and rf systems of a high gradient X-band photoinjector have been measured experimentally. The laser oscillator is a self-modelocked Titanium:Sapphire system operating at the 108th subharmonic of the rf gun. The X-band signal is produced from the laser by a phase-locked dielectric resonance oscillator, and amplified by a pulsed TWT and klystron. A comparison between the klystron and TWT amplifier phase noise and the fields excited in the rf gun demonstrates the filtering effect of the high Q structure, thus indicating that the rf gun can be used as a master oscillator, and could be energized by either a rf oscillator such as a magnetron or a compact source such as a cross-field amplifier. In particular, the rf gun can play the role of a pulsed rf clock to synchronize the photocathode laser system: direct drive of a synchronously modelocked AlGaAs quantum well laser has been achieved using the X-band gun rf fields. This novel, GHz repetition rate, laser system is being developed to replace the more conventional femtosecond Ti:Al2O3 system. Some advantages include pumping this laser with a stabilized current source instead of a costly, low efficiency pump laser. Finally, dark current measurements and initial photoelectron measurements are reported

  12. Amplification of Short Pulse High Power UV Laser

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    At recent year, with the development of CPA and other amplification technology, laser intensity achieves great increase and laser power can be high to PW(105) now, this ultrashort pulse lasers offer scientists a route to investigate laser-matter interaction in an absolute new regime.So far the researches on ultrashort pulse laser-matter interaction concentrated on infrared regime, yet ultraviolet laser has the advantage in intense field physics and ICF researches for its short wavelength and less nonlinear effects. KrF excimer is the best medium in UV ultrashort pulse amplification for its small saturation energy and high contrast ratio accessible.

  13. 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.

  14. Gd(III)-Gd(III) distance measurements with chirp pump pulses

    Science.gov (United States)

    Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar

    2015-10-01

    The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S = 7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero

  15. Spectroscopy of the hydrogen 1 S -3 S transition with chirped laser pulses

    Science.gov (United States)

    Yost, D. C.; Matveev, A.; Grinin, A.; Peters, E.; Maisenbacher, L.; Beyer, A.; Pohl, R.; Kolachevsky, N.; Khabarova, K.; Hänsch, T. W.; Udem, Th.

    2016-04-01

    We identify a systematic present in two-photon direct frequency comb spectroscopy (DFCS) which is a result of chirped laser pulses and is a manifestation of the first-order Doppler effect. We carefully analyze this systematic and propose methods for its mitigation within the context of our measurement of the hydrogen 1 S -3 S transition. We also report on our determination of the absolute frequency of this transition, which is comparable to a previous measurement using continuous-wave spectroscopy [O. Arnoult et al., Eur. Phys. J. D 60, 243 (2010), 10.1140/epjd/e2010-00249-6], but was obtained with a different experimental method.

  16. The influence of oceanic turbulence on the spectral properties of chirped Gaussian pulsed beam

    Science.gov (United States)

    Liu, Dajun; Wang, Yaochuan; Wang, Guiqiu; Yin, Hongming; Wang, Jinren

    2016-08-01

    Based on the extended Huygens-Fresnel principle, the spectral behaviors of a chirped Gaussian pulsed beam propagating in oceanic turbulence are illustrated. The influence of the parameters of oceanic turbulence (the rate of dissipation of turbulent kinetic energy per unit mass of fluid, rate of dissipation of mean-square temperature, relative strength of temperature and salinity fluctuations), relative position parameter and propagation distance on the spectra shift is analysed and given by numerical examples. The research results have the potential application in underwater wireless laser communication and remote sensing.

  17. Stimulated Raman scattering effect on femtosecond pulse generation using a parabolic amplification and a pulse compressor

    OpenAIRE

    Soh, Daniel B.S.; Grudinin, A.B.; Nilsson, J.; Y. Jeong; Yoo, S.; Kim, J.; Codemard, C.; Dupriez, P.

    2005-01-01

    An explicit analytical form for the Stokes pulse evolution in parabolic amplification is derived for the first time. In order to achieve efficient pulse compression, the parabolic amplifiers should be operated in the small Stokes pulse regime where the signal pulse is not seriously deteriorated. An analytical expression to obtain the critical fibre length for small Stokes pulse regime is also derived. The pulse compression of the output signal at various fiber lengths also confirms that ...

  18. 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.

  19. Fiber grating compression of giant-chirped nanosecond pulses from an ultra-long nanotube mode-locked fiber laser.

    Science.gov (United States)

    Woodward, R I; Kelleher, E J R; Runcorn, T H; Loranger, S; Popa, D; Wittwer, V J; Ferrari, A C; Popov, S V; Kashyap, R; Taylor, J R

    2015-02-01

    We demonstrate that the giant chirp of coherent, nanosecond pulses generated in an 846 m long, all-normal dispersion, nanotube mode-locked fiber laser can be compensated using a chirped fiber Bragg grating compressor. Linear compression to 11 ps is reported, corresponding to an extreme compression factor of ∼100. Experimental results are supported by numerical modeling, which is also used to probe the limits of this technique. Our results unequivocally conclude that ultra-long cavity fiber lasers can support stable dissipative soliton attractors and highlight the design simplicity for pulse-energy scaling through cavity elongation. PMID:25680054

  20. Design considerations for a high power, ultrabroadband optical parametric chirped-pulse amplifier.

    Science.gov (United States)

    Prandolini, M J; Riedel, R; Schulz, M; Hage, A; Höppner, H; Tavella, F

    2014-01-27

    A conceptual design of a high power, ultrabroadband optical parametric chirped-pulse amplifier (OPCPA) was carried out comparing nonlinear crystals (LBO and BBO) for 810 nm centered, sub-7.0 fs pulses with energies above 1 mJ. These amplifiers are only possible with a parallel development of kilowatt-level OPCPA-pump amplifiers. It is therefore important to know good strategies to use the available OPCPA-pump energy efficiently. Numerical simulations, including self- and cross-phase modulation, were used to investigate the critical parameters to achieve sufficient spectral and spatial quality. At high output powers, thermal absorption in the nonlinear crystals starts to degrade the output beam quality. Strategies to minimize thermal effects and limits to the maximum average power are discussed. PMID:24515165

  1. High peak-power monolithic femtosecond ytterbium fiber chirped pulse amplifier with a spliced-on hollow core fiber compressor.

    Science.gov (United States)

    Verhoef, A J; Jespersen, K; Andersen, T V; Grüner-Nielsen, L; Flöry, T; Zhu, L; Baltuška, A; Fernández, A

    2014-07-14

    We demonstrate a monolithic Yb-fiber chirped pulse amplifier that uses a dispersion matched fiber stretcher and a spliced-on hollow core photonic bandgap fiber compressor. For an output energy of 77 nJ, 220 fs pulses with 92% of the energy contained in the main pulse, can be obtained with minimal nonlinearities in the system. 135 nJ pulses are obtained with 226 fs duration and 82 percent of the energy in the main pulse. Due to the good dispersion match of the stretcher to the hollow core photonic bandgap fiber compressor, the duration of the output pulses is within 10% of the Fourier limited duration. PMID:25090494

  2. Production of Picosecond, Kilojoule, and Petawatt Laser Pulses via Raman Amplification of Nanosecond Pulses

    OpenAIRE

    Trines, R. M. G. M.; Fiúza, F.; Bingham, R.; Fonseca, R. A.; Silva, L. O.; Cairns, R. A.; Norreys, P. A.

    2011-01-01

    Raman amplification in plasma has been promoted as a means of compressing picosecond optical laser pulses to femtosecond duration to explore the intensity frontier. Here we show for the first time that it can be used, with equal success, to compress laser pulses from nanosecond to picosecond duration. Simulations show up to 60% energy transfer from pump pulse to probe pulse, implying that multikilojoule ultraviolet petawatt laser pulses can be produced using this scheme. This has important co...

  3. Isolated sub-30-attosecond pulse generation using a multicycle two-color chirped laser and a static electric field

    International Nuclear Information System (INIS)

    We present a theoretical investigation of high-order harmonic generation in a chirped two-color laser field, which is synthesized by a 10-fs/800-nm fundamental chirped pulse and a 10-fs/1760-nm subharmonic pulse. It is shown that a supercontinuum can be produced using the multicycle two-color chirped field. However, the supercontinuum reveals a strong modulation structure, which is not good for the generation of an isolated attosecond pulse. By adding a static electric field to the multicycle two-color chirped field, not only the harmonic cutoff is extended remarkably, but also the quantum paths of the high-order harmonic generation (HHG) are modified significantly. As a result, both the extension of the supercontinuum and the selection of a single quantum path are achieved, producing an isolated 23-as pulse with a bandwidth of about 170.6 eV. Furthermore, the influences of the laser intensities on the supercontinuum and isolated attosecond pulse generation are investigated. (atomic and molecular physics)

  4. Quantum phase amplification for temporal pulse shaping and super-resolution in remote sensing

    Science.gov (United States)

    Yin, Yanchun

    The use of nonlinear optical interactions to perform nonclassical transformations of electromagnetic field is an area of considerable interest. Quantum phase amplification (QPA) has been previously proposed as a method to perform nonclassical manipulation of coherent light, which can be experimentally realized by use of nonlinear optical mixing processes, of which phase-sensitive three-wave mixing (PSTWM) is one convenient choice. QPA occurs when PSTWM is operated in the photon number deamplification mode, i.e., when the energy is coherently transferred among the low-frequency signal and idler waves and the high-frequency pump wave. The final state is nonclassical, with the field amplitude squeezed and the phase anti-squeezed. In the temporal domain, the use of QPA has been studied to facilitate nonlinear pulse shaping. This novel method directly shapes the temporal electric field amplitude and phase using the PSTWM in a degenerate and collinear configuration, which has been analyzed using a numerical model. Several representative pulse shaping capabilities of this technique have been identified, which can augment the performance of common passive pulse shaping methods operating in the Fourier domain. The analysis indicates that a simple quadratic variation of temporal phase facilitates pulse compression and self-steepening, with features significantly shorter than the original transform-limited pulse. Thus, PSTWM can act as a direct pulse compressor based on the combined effects of phase amplification and group velocity mismatch, even without the subsequent linear phase compensation. Furthermore, it is shown numerically that pulse doublets and pulse trains can be produced at the pump frequency by utilizing the residual linear phase of the signal. Such pulse shaping capabilities are found to be within reach of this technique in common nonlinear optical crystals pumped by pulses available from compact femtosecond chirped-pulse amplification laser systems. The use of

  5. 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.

  6. Ultrashort pulse amplification in cryogenically cooled amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Backus, Sterling J.; Kapteyn, Henry C.; Murnane, Margaret Mary

    2004-10-12

    A laser amplifier system amplifies pulses in a single "stage" from .about.10.sup.-9 joules to more than 10.sup.-3 joules, with average power of 1-10 watts, and beam quality M.sup.2 <2. The laser medium is cooled substantially below room temperature, as a means to improve the optical and thermal characteristics of the medium. This is done with the medium inside a sealed, evacuated or purged cell to avoid moisture or other materials condensing on the surface. A "seed" pulse from a separate laser is passed through the laser medium, one or more times, in any of a variety of configurations including single-pass, multiple-pass, and regenerative amplifier configurations.

  7. Energy and angular differential probabilities for photoionization of He using chirped attosecond soft-x-ray pulses

    International Nuclear Information System (INIS)

    Based on the time-dependent close-coupling method, energy and angular differential probabilities for various ionization processes of He atoms subjected to intense attosecond soft-x-ray pulses with a photon energy of 91.6 eV and a peak intensity of 1015 W/cm2 are calculated to explore their dependence on the duration and the chirp of the pulse. It is found that the single and the double electron energy distributions for two-photon double ionization are rather sensitive to chirps. That is, both the magnitudes and locations of the sequential peaks in the single electron energy distributions vary strongly with chirps and the two-electron energy distributions being broadened and stretched along the equal energy sharing direction as opposed to the usual total excess energy direction for the case of zero chirp. In addition, our calculation also reveals an unexpected structure formed between the two sequential peaks. In order to better understand the chirp effects on both independent-electron and correlated electron emissions and their relations to the origin of the structure, we analyzed the corresponding probability differential in energy and angle.

  8. Pulse Amplification in Dispersion-Decreasing Fibers with Symbolic Computation

    International Nuclear Information System (INIS)

    The pulse amplification in the dispersion-decreasing fiber (DDF) is investigated via symbolic computation to solve the variable-coefficient higher-order nonlinear Schroedinger equation with the effects of third-order dispersion, self-steepening, and stimulated Raman scattering. The analytic one-soliton solution of this model is obtained with a set of parametric conditions. Based on this solution, the fundamental soliton is shown to be amplified in the DDF. The comparison of the amplitude of pulses for different dispersion profiles of the DDF is also performed through the graphical analysis. The results of this paper would be of certain value to the study of signal amplification and pulse compression. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  9. Coherent strong-field control of multiple states by a single chirped femtosecond laser pulse

    CERN Document Server

    Krug, M; Wollenhaupt, M; Sarpe-Tudoran, C; Baumert, T; Ivanov, S S; Vitanov, N V

    2011-01-01

    We present a joint experimental and theoretical study on strong-field photo-ionization of sodium atoms using chirped femtosecond laser pulses. By tuning the chirp parameter, selectivity among the population in the highly excited states 5p, 6p, 7p and 5f, 6f is achieved. Different excitation pathways enabling control are identified by simultaneous ionization and measurement of photoelectron angular distributions employing the velocity map imaging technique. Free electron wave packets at an energy of around 1 eV are observed. These photoelectrons originate from two channels. The predominant 2+1+1 Resonance Enhanced Multi-Photon Ionization (REMPI) proceeds via the strongly driven two-photon transition $4s\\leftarrow\\leftarrow3s$, and subsequent ionization from the states 5p, 6p and 7p whereas the second pathway involves 3+1 REMPI via the states 5f and 6f. In addition, electron wave packets from two-photon ionization of the non-resonant transiently populated state 3p are observed close to the ionization threshold....

  10. Characteristics of spatial modulation in nonlinear propagation of broad-band lasers stacked by chirped pulses

    International Nuclear Information System (INIS)

    To identify the potential risks of spatial modulation of broad-band laser beams stacked by chirped pulses on the safety of optics, this paper numerically investigated the effect of temporal modulation on the generation and growth of spatial modulation during its nonlinear propagation. When there is no additional spatial modulation and the B integral is limited in the practical working range(usually less than 2.0 rad), no spatial modulation will be generated for both normal dispersion and anomalous dispersion;while with the B integral further increasing, spatial modulation will emerge with a rapid growth. When there is additional spatial modulation for anomalous dispersion, the spatial modulation with additional temporal modulation will grow more quickly than that without additional temporal modulation. However, for normal dispersion,the growth of spatial modulation for both cases is similar. (authors)

  11. Experimental validation of a linear model for data reduction in chirp-pulse microwave CT.

    Science.gov (United States)

    Miyakawa, M; Orikasa, K; Bertero, M; Boccacci, P; Conte, F; Piana, M

    2002-04-01

    Chirp-pulse microwave computerized tomography (CP-MCT) is an imaging modality developed at the Department of Biocybernetics, University of Niigata (Niigata, Japan), which intends to reduce the microwave-tomography problem to an X-ray-like situation. We have recently shown that data acquisition in CP-MCT can be described in terms of a linear model derived from scattering theory. In this paper, we validate this model by showing that the theoretically computed response function is in good agreement with the one obtained from a regularized multiple deconvolution of three data sets measured with the prototype of CP-MCT. Furthermore, the reliability of the model as far as image restoration in concerned, is tested in the case of space-invariant conditions by considering the reconstruction of simple on-axis cylindrical phantoms. PMID:12022626

  12. Micro-joule sub-10-fs VUV pulse generation by MW pump pulse using highly efficient chirped-four-wave mixing in hollow-core photonic crystal fibers

    CERN Document Server

    Im, Song-Jin

    2013-01-01

    We theoretically study chirped four-wave mixing for VUV pulse generation in hollow-core photonic crystal fibers. We predict the generation of sub-10-fs VUV pulses with energy of up to hundreds of microjoule by broad-band chirped idler pulses at 830 nm and MW pump pulses with narrow-band at 277 nm. MW pump could be desirable to reduce the complexity of the laser system or use a high repetition rate-laser system. The energy conversion efficiency from pump pulse to VUV pulse reaches to 30%. This generation can be realized in kagome-lattice hollow-core PCF filled with noble gas of high pressure with core-diameter less than 40 micrometers which would enable technically simple or highly efficient coupling to fundamental mode of the fiber.

  13. The effect of frequency chirping on electron-positron pair production in the one- and two-color laser pulse fields

    CERN Document Server

    Abdukerim, Nuriman; Xie, Bai-Song

    2016-01-01

    The effect of the frequency chirping on momentum spectrum and pair production rate in one- and two-color laser pulse fields is investigated by solving the quantum Vlasov equation. A small frequency chirp shifts the momentum spectrum along the momentum axis. The positive and negative frequency chirp parameters play the same role in increasing the pair number density. The sign change of frequency chirp parameter at the moment $t=0$ leads pulse shape and momentum spectrum to be symmetric, and the number density to be increased. The number density of produced pairs in the two-color pulse field is much higher than that in the one-color pulse field and the larger frequency chirp pulse field dominates more strongly. In the two-color pulse fields, the relation between the frequency ratio of two colors and the number density is not sensitive to the parameters of small frequency chirp added in either low frequency strong field or high frequency weak field but sensitive to the parameters of large frequency chirp added i...

  14. High power amplification of a tailored-pulse fiber laser

    Science.gov (United States)

    Saby, Julien; Sangla, Damien; Caplette, Stéphane; Boula-Picard, Reynald; Drolet, Mathieu; Reid, Benoit; Salin, François

    2013-02-01

    We demonstrate the amplification of a 1064nm pulse-programmable fiber laser with Large Pitch Rod-Type Fibers of various Mode field diameters from 50 to 70 μm. We have developed a high power fiber amplifier at 1064nm delivering up to 100W/1mJ at 15ns pulses and 30W/300μJ at 2ns with linearly polarized and diffraction limited output beam (M²LBO crystals leading to 50W at 532nm and 25W at 355nm with a diffraction limited output. Similar experiments performed at 1032nm are also reported.

  15. Isotopologue-Sensitive Detection Using Chirped-Pulse Ft-Mw Spectroscopy: Minor Species of Propofol

    Science.gov (United States)

    Lesarri, Alberto; Neill, Justin; Muckle, Matt; Shipman, Steven T.; Pate, Brooks H.; Suenram, Richard D.; Caminati, Walther

    2009-06-01

    The capabilities of chirped-pulse FT-microwave spectroscopy to achieve full-bandwidth (11 GHz) isotopologue-sensitive detection have been tested on the 13-heavy atoms molecule of propofol (2,6-diisopropylphenol). The analysis of the rotational spectrum using moderate signal averaging (10 k FIDs) had previously detected the presence of two conformers arising from the combined internal rotations of the hydroxyl and the two isopropyl groups. In the new experiment reported here 600 k FID's were coherently averaged, using three pulsed nozzle sources and reading multiple FIDs per sample injection cycle to reduce the total acquisition time and sample consumption. The new spectrum revealed a very large number of weak transitions, suggesting that full-band ^{13}C sensitivity had been surpassed. The new data have resulted in the assignment of a third conformer of propofol, followed by all twelve ^{13}C-monosubstituted species in natural abundance for the most stable conformer. The isotopic information confirmed the molecular structure for the preferred conformation of propofol, validating the ab initio predictions for this compound. The potential function for the OH internal rotation has been determined using a flexible model. A. Lesarri, S. T. Shipman, G. G. Brown, L. Alvarez-Valtierra, R. D. Suenram and B. H. Pate, 63^rd OSU Int. Symp. On Mol. Spectrosc., Columbus, OH, 2008, RH07 In the

  16. Production of picosecond, kilojoule, and petawatt laser pulses via Raman amplification of nanosecond pulses.

    Science.gov (United States)

    Trines, R M G M; Fiúza, F; Bingham, R; Fonseca, R A; Silva, L O; Cairns, R A; Norreys, P A

    2011-09-01

    Raman amplification in plasma has been promoted as a means of compressing picosecond optical laser pulses to femtosecond duration to explore the intensity frontier. Here we show for the first time that it can be used, with equal success, to compress laser pulses from nanosecond to picosecond duration. Simulations show up to 60% energy transfer from pump pulse to probe pulse, implying that multikilojoule ultraviolet petawatt laser pulses can be produced using this scheme. This has important consequences for the demonstration of fast-ignition inertial confinement fusion. PMID:21981507

  17. Generation and amplification of nanosecond pulses by iodine lasers

    Energy Technology Data Exchange (ETDEWEB)

    Zuev, V.S.; Katulin, V.A.; Nosach, V.Y.; Petrov, A.L.

    1982-12-01

    Results are reported of experimental investigations of high-power photodissociation iodine laser pumped by lamps and by radiation from high-current electric discharges. The basic parameters of the working medium, the parameters of both lamp-pumped and discharge-pumped lasers, and methods of shaping of a short pulse with diffraction directivity of the radiation are investigated. The possibility of effective amplification of a short pulse by an iodine amplifier pumped with an open high-current discharge is demonstrated. An iodine laser generating a pulse of duration 1 nsec, divergence 10/sup -4/ rad, and energy 100 J at a contrast 10/sup 8/ and 300 J at a contrast 10/sup 2/-10/sup 3/ is described.

  18. PULSE REFERENCED CONTROL METHOD FOR ENHANCED POWER AMPLIFICATION OF A PULSE MODULATED SIGNAL

    DEFF Research Database (Denmark)

    1998-01-01

    To correct for any source of non-linearity and noise introduced in the power amplification of a pulse modulated signal, a correction unit is applied in-between the pulse modulator and the switching power amplification stage. The correction unit is controlled to have a compensating effect, by...... introducing continuous delays on the individual pulse edges on the basis of error information provided by an error processing block. One preferred embodiment of the invention comprises: a Correction Unit with means to control the delays of the individual pulse edges as a function of a control input signal $i......(v¿e?); a state feedback block A with compensation; a reference shaping block $i(R) to modify the pulsed reference $i(v¿r?) for optimized error estimation; a difference block to generate an error signal and a compensator $i(C) to shape this error. The invention makes it possible to implement practical...

  19. Quasimonoenergetic GeV electron bunch generation by the wake-field of the chirped laser pulse

    International Nuclear Information System (INIS)

    One-dimensional nonlinear analysis of wake-field generation and electron bunch acceleration by a chirped laser pulse were investigated numerically. It was found that the optimum linear chirp parameter leads to the wake-field amplitude increase by one order of magnitude and accordingly the acceleration gradient. In our external injection scheme, electrons were accelerated using the initial energy of 100 KeV (γin=1.2). When the pulse passes through the electron bunch most part of the electrons trapped in the first cycle of the laser wake-field and accelerate to about 1 GeV in 1.8 mm. We concluded that the expensive electron preacceleration mechanism could be omitted in a laser-aided electron acceleration scheme.

  20. Acousto-optical adaptive correction of a chirped laser pulse spectral profile in a Nd-phosphate glass regenerative amplifier

    International Nuclear Information System (INIS)

    We present results of experimental research carried out with the help of an acousto-optical light dispersive delay line (LDDL) on spectral correction of chirped laser pulses in a Nd-doped phosphate glass regenerative amplifier (RA) characterized by high gain (G ≈ 4 × 107). The spectral resolution of the LDDL was equal to 1.1 cm−1 at a diffraction efficiency greater than 80%. The use of the LDDL made it possible to implement operating conditions of the RA under which the duration of the output chirped pulse did not shorten in comparison with the duration of the input one, which meant that the width of the spectral emission could be preserved. (letter)

  1. Ultrafast and efficient coherence creation in {\\Lambda}-like atomic systems driven by nonlinearly chirped few-cycle pulses

    OpenAIRE

    Sarma, Amarendra K.; Kumar, Parvendra

    2011-01-01

    We report an ultrafast and efficient way to create the maximum coherence between the two lower states in a -like atomic systems, driven by two nonlinearly chirped few-cycle pulses. The phenomenon of coherent population trapping and electromagnetically induced population transfer are investigated by solving the appropriate density matrix equations without invoking the rotating wave approximation. The robustness of the scheme for maximum coherence against the variation of the laser parameters a...

  2. Optimization of single attosecond x-ray pulses by genetic algorithm control of the chirp and initial phase of 5 fs laser pulses

    International Nuclear Information System (INIS)

    We show that the peak intensity of single attosecond x-ray pulses is enhanced by 1 or 2 orders of magnitude, the pulse duration is greatly compressed, and the optimal propagation distance is shortened by genetic algorithm optimization of the chirp and initial phase of 5 fs laser pulses. However, as the laser intensity increases, more efficient nonadiabatic self-phase matching can lead to a dramatically enhanced harmonic yield, and the efficiency of optimization decreases in the enhancement and compression of the generated attosecond pulses

  3. Production of picosecond, kilojoule, petawatt laser pulses via Raman amplification of nanosecond pulses

    CERN Document Server

    Trines, R; Bingham, R; Fonseca, R A; Silva, L O; Cairns, R A; Norreys, P A

    2011-01-01

    Raman amplification in plasma has been promoted as a means of compressing picosecond optical laser pulses to femtosecond duration to explore the intensity frontier. Here we show for the first time that it can be used, with equal success, to compress laser pulses from nanosecond to picosecond duration. Simulations show up to 60% energy transfer from pump to probe pulses, implying that multi-kiloJoule ultra-violet petawatt laser pulses can be produced using this scheme. This has important consequences for the demonstration of fast-ignition inertial confinement fusion.

  4. Chirped Pulse-Fourier Transform Microwave Spectroscopy of Ethyl 3-METHYL-3-PHENYLGLYCIDATE (strawberry Aldehyde)

    Science.gov (United States)

    Shipman, Steven T.; Neill, Justin L.; Muckle, Matt T.; Suenram, Richard D.; Pate, Brooks H.

    2009-06-01

    Strawberry aldehyde (C_{12} O_3 H_{14}), a common artificial flavoring compound, has two non-interconvertible conformational families defined by the relative stereochemistry around its epoxide carbons. In one family, referred to as the trans because the two large substituents (a phenyl ring and an ethyl ester) are on opposite sides of the epoxide ring, these two substituents are unable to interact with each other. However, in the cis family, there is a long-range interaction that is difficult to accurately capture in electronic structure calculations. Three trans and two cis conformations have been assigned by broadband chirped pulse Fourier transform microwave spectroscopy, along with the C-13 isotopomers in natural abundance for one conformer from each of the families. The agreement of the rotational constants, relative dipole moments, and relative energies between theory and experiment is excellent, even at relatively crude levels of theory, for the trans family, but is quite poor for the cis conformers. In addition, due to the reactivity of strawberry aldehyde and the high temperature to which it must be heated to yield a suitable vapor pressure, several decomposition products have been assigned, and more, as of yet unassigned, are likely to be present. This project demonstrates some of the challenges in performing large-molecule rotational spectroscopy.

  5. Femtosecond pulse generation and amplification in Yb-doped fibre oscillator–amplifier system

    Indian Academy of Sciences (India)

    P K Mukhopadhyay

    2010-11-01

    In recent times ytterbium (Yb) doped fibre-based mode-locked master oscillator and power amplifier have attracted a great deal of interest because of their inherent advantages like flexibility, reliability, compactness, high power handling capability and diffraction limited output beam quality as compared to the solid-state counterpart. But, to successfully develope of high-power femtosecond oscillator–amplifier system based on Yb- doped fibre, an appropriate choice of the mode-locking regime and the amplifier geometry are required. Development of an all-fibre integrated high-power Yb-doped fibre oscillator–amplifier system in which the advantages of a fibre-based system can be fully exploited remained a challenge as it requires the careful optimization of dispersion, nonlinearity, gain and ASE contribution. In this article, femto-second pulse generation in Yb-doped fibre oscillator in different mode-locking regimes are reviewed and the details of development and characterization of an all-fibre, high-power, low-noise amplifier system seeded by an all-normal-dispersion mode-locked Yb-doped fibre laser oscillator is described. More than 10 W of average power is obtained from the fibre oscillator–amplifier system at a repetition rate of 43 MHz with diffraction-limited beam quality. Amplified pulses are de-chirped to sub-160 fs duration in a grating compressor. This is the first 10 W-level source of femtosecond pulses with completely fibre-integrated amplification comprised of commercially available components.

  6. Stabilization and time resolved measurement of the frequency evolution of a modulated diode laser for chirped pulse generation

    Science.gov (United States)

    Varga-Umbrich, K.; Bakos, J. S.; Djotyan, G. P.; Ignácz, P. N.; Ráczkevi, B.; Sörlei, Zs; Szigeti, J.; Kedves, M. Á.

    2016-05-01

    We have developed experimental methods for the generation of chirped laser pulses of controlled frequency evolution in the nanosecond pulse length range for coherent atomic interaction studies. The pulses are sliced from the radiation of a cw external cavity diode laser while its drive current, and consequently its frequency, are sinusoidally modulated. By the proper choice of the modulation parameters, as well as of the timing of pulse slicing, we can produce a wide variety of frequency sweep ranges during the pulse. In order to obtain the required frequency chirp, we need to stabilize the center frequency of the modulated laser and to measure the resulting frequency evolution with appropriate temporal resolution. These tasks have been solved by creating a beat signal with a reference laser locked to an atomic transition frequency. The beat signal is then analyzed, as well as its spectral sideband peaks are fed back to the electronics of the frequency stabilization of the modulated laser. This method is simple and it has the possibility for high speed frequency sweep with narrow linewidth that is appropriate, for example, for selective manipulation of atomic states in a magneto-optical trap.

  7. a Chirped Pulse Ftmw Study of the Structure of Phenol Dimer

    Science.gov (United States)

    Steber, Amanda L.; Neill, Justin L.; Zaleski, Daniel P.; Pate, Brooks H.; Lesarri, Alberto

    2011-06-01

    Phenol dimer has been studied extensively and is considered a benchmark molecular complex for ab initio theory due to a long range dispersion interaction between the rings as well as an intermolecular hydrogen bond. Previously, the structure had been determined using RCS and high resolution UV measurements; however, several assumptions were integrated into the structure because a full isotopically substituted structure could not be determined. In this study, the rotational spectrum of the dimer as well as 13C and 18O isotopologue spectra that were seen in natural abundance were obtained using chirped pulse Fourier transform microwave spectroscopy (CP-FTMW). The structure was determined using both linear least squares fitting (r_0 structure) and the Kraitchman substitution analysis (r_s structure). Ab initio calculations were performed for the dimer using MP2/cc-pVTZ cp, B3LYP/6-31G(d,p), M06-2X/6-31G(d,p), and M06-2X/6-311++G(d,p), while CCSD calculations are currently under way. Changing the level of theory and the basis set dramatically changes the structure. The MP2 calculation underestimates the hinge angle (C-O-O-C dihedral angle), while the B3LYP overestimates it. The M06-2X calculations seem to give the best cost-to-benefit ratio when compared to the r_s structure, but they show poorer agreement with increasing basis set size. L. L. Connell, S. M. Ohline, P. W. Joireman, T. C. Corcoran, and P. M. Felker, J.Chem.Phys. 96, 2585 (1992) A. Weichert, C. Riehn, and B. Brutschy, J. Phys. Chem. A 105, 5679 (2001) M. Schmitt, M. Böhm, C. Ratzer, D. Krügler, K. Kleinermanns, I. Kalkman, G. Berden, and W. L. Meerts, Chem. Phys. Chem. 7, 1241 (2006) P. Jurecka, J. Sponer, J. Cerny, and P. Hobza, Phys. Chem. Chem. Phys. 8, 1985 (2006)

  8. Chirped-Pulse Ftmw Spectroscopy of the Lactic ACID-H_2O System

    Science.gov (United States)

    Kisiel, Zbigniew; Białkowska-Jaworska, Ewa; Zaleski, Daniel P.; Neill, Justin L.; Steber, Amanda L.; Pate, Brooks H.

    2011-06-01

    The previous study of the rotational spectrum of lactic acid in supersonic expansion revealed rather temperamental behaviour of signal intensity suggestive of considerable clusterization. Lactic acid samples contain an appreciable amount of water so that the presence of clusters with water, as well as lactic dimers is suspected. Several, mainly computational, studies of such species have already been published. Investigation of the chirped-pulse rotational spectrum of a heated lactic acid (LA) sample diluted in Ne carrier gas allowed unambiguous assignment of the LA-H_2O, LA-(H_2O)_2, and LA-(H_2O)_3 species. In addition, the rotational spectrum of the AaT conformer of lactic acid has been assigned. This conformer involves an intramolecular hydrogen bond to the hydroxyl of the carboxylic group and it has been estimated to be less stable by ca 10 kJ/mol than the most stable SsC conformer. The evidence for the assignment and a discussion of the derived properties for the new species are presented. L.Pszczółkowski, E.Białkowska-Jaworska, Z.Kisiel, J. Mol. Spectrosc. 234, 106 (2005). J.Sadlej, J.Cz.Dobrowolski, J.E.Rode, M.H.Jamróz, PCCP 8, 101 (2006) M.Losada, H.Tran, Y.Xu, J. Chem. Phys. 128, 014508 (2008) A.Smaga, J.Sadlej, J. Phys. Chem. A 114, 4427 (2010). A.Borba, A.Gomez-Zavaglia, L.Łapinski, R.Fausto, PCCP 6, 2101 (2004).

  9. Chirped femtosecond pulses in the higher-order nonlinear Schrödinger equation with non-Kerr nonlinear terms and cubic-quintic-septic nonlinearities

    Science.gov (United States)

    Triki, Houria; Biswas, Anjan; Milović, Daniela; Belić, Milivoj

    2016-05-01

    We consider a high-order nonlinear Schrödinger equation with competing cubic-quintic-septic nonlinearities, non-Kerr quintic nonlinearity, self-steepening, and self-frequency shift. The model describes the propagation of ultrashort (femtosecond) optical pulses in highly nonlinear optical fibers. A new ansatz is adopted to obtain nonlinear chirp associated with the propagating femtosecond soliton pulses. It is shown that the resultant elliptic equation of the problem is of high order, contains several new terms and is more general than the earlier reported results, thus providing a systematic way to find exact chirped soliton solutions of the septic model. Novel soliton solutions, including chirped bright, dark, kink and fractional-transform soliton solutions are obtained for special choices of parameters. Furthermore, we present the parameter domains in which these optical solitons exist. The nonlinear chirp associated with each of the solitonic solutions is also determined. It is shown that the chirping is proportional to the intensity of the wave and depends on higher-order nonlinearities. Of special interest is the soliton solution of the bright and dark type, determined for the general case when all coefficients in the equation have nonzero values. These results can be useful for possible chirped-soliton-based applications of highly nonlinear optical fiber systems.

  10. Efficient terahertz wave generation from GaP crystals pumped by chirp-controlled pulses from femtosecond photonic crystal fiber amplifier

    International Nuclear Information System (INIS)

    A chirp-tunable femtosecond 10 W, 42 MHz photonic-crystal-fiber oscillator-amplifier system that is capable of delivering sub-60 fs light pulses at 1040 nm is used to demonstrate high-efficiency terahertz radiation generation via optical rectification in GaP crystals only a few millimeters in length. The optimization of the chirp of the fiber-laser pulses is shown to radically enhance the terahertz output, indicating one possible way to more efficiently use these extended nonlinear crystals in compact fiber-pumped terahertz radiation sources

  11. Multichannel molecular high-order harmonic generation from HeH2+ with the combination of a chirped laser and a unipolar pulse

    Science.gov (United States)

    Zhang, Jun; Du, Hui; Liu, Hai-Feng; Guo, Jing; Liu, Xue-Shen

    2016-05-01

    The high-order harmonics from the asymmetric molecule HeH2+ with the combination of a chirped laser and a unipolar pulse is investigated by solving non-Born-Oppenheimer approximation time-dependent Schrödinger equation. We illustrate the multichannel molecular high-order harmonic generation by using a chirped laser pulse with carrier envelope phase (CEP) φ = 0 plus a unipolar pulse, and a chirped laser pulse with CEP φ = π minus a unipolar pulse, respectively. Due to the presence of a permanent dipole moment, the three-step model is generalized to a four-step model in molecular high-order harmonic generation (MHOHG). The results show that an ultrabroad supercontinuum spectrum with a spectral width of about 65 orders from 163 orders to 228 orders and a two-plateau structure can be observed. Furthermore, the time-frequency analysis shows that the short quantum trajectory is left and the long one is suppressed with the combination of a chirped laser and a unipolar pulse.

  12. Selective population transfer and creation of an arbitrary superposition between quantum states in a Λ-type four-level system by a single linearly chirped pulse

    Science.gov (United States)

    Zhang, Zhenhua; Tian, Jin; Du, Juan

    2016-05-01

    We present a simple and robust way to execute selective population transfer and creation of an arbitrary superposition between quantum states in a Λ-type four-level system with doublet ground states driven by a single linearly chirped pulse. It is demonstrated that the population in the initial state can be completely and flexibly transferred to either of the target states by manipulating the chirp rate and detuning of the laser pulse. Besides, the formation of an arbitrary superposition between the initial state and either of the target states through properly changing the chirp rate and detuning is also exhibited. The results of this method can be useful for selective quantum coherent control in systems with multiple target states.

  13. Design of a petawatt optical parametric chirped pulse amplification upgrade of the kilojoule iodine laser PALS

    Czech Academy of Sciences Publication Activity Database

    Novák, Ondřej; Divoký, Martin; Turčičová, Hana; Straka, Petr

    2013-01-01

    Roč. 31, č. 2 (2013), s. 211-218. ISSN 0263-0346 R&D Projects: GA ČR GA202/06/0814; GA MŠk(CZ) LC528; GA MŠk LN00A100 Grant ostatní: 6.FW, LASERLAB-EUROPE(XE) RII3-CT-2003-506350 Institutional support: RVO:68378271 Keywords : VULCAN petawatt * system * prospects * facility * program Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.701, year: 2013 http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8950936

  14. The Marriage of Spectroscopy and Dynamics: Chirped-Pulse Fourier-Transform Mm-Wave Cp-Ft Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Abeysekera, Chamara; Oldham, James M.; Suits, Arthur G.; Park, G. Barratt; Field, Robert W.

    2012-06-01

    A new experimental scheme is presented that combines two powerful emerging technologies: chirped-pulse Fourier-transform mm-Wave spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates, and perform unique spectroscopic, kinetics, and dynamics measurements. Chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy, pioneered by Pate and coworkers, allows rapid acquisition of broadband microwave spectrum through advancements in waveform generation and oscilloscope technology. This revolutionary approach has successfully been adapted to higher frequencies by the Field group at MIT. Our new apparatus will exploit amplified chirped pulses in the range of 26-40 GHz, in combination with a pulsed uniform supersonic flow from a Laval nozzle. This nozzle source, pioneered by Rowe, Sims, and Smith for low temperature kinetics studies, produces thermalized reactants at high densities and low temperatures perfectly suitable for reaction dynamics experiments studied using the CP-mmW approach. This combination of techniques shall enhance the thousand-fold improvement in data acquisition rate achieved in the CP method by a further 2-3 orders of magnitude. A pulsed flow alleviates the challenges of continuous uniform flow, e.g. large gas loads and reactant consumption rates. In contrast to other pulsed Laval systems currently in use, we will use a fast piezo valve and small chambers to achieve the desired pressures while minimizing the gas load, so that a 10 Hz repetition rate can be achieved with one turbomolecular pump. The proposed technique will be suitable for many diverse fields, including fundamental studies in spectroscopy and reaction dynamics, reaction kinetics, combustion, atmospheric chemistry, and astrochemistry. We expect a significant advancement in the ability to

  15. Chirped four-wave mixing

    NARCIS (Netherlands)

    DUPPEN, K; DEHAAN, F; NIBBERING, ETJ; WIERSMA, DA

    1993-01-01

    We will demonstrate that four-wave mixing with linearly chirped (phase-modulated) pulses is a unique tool for obtaining information on the dynamics and level structure of,a system. Especially, it will be shown that the transient-grating-scattering type of experiment with chirped pulses provides an i

  16. 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...

  17. Coherent ladar imaging of the SEASAT satellite retro-reflector array using linear-FM chirp waveforms and pulse-compression

    Science.gov (United States)

    Youmans, Douglas G.

    2007-04-01

    Coherent ladar imaging of satellite retro-reflector arrays is analyzed to determine some of the potential capabilities of coherent ladar systems for long range imaging. The satellites are at mega-meters of slant range and are basically angularly unresolved assuming a nominal one meter telescope used at a laser wavelength of 1.064 μm corresponding to a 281,625 GHz center-frequency. A coherent ladar may have a selectable waveform ranging from single nanosecond pulses through tone-pulses, but the imaging waveform considered here is the linear-FM chirp pulse-compression ladar waveform, which consists of a series of frequency chirps over a long period of time. The linear-FM chirp return is pulse compressed digitally using several possible approaches. Image reconstruction follows basic ISAR algorithms in forming a "range-resolved Doppler and intensity" (RRDI) image. A retro-reflector ring on the SEASAT satellite is used to illustrate the ladar's capability, although we spin the satellite faster than the true rotation rate to demonstrate waveform resolution. Several other useful algorithms as (multi-chirp) range-time-intensity (RTI matrix) range-bin summation and segmented-spectrum frequency-bin summation are also discussed. A covariance matrix calculation is applied to the RTI matrix and also to the segmented-spectrum matrix for the extraction of additional target information.

  18. Coherent population transfer and optical dipole force by chirped Gaussian femtosecond pulses in four level {sup 87}Rb

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Subhadeep, E-mail: aksarma@iitg.ernet.in; Sarma, Amarendra K., E-mail: aksarma@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati-781039, Assam (India)

    2014-10-15

    We report coherent population transfer(CPT) in a four level atomic system, coupled by three chirped Gaussian femtosecond pulses. CPT is studied under two specific conditions beyond the RWA. It is observed that nearly complete population transfer to the states |3> and |4> can be achieved by maintaining proper resonance condition and judiciously choosing the laser parameters. In addition to this, the transverse optical dipole force on the four-level atomic system is numerically studied. The transverse force provides an acceleration to an atom which is eight order of magnitude higher than earth’s gravitational acceleration g. The force changes from a focusing force to a defocusing one as the initial population changes from the ground states to the excited states.

  19. Broadband Chirped-Pulse Fourier Transform Microwave Spectroscopy and Molecular Structure of the ARGON-1-CHLORO-1-FLUOROETHYLENE Complex

    Science.gov (United States)

    Marshall, Mark D.; Leung, Helen O.

    2013-06-01

    Previous studies of argon complexes with fluoroethylenes have revealed a preference for a geometry that maximizes the contact of the argon atom with heavy atoms on the fluoroethylene. We have observed a continuation of this trend when one of the fluorine atoms is replaced by chlorine. As part of a systematic study of the effect of chlorine substitution on intermolecular interactions, we have examined the argon-1-chloro-1-fluoroethylene complex, and obtained the 5.6 - 18.1 GHz chirped-pulse Fourier transform microwave spectrum of this species. Transitions for both the ^{35}Cl and ^{37}Cl isotopologues are observed and analyzed to provide geometric parameters for this non-planar complex. The structure is found to be similar to those of analogous complexes and agrees well with ab initio predictions. Z. Kisiel, P.W. Fowler, and A.C. Legon, J. Chem. Phys. {95,} 2283 (1991).

  20. Broadband Chirped-Pulse Fourier Transform Microwave Spectroscopy and Molecular Structure of the ARGON-{ {(Z)}}-1-CHLORO-2-FLUOROETHYLENE Complex

    Science.gov (United States)

    Marshall, Mark D.; Leung, Helen O.

    2012-06-01

    A chirped-pulse Fourier transform microwave spectrometer is used to obtain the 6--18 GHz rotational spectrum of the gas-phase complex formed between argon and (Z)-1-chloro-2-fluoroethylene. Both the 35Cl and 37Cl isotopologues are observed in natural abundance, and analysis of these spectra provides predictions for both singly-substituted 13C species with sufficient precision to allow their observation with minimal searching using the more sensitive narrow band Balle-Flygare cavity technique. The non-planar structure of the complex is similar to previously observed argon-fluoroethylene complexes with the argon atom closer to the fluorine than to the chlorine. In contrast to the argon-vinyl chloride and argon-cis-1,2-difluoroethylene complexes, tunneling of the argon atom between the two equivalent, non-planar geometries is not observed.

  1. Multi-mJ, kHz, 2.1 μm optical parametric chirped-pulse amplifier and high-flux soft x-ray high-harmonic generation.

    Science.gov (United States)

    Hong, Kyung-Han; Lai, Chien-Jen; Siqueira, Jonathas P; Krogen, Peter; Moses, Jeffrey; Chang, Chun-Lin; Stein, Gregory J; Zapata, Luis E; Kärtner, Franz X

    2014-06-01

    We report on a multi-mJ 2.1 μm optical parametric chirped-pulse amplification (OPCPA) system operating at 1 kHz repetition rate, pumped by a picosecond cryogenic Yb:YAG laser, and the demonstration of soft x-ray high-harmonic generation (HHG) with a flux of ∼2×10(8)  photon/s/1% bandwidth at 160 eV in Ar. The 1 kHz cryogenic Yb:YAG pump laser amplifies pulses up to 56 mJ and delivers compressed 42 mJ, 17 ps pulses to the 2.1 μm OPCPA system. In the three-stage OPCPA chain, we have obtained up to 2.6 mJ of output energies at 2.1 μm and pulses compressed to 40 fs with good beam quality. Finally, we show cut-off extension of HHG driven by this 2.1 μm source in Ar and N2 gas cells to 190 eV with high photon flux. Our 3D propagation simulation confirms the generation of soft x-ray attosecond pulses from the experiment with Ar. PMID:24875998

  2. Chirped Dissipative Solitons

    CERN Document Server

    Kalashnikov, Vladimir L

    2010-01-01

    The analytical theory of chirped dissipative soliton solutions of nonlinear complex Ginzburg-Landau equation is exposed. Obtained approximate solutions are easily traceable within an extremely broad range of the equation parameters and allow a clear physical interpretation as a representation of the strongly chirped pulses in mode-locked both solid-state and fiber oscillators. Scaling properties of such pulses demonstrate a feasibility of sub-mJ pulse generation in the continuous-wave mode-locking regime directly from an oscillator operating at the MHz repetition rate.

  3. High-average-power 2 μm few-cycle optical parametric chirped pulse amplifier at 100 kHz repetition rate.

    Science.gov (United States)

    Shamir, Yariv; Rothhardt, Jan; Hädrich, Steffen; Demmler, Stefan; Tschernajew, Maxim; Limpert, Jens; Tünnermann, Andreas

    2015-12-01

    Sources of long wavelengths few-cycle high repetition rate pulses are becoming increasingly important for a plethora of applications, e.g., in high-field physics. Here, we report on the realization of a tunable optical parametric chirped pulse amplifier at 100 kHz repetition rate. At a central wavelength of 2 μm, the system delivered 33 fs pulses and a 6 W average power corresponding to 60 μJ pulse energy with gigawatt-level peak powers. Idler absorption and its crystal heating is experimentally investigated for a BBO. Strategies for further power scaling to several tens of watts of average power are discussed. PMID:26625047

  4. Theory of Pulse Train Amplification Without Patterning Effects in Quantum Dot Semiconductor Optical Amplifiers

    DEFF Research Database (Denmark)

    Uskov, Alexander V.; Berg, Tommy Winther; Mørk, Jesper

    2004-01-01

    A theory for pulse amplification and saturation in quantum dot (QD) semiconductor optical amplifiers (SOAs) is developed. In particular, the maximum bit rate at which a data stream of pulses can be amplified without significant patterning effects is investigated. Simple expressions are derived that...

  5. 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. PMID:24787591

  6. High power pulse amplification of ytterbium-doped double-clad fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    Liping Chang; Wei Fan; Jialin Chen; Li Wang; Bai Chen; Zunqi Lin

    2007-01-01

    By solving a set of time-dependent equations, the characteristics of the ytterbium-doped double-clad fiber amplifier are presented. Besides the steady state in the fiber of the upper-state population, pump power and amplified spontaneous emission without the input signal, the dynamic characteristics of the high power Gaussian pulse amplification like the evolution of pulse waveform distortion, upper-state population distribution and stored energy and pulse energy of the amplifier under the forward and backward pump,are simulated. The relations between the output pulse energy of the amplifier and the different input pulse peak power or pump power are also discussed. The models and results can provide important guide for the design and optimization of the high power pulse amplification.

  7. High energy micro electron beam generation using chirped laser pulse in the presence of an axial magnetic field

    International Nuclear Information System (INIS)

    In this paper, the generation of high-quality and high-energy micro electron beam in vacuum by a chirped Gaussian laser pulse in the presence of an axial magnetic field is numerically investigated. The features of energy and angular spectra, emittances, and position distribution of electron beam are compared in two cases, i.e., in the presence and absence of an external magnetic field. The electron beam is accelerated with higher energy and qualified in spatial distribution in the presence of the magnetic field. The presence of an axial magnetic field improves electron beam spatial quality as well as its gained energy through keeping the electron motion parallel to the direction of propagation for longer distances. It has been found that a 64 μm electron bunch with about MeV initial energy becomes a 20 μm electron beam with high energy of the order of GeV, after interacting with a laser pulse in the presence of an external magnetic field

  8. High energy micro electron beam generation using chirped laser pulse in the presence of an axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Akou, H., E-mail: h.akou@nit.ac.ir; Hamedi, M. [Department of Physics, Faculty of Basic Science, Babol University of Technology, Babol 47148-71167 (Iran, Islamic Republic of)

    2015-10-15

    In this paper, the generation of high-quality and high-energy micro electron beam in vacuum by a chirped Gaussian laser pulse in the presence of an axial magnetic field is numerically investigated. The features of energy and angular spectra, emittances, and position distribution of electron beam are compared in two cases, i.e., in the presence and absence of an external magnetic field. The electron beam is accelerated with higher energy and qualified in spatial distribution in the presence of the magnetic field. The presence of an axial magnetic field improves electron beam spatial quality as well as its gained energy through keeping the electron motion parallel to the direction of propagation for longer distances. It has been found that a 64 μm electron bunch with about MeV initial energy becomes a 20 μm electron beam with high energy of the order of GeV, after interacting with a laser pulse in the presence of an external magnetic field.

  9. Ultra-broad bandwidth parametric amplification at degeneracy.

    Science.gov (United States)

    Limpert, J; Aguergaray, C; Montant, S; Manek-Hönninger, I; Petit, S; Descamps, D; Cormier, E; Salin, F

    2005-09-19

    We report on a novel approach of ultra-broad bandwidth parametric amplification around degeneracy. A bandwidth of up to 400 nm centered around 800 nm is amplified in a BBO crystal by using chirped pump pulses with a bandwitdth as broad as 10 nm. A supercontinuum signal is generated in a microstructured fiber, having to first order a quadratic chirp, which is necessary to ensure temporal overlap of the interacting waves over this broad bandwidth. Furthermore, we discuss the potential of this approach for an octave-spanning parametric amplification. PMID:19498762

  10. Tailoring the amplification of attosecond pulse through detuned X-ray FEL undulator.

    Science.gov (United States)

    Kumar, Sandeep; Kang, Heung-Sik; Kim, Dong Eon

    2015-02-01

    We demonstrate that the amplification of attosecond pulse in X-ray free electron laser (FEL) undulator can be tailored. The characteristic of the amplification of an isolated attosecond pulse in the FEL undulator is investigated. An isolated 180 attoseconds full width half maximum (FWHM) pulse at 1.25 nm with a spectral bandwidth of 1% is injected into an undulator. The simulation results show that for a direct seeding of 3MW, the seed is amplified to the peak power of 106 GW (40 μJ, an output pulse-width of 383 attoseconds) in the presence of a detuning at FEL resonance condition in 100-m long undulator. We note that the introduction of detuning leads to the better performance compared to the case without detuning: shorter by 15.5% in a pulse-width and higher by 76.6% in an output power. Tapering yields a higher power (116% increases in the output power compared to the case without detuning) but a longer pulse (15.4% longer in the pulse-width). It was observed that ± Δλ(r)/8 (Δλ(r)/λ(r) ~1%) is the maximum degree of detuning, beyond which the amplification becomes poor: lower in the output power and longer in the pulse duration. The minimum power for a seed pulse needs to be higher than 1 MW for the successful amplification of an attosecond pulse at 1.25 nm. Also, the electron beam energy-spread must be less than 0.1% for a suitable propagation of attosecond pulse along the FEL undulator under this study. PMID:25836141

  11. Features of Raman amplification in KGW and barium nitrate crystals at excitation by femtosecond pulses

    International Nuclear Information System (INIS)

    Measurements of Raman amplification in KGd(WO4)2 (KGW) and barium nitrate crystals at femtosecond excitation demonstrate spectral transformation of amplification band with change of pump parameters. The half-height amplification bandwidth of up to 45 nm (650 cm-1) what is 5 times larger than the pumping pulse spectral band 8.5 nm (130 cm-1) was observed for KGW crystal. Implementation of impulsive excitation for the low-frequency vibrations allows estimations of the dephasing times and linewidths for the 87 and 83 cm-1 Raman lines in KGW and barium nitrate

  12. Amplification of critical velocity ionization by a pulsed neutral beam

    International Nuclear Information System (INIS)

    Numerical results of computer simulations on critical ionization velocity (CIV) discharges in pulsed neutral beams are presented. In a typical CIV scenario, neutral molecules as well as newly created ions are traveling across the ambient magnetic field. The ions slow down as they transfer kinetic energy to the electrons via plasma waves. For a single pulse of neutral gas, there is a finite contact time between the beam and the plasma; the contact time is governed by the length of the pulse and the velocity of neutrals. The injection of multiple pulsed neutral beam into a magnetized plasma has the advantage that succeeding pulses may extend the effective contact time of a single pulse. Using the particle-in-cell method of computer simulations, the authors show a detailed time history of the CIV process as a result of the interplay between plasma (wave-particle) interactions and collisional (ionization, charge exchange) processes. It is found that ions slowing down and lagging behind the pulses can still contribute to electron heating. Simulation results show that CIV in a multiple pulsed beam is more efficient than that in a single continuous pulse

  13. Impacts of seed power on amplification performance in pulsed double-clad fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    Fangpei Zhang; Jianqiang Zhu; Zhijiang Wang; Qihong Lou; Jun Zhou; Hongming Zhao; Songtao Du; Jingxing Dong; Yunrong Wei; Bing He; Jinyan Li

    2008-01-01

    A pulsed master-oscillator fiber power amplifier system with near diffraction-limited output by use of China-made large-mode-area fiber and a (2 + 1) × 1 multimode combiner is reported. The effect of the seed power on the amplification performance is found. For the seed power, there exists a range within which the pulsed fiber amplifier can operate safely and reliably at a certain pump power. With the seed average power of 70 mW, the amplification performances of the fiber amplifier are investigated.

  14. Coherent pulse stacking amplification using low-finesse Gires-Tournois interferometers.

    Science.gov (United States)

    Zhou, Tong; Ruppe, John; Zhu, Cheng; Hu, I-Ning; Nees, John; Galvanauskas, Almantas

    2015-03-23

    We demonstrate a new technique of coherent pulse stacking (CPS) amplification to overcome limits on achievable pulse energies from optical amplifiers. CPS uses reflecting resonators without active cavity-dumpers to transform a sequence of phase- and amplitude-modulated optical pulses into a single output pulse. Experimental validation with a single reflecting resonator demonstrates a near-theoretical stacked peak-power enhancement factor of ~2.5 with 92% and 97.4% efficiency for amplified nanosecond and femtosecond pulses. We also show theoretically that large numbers of equal-amplitude pulses can be stacked using sequences of multiple reflecting resonators, thus providing a new path for generating very high-energy pulses from ultrashort pulse fiber amplifier systems. PMID:25837085

  15. Microwave spectral taxonomy: A semi-automated combination of chirped-pulse and cavity Fourier-transform microwave spectroscopy

    Science.gov (United States)

    Crabtree, Kyle N.; Martin-Drumel, Marie-Aline; Brown, Gordon G.; Gaster, Sydney A.; Hall, Taylor M.; McCarthy, Michael C.

    2016-03-01

    Because of its structural specificity, rotational spectroscopy has great potential as an analytical tool for characterizing the chemical composition of complex gas mixtures. However, disentangling the individual molecular constituents of a rotational spectrum, especially if many of the lines are entirely new or unknown, remains challenging. In this paper, we describe an empirical approach that combines the complementary strengths of two techniques, broadband chirped-pulse Fourier transform microwave spectroscopy and narrowband cavity Fourier transform microwave spectroscopy, to characterize and assign lines. This procedure, called microwave spectral taxonomy, involves acquiring a broadband rotational spectrum of a rich mixture, categorizing individual lines based on their relative intensities under series of assays, and finally, linking rotational transitions of individual chemical compounds within each category using double resonance techniques. The power of this procedure is demonstrated for two test cases: a stable molecule with a rich spectrum, 3,4-difluorobenzaldehyde, and products formed in an electrical discharge through a dilute mixture of C2H2 and CS2, in which spectral taxonomy has enabled the identification of propynethial, HC(S)CCH.

  16. Quasitransient backward Raman amplification of powerful laser pulses in dense plasmas with multicharged ions

    Science.gov (United States)

    Malkin, V. M.; Fisch, N. J.

    2010-07-01

    The range of plasma parameters, where the efficient quasitransient backward Raman amplification (QBRA) of powerful laser pulses is possible, is determined for dense plasmas with multicharged ions. Approximate scalings that portray in a simple way the efficient QBRA range in multidimensional parameter space are found. The calculation, applicable to infrared, ultraviolet, soft x-ray, and x-ray laser pulses, takes into account plasma heating by the lasers. It is shown that efficient QBRA can survive even the nonsaturated linear Landau damping of the Langmuir wave mediating the energy transfer from the pump to the seed laser pulse; moreover, this survival does not require very intense seed laser pulses.

  17. Quasitransient backward Raman amplification of powerful laser pulses in dense plasmas with multicharged ions

    International Nuclear Information System (INIS)

    The range of plasma parameters, where the efficient quasitransient backward Raman amplification (QBRA) of powerful laser pulses is possible, is determined for dense plasmas with multicharged ions. Approximate scalings that portray in a simple way the efficient QBRA range in multidimensional parameter space are found. The calculation, applicable to infrared, ultraviolet, soft x-ray, and x-ray laser pulses, takes into account plasma heating by the lasers. It is shown that efficient QBRA can survive even the nonsaturated linear Landau damping of the Langmuir wave mediating the energy transfer from the pump to the seed laser pulse; moreover, this survival does not require very intense seed laser pulses.

  18. Direct amplification of ultrashort pulses in μ-pulling-down Yb:YAG single crystal fibers

    OpenAIRE

    Zaouter, Yoann; Martial, Igor; Aubry, Nicolas; Didierjean, Julien; Hönninger, Clemens; Mottay, Eric; Druon, Frédéric; Georges, Patrick

    2011-01-01

    We demonstrated that Yb:YAG single crystal fibers have a strong potential for the amplification of femtosecond pulses. Seeded by 230 fs pulses with an average power of 400 mW at 30 MHz delivered by a passively mode-locked Yb:KYW oscillator, the system produced 330 fs pulses with an average power of 12 W. This is the shortest pulse duration ever produced by an Yb:YAG amplifier. The gain in the single crystal fiber reached a value as high as 30 in a simple double-pass configuration.

  19. Direct amplification of ultrashort pulses in μ-pulling-down Yb:YAG single crystal fibers.

    Science.gov (United States)

    Zaouter, Yoann; Martial, Igor; Aubry, Nicolas; Didierjean, Julien; Hönninger, Clemens; Mottay, Eric; Druon, Frederic; Georges, Patrick; Balembois, François

    2011-03-01

    We demonstrated that Yb:YAG single crystal fibers have a strong potential for the amplification of femtosecond pulses. Seeded by 230 fs pulses with an average power of 400 mW at 30 MHz delivered by a passively mode-locked Yb:KYW oscillator, the system produced 330 fs pulses with an average power of 12 W. This is the shortest pulse duration ever produced by an Yb:YAG amplifier. The gain in the single crystal fiber reached a value as high as 30 in a simple double-pass configuration. PMID:21368970

  20. Open-path quantum cascade laser-based system for simultaneous remote sensing of methane, nitrous oxide, and water vapor using chirped-pulse differential optical absorption spectroscopy

    Science.gov (United States)

    Castillo, Paulo; Diaz, Adrian; Thomas, Benjamin; Gross, Barry; Moshary, Fred

    2015-10-01

    Methane and Nitrous Oxide are long-lived greenhouse gases in the atmosphere with significant global warming effects. We report on application of chirped-pulsed quantum cascade lasers (QCLs) to simultaneous measurements of these trace gases in both open-path fence-line and backscatter systems. The intra-pulse thermal frequency chip in a QCL can be time resolved and calibrated to allow for high resolution differential optical absorption spectroscopy over the spectral window of the chip, which for a DFB-QCL can be reach ~2cm-1 for a 500 nsec pulse. The spectral line-shape of the output from these lasers are highly stable from pulse to pulse over long period of time (> 1 day), and the system does not require frequent calibrations.

  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. Highly skin-conformal microhairy sensor for pulse signal amplification.

    Science.gov (United States)

    Pang, Changhyun; Koo, Ja Hoon; Nguyen, Amanda; Caves, Jeffrey M; Kim, Myung-Gil; Chortos, Alex; Kim, Kwanpyo; Wang, Paul J; Tok, Jeffrey B-H; Bao, Zhenan

    2015-01-27

    A bioinspired microhairy sensor is developed to enable ultraconformability on nonflat surfaces and significant enhancement in the signal-to-noise ratio of the retrieved signals. The device shows ≈12 times increase in the signal-to-noise ratio in the generated capacitive signals, allowing the ultraconformal microhair pressure sensors to be capable of measuring weak pulsations of internal jugular venous pulses stemming from a human neck. PMID:25358966

  3. Amplification of ultrashort electromagnetic pulses propagating along quasi-continuous electron beams

    Science.gov (United States)

    Baryshev, V. R.; Ginzburg, N. S.; Zotova, I. V.; Sergeev, A. S.; Rozental, R. M.; Yalandin, M. I.

    2009-01-01

    Specific features of amplification of short electromagnetic pulses propagating along steady-state nonequilibrium electron flows with a group velocity differing from the translational velocity of particles are analyzed. It is shown that an amplitude level substantially higher than the saturation level in amplification of quasi-continuous signals can be attained by permanent injection of electrons without initial modulation to one of the pulse fronts. The effective duration of the pulse being amplified is reduced simultaneously. The Cherenkov and undulator interaction mechanisms are considered. Analysis is carried out using a simple 1D model based on the averaged description of the electron-wave interaction, as well as direct numerical simulation based on the KARAT code taking into account the parameters of planned experiments on observation of this effect.

  4. Broadband Chirped-Pulse Fourier-Transform Microwave Spectroscopic Investigation of the Structures of Three Diethylsilane Conformers

    Science.gov (United States)

    Steber, Amanda L.; Obenchain, Daniel A.; Peebles, Rebecca A.; Peebles, Sean A.; Neill, Justin L.; Muckle, Matt T.; Pate, Brooks H.; Guirgis, Gamil A.

    2009-06-01

    The rotational spectrum of diethylsilane has been assigned using broadband chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy. Previously, Fourier-transform microwave rotational spectra were observed using a Balle-Flygare type instrument for the ^{28}Si isotopologues of the gauche-gauche, trans-gauche, and trans-trans conformers. In the present study, a broadband microwave spectrum was obtained at the University of Virginia, taking advantage of the ability to perform deep signal averaging to increase the measurement sensitivity. To obtain a full structural determination of the conformers of this molecule, spectra for the ^{29}Si, ^{30}Si, and single ^{13}C substitutions for the gauche-gauche, the trans-gauche, and the trans-trans species were assigned. Substitution (r_s) structures and inertial fit (r_0) structures were determined and a comparison between the experimental and ab initio structures will be presented. For the ^{28}Si isotopologues, the percent differences between the experimental and ab initio rotational constants are less than 1.5% for the trans-trans and trans-gauche and are between 2.0 and 5.0% for the gauche-gauche conformer. The structural parameters will be compared between this molecule, diethylgermane and other silicon containing molecules and the relative abundances of the three conformers will be discussed. S.A. Peebles, M.M. Serafin, R.A. Peebles, G.A. Guirgis, and H.D. Stidham J. Phys. Chem. A, (2009), DOI: 10.1021/jp811049n.

  5. Efficient noncollinear parametric amplification of weak femtosecond pulses in the visible and near-infrared spectral range.

    Science.gov (United States)

    Krylov, V; Ollikainen, O; Gallus, J; Wild, U; Rebane, A; Kalintsev, A

    1998-01-15

    We report measurement of efficient amplification of weak femtosecond supercontinuum seed pulses by use of a noncollinear optical parametric process in BBO crystal pumped with 150-fs pulses from a frequency-doubled regenerative-amplified Ti:sapphire laser at 390nm . The highest amplification factor, 10(8) , was achieved for 3x10(-16)J energy seed pulses at wavelength of 560nm. PMID:18084425

  6. Inverse bremsstrahlung stabilization of noise in the generation of ultrashort intense pulses by backward Raman amplification

    International Nuclear Information System (INIS)

    Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the subcritical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation

  7. Photoacoustic imaging using lock-in amplification and pulsed fiber lasers

    Science.gov (United States)

    Shi, Wei; Hajireza, Parsin; Zemp, Roger

    2016-03-01

    Photoacoustic (PA) imaging is a non-invasive, non-ionizing imaging technology with high optical contrast between blood and tissue, and with high sensitivity of hemoglobin concentration and oxygen saturation due to different optical absorption spectra resulting from different oxygenation of hemoglobin. Most PA imaging systems implement a nanosecond pulsed laser source as excitation source to induce PA signal, and rely on broadband amplifiers to record time-domain PA signals [1-6]. Some groups, however, have reported using modulated continuous-wave lasers as an excitation source for frequency-domain imaging [7-9]. Frequency-domain imaging offers the potential of lock-in amplification which has sensitivities as low as nV even in noise orders of magnitude higher than the signal. However, although modulated CW sources works for low cost and compact PA imaging, it does not satisfy thermal and stress confinement conditions required for optimal PA signal strength. Here, we investigate a PA methodology using pulsed fiber lasers as excitation laser source combined with lock-in amplification technology. For comparison, we also studied time-domain PA methodology. Phantom studies show that signal-to-noise ratio (SNR) obtained with frequency domain PA imaging is significantly more sensitive than that obtained using time-domain PA imaging when the laser pulse repetition rate (PRR) matches the bandwidth of ultrasound transducer. Therefore, high sensitive PA imaging technology using pulsed fiber laser sources with lock-in amplification may potentially greatly extend the depth of PA imaging.

  8. Ultraintense and Ultrashort Laser Pulses from Raman Amplification in Plasma for Laser-Plasma Accelerators

    CERN Document Server

    Sup-Hur, Min; Kim, Guang-Hoon; Lindberg, Ryan R; Suk, Hyyong; Wurtele, Jonathan

    2005-01-01

    We present analysis and simulations of kinetic effects in the Raman pulse amplification in plasma. An ultraintense and ultrashort laser pulse is a very essential part in an advanced acceleration scheme using laser and plasma. To make strong pulses, a noble scheme of using Raman backscatter in plasma was proposed and has been studied intensively.* The Raman amplification in plasma does not have a restriction in material damage threshold. However, for the new amplifier to be a promising alternative of the CPA technique, more extensive studies on various issues are required. One of the fundamental issues is the electron kinetic effect such as particle trapping or wavebreaking. We present a theoretical analysis of the kinetic effect; a new kinetic term is derived to be added to the fluid model and the effect of the new term is verified by averaged-PIC (aPIC)** simulations. Various one dimensional and semi-two dimensional aPIC simulations of pulse amplification are presented. We discuss the future application of t...

  9. Experimental and theoretical demonstration of amplifying pulse compression using an SOA- based Mach-Zehnder Interferometer

    DEFF Research Database (Denmark)

    Nielsen, Mads Lønstrup; Dagens, B.

    2004-01-01

    A pulse compression scheme based on a semiconductor optical amplifier -(SOA)based Mach-Zehnder interferometer (MZI) is proposed. It is independent of the initial chirp of the pulses, provides amplification, and can potentially be integrated with a simple pulse source. Experimental demonstration of...

  10. Self similar solution of superradiant amplification of ultrashort laser pulses in plasma

    International Nuclear Information System (INIS)

    Based on the self-similar method, superradiant amplification of ultrashort laser pulses by the counterpropagating pump in a plasma is investigated. Here, we present a governing system of partial differential equations for the signal pulse and the motion of the electrons. These equations are transformed to ordinary differential equations by the self-similar method and numerically solved. It is found that the increase of the signal intensity is proportional to the square of the propagation distance and the signal frequency has a red shift. Also, depending on the pulse width, the signal breaks up into a train of short pulses or its duration decreases with the inverse square root of the distance. Moreover, we identified two distinct categories of the electrons by the phase space analysis. In the beginning, one of them is trapped in the ponderomotive potential well and oscillates while the other is untrapped. Over time, electrons of the second kind also join to the trapped electrons. In the potential well, the electrons are bunched to form an electron density grating which reflects the pump pulse into the signal pulse. It is shown that the backscattered intensity is enhanced with the increase of the electron bunching parameter which leads to the enhanced efficiency of superradiant amplification

  11. Ultrafast pulse amplification in mode-locked vertical external-cavity surface-emitting lasers

    International Nuclear Information System (INIS)

    A fully microscopic many-body Maxwell–semiconductor Bloch model is used to investigate the influence of the non-equilibrium carrier dynamics on the short-pulse amplification in mode-locked semiconductor microlaser systems. The numerical solution of the coupled equations allows for a self-consistent investigation of the light–matter coupling dynamics, the carrier kinetics in the saturable absorber and the multiple-quantum-well gain medium, as well as the modification of the light field through the pulse-induced optical polarization. The influence of the pulse-induced non-equilibrium modifications of the carrier distributions in the gain medium and the saturable absorber on the single-pulse amplification in the laser cavity is identified. It is shown that for the same structure, quantum wells, and gain bandwidth the non-equilibrium carrier dynamics lead to two preferred operation regimes: one with pulses in the (sub-)100 fs-regime and one with multi-picosecond pulses. The recovery time of the saturable absorber determines in which regime the device operates

  12. Time of Arrival Based on Chirp Pulses as a means to Perform Localization in IEEE 802.15.4a Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    NAUWELAERS, B.

    2010-05-01

    Full Text Available This paper introduces the technology Time of Arrival (TOA based on chirp pulses (according to IEEE 802.15.4a as a means to perform localization in Wireless Sensor Networks (WSN's active at 2.4 GHz. Advantages and disadvantages of the technology are discussed and act as a guideline for improving localization accuracy. Tests concerning TOA are performed by means of the location engine of Nanotron. Adapting this engine leads to improved localization results. It is shown that TOA measurements are susceptible to reflections and dynamic environments.

  13. Ultrabroadband noncollinear optical parametric amplification with LBO crystal.

    Science.gov (United States)

    Zhao, Baozhen; Jiang, Yongliang; Sueda, Keiich; Miyanaga, Noriaki; Kobayashi, Takayoshi

    2008-11-10

    Ultrabroadband visible noncollinear optical parametric amplification (NOPA) was achieved in an LBO crystal, with a continuum seed pulse generated from a sapphire plate. The spectral bandwidth of the amplified visible pulse was about 200 nm, which can support sub-5 fs pulse amplification. An amplified output of 0.21 microJ with an average gain of about 210 was achieved. This provides, to the best of our knowledge, the first-time demonstration of such broadband amplification with a biaxial nonlinear optical crystal. Both the simulation and experimental results indicate that the LBO has a great potential as nonlinear medium in power amplifier for TW to PW noncollinear optical parametric chirped pulse amplification (NOPCPA) systems. PMID:19581976

  14. Nondegenerate parametric generation of 2.2-mJ, few-cycle 2.05-μm pulses using a mixed phase matching scheme

    International Nuclear Information System (INIS)

    We describe the production of 2.2-mJ, ∼6 optical-cycle-long mid-infrared laser pulses with a carrier wavelength of 2.05 μm in a two-stage β-BaB2O4 nondegenerate optical parametric amplifier design with a mixed phase matching scheme, which is pumped by a standard Ti:sapphire chirped-pulse amplification system. It is demonstrated that relatively high pulse energies, short pulse durations, high stability, and excellent beam profiles can be obtained using this simple approach, even without the use of optical parametric chirped-pulse amplification

  15. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    International Nuclear Information System (INIS)

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam

  16. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    Science.gov (United States)

    Ginzburg, N. S.; Zotova, I. V.; Sergeev, A. S.; Zaslavsky, V. Yu.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V.

    2015-11-01

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by "fresh" electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam.

  17. Flux amplification and sustainment of ST plasmas by multi-pulsed coaxial helicity injection on HIST

    Science.gov (United States)

    Higashi, T.; Ishihara, M.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2010-11-01

    The Helicity Injected Spherical Torus (HIST) device has been developed towards high-current start up and sustainment by Multi-pulsed Coaxial Helicity Injection (M-CHI) method. Multiple pulses operation of the coaxial plasma gun can build the magnetic field of STs and spheromak plasmas in a stepwise manner. So far, successive gun pulses on SSPX at LLNL were demonstrated to maintain the magnetic field of spheromak in a quasi-steady state against resistive decay [1]. The resistive 3D-MHD numerical simulation [2] for STs reproduced the current amplification by the M-CHI method and confirmed that stochastic magnetic field was reduced during the decay phase. By double pulsed operation on HIST, the plasma current was effectively amplified against the resistive decay. The life time increases up to 10 ms which is longer than that in the single CHI case (4 ms). The edge poloidal fields last between 0.5 ms and 6 ms like a repetitive manner. During the second driven phase, the toroidal ion flow is driven in the same direction as the plasma current as well as in the initial driven phase. At the meeting, we will discuss a current amplification mechanism based on the merging process with the plasmoid injected secondly from the gun. [1] B. Hudson et al., Phys. Plasmas Vol.15, 056112 (2008). [2] Y. Kagei et al., J. Plasma Fusion Res. Vol.79, 217 (2003).

  18. Raman amplification in plasma: thermal effects and damping

    Science.gov (United States)

    Farmer, J. P.; Ersfeld, B.; Raj, G.; Jaroszynski, D. A.

    2009-05-01

    The role of thermal effects on Raman amplification are investigated. The direct effects of damping on the process are found to be limited, leading only to a decrease from the peak output intensity predicted by cold plasma models. However, the shift in plasma resonance due to the Bohm-Gross shift can have a much larger influence, changing the required detuning between pump and probe and introducing an effective chirp through heating of the plasma by the pump pulse. This "thermal chirp" can both reduce the efficiency of the interaction and alter the evolution of the amplified probe, avoiding the increase in length observed in the linear regime without significant pump depletion. The influence of this chirp can be reduced by using a smaller ratio of laser frequency to plasma frequency, which simultaneously increases the growth rate of the probe and decreases the shift in plasma resonance. As such, thermal effects only serve to suppress the amplification of noise at low growth rates. The use of a chirped pump pulse can be used to suppress noise for higher growth rates, and has a smaller impact on the peak output intensity for seeded amplification. For the parameter ranges considered, Landau damping was found to be negligible, as Landau damping rates are typically small, and the low collisionality of the plasma causes the process to saturate quickly.

  19. Quasitransient regimes of backward Raman amplification of intense x-ray pulses

    Science.gov (United States)

    Malkin, V. M.; Fisch, N. J.

    2009-10-01

    New powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulses, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can automatically suppress deleterious instabilities of BRA to the thermal noise. The class of “quasitransient” BRA regimes identified here shows that it may be feasible to observe x-ray BRA within available x-ray facilities.

  20. Quasitransient regimes of backward Raman amplification of intense x-ray pulses

    International Nuclear Information System (INIS)

    New powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulses, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can automatically suppress deleterious instabilities of BRA to the thermal noise. The class of 'quasitransient' BRA regimes identified here shows that it may be feasible to observe x-ray BRA within available x-ray facilities.

  1. Simple Yb:YAG femtosecond booster amplifier using divided-pulse amplification.

    Science.gov (United States)

    Pouysegur, Julien; Weichelt, Birgit; Guichard, Florent; Zaouter, Yoann; Hönninger, Clemens; Mottay, Eric; Druon, Frédéric; Georges, Patrick

    2016-05-01

    A hybrid-system approach using a low-gain Yb:YAG single crystal booster amplifier behind a state-of-the-art industrial high-power femtosecond fiber system is studied to significantly increase the output pulse energy of the fiber amplifier. With this system, more than 60 W of average power is demonstrated at 100 kHz for pulse duration of 400 fs, corresponding to an energy per pulse of 600 µJ. Reducing the repetition rate, the energy is increased up to 2.5 mJ (before compression), which corresponds to the limitation due to laser damage threshold of the optical coatings. To scale further the energy, passive divided-pulse amplification is then implemented at the entrance of the bulk amplifier. Using this geometry, a safe nominal operating point is presented with output pulse energies of 3 mJ before and 2.3 mJ after compression and with a pulse duration of 520 fs, corresponding to a peak power of 4.4 GW. PMID:27137601

  2. Application of Yb:YAG short pulse laser system

    Energy Technology Data Exchange (ETDEWEB)

    Erbert, Gaylen V.; Biswal, Subrat; Bartolick, Joseph M.; Stuart, Brent C.; Crane, John K.; Telford, Steve; Perry, Michael D.

    2004-07-06

    A diode pumped, high power (at least 20W), short pulse (up to 2 ps), chirped pulse amplified laser using Yb:YAG as the gain material is employed for material processing. Yb:YAG is used as the gain medium for both a regenerative amplifier and a high power 4-pass amplifier. A single common reflective grating optical device is used to both stretch pulses for amplification purposes and to recompress amplified pulses before being directed to a workpiece.

  3. Pulse Compression by Filamentation in Argon with an Acoustic Optical Programmable Dispersive Filter for Predispersion Compensation

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-Wei; JIANG Yong-Liang; LENG Yu-Xin; LIU Jun; GE Xiao-Chun; LI Ru-Xin; XU Zhi-Zhan

    2006-01-01

    @@ We have experimentally demonstrated pulses 0.4 mJ in duration smaller than 12 fs with an excellent spatial beam profile by self-guided propagation in argon. The original 52fs pulses from the chirped pulsed amplification laser system are first precompressed to 32 fs by inserting an acoustic optical programmable dispersive filter instrument into the laser system for spectrum reshaping and dispersion compensation, and the pulse spectrum is subsequently broadened by filamentation in an argon cell. By using chirped mirrors for post-dispersion compensation, the pulses are successfully compressed to smaller than 12fs.

  4. Compact dual-crystal optical parametric amplification for broadband IR pulse generation using a collinear geometry.

    Science.gov (United States)

    Hong, Zuofei; Zhang, Qingbin; Lu, Peixiang

    2013-04-22

    A novel compact dual-crystal optical parametric amplification (DOPA) scheme, collinearly pumped by a Ti:sapphire laser (0.8 μm), is theoretically investigated for efficiently generating broadband IR pulses at non-degenerate wavelengths (1.2 μm~1.4 μm and 1.8 μm~2.1 μm). By inserting a pair of barium fluoride (BaF(2)) wedges between two thin β-barium borate (BBO) crystals, the group velocity mismatch (GVM) between the three interacting pulses can be compensated simultaneously. In this case, the obtained signal spectrum centered at 1.3 μm is nearly 20% broader and the conversion efficiency is increased, but also the pulse contrast and beam quality are improved due to the better temporal overlap. Furthermore, sub-two-cycle idler pulses with carrier-envelope phase (CEP) fluctuation of sub-100-mrad root mean square (RMS) can be generated. Because a tunable few-cycle IR pulse with millijoule energy is attainable in this scheme, it will contribute to ultrafast community and be particularly useful as a driving or controlling field for the generation of ultrafast coherent x-ray supercontinuum. PMID:23609660

  5. 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.

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

    International Nuclear Information System (INIS)

    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 a0 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

  7. Arterial pulse pressure amplification described by means of a nonlinear wave model: characterization of human aging

    Science.gov (United States)

    Alfonso, M.; Cymberknop, L.; Armentano, R.; Pessana, F.; Wray, S.; Legnani, W.

    2016-04-01

    The representation of blood pressure pulse as a combination of solitons captures many of the phenomena observed during its propagation along the systemic circulation. The aim of this work is to analyze the applicability of a compartmental model for propagation regarding the pressure pulse amplification associated with arterial aging. The model was applied to blood pressure waveforms that were synthesized using solitons, and then validated by waveforms obtained from individuals from differentiated age groups. Morphological changes were verified in the blood pressure waveform as a consequence of the aging process (i.e. due to the increase in arterial stiffness). These changes are the result of both a nonlinear interaction and the phenomena present in the propagation of nonlinear mechanic waves.

  8. Bandwidth of Gaussian weighted Chirp

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.

    1993-01-01

    Four major time duration and bandwidth expressions are calculated for a linearly frequency modulated sinusoid with Gaussian shaped envelope. This includes a Gaussian tone pulse. The bandwidth is found to be a nonlinear function of nominal time duration and nominal frequency excursion of the chirp...

  9. Laser pulse amplification and dispersion compensation in an effectively extended optical cavity containing Bose-Einstein condensates

    OpenAIRE

    Sennaroğlu, Alphan; Müstecaplıoğlu, Özgür Esat; Tarhan, D.

    2013-01-01

    Laser pulse amplification and dispersion compensation in effectively extended optical cavity containing Bose-Einstein condensates D Tarhan1, A Sennaroglu2, ¨O E M¨ustecaplıo˘glu2 1Harran University, Department of Physics, 63300, S¸anlıurfa, Turkey 2Ko¸c University, Department of Physics, 34450, Sarıyer, Istanbul, Turkey E-mail: Abstract. We review and critically evaluate our proposal of a pulse amplification scheme based on two Bose-Einstein cond...

  10. Optical Parametric Amplification for High Peak and Average Power

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I

    2001-11-26

    Optical parametric amplification is an established broadband amplification technology based on a second-order nonlinear process of difference-frequency generation (DFG). When used in chirped pulse amplification (CPA), the technology has been termed optical parametric chirped pulse amplification (OPCPA). OPCPA holds a potential for producing unprecedented levels of peak and average power in optical pulses through its scalable ultrashort pulse amplification capability and the absence of quantum defect, respectively. The theory of three-wave parametric interactions is presented, followed by a description of the numerical model developed for nanosecond pulses. Spectral, temperature and angular characteristics of OPCPA are calculated, with an estimate of pulse contrast. An OPCPA system centered at 1054 nm, based on a commercial tabletop Q-switched pump laser, was developed as the front end for a large Nd-glass petawatt-class short-pulse laser. The system does not utilize electro-optic modulators or multi-pass amplification. The obtained overall 6% efficiency is the highest to date in OPCPA that uses a tabletop commercial pump laser. The first compression of pulses amplified in highly nondegenerate OPCPA is reported, with the obtained pulse width of 60 fs. This represents the shortest pulse to date produced in OPCPA. Optical parametric amplification in {beta}-barium borate was combined with laser amplification in Ti:sapphire to produce the first hybrid CPA system, with an overall conversion efficiency of 15%. Hybrid CPA combines the benefits of high gain in OPCPA with high conversion efficiency in Ti:sapphire to allow significant simplification of future tabletop multi-terawatt sources. Preliminary modeling of average power limits in OPCPA and pump laser design are presented, and an approach based on cascaded DFG is proposed to increase the average power beyond the single-crystal limit. Angular and beam quality effects in optical parametric amplification are modeled

  11. Generation of multi-hundred petawatt pulses by resonant Raman amplification in plasma

    Science.gov (United States)

    Wu, Zhaohui; Zuo, Yanlei; Su, Jingqin; Liu, Lanqin; Zhang, Zhimeng; Li, Zhilin; Jiao, Zhihong; Wei, Xiaofeng

    2015-03-01

    Backward Raman amplification (BRA) in plasma has been proposed to produce overcritical high-power laser pulses. In this paper, an application based on CPA and BRA is promoted to generate multi-hundred petawatt laser pulses. The compression of short-wavelength (around 351 nm) and picosecond pulses has been proposed for high output intensity and short plasma length. This principle was employed in an application and a scheme is demonstrated using a full-kinetic particle-in-cell (PIC) code. The PIC code is also used to optimize key parameters in the resonant interaction. According to the simulated result using optimized parameters, the output seed fluence is amplified to 6.5 kJ/cm2 and the full-width at half-maximum duration is compressed to 13 fs, showing an energy transfer over 60%. Extending the result to the multidimensional case, a total energy of 3.9 kJ and a laser power of 300 PW are achievable, in a 0.6 cm2 interaction spot. This result is helpful for the improvement of high-energy density physics.

  12. Numerical modeling of quasitransient backward Raman amplification of laser pulses in moderately undercritical plasmas with multicharged ions

    International Nuclear Information System (INIS)

    It was proposed recently that powerful optical laser pulses could be efficiently compressed through backward Raman amplification in ionized low density solids, in spite of strong damping of the resonant Langmuir wave. It was argued that, even for nonsaturated Landau damping of the Langmuir wave, the energy transfer from the pump laser pulse to the amplified seed laser pulse can nevertheless be highly efficient. This work numerically examines such regimes of strong damping, called quasitransient regimes, within the simplest model that takes into account the major effects. The simulations indicate that compression of powerful optical laser pulses in ionized low density solids indeed can be highly efficient.

  13. Numerical modeling of quasitransient backward Raman amplification of laser pulses in moderately undercritical plasmas with multicharged ions

    Science.gov (United States)

    Balakin, A. A.; Fisch, N. J.; Fraiman, G. M.; Malkin, V. M.; Toroker, Z.

    2011-10-01

    It was proposed recently that powerful optical laser pulses could be efficiently compressed through backward Raman amplification in ionized low density solids, in spite of strong damping of the resonant Langmuir wave. It was argued that, even for nonsaturated Landau damping of the Langmuir wave, the energy transfer from the pump laser pulse to the amplified seed laser pulse can nevertheless be highly efficient. This work numerically examines such regimes of strong damping, called quasitransient regimes, within the simplest model that takes into account the major effects. The simulations indicate that compression of powerful optical laser pulses in ionized low density solids indeed can be highly efficient.

  14. Effect of the frequency chirp on laser wakefield acceleration

    CERN Document Server

    Pathak, V B; Fonseca, R A; Silva, L O

    2011-01-01

    The role of laser frequency chirps in the laser wakefield accelerator is examined. We show that in the linear regime, the evolution of the laser pulse length is affected by the frequency chirp, and that positive (negative) chirp compresses (stretches) the laser pulse, thereby increasing (decreasing) the peak vector potential and wakefield amplitude. In the blowout regime, the frequency chirp can be used to fine tune the localized etching rates at the front of the laser. In our simulations, chirped laser pulses can lead to 15% higher self-trapped electrons, and 10% higher peak energies as compare to the transform-limited pulse. Chirps may be used to control the phase velocity of the wake, and to relax the self-guiding conditions at the front of the laser. Our predictions are confirmed by multi-dimensional particle-in-cell simulations with OSIRIS.

  15. Grism compressor for carrier-envelope phase-stable millijoule-energy chirped pulse amplifier lasers featuring bulk material stretcher.

    Science.gov (United States)

    Ricci, A; Jullien, A; Forget, N; Crozatier, V; Tournois, P; Lopez-Martens, R

    2012-04-01

    We demonstrate compression of amplified carrier-envelope phase (CEP)-stable laser pulses using paired transmission gratings and high-index prisms, or grisms, with chromatic dispersion matching that of a bulk material pulse stretcher. Grisms enable the use of larger bulk stretching factors and thereby higher energy pulses with lower B-integral in a compact amplifier design suitable for long-term CEP control. PMID:22466193

  16. Self starting additive pulse modelocking of a Nd:LMA laser

    OpenAIRE

    Phillips, M. W.; Chang, Z.; Barr, J.R.M.; Hughes, D. W.; Danson, C. N.; Edwards, C.B.; Hanna, D.C.

    1992-01-01

    A Ti:sapphire-pumped Nd:LMA laser has been passively mode locked by using additive-pulse mode locking, which generates 600-fs-duration pulses at 1.054-µm. The wavelength, pulse duration, and long-term stability of the laser make it eminently suitable as a front-end oscillator of a high-power, chirped-pulse amplifier experiment based on 1.053-µm amplification in Nd:phosphate glass.

  17. Induced chirp in laser wake-field generation

    International Nuclear Information System (INIS)

    Particle-in-cell simulation is used to illustrate induced chirp in the laser wake-field generation experiment. The evolution of the laser pulse characteristics and the wake-field amplitude is investigated numerically. The local frequency of the laser pulse is influenced during wake-field excitation. The numerical result shows that the negative Gaussian chirp profile is the mainly induced chirp throughout the laser pulse. Hence, the induced negative Gaussian chirp has a significant influence on wake-field generation and consequently on the acceleration gradient in the wake-field acceleration.

  18. A Novel Femtosecond Laser System for Attosecond Pulse Generation

    OpenAIRE

    Jianqiang Zhu; Xinglong Xie; Meizhi Sun; Qunyu Bi; Jun Kang

    2012-01-01

    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 K...

  19. Inverse Bremsstrahlung Stabilization of Noise in the Generation of Ultra-short Intense Pulses by Backward Raman Amplification

    International Nuclear Information System (INIS)

    Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the sub-critical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation

  20. Optimized Optical Rectification and Electro-optic Sampling in ZnTe Crystals with Chirped Femtosecond Laser Pulses

    DEFF Research Database (Denmark)

    Erschens, Dines Nøddegaard; Turchinovich, Dmitry; Jepsen, Peter Uhd

    2011-01-01

    We report on optimization of the intensity of THz signals generated and detected by optical rectification and electro-optic sampling in dispersive, nonlinear media. Addition of a negative prechirp to the femtosecond laser pulses used in the THz generation and detection processes in 1-mm thick Zn......Te crystals leads to an increase of the THz intensity of more than 30% at low laser intensity and up to 60% at higher laser intensity. Dispersion compensation in the ZnTe crystal, which becomes significant for laser pulses with durations much less than 100 fs, is responsible for the enhanced generation and...

  1. 12  mJ kW-class ultrafast fiber laser system using multidimensional coherent pulse addition.

    Science.gov (United States)

    Kienel, Marco; Müller, Michael; Klenke, Arno; Limpert, Jens; Tünnermann, Andreas

    2016-07-15

    An ultrafast fiber-chirped-pulse amplification system using a combination of spatial and temporal coherent pulse combination is presented. By distributing the amplification among eight amplifier channels and four pulse replicas, up to 12 mJ pulse energy with 700 W average power and 262 fs pulse duration have been obtained with a system efficiency of 78% and excellent beam quality. To the best of our knowledge, this is the highest energy achieved by an ultrafast fiber-based laser system to date. PMID:27420531

  2. Amplification of picosecond pulses to 100 W by an Yb:YAG thin-disk with CVBG compressor

    Science.gov (United States)

    Smrž, Martin; Chyla, Michal; Novák, Ondřej; Miura, Taisuke; Endo, Akira; Mocek, Tomáś

    2015-05-01

    High average power picosecond lasers have become an import tool in many fields of science and industry. We report on progress in development of 100 kHz, 100 W picosecond Yb:YAG thin disk laser amplifier with fundamental spatial mode at the HiLASE laser center. More efficient direct pumping to an upper laser level has been employed in order to suppress thermal loading of the thin disk active medium and to increase system stability. We also carefully analyzed and described all benefits of this so called zero phonon line pumping (ZPL) for fundamental spatial mode cavity design and successfully increased extraction efficiency of the amplifier to > 28 %. A novel approach of high-power picosecond pulse compression using a space saving and easy-to-align chirped-volume Bragg grating (CVBG) with high dispersion and high net efficiency approaching 88 % allowed us to build a robust and highly compact pulse compressor. A 100 kHz train of sub-1-milijoule pulses compressed bellow 2 ps (FWHM) in almost diffraction limited Gaussian beam has been successfully generated from this highly compact (900 x 1200 mm) thin-disk-based Yb:YAG regenerative amplifier.

  3. Saturated multikilovolt x-ray amplification with Xe clusters: single-pulse observation of Xe(L) spectral hole burning

    International Nuclear Information System (INIS)

    Single-pulse measurements of spectral hole burning of Xe(L) 3d → 2p hollow atom transition arrays observed from a self-trapped plasma channel provide new information on the dynamics of saturated amplification in the λ ∼ 2.8-2.9 A region. The spectral hole burning on transitions in the Xe34+ and Xe35+ arrays reaches full suppression of the spontaneous emission and presents a corresponding width Δ h-bar ωx ∼ = 60 eV, a value adequate for efficient amplification of multikilovolt x-ray pulses down to a limiting length τx ∼ 30 as. The depth of the suppression at 2.86 A indicates that the gain-to-loss ratio is ≥10. An independent determination of the x-ray pulse energy from damage produced on the surface of a Ti foil in the far field of the source gives a pulse energy of 20-30 μJ, a range that correlates well with the observation of the spectral hole burning and indicates an overall extraction efficiency of ∼10%. (letter to the editor)

  4. Chirped optical solitons in single-mode birefringent fibers

    Science.gov (United States)

    Mahmood, M. F.

    1996-12-01

    The trapping behavior of two chirped solitons forming a bound state in a single-mode birefringent fiber is investigated on the basis of a model of coupled nonlinear Schroedinger equations. The positive initial chirp plays an important role in controlling the threshold amplitude for soliton trapping without causing excessive pulse broadening.

  5. SAR processing with stepped chirps and phased array antennas.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2006-09-01

    Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

  6. The Application of Cryogenic Laser Physics to the Development of High Average Power Ultra-Short Pulse Lasers

    OpenAIRE

    Brown, David C.; Sten Tornegård; Joseph Kolis; Colin McMillen; Cheryl Moore; Liurukara Sanjeewa; Christopher Hancock

    2016-01-01

    Ultrafast laser physics continues to advance at a rapid pace, driven primarily by the development of more powerful and sophisticated diode-pumping sources, the development of new laser materials, and new laser and amplification approaches such as optical parametric chirped-pulse amplification. The rapid development of high average power cryogenic laser sources seems likely to play a crucial role in realizing the long-sought goal of powerful ultrafast sources that offer concomitant high peak a...

  7. Demonstration of Detuning and Wavebreaking Effects on Raman Amplification Effciency in Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yampolsky, N. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Fisch, N. J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Malkin, V. M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Valeo, E. J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Lindberg, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Wurtele, J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Ren, J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Li, S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Morozov, A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Suckewer, S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2008-11-01

    A plasma-based resonant backward Raman amplifier/compressor for high power amplification of short laser pulses might, under ideal conditions, convert as much as 90% of the pump energy to the seed pulse. While the theoretical highest possible efficiency of this scheme has not yet been achieved, larger efficiencies than ever before obtained experimentally (6.4%) are now being reported, and these efficiencies are accompanied by strong pulse compression. Based on these recent extensive experiments, it is now possible to deduce that the experimentally realized efficiency of the amplifier is likely constrained by two factors, namely the pump chirp and the plasma wavebreaking, and that these experimental observations may likely involve favorable compensation between the chirp of the laser and the density variation of the mediating plasma. Several methods for further improvement of the amplifier effciency in current experiments are suggested.

  8. Demonstration of Detuning and Wavebreaking Effects on Raman Amplification Efficiency in Plasma

    International Nuclear Information System (INIS)

    A plasma-based resonant backward Raman amplifier/compressor for high power amplification of short laser pulses might, under ideal conditions, convert as much as 90% of the pump energy to the seed pulse. While the theoretical highest possible efficiency of this scheme has not yet been achieved, larger efficiencies than ever before obtained experimentally (6.4%) are now being reported, and these efficiencies are accompanied by strong pulse compression. Based on these recent extensive experiments, it is now possible to deduce that the experimentally realized efficiency of the amplifier is likely constrained by two factors, namely the pump chirp and the plasma wavebreaking, and that these experimental observations may likely involve favorable compensation between the chirp of the laser and the density variation of the mediating plasma. Several methods for further improvement of the amplifier efficiency in current experiments are suggested

  9. 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.

  10. Influences of finite gain bandwidth on pulse propagation in parabolic fiber amplifiers with distributed gain profiles

    Institute of Scientific and Technical Information of China (English)

    Zhao Jia-Sheng; Li Pan; Chen Xiao-Dong; Feng Su-Juan; Mao Qing-He

    2012-01-01

    The evolutions of the pulses propagating in decreasing and increasing gain distributed fiber amplifiers with finite gain bandwidths are investigated by simulations with the nonlinear Schrodinger equation.The results show that the parabolic pulse propagations in both the decreasing and the increasing gain amplifiers are restricted by the finite gain bandwidth.For a given input pulse,by choosing a small initial gain coefficient and gain variation rate,the whole gain for the pulse amplification limited by the gain bandwidth may be higher,which is helpful for the enhancement of the output linearly chirped pulse energy.Compared to the decreasing gain distributed fiber amplifier,the increasing gain distributed amplifier may be more conducive to suppress the pulse spectral broadening and increase the critical amplifier length for achieving a larger output linearly chirped pulse energy.

  11. Induction cascade with electro-explosive commutation of current for amplification of electric pulse power

    CERN Document Server

    Grabovskij, E V; Kuznetsov, V V; Lototskij, A P; Khaustov, E V; Khalimullin, Y A; Kasyanov, N Y; Kormilitsyn, A I; Filatov, V A; Shkolnikov, E Y

    2002-01-01

    Paper describes a circuit of power amplification induction cascade based on a two-loop solenoid and electrically exploded conductors serving as current breakers. Due to retention of the general magnetic flow current breaking in the first loop of accumulator results in current amplification in the second loop and in accelerated actuation of the second electrically exploded conductor. Current switching to load occurs with 20-fold reduction of charging current front duration and increase of its amplitude. Time to charge coil is selected within 300-350 mu s limits

  12. Amplification of UV Ultra-short pulse in KrF Amplifier

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ultra-short pulse and laser matter interaction has been becoming the front field of modern physics forits fast progress in very recent years. Suitable way in amplifying short pulse is of great importance toachieve high energy and intensity on target. Electron pumped KrF laser have the advantages of largeaperture and high pump rate, and involve the possibility of amplifying a short pulse to large energy in

  13. Integrated pulse stretchers for high-energy CPA and OPCPA systems

    Science.gov (United States)

    Shah, Lawrence; Bodnar, Nathan; Roumayah, Patrick; Webb, Benjamin; Bradford, Joshua; Richardson, Martin

    2016-03-01

    Pulse stretchers are critical components in chirped pulse amplification (CPA) and optical parametric CPA (OPCPA) laser systems. In CPA systems, pulse stretching and compression is typical accomplished using bulk diffraction gratings; however integrated devices such volume or fiber Bragg gratings can provide similar optical performance with significantly smaller footprint and simplified alignment. In this work, we discuss the use of such integrated devices to stretch a 100 fs pulse to 400 ps with customized third order dispersion for use in a multi-TW Ti:Sapphire system as well as integrated optics to control the pulse duration in pump lasers for OPCPA systems.

  14. High harmonic attosecond pulse train amplification in a free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    McNeil, B.W.; Sheehy, B.; Thompson, N.R.; Dunning, D.J.

    2011-03-04

    It is shown using three-dimensional simulations that the temporal structure of an attosecond pulse train, such as that generated via high harmonic generation in noble gases, may be retained in a free electron laser amplifier through to saturation using a mode-locked optical klystron configuration. At wavelengths of {approx}12 nm, a train of attosecond pulses of widths {approx}300 as with peak powers in excess of 1 GW are predicted.

  15. High harmonic attosecond pulse train amplification in a free electron laser

    International Nuclear Information System (INIS)

    It is shown using three-dimensional simulations that the temporal structure of an attosecond pulse train, such as that generated via high harmonic generation in noble gases, may be retained in a free electron laser amplifier through to saturation using a mode-locked optical klystron configuration. At wavelengths of ∼12 nm, a train of attosecond pulses of widths ∼300 as with peak powers in excess of 1 GW are predicted.

  16. Modeling of an Ultra-Short X-Ray Laser Pulse Amplification Through an Optical-Field-Ionized Gas Using a Maxwell-Bloch Treatment

    Science.gov (United States)

    Robillart, B.; Maynard, G.; Cros, B.; Boudaa, A.; Dubau, J.; Sebban, S.; Goddet, JP.

    It has been recently demonstrated experimentally that seeding a high-harmonic pulse into an Optical-Field-Ionized gas can generate a coherent soft x-ray laser beam of up to 1üJ. In order to analyze the physical processes involved in the amplification of the x-ray laser pulse through the plasma amplifier a 3D numerical code named COFIXE_MB has been developed using a Maxwell-Bloch treatment. It brings detailed information about the x-ray pulse evolution, especially regarding the fast evolution of the pulse temporal profile and the spatial filtering of the wave front structure by the amplifier.

  17. Calculation on amplification of short light pulses with high-peak power in nonlinear medium

    International Nuclear Information System (INIS)

    Propagation and amplification of partially coherent light (PCL) is simulated with a 3-D propagation code and fast Fourier transformation. The PCL is useful to realize highly uniform irradiation on a target in inertial confinement fusion experiments. On the other hand, the PCL has speckle structure in space and time owing to partial coherence. The intensity modulation due to speckles is enhanced by self-focusing and degenerated by self-phase-modulation in laser glasses due to nonlinear refractive index. Calculations on the laser propagation for the PCL show that spectral broadening and smoothing of the beam pattern occur. Experimental results agree well coincident with the simulation results. (author)

  18. Plasma-based creation of short light pulses: analysis and simulation of amplification and focusing

    Czech Academy of Sciences Publication Activity Database

    Riconda, C.; Weber, Stefan A.; Lancia, L.; Marqués, J.-R.; Mourou, G.; Fuchs, J.

    2015-01-01

    Roč. 57, č. 1 (2015), s. 014002. ISSN 0741-3335 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant ostatní: ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : plasma-based amplification * PIC simulations * parametric instabilities Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.186, year: 2014

  19. High-power KrF laser ASHURA and multi-pulse amplification

    International Nuclear Information System (INIS)

    Achieved performance of the ASHURA, a 700-Joule KrF system, is described. Nanosecond pulses (3 to 20 ns) with a band width of 40 cm-1 have been produced by gain switching of a pre-amplifier. The pulses have been six-time angularly multiplexed and double-pass amplified by two electron-beam pumped amplifiers. The output from the main amplifier is strongly saturated, and maximum energy of 660 J has been extracted in 90 ns with the stage gain of 40. Focused by f = 1 m spherical lenses, peak power density of 2 x 1014 W/cm2 on target has been achieved by 5 beam overlapping. Energy density ratio of pre-pulse on target has been suppressed below 1/107. (author)

  20. Spectral characteristics of chirped pulsed Gaussian beams propagating in turbulent atmosphere%啁啾脉冲高斯光束在大气湍流中的传输特性

    Institute of Scientific and Technical Information of China (English)

    曾祥梅; 段作梁; 常凌颖; 张美志

    2013-01-01

    基于广义惠更斯-菲涅耳原理,推导出啁啾脉冲高斯光束在湍流大气中传输的光谱解析表达式,并对解析表达式进行了数值仿真.结果表明:啁啾参数越大,光源谱宽越宽;当光源相对谱宽大于0.336时,轴上点光谱产生蓝移;湍流使得轴上点光谱的相对频移量减小,相对频移量随源光谱宽的增大而非线性增大;增大光束束腰半径可减小湍流对光谱频移、光束展宽的影响.%Based on the extended Huygens-Fresnel principle,analytical expressions are derived for the cross-spectral density matrix of chirped pulsed Gaussian beams propagating in turbulent atmosphere,which are then numerically simulated.It is shown that there are blue shifts in the spectra of axis point when the spectral width of chirped pulsed Gaussian beams is more than a certain value of 0.336.The turbulence induces the decrease of relative frequency shift of on-axis spectra; the relative frequency shift of on-axis spectra increases nonlinearly with the increasing light source spectral width.Increasing the beam waist radius can inhibit the relative frequency shift and the beam broadening.

  1. Unidirectional Amplification and Shaping of Optical Pulses by Three-Wave Mixing with Negative Phonons

    CERN Document Server

    Popov, Alexander K; Myslivets, Sergey A; Slabko, Vitaly V

    2013-01-01

    A possibility to greatly enhance frequency-conversion efficiency of stimulated Raman scattering is shown by making use of extraordinary properties of three-wave mixing of ordinary and backward waves. Such processes are commonly attributed to negative-index plasmonic metamaterials. This work demonstrates the possibility to replace such metamaterials that are very challenging to engineer by readily available crystals which support elastic waves with contra-directed phase and group velocities. The main goal of this work is to investigate specific properties of indicated nonlinear optical process in short pulse regime and to show that it enables elimination of fundamental detrimental effect of fast damping of optical phonons on the process concerned. Among the applications is the possibility of creation of a family of unique photonic devices such as unidirectional Raman amplifiers and femtosecond pulse shapers with greatly improved operational properties.

  2. Generation of multi-wavelength picosecond pulses with tunable pulsewidth and channel spacing using a Raman amplification-based adiabatic soliton compressor.

    Science.gov (United States)

    Nguyen-The, Quang; Tan, Hung Nguyen; Matsuura, Motoharu; Kishi, Naoto

    2012-01-16

    We experimentally demonstrate pulsewidth-tunable picosecond multi-wavelength pulse generation at 10 Gb/s by the use of a Raman amplification-based adiabatic soliton compressor (RA-ASC). Multi-wavelength seed pulse trains are generated by a commercially available electroabsorption modulator and then compressed by using the RA-ASC. The pulsewidths of the compressed pulses can be simultaneously controlled from 16.0 ps to 2.0 ps by adjusting Raman pump power. Operating wavelength range of our scheme are also investigated, showing the possibility for wide channel spacing operations. PMID:22274467

  3. Femtosecond pulse parametric amplification at narrowband high power gas laser pumping

    Czech Academy of Sciences Publication Activity Database

    Novák, Ondřej; Turčičová, Hana; Divoký, Martin; Smrž, Martin; Huynh, Jaroslav; Straka, Petr

    2012-01-01

    Roč. 37, č. 11 (2012), s. 2100-2102. ISSN 0146-9592 R&D Projects: GA ČR GA202/06/0814; GA MŠk(CZ) LC528 Grant ostatní: Integrated European Laser Laboratories(XE) RII3-CT-2003-506350 Institutional research plan: CEZ:AV0Z10100523 Keywords : OPCPA * ultrashort laser pulses * optical parametric amplifiers * iodine lasers * gas lasers * nonlinear optical crystals * petawatt lasers Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.385, year: 2012 http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-37-11-2100

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

    Science.gov (United States)

    Vieira, J; Trines, R M G M; 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 characterized 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 ultra-high-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 nonlinear optics and high-energy-density science, compact plasma-based accelerators and light sources. PMID:26817620

  5. 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 ...

  6. Chirped dissipative solitons of the complex cubic-quintic nonlinear Ginzburg-Landau equation

    OpenAIRE

    Kalashnikov, V. L.

    2009-01-01

    Approximate analytical chirped solitary pulse (chirped dissipative soliton) solutions of the one-dimensional complex cubic-quintic nonlinear Ginzburg-Landau equation are obtained. These solutions are stable and highly-accurate under condition of domination of a normal dispersion over a spectral dissipation. The parametric space of the solitons is three-dimensional, that makes theirs to be easily traceable within a whole range of the equation parameters. Scaling properties of the chirped dissi...

  7. Patch diameter limitation due to high chirp rates in focused SAR images

    Science.gov (United States)

    Doerry, Armin W.

    1994-10-01

    Polar-format processed synthetic aperture radar (SAR) images have a limited focused patch diameter that results from unmitigated phase errors. Very high chirp rates, encountered with fine-resolution short-pulse radars, exasperate the problem via a residual video phase error term. This letter modifies the traditional maximum patch diameter expression to include effects of very high chirp rates.

  8. Integrated single grating compressor for variable pulse front tilt in simultaneously spatially and temporally focused systems.

    Science.gov (United States)

    Block, Erica; Thomas, Jens; Durfee, Charles; Squier, Jeff

    2014-12-15

    A Ti:Al(3)O(2) multipass chirped pulse amplification system is outfitted with a single-grating, simultaneous spatial and temporal focusing (SSTF) compressor platform. For the first time, this novel design has the ability to easily vary the beam aspect ratio of an SSTF beam, and thus the degree of pulse-front tilt at focus, while maintaining a net zero-dispersion system. Accessible variation of pulse front tilt gives full spatiotemporal control over the intensity distribution at the focus and could lead to better understanding of effects such as nonreciprocal writing and SSTF-material interactions. PMID:25503029

  9. Fourier Transforms of Finite Chirps

    Directory of Open Access Journals (Sweden)

    Fickus Matthew

    2006-01-01

    Full Text Available Chirps arise in many signal processing applications. While chirps have been extensively studied as functions over both the real line and the integers, less attention has been paid to the study of chirps over finite groups. We study the existence and properties of chirps over finite cyclic groups of integers. In particular, we introduce a new definition of a finite chirp which is slightly more general than those that have been previously used. We explicitly compute the discrete Fourier transforms of these chirps, yielding results that are number-theoretic in nature. As a consequence of these results, we determine the degree to which the elements of certain finite tight frames are well distributed.

  10. Resonant nonstationary amplification of polychromatic laser pulses and conical emission in an optically dense ensemble of neon metastable atoms

    CERN Document Server

    Bagayev, S N; Mekhov, I B; Moroshkin, P V; Chekhonin, I A; Davliatchine, E M; Kindel, E

    2003-01-01

    Experimental and numerical investigation of single beam and pump-probe interaction with a resonantly absorbing dense extended medium under strong and weak field-matter coupling is presented. Significant probe beam amplification and conical emission were observed. Under relatively weak pumping and high medium density, when the condition of strong coupling between field and resonant matter is fulfilled, the probe amplification spectrum has a form of spectral doublet. Stronger pumping leads to the appearance of a single peak of the probe beam amplification at the transition frequency. The greater probe intensity results in an asymmetrical transmission spectrum with amplification at the blue wing of the absorption line and attenuation at the red one. Under high medium density, a broad band of amplification appears. Theoretical model is based on the solution of the Maxwell-Bloch equations for a two-level system. Different types of probe transmission spectra obtained are attributed to complex dynamics of a coherent...

  11. Controlling over Superintense Electromagnetic Pulse Parameters with FEL

    CERN Document Server

    Oganesyan, S G

    2005-01-01

    We have studied propagation of a Gaussian electromagnetic pulse through a long FEL. Our analysis is based on the Maxwell and Klein-Gordon equations and takes into account both the active and dispersive properties of an electron beam. The laser output in (a) linear and (b) nonlinear complex phase regimes has been considered. We obtained expressions for FEL operative bandwidth and characteristic time, and introduced conception of long and short pulses. We have discovered a stabilization effect in the case (a). Namely, short pulses with random initial lengths have the same ones after coupling. The Rayleigh regions caused by dispersion and amplification (absorption) are obtained for long pulse in the case (b). If the carried frequency is under maximum gaining, then one observes only the pulse expansion. The most interesting effects have been discovered in the absorption regime. Here the FEL can operate as a slight compressor or as an explosive stretcher. Besides, FEL device makes it possible the chirping of pulse...

  12. Suppression of parasitic noise by strong Langmuir wave damping in quasitransient regimes of backward Raman amplification of intense laser pulses in plasmas.

    Science.gov (United States)

    Malkin, Vladimir; Fisch, Nathaniel

    2009-11-01

    Currently built powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulsed, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can suppress deleterious instabilities of BRA seeded by the thermal noise. This shows that it may be feasible to observe x-ray BRA for the first time soon.

  13. Combining Harmonic Generation and Laser Chirping to Achieve High Spectral Density in Compton Sources

    CERN Document Server

    Terzić, Balša; Krafft, Geoffrey A

    2015-01-01

    Recently various laser-chirping schemes have been investigated with the goal of reducing or eliminating ponderomotive line broadening in Compton or Thomson scattering occurring at high laser intensities. As a next level of detail in the spectrum calculations, we have calculated the line smoothing and broadening expected due to incident beam energy spread within a one-dimensional plane wave model for the incident laser pulse, both for compensated (chirped) and unchirped cases. The scattered compensated distributions are treatable analytically within three models for the envelope of the incident laser pulses: Gaussian, Lorentzian, or hyperbolic secant. We use the new results to demonstrate that the laser chirping in Compton sources at high laser intensities: (i) enables the use of higher order harmonics, thereby reducing the required electron beam energies; and (ii) increases the photon yield in a small frequency band beyond that possible with the fundamental without chirping. This combination of chirping and h...

  14. 200W fs Innoslab amplifier with 400μJ pulse energy for industrial applications

    Science.gov (United States)

    Mans, T.; Hönninger, C.; Dolkemeyer, J.; Letan, A.; Schnitzler, C.; Mottay, E.

    2013-03-01

    We demonstrate a femtosecond Yb:YAG InnoSlab laser amplifier producing 450-μJ pulse energy at 500kHz pulse repetition rate. Ultrafast operation at high energy and high average power could be obtained without the use of chirped pulse amplification on the power amplifier end. The laser setup consists of a compact and robust femtosecond fiber based seed laser producing up to 4μJ pulses with pulse durations down to 260fs. Pulses from the seed source are directly amplified to high pulse energy and average power in an optimized Innoslab amplifier. This laser source is ideally suited for large scale industrial applications requiring high average power ultrashort pulses for high throughput and productivity.

  15. Nonequilibrium plasma channel in gaseous media formed by powerful UV laser as a waveguide for transportation and amplification of short microwave pulses

    International Nuclear Information System (INIS)

    The evolution of strongly nonequilibrium plasma in a channel created in gaseous media by powerful UV femtosecond laser pulse is studied. It is demonstrated that such a plasma channel can be used as a waveguide for both transportation and amplification of the microwave radiation. The specific features of such a plasma waveguide are studied on the basis of the self-consistent solution of the kinetic Boltzmann equation for the electron energy distribution function in different spatial points of the gas media and the wave equation in paraxial approximation for the microwave radiation guided and amplified in the channel. The results of modeling for rare gases (xenon) and air are compared. The amplification factor in xenon plasma in dependence on channel radius, intensity and frequency of the input RF radiation is analyzed. (letter)

  16. Resonant nonstationary amplification of polychromatic laser pulses and conical emission in an optically dense ensemble of neon metastable atoms

    OpenAIRE

    Bagayev, S. N.; Egorov, V. S.; Mekhov, I. B.; Moroshkin, P. V.; Chekhonin, I. A.; Davliatchine, E. M.; Kindel, E.

    2003-01-01

    Experimental and numerical investigation of single-beam and pump-probe interaction with a resonantly absorbing dense extended medium under strong and weak field-matter coupling is presented. Significant probe beam amplification and conical emission were observed. Under relatively weak pumping and high medium density, when the condition of strong coupling between field and resonant matter is fulfilled, the probe amplification spectrum has a form of spectral doublet. Stronger pumping leads to t...

  17. Femtosecond Innoslab amplifier with 300W average power and pulse energies in the mJ-regime

    Science.gov (United States)

    Mans, T.; Graf, R.; Dolkemeyer, J.; Schnitzler, C.

    2014-02-01

    We demonstrate a femtosecond Yb:YAG InnoSlab laser amplifier producing powers High energy and high average power could be obtained with the use of chirped pulse amplification on the power amplifier end. The laser setup consists of a seed laser with 10mW average power at pulse repetition rates of 100kHz to 1MHz, a pre-amplifier stage, a highpower InnoSlab-amplifier stage and a grating based pulse compressor. This laser source is suited for pumping of OPCPA setups und parallelisation of applications in materials processing.

  18. Longitudinal Coherence Preservation and Chirp Evolution in a High Gain Laser Seeded Free Electron Laser Amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, J.B.; /BNL, NSLS; Wu, Juhao; /SLAC; Wang, X.J.; Watanabe, T.; /BNL, NSLS

    2006-06-07

    In this letter we examine the start-up of a high gain free electron laser in which a frequency-chirped coherent seed laser pulse interacts with a relativistic electron beam. A Green function formalism is used to evaluate the initial value problem. We have fully characterized the startup and evolution through the exponential growth regime. We obtain explicit expressions for the pulse duration, bandwidth and chirp of the amplified light and show that the FEL light remains fully longitudinally coherent.

  19. Tunable pulse width and multi-megawatt peak-power pulses from a nonlinearly compressed monolithic fiber MOPA system

    Science.gov (United States)

    Yamashita, Ryutarou; Maeda, Kazuo; Watanabe, Goro; Tei, Kazuyoku; Yamaguchi, Shigeru; Enokidani, Jun; Sumida, Shin

    2016-03-01

    We report on tunable pulse width and high peak power pulse generation from a nonlinearly compressed monolithic fiber MOPA system. The master seed source employs a Mach-Zehnder intensity modulator (MZIM). This seed source has operational flexibility with respect to pulse width, 90 ps to 2 ns and repetition rate, 200 kHz to 2 MHz. The seed pulses are amplified by a monolithic three-stage amplifier system based on polarization maintain Yb-doped fibers. The maximum output power was 32 W at the shortest pulse condition, the pulse width of 90 ps and the repetition rate of 750 kHz. A spectral width after amplification was broadened to 0.73 nm at RMS width. Both of ASE and SRS are not observed in the spectrum. After amplification, we also demonstrated pulse compression with a small piece of chirped volume Bragg-grating (CVBG) which has the dispersion rate of 81 ps/nm. As a result of pulse compression, the shortest pulse width was reduced from 90 ps to 3.5 ps, which brought an increase of the peak power up to 3.2 MW. The compressed pulses are clean with little structure in their wings. We can expand the operation range of the monolithic fiber MOPA system in pulse width, 3.5 ps to 2 ns.

  20. Broadband asymmetric conical emission via cascaded second-order nonlinear polarization during the propagation of femtosecond laser pulses in a BBO crystal

    International Nuclear Information System (INIS)

    We investigate the propagation of femtosecond laser pulses in a 5-mm-thick BBO crystal along the direction of type-I phase-matched second-harmonic generation. An intensity-asymmetric broadband conical emission (500-2000 nm) is demonstrated when a suitable chirp is introduced. It is generated by optical parametric amplification pumped by the second-harmonic light and seeded by the fundamental light which is broadened by cascaded nonlinear processes during second-harmonic generation. (authors)

  1. Pulse-shaping strategies in short-pulse fiber amplifiers

    International Nuclear Information System (INIS)

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  2. Pulse-shaping strategies in short-pulse fiber amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Schimpf, Damian Nikolaus

    2010-02-09

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  3. Random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and phage-typing in the analysis of a hospital outbreak of Salmonella enteritidis

    DEFF Research Database (Denmark)

    Skibsted, U.; Baggesen, Dorte Lau; Dessau, R.;

    1998-01-01

    Isolates of Salmonella Enteritidis from 81 patients from Herlev Hospital or from Copenhagen County were analysed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and phage-typing. Fourteen polymorphic markers from five decamer primers unambiguously placed...... (both PFGE type I) formed the fifth group. The sixth group of four isolates was not phage typeable and was PFGE type III. Forty outbreak-related isolates of phage-type 6 were resolved into three strains. No diversity of phage-type 6 was found among isolates unrelated to the outbreak. It is concluded...

  4. Resonant nonstationary amplification of polychromatic laser pulses and conical emission in an optically dense ensemble of neon metastable atoms

    International Nuclear Information System (INIS)

    Experimental and numerical investigation of single-beam and pump-probe interaction with a resonantly absorbing dense extended medium under strong and weak field-matter coupling is presented. Significant probe beam amplification and conical emission were observed. Under relatively weak pumping and high medium density, when the condition of strong coupling between field and resonant matter is fulfilled, the probe amplification spectrum has a form of spectral doublet. Stronger pumping leads to the appearance of a single peak of the probe beam amplification at the transition frequency. The greater probe intensity results in an asymmetrical transmission spectrum with amplification at the blue wing of the absorption line and attenuation at the red one. Under high medium density, a broadband of amplification appears. The theoretical model is based on the solution of the Maxwell-Bloch equations for a two-level system. Different types of probe transmission spectra obtained are attributed to complex dynamics of a coherent medium response to broadband polychromatic radiation of a multimode dye laser

  5. An Overview of High Energy Short Pulse Technology for Advanced Radiography of Laser Fusion Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Barty, C J; Key, M; Britten, J; Beach, R; Beer, G; Brown, C; Bryan, S; Caird, J; Carlson, T; Crane, J; Dawson, J; Erlandson, A C; Fittinghoff, D; Hermann, M; Hoaglan, C; Iyer, A; Jones, L; Jovanovic, I; Komashko, A; Landen, O; Liao, Z; Molander, W; Mitchell, A; Moses, E; Nielsen, N; Nguyen, H; Nissen, J; Payne, S; Pennington, D; Risinger, L; Rushford, M; Skulina, K; Spaeth, M; Stuart, B; Tietbohl, G; Wattellier, B

    2004-06-18

    The technical challenges and motivations for high-energy, short-pulse generation with NIF-class, Nd:glass laser systems are reviewed. High energy short pulse generation (multi-kilojoule, picosecond pulses) will be possible via the adaptation of chirped pulse amplification laser techniques on the NIF. Development of meter-scale, high efficiency, high-damage-threshold final optics is a key technical challenge. In addition, deployment of HEPW pulses on NIF is constrained by existing laser infrastructure and requires new, compact compressor designs and short-pulse, fiber-based, seed-laser systems. The key motivations for high energy petawatt pulses on NIF is briefly outlined and includes high-energy, x-ray radiography, proton beam radiography, proton isochoric heating and tests of the fast ignitor concept for inertial confinement fusion.

  6. Generation of ultrashort 90 µJ deep-ultraviolet pulses by dual broadband frequency doubling with β-BaB2O4 crystals at 1 kHz

    Science.gov (United States)

    Zhou, Chun; Kanai, Teruto; Watanabe, Shuntaro

    2015-01-01

    Fourth-harmonic pulses of a 1 kHz chirped-pulse amplification (CPA) Ti:sapphire laser have been generated by a scheme of dual broadband frequency doubling with two β-BaB2O4 (BBO) crystals. The pulse energy was 90 µJ with a bandwidth of 2.7 nm (full width at half maximum, FWHM) at a central wavelength of 220 nm. The pulse width was measured to be 45 fs by autocorrelation with the two-photon fluorescence of CaF2, which was much smaller than that (120 fs) obtained by conventional frequency conversion.

  7. Semi-classical calculations of ultracold and cold collisions with frequency-chirped light

    International Nuclear Information System (INIS)

    There has been considerable interest in using shaped laser pulses as a means to control the dynamics of atoms and molecules. We conduct semi-classical Monte-Carlo simulations of ultracold collisions utilizing frequency-chirped laser light on a nanosecond timescale. Recent experiments demonstrated partial control of light-assisted collisional mechanisms with relatively slow chirp rates (10 GHz/μs). Collisions induced with positive chirped light enhance the inelastic collisional loss rate of atoms from a magneto-optical trap due to rapid adiabatic passage, whereas trap loss collisions can be coherently blocked when negative chirped light is used. Early quantum and classical simulations show that for negative chirps, laser frequency continually interacts with the atom pair during the collision. We investigate how this process depends on the chirp rate and show that by moderately speeding up the chirp (>50 GHz/μs), we can significantly enhance coherent processes. We extend our semi-classical model to examine using pulse shaping as a means to coherently control collisions and show that features in the pulse shape should be on the order of or less than 1 ns. We also show that coherent control of collisions using this technique can be extended to temperatures exceeding 1 K. (author)

  8. Random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and phage-typing in the analysis of a hospital outbreak of Salmonella enteritidis

    DEFF Research Database (Denmark)

    Skibsted, U.; Baggesen, Dorte Lau; Dessau, R.; Lisby, G.

    1998-01-01

    Isolates of Salmonella Enteritidis from 81 patients from Herlev Hospital or from Copenhagen County were analysed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and phage-typing. Fourteen polymorphic markers from five decamer primers unambiguously placed...... that RAPD is useful as a tool in investigations of microbial outbreaks in its own right, or to supplement phage-typing and PFGE of Salmonella Enteritidis.......Isolates of Salmonella Enteritidis from 81 patients from Herlev Hospital or from Copenhagen County were analysed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and phage-typing. Fourteen polymorphic markers from five decamer primers unambiguously placed...... (both PFGE type I) formed the fifth group. The sixth group of four isolates was not phage typeable and was PFGE type III. Forty outbreak-related isolates of phage-type 6 were resolved into three strains. No diversity of phage-type 6 was found among isolates unrelated to the outbreak. It is concluded...

  9. Short-pulse propagation in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina

    Fiber optical parametric amplifiers (FOPAs) are attractive because they can provide large gain over a broad range of central wavelengths, depending only on the availability of a suitable pump laser. In addition, FOPAs are suitable for the realization of all-optical signal processing functionalities...... and can operate with a potentially low noise figure with respect to erbium-doped fiber amplifiers and Raman amplifiers, when working in phase-sensitive configurations. A characterization of the signal distortion mechanisms introduced by FOPAs is relevant for investigating the applicability of FOPAs...... pulses fiber laser source is implemented to obtain an all-fiber system. The advantages of all fiber-systems are related to their reliability, long-term stability and compactness. Fiber optical parametric chirped pulse amplification is promising for the amplification of such signals thanks to the inherent...

  10. Group velocity dispersion and polarization mode dispersion compensation by high-birefringence linearly chirped fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Muguang Wang(王目光); Tangjun Li(李唐军); Shuisheng Jian(简水生)

    2004-01-01

    A high-birefringence linearly chirped fiber Bragg grating (FBG) is written into a polarization-maintaining photosensitive fiber by ultraviolet (UV) beam through a linearly chirped phase mask. Its performance as group velocity dispersion (GVD) and polarization mode dispersion (PMD) compensator is demonstrated in short pulse fiber optical transmission systems.

  11. Non-filamentated ultra-intense and ultra-short pulse fronts in three-dimensional Raman seed amplification

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, G.; Spatschek, K. H. [Institut für Theoretische Physik, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf (Germany)

    2014-05-15

    Ultra-intense and ultra-short laser pulses may be generated up to the exawatt-zetawatt regime due to parametric processes in plasmas. The minimization of unwanted plasma processes leads to operational limits which are discussed here with respect to filamentation. Transverse filamentation, which originally was derived for plane waves, is being investigated for seed pulse propagation in the so called π-pulse limit. A three-dimensional (3D) three-wave-interaction model is the basis of the present investigation. To demonstrate the applicability of the three-wave-interaction model, the 1D pulse forms are compared with those obtained from 1D particle in cell and Vlasov simulations. Although wave-breaking may occur, the kinetic simulations show that the leading pumped pulse develops a form similar to that obtained from the three-wave-interaction model. In the main part, 2D and 3D filamentation processes of (localized) pulses are investigated with the three-wave-interaction model. It is shown that the leading pulse front can stay filamentation-free, whereas the rear parts show transverse modulations.

  12. An overview of LLNL high-energy short-pulse technology for advanced radiography of laser fusion experiments

    International Nuclear Information System (INIS)

    The technical challenges and motivations for high-energy, short-pulse generation with the National Ignition Facility (NIF) and possibly other large-scale Nd : glass lasers are reviewed. High-energy short-pulse generation (multi-kilojoule, picosecond pulses) will be possible via the adaptation of chirped pulse amplification laser techniques on NIF. Development of metre-scale, high-efficiency, high-damage-threshold final optics is a key technical challenge. In addition, deployment of high energy petawatt (HEPW) pulses on NIF is constrained by existing laser infrastructure and requires new, compact compressor designs and short-pulse, fibre-based, seed-laser systems. The key motivations for HEPW pulses on NIF is briefly outlined and includes high-energy, x-ray radiography, proton beam radiography, proton isochoric heating and tests of the fast ignitor concept for inertial confinement fusion. (author)

  13. Detectors for alpha particles and X-rays operating in ambient air in pulse counting mode and/or with gas amplification

    CERN Document Server

    Charpak, Georges; Breuil, P; Peskov, Vladimir

    2008-01-01

    Ionization chambers working in ambient air in current detection mode are widely used in several applications such as smoke detection, dosimetry, therapeutic beam monitoring and cetera. The aim of this work was to investigate if gaseous detectors can operate in ambient air in pulse counting mode as well as with gas amplification. . To investigate the feasibility of this method two types of open- end gaseous detectors were build and successfully tested. The first one was a single wire or multiwire cylindrical geometry detector operating in pulse mode at a gas gain of 1. The second type alpha detector was an innovative GEM-like detector with resistive electrodes operating in air in avalanche mode at high gas gains (up to 10E4). A detailed comparison between these two detectors is given as well as comparison with the commercially available alpha detectors. The main advantages of gaseous detectors operating in air in a pulse detection mode are their simplicity, low cost and high sensitivity. One of the possible ap...

  14. Yb:YAG single-crystal fiber amplifiers for picosecond lasers using the divided pulse amplification technique.

    Science.gov (United States)

    Lesparre, Fabien; Gomes, Jean Thomas; Délen, Xavier; Martial, Igor; Didierjean, Julien; Pallmann, Wolfgang; Resan, Bojan; Druon, Frederic; Balembois, François; Georges, Patrick

    2016-04-01

    A two-stage master-oscillator power-amplifier (MOPA) system based on Yb:YAG single-crystal-fiber (SCF) technology and designed for high peak power is studied to significantly increase the pulse energy of a low-power picosecond laser. The first SCF amplifier has been designed for high gain. Using a gain medium optimized in terms of doping concentration and length, an optical gain of 32 dB has been demonstrated. The second amplifier stage designed for high energy using the divided pulse technique allows us to generate a recombined output pulse energy of 2 mJ at 12.5 kHz with a pulse duration of 6 ps corresponding to a peak power of 320 MW. Average powers ranging from 25 to 55 W with repetition rates varying from 12.5 to 500 kHz have been demonstrated. PMID:27192304

  15. Enabling pulse compression and proton acceleration in a modular ICF driver for nuclear and particle physics applications

    CERN Document Server

    Terranova, F; Collier, J L; Kiriyama, H; Pegoraro, F

    2005-01-01

    The existence of efficient ion acceleration regimes in collective laser-plasma interactions opens up the possibility to develop high-energy physics facilities in conjunction with projects for inertial confinement nuclear fusion (ICF) and neutron spallation sources. In this paper, we show that the pulse compression requests to make operative these acceleration mechanisms do not fall in contradiction with current designs for an ICF driver. In particular, we discuss explicitly a solution that exploits optical parametric chirped pulse amplification and the intrinsic modularity of ICF power plants.

  16. Alignment of chirped-pulse compressor

    International Nuclear Information System (INIS)

    An original method of alignment of grating compressors for ultrahigh-power CPA laser systems is proposed. The use of this method for adjustment of the grating compressor of a PEARL subpetawatt laser complex made it possible to align the diffraction gratings with a second accuracy in all three angular degrees of freedom, including alignment of the grooves, and to adjust the angles of beam incidence on the grating with a high accuracy. A simple method for measuring the difference in the groove densities of gratings with accuracy better than 0.005 lines mm-1 is proposed and tested. (control of laser radiation parameters)

  17. Alignment of chirped-pulse compressor

    Energy Technology Data Exchange (ETDEWEB)

    Yakovlev, I V [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation)

    2012-11-30

    An original method of alignment of grating compressors for ultrahigh-power CPA laser systems is proposed. The use of this method for adjustment of the grating compressor of a PEARL subpetawatt laser complex made it possible to align the diffraction gratings with a second accuracy in all three angular degrees of freedom, including alignment of the grooves, and to adjust the angles of beam incidence on the grating with a high accuracy. A simple method for measuring the difference in the groove densities of gratings with accuracy better than 0.005 lines mm{sup -1} is proposed and tested. (control of laser radiation parameters)

  18. Amplification of picosecond pulse by electron-beam pumped KrF laser amplifiers. Denshi beam reiki KrF laser zofukuki ni yoru piko byo pulse no zofuku

    Energy Technology Data Exchange (ETDEWEB)

    Okuda, I.; Tomie, T.; Owadano, Y.; Yano, M. (Electrotechnical Laboratory, Tsukuba (Japan))

    1991-08-20

    Experiments on the amplification of a picosecond pulse by electron-beam pumped KrF laser amplifiers were carried out for the purpose of its application to the field such as excitation light source for soft X-ray laser which requires large energy besides peak power. The picosecond pulse was amplified by a discharge pumped KrF amplifier and two electron-beam pumped KrF amplifiers(at the middle stage and the final stage). The energy of 4J, which was the largest energy for short pulse excimer laser so far, was obtained by these devices. About 90% of the window area of the final amplifier with 29cm diameter was filled by the input beam, and energy density of the picosecond beam reached 3.9 times saturation energy density. Measured energy of amplified spontaneous emission(ASE) showed good agreement with the theoretically estimated value. Most of ASE was derived from the discharge pumped laser as the first amplifier. As for the focused power density, the power density ratio of the picosecond pulse to ASE was estimated to be as large as 10{sup 5}. 11 refs., 4 figs.

  19. Chirped standing wave acceleration of ions with intense lasers

    CERN Document Server

    Mackenroth, Felix; Marklund, Mattias

    2016-01-01

    We propose a novel mechanism for ion acceleration based on the guided motion of electrons from a thin target. The electron motion is locked to the moving nodes of a standing wave formed by a chirped laser pulse reflected from a mirror behind the target. This provides a stable longitudinal field of charge separation, thus giving rise to chirped standing wave acceleration (CSWA) of the residual ions of the layer. We demonstrate, both analytically and numerically, that quasi-monoenergetic ion beams with energies of the order 100 MeV are feasible for realistic pulse energies of 10 J. Moreover, a scaling law for higher laser intensities and layer densities is presented, indicating stable GeV-level energy gains of dense ion bunches, for soon-to-be available laser intensities.

  20. Dense monoenergetic proton beams from chirped laser-plasma interaction

    CERN Document Server

    Galow, Benjamin J; Liseykina, Tatyana V; Harman, Zoltan; Keitel, Christoph H

    2011-01-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen plasma cell is studied analytically and by means of particle-in-cell simulations, respectively. Feasibility of generating ultra-intense (10^7 particles per bunch) and phase-space collimated beams of protons (energy spread of about 1 %) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10^21 W/cm^2.

  1. Two modified discrete chirp Fourier transform schemes

    Institute of Scientific and Technical Information of China (English)

    樊平毅; 夏香根

    2001-01-01

    This paper presents two modified discrete chirp Fourier transform (MDCFT) schemes.Some matched filter properties such as the optimal selection of the transform length, and its relationship to analog chirp-Fourier transform are studied. Compared to the DCFT proposed previously, theoretical and simulation results have shown that the two MDCFTs can further improve the chirp rate resolution of the detected signals.

  2. Polarization-maintaining fiber pulse compressor by birefringent hollow-core photonic bandgap fiber.

    Science.gov (United States)

    Shirakawa, Akira; Tanisho, Motoyuki; Ueda, Ken-Ichi

    2006-12-11

    Structural birefringent properties of a hollow-core photonic-bandgap fiber were carefully investigated and applied to all-fiber chirped-pulse amplification as a compressor. The group birefringence of as high as 6.9x10(-4) and the dispersion splitting by as large as 149 ps/nm/km between the two principal polarization modes were observed at 1557 nm. By launching the amplifier output to one of the polarization modes a 17-dB polarization extinction ratio was obtained without any pulse degradation originating from polarization-mode dispersion. A hybrid fiber stretcher effectively compensates the peculiar dispersion of the photonic-bandgap fiber and pedestal-free 440-fs pulses with a 1-W average power and 21-nJ pulse energy were obtained. Polarization-maintaining fiber-pigtail output of high-power femtosecond pulses is useful for various applications. PMID:19529631

  3. Quantum Fluctuations in the Chirped Pendulum

    CERN Document Server

    Murch, K W; Barth, I; Naaman, O; Aumentado, J; Friedland, L; Siddiqi, I

    2010-01-01

    An anharmonic oscillator when driven with a fast, frequency chirped voltage pulse can oscillate with either small or large amplitude depending on whether the drive voltage is below or above a critical value-a well studied classical phenomenon known as autoresonance. Using a 6 GHz superconducting resonator embedded with a Josephson tunnel junction, we have studied for the first time the role of noise in this non-equilibrium system and find that the width of the threshold for capture into autoresonance decreases as the square root of T, and saturates below 150 mK due to zero point motion of the oscillator. This unique scaling results from the non-equilibrium excitation where fluctuations, both quantum and classical, only determine the initial oscillator motion and not its subsequent dynamics. We have investigated this paradigm in an electrical circuit but our findings are applicable to all out of equilibrium nonlinear oscillators.

  4. Recent progress in the development of pulse compression gratings

    Directory of Open Access Journals (Sweden)

    Hocquet S.

    2013-11-01

    Full Text Available The PETAL facility uses chirped pulse amplification (CPA technique. This system needs large pulse compression gratings that request damage threshold better than 4 J/cm2 in normal beam at 1.053 μm for 500 fs pulses. In this paper, we will show recent grating designs with either multilayer dielectrics or hybrid metal-dielectric structures. We have shown in previous works that damage threshold is driven by the enhancement of the near electric field inside the pillars of the grating. This was evidenced from a macroscopic point of view by means of laser damage testing. We will show that damage morphology during damage initiation at the scale of the grating groove is also consistent with this electric field dependence.

  5. Detection of Panton-Valentine Leukocidin DNA from methicillin-resistant Staphylococcus aureus by resistive pulse sensing and loop-mediated isothermal amplification with gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Alice Kar Lai, E-mail: s0907465@cuhk.mail.serv.edu.hk [Program of Biochemistry, School of Life Sciences, The Chinese University of Hong Kong (Hong Kong); Lu, Haifei, E-mail: hflu@ee.cuhk.edu.hk [Center for Advanced Research in Photonics, Department of Electronic Engineering, The Chinese University of Hong Kong (Hong Kong); Wu, Shu Yuen, E-mail: sywu@ee.cuhk.edu.hk [Center for Advanced Research in Photonics, Department of Electronic Engineering, The Chinese University of Hong Kong (Hong Kong); Kwok, Ho Chin, E-mail: hckwock@ee.cuhk.edu.hk [Center for Advanced Research in Photonics, Department of Electronic Engineering, The Chinese University of Hong Kong (Hong Kong); Ho, Ho Pui, E-mail: hpho@ee.cuhk.edu.hk [Center for Advanced Research in Photonics, Department of Electronic Engineering, The Chinese University of Hong Kong (Hong Kong); Yu, Samuel, E-mail: samscyu@gmail.com [The MacDiarmid Institute for Advanced Materials and Nanotechnology, Christchurch (New Zealand); Izon Science, PO Box 39-168, Harewood, Christchurch 8545 (New Zealand); Cheung, Anthony Ka Lun, E-mail: kalun2004@hotmail.com [Program of Biochemistry, School of Life Sciences, The Chinese University of Hong Kong (Hong Kong); Kong, Siu Kai, E-mail: skkong@cuhk.edu.hk [Program of Biochemistry, School of Life Sciences, The Chinese University of Hong Kong (Hong Kong)

    2013-06-11

    Graphical abstract: -- Highlights: •A novel diagnostic assay is developed to detect the MRSA's Panton-Valentine Leukocidin toxin. •Detection is based on target DNA amplification at one single temperature at 65 °C by LAMP. •Amplicons are then hybridized with 2 Au-nanoparticles with specific DNA probes for sensing. •The supra-assemblies are subsequently sensed by resistive pulse sensing. •Detection limit: ∼200 copies of DNA; time for detection: completed within 2 h. -- Abstract: This report describes a novel diagnostic assay for rapid detection of the Panton-Valentine Leukocidin (PVL) toxin of methicillin-resistant Staphylococcus aureus (MRSA) utilizing resistive pulse sensing (RPS), loop-mediated isothermal DNA amplification (LAMP) in combination with gold nanoparticles (AuNPs). The PVL DNA from MRSA was specifically amplified by LAMP using four primers at one temperature (65 °C). The DNA products with biotin were then conjugated to a first AuNP1 (55 ± 2 nm) through biotin–avidin binding. A second AuNP2 (30 ± 1.5 nm) coated with a specific DNA probe hybridized with the LAMP DNA products at the loop region to enhance assay sensitivity and specificity, to generate supra-AuNP1-DNA-AuNP2 assemblies. Scanning electron microscopy confirmed the presence of these supra-assemblies. Using RPS, detection and quantitation of the agglomerated AuNPs were performed by a tunable fluidic nanopore sensor. The results demonstrate that the LAMP-based RPS sensor is sensitive and rapid for detecting the PVL DNA. This technique could achieve a limit of detection (LOD) up to about 500 copies of genomic DNA from the bacteria MRSA MW2 and the detection can be completed within two hours with a straightforward signal-to-readout setup. It is anticipated that this LAMP-based AuNP RPS may become an effective tool for MRSA detection and a potential platform in clinical laboratory to report the presence or absence of other types of infectious agents.

  6. Detection of Panton-Valentine Leukocidin DNA from methicillin-resistant Staphylococcus aureus by resistive pulse sensing and loop-mediated isothermal amplification with gold nanoparticles

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •A novel diagnostic assay is developed to detect the MRSA's Panton-Valentine Leukocidin toxin. •Detection is based on target DNA amplification at one single temperature at 65 °C by LAMP. •Amplicons are then hybridized with 2 Au-nanoparticles with specific DNA probes for sensing. •The supra-assemblies are subsequently sensed by resistive pulse sensing. •Detection limit: ∼200 copies of DNA; time for detection: completed within 2 h. -- Abstract: This report describes a novel diagnostic assay for rapid detection of the Panton-Valentine Leukocidin (PVL) toxin of methicillin-resistant Staphylococcus aureus (MRSA) utilizing resistive pulse sensing (RPS), loop-mediated isothermal DNA amplification (LAMP) in combination with gold nanoparticles (AuNPs). The PVL DNA from MRSA was specifically amplified by LAMP using four primers at one temperature (65 °C). The DNA products with biotin were then conjugated to a first AuNP1 (55 ± 2 nm) through biotin–avidin binding. A second AuNP2 (30 ± 1.5 nm) coated with a specific DNA probe hybridized with the LAMP DNA products at the loop region to enhance assay sensitivity and specificity, to generate supra-AuNP1-DNA-AuNP2 assemblies. Scanning electron microscopy confirmed the presence of these supra-assemblies. Using RPS, detection and quantitation of the agglomerated AuNPs were performed by a tunable fluidic nanopore sensor. The results demonstrate that the LAMP-based RPS sensor is sensitive and rapid for detecting the PVL DNA. This technique could achieve a limit of detection (LOD) up to about 500 copies of genomic DNA from the bacteria MRSA MW2 and the detection can be completed within two hours with a straightforward signal-to-readout setup. It is anticipated that this LAMP-based AuNP RPS may become an effective tool for MRSA detection and a potential platform in clinical laboratory to report the presence or absence of other types of infectious agents

  7. Short pulse laser train for laser plasma interaction experiments

    International Nuclear Information System (INIS)

    A multiframe, high-time resolution pump-probe diagnostic consisting of a consecutive train of ultrashort laser pulses (∼ps) has been developed for use with a chirped pulse amplification (CPA) system. A system of high quality windows is used to create a series of 1054 nm picosecond-laser pulses which are injected into the CPA system before the pulse stretcher and amplifiers. By adding or removing windows in the pulse train forming optics, the number of pulses can be varied. By varying the distance and thickness of the respective optical elements, the time in between the pulses, i.e., the time in between frames, can be set. In our example application, the CPA pulse train is converted to 527 nm using a KDP crystal and focused into a preformed plasma and the reflected laser light due to stimulated Raman scattering is measured. Each pulse samples different plasma conditions as the plasma evolves in time, producing more data on each laser shot than with a single short pulse probe. This novel technique could potentially be implemented to obtain multiple high-time resolution measurements of the dynamics of physical processes over hundreds of picoseconds or even nanoseconds with picosecond resolution on a single shot

  8. Molecular typing of enterohemorrhagic Escherichia coli O157:H7 isolated in Okayama Prefecture using pulsed field gel electrophoresis and random amplification of polymorphic DNA.

    Directory of Open Access Journals (Sweden)

    Funamori Y

    1999-08-01

    Full Text Available Three outbreaks and many isolated cases of enterohemorrhagic Escherichia coli O157:H7 occurred in 1996 and 1997 in Okayama Prefecture, Japan. In an attempt to investigate the route of these infections, the strains isolated from the 3 outbreaks (total 33 strains and 15 isolated cases (total 15 strains were investigated using random amplification of polymorphic DNA (RAPD and pulsed-field gel electrophoresis (PFGE. In addition, 10 strains from an outbreak in Tojo Cho, Hiroshima Prefecture (June 1996, 2 strains from the particular types of meat in Kochi Prefecture, and 42 strains isolated from bovine feces in a farm in Okayama Prefecture were also investigated in the same manner. PFGE was much more useful than RAPD for molecular typing of the clinical isolates, in that it allowed us to classify them into 10 PFGE groups. We noted that the strains differed according to the time and place of the outbreaks (or isolated cases. This indicates that O157:H7 infections in Okayama Prefecture were caused by different strains (although some cases were aggravated by the same strains as were found in other areas. The isolates from bovine feces were classified into 5 groups by PFGE profiles, but none of them were identical to those of the clinical isolates.

  9. Compensation of nonlinear phase shifts with third-order dispersion in short-pulse fiber amplifiers.

    Science.gov (United States)

    Zhou, Shian; Kuznetsova, Lyuba; Chong, Andy; Wise, Frank

    2005-06-27

    We show that nonlinear phase shifts and third-order dispersion can compensate each other in short-pulse fiber amplifiers. This compen-sation can be exploited in any implementation of chirped-pulse amplification, with stretching and compression accomplished with diffraction gratings, single-mode fiber, microstructure fiber, fiber Bragg gratings, etc. In particular, we consider chirped-pulse fiber amplifiers at wavelengths for which the fiber dispersion is normal. The nonlinear phase shift accumulated in the amplifier can be compensated by the third-order dispersion of the combination of a fiber stretcher and grating compressor. A numerical model is used to predict the compensation, and experimental results that exhibit the main features of the calculations are presented. In the presence of third-order dispersion, an optimal nonlinear phase shift reduces the pulse duration, and enhances the peak power and pulse contrast compared to the pulse produced in linear propagation. Contrary to common belief, fiber stretchers can perform as well or better than grating stretchers in fiber amplifiers, while offering the major practical advantages of a waveguide medium. PMID:19498473

  10. Pulse Self-trapping Robustness to Polarization Mode Dispersion in Optical Fiber

    Institute of Scientific and Technical Information of China (English)

    CHEN Weicheng; XU Wencheng; LUO Aiping; CUI Hu; CHEN Yongzhu; LIU Songhao

    2002-01-01

    In this paper, pulse self-trapping robustness to polarization mode dispersion in optical fibers is studied. Nonlinear pulse can be used to suppress PMD despite the input pulse shapes is found. When the nonlinear effect is stronger (initial pulse amplitude is larger), the suppression degree to PMD is better. As the initial chirp is considered, we find that the chirp is harmful to suppress PMD. The more is initial chirp, the more is the PMD value.

  11. Blue-enhanced supercontinuum generation pumped by a giant-chirped SESAM mode-locked fiber laser

    Science.gov (United States)

    Gao, Shoufei; Wang, Yingying; Sun, Ruoyu; Jin, Dongchen; Liu, Jiang; Wang, Pu

    2016-08-01

    We report on a blue-enhanced supercontinuum generation pumped by a giant-chirped SESAM mode-locked 1064-nm fiber laser, in which the giant chirp is introduced by a piece of 3.5-km single-mode fiber outside of the cavity. The giant-chirped pump source with 2.2-nm spectral bandwidth and 186-ps pulse width is used to enhance dispersive waves generation in blue wavelength. An extremely wide optical spectrum with a broad 3-dB spectral bandwidth of 311 nm (from 446 to 757 nm) and a maximum spectral power density of 4 mW/nm at 464 nm is obtained.

  12. Coherent Combining of Optical Pulses in Spatial, Spectral and Time Domains

    Science.gov (United States)

    Zhou, Tong

    Petawatt-level laser pulses have many potential applications in science and industry, but will require three orders of magnitude increase in pulse repetition rate from existing solid-state laser technology. Fiber lasers can operate at such repetition rates, but are limited in pulse energy. To overcome the gap between current achievable fiber-laser pulse energies (˜mJ) and required pulse energies for high-energy applications (up to 10J), this dissertation work explores four novel techniques: (1) Coherent beam combining in the spatial domain; (2) Coherent spectral combining in spatial and spectral domains; (3) Coherent pulse stacking amplification in the time domain; (4) N-squared coherent combining in spatial and time domains. (1) We demonstrate coherent femtosecond pulse beam combining of up to four chirped-pulse fiber amplifier channels. Theoretical and experimental analysis of combining efficiency dependence on amplitude/phase noise shows the scalability to a large number of channels. (2) We demonstrate coherent femtosecond pulse spectral synthesis by combining three parallel fiber chirped-pulse amplifiers, each amplifying different pulse spectra. This technique simultaneously overcomes individual-amplifier energy/power limitations, and spectral gain narrowing in a single fiber amplifier. (3) We propose and demonstrate a new technique of coherent pulse stacking (CPS) amplification, which uses reflecting resonators to transform a sequence of phase/amplitude modulated optical pulses into a single output pulse. Experimental validation with a single resonator is demonstrated. We show theoretically that the extension to stacking a large number of equal-amplitude pulses can be achieved using multiple reflecting resonators, which enables the extraction of all stored energy in large-core fiber amplifiers. (4) We propose and demonstrate N-squared coherent combining using resonant optical cavities, a novel pulse combining technique based on both spatial combining and

  13. Generation of Ultra-high Intensity Laser Pulses

    International Nuclear Information System (INIS)

    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 1025 W/cm2 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. 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.

  15. 500 MW peak power degenerated optical parametric amplifier delivering 52 fs pulses at 97 kHz repetition rate.

    Science.gov (United States)

    Rothhardt, J; Hädrich, S; Röser, F; Limpert, J; Tünnermann, A

    2008-06-01

    We present a high peak power degenerated parametric amplifier operating at 1030 nm and 97 kHz repetition rate. Pulses of a state-of-the art fiber chirped-pulse amplification (FCPA) system with 840 fs pulse duration and 410 microJ pulse energy are used as pump and seed source for a two stage optical parametric amplifier. Additional spectral broadening of the seed signal in a photonic crystal fiber creates enough bandwidth for ultrashort pulse generation. Subsequent amplification of the broadband seed signal in two 1 mm BBO crystals results in 41 microJ output pulse energy. Compression in a SF 11 prism compressor yields 37 microJ pulses as short as 52 fs. Thus, pulse shortening of more than one order of magnitude is achieved. Further scaling in terms of average power and pulse energy seems possible and will be discussed, since both concepts involved, the fiber laser and the parametric amplifier have the reputation to be immune against thermo-optical effects. PMID:18545609

  16. Numerical simulation for characterizing femtosecond optical pulses with the SPIDER algorithm

    Institute of Scientific and Technical Information of China (English)

    Chai Lu; He Tie-Ying; Gao Feng; Wang Qing-Yue; Xing Qi-Rong; Zhang Zhi-Gang

    2004-01-01

    In this article based on the spectral phase interferometry for direct electric-field reconstruction (SPIDER), the femtosecond pulses with various phase characters are numerically simulated. The spectral phases and amplitudes of the transform-limited pulse, the linear chirped pulse, the cubic dispersion pulse, the quartic dispersion pulse, the self-phase modulation pulse and the pulses with the combination of different chirped characters are retrieved. These characterized pulses are applicable to the real-time measurement as samples for diagnosing the chirped characters of pulses quickly.

  17. Raw Knudsen Engineering 3260 CHIRP subbottom - CHIRP Subbottom Profiler data for the U.S. Atlantic margin.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knudsen Engineering 3260 CHIRP subbottom - CHIRP Subbottom Profiler data were collected in Raw Knudsen SEG-Y Datagram format.

  18. Relativistic Tennis with Photons: Demonstration of Frequency Upshifting by a Relativistic Flying Mirror through Two Colliding Laser Pulses

    CERN Document Server

    Kando, M; Pirozhkov, A S; Ma, J; Daito, I; Chen, L -M; Esirkepov, T Zh; Ogura, K; Homma, T; Hayashi, Y; Kotaki, H; Sagisaka, A; Mori, M; Koga, J K; Daido, H; Bulanov, S V; Kimura, T; Kato, Y; Tajima, T

    2007-01-01

    Since the advent of chirped pulse amplification1 the peak power of lasers has grown dramatically and opened the new branch of high field science, delivering the focused irradiance, electric fields of which drive electrons into the relativistic regime. In a plasma wake wave generated by such a laser, modulations of the electron density naturally and robustly take the shape of paraboloidal dense shells, separated by evacuated regions, moving almost at the speed of light. When we inject another counter-propagating laser pulse, it is partially reflected from the shells, acting as relativistic flying (semi-transparent) mirrors, producing an extremely time-compressed frequency-multiplied pulse which may be focused tightly to the diffraction limit. This is as if the counterstreaming laser pulse bounces off a relativistically swung tennis racket, turning the ball of the laser photons into another ball of coherent X-ray photons but with a form extremely relativistically compressed to attosecond and zeptosecond levels....

  19. Helium in chirped laser fields as a time-asymmetric atomic switch

    Czech Academy of Sciences Publication Activity Database

    Kaprálová-Žďánská, Petra Ruth; Moiseyev, N.

    2014-01-01

    Roč. 141, č. 1 (2014), "014307-1"-"014307-14". ISSN 0021-9606 R&D Projects: GA ČR GAP205/11/0571 Institutional support: RVO:68378271 Keywords : laser excitation * chirped pulses * non-hermitian quantum mechanics * time-asymmetry Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 2.952, year: 2014

  20. Towards attosecond XUV pulses

    International Nuclear Information System (INIS)

    We are constructing a system for attosecond pulse generation via high-order harmonics generation in noble gases. To obtain a single attosecond pulse rather than a pulse train, we employ the regime of a few-cycle-pulse-driven harmonics generation. To achieve it, we are developing an external pulse compressor down to 7 - 10 fs using a gas-filled hollow fiber followed by chirped mirrors. We also proposed the method of high-energy attosecond pulse generation using high-order harmonics generated during the interaction of a relativistic-irradiance laser pulse with a thin foil. (author)

  1. Simulation Model of Rapid TAE Chirping

    Science.gov (United States)

    Wang, Ge; Berk, H. L.

    2010-11-01

    Spontaneous nonlinear coherent frequency chirping structures can arise due to the resonant interaction of energetic particles with a discrete toroidal Alfven eigenmode (TAE). The initial development of a coherent structure is quantitatively described by a now standard hole-clump chirping theory. However, it is still unclear what conditions are needed for the TAE chirping frequency to deviate far from the bulk plasma eigenfrequency and enter the Alfven continuum. In our model, the linear TAE controlling equation is derived from the Berk-Mett quadratic form. The interaction is studied with the linear wave with the nonlinear response of energetic particles. For the present study we simplify the wave to a single symmetric couplet while a two-dimensional distribution is used to describe the energetic particles. In order to resolve the fine structure in the phase space, the numerical scheme integrates the Vlasov equation in the Fourier transformed phase space using a method developed by Breizman and Petviashvili. The simulation results show the saturated wave amplitude and square root law of the initial chirping are in accord with previous theory. We have found conditions where the chirping signal enters the Alfven continuum and a larger amplitude and more rapidly chirping signal then develops. Plots of the phase space structure can reproduce the shape of the separatrix structure that partitions the trapped and passing particles. We attempt to relate the portrait of the phase space structure with the measured wave amplitude and chirping frequency.

  2. Broadband Asymmetric Conical Emission via Cascaded Second-Order Nonlinear Polarization during the Propagation of Femtosecond Laser Pulses in a BBO Crystal

    International Nuclear Information System (INIS)

    We investigate the propagation of femtosecond laser pulses in a 5-mm-thick BBO crystal along the direction of type-I phase-matched second-harmonic generation. An intensity-asymmetric broadband conical emission (500–2000 nm) is demonstrated when a suitable chirp is introduced. It is generated by optical parametric amplification pumped by the second-harmonic light and seeded by the fundamental light which is broadened by cascaded nonlinear processes during second-harmonic generation. (fundamental areas of phenomenology(including applications))

  3. Adaptive Algorithm for Chirp-Rate Estimation

    Directory of Open Access Journals (Sweden)

    Igor Djurović

    2009-01-01

    Full Text Available Chirp-rate, as a second derivative of signal phase, is an important feature of nonstationary signals in numerous applications such as radar, sonar, and communications. In this paper, an adaptive algorithm for the chirp-rate estimation is proposed. It is based on the confidence intervals rule and the cubic-phase function. The window width is adaptively selected to achieve good tradeoff between bias and variance of the chirp-rate estimate. The proposed algorithm is verified by simulations and the results show that it outperforms the standard algorithm with fixed window width.

  4. 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

  5. Development of rf electron gun with energy chirp cell for ultra-short bunch generation

    International Nuclear Information System (INIS)

    We have been developing an S-band photocathode rf electron gun at Waseda University. Our rf-gun cavity was firstly designed by BNL and then, modified by our group. In this paper, we will introduce a newly designed rf-gun cavity with energy chirping cell. To generate an energy chirped electron bunch, we attached extra-cell for 1.6cell rf-gun cavity. Cavity design was done by Superfish and particle tracing by PARMELA. By optimizing the chirping cell, we observed linear chirped electron bunch. The front electron have lower energy than rear. Then transporting about 2m, the bunch can be compressed down to 200fsec electron bunch with the charge of 100pC. This ultrashort bunch will be able to use for generating CSR THz radiation, pumping some material to be studied by pulse radiolysis method, and so on. In this conference, the design of chirping cell attached rf-gun, the results of tracing simulation and plan of manufacturing will be presented. (author)

  6. Ultrasound Elasticity Imaging System with Chirp-Coded Excitation for Assessing Biomechanical Properties of Elasticity Phantom

    Directory of Open Access Journals (Sweden)

    Guan-Chun Chun

    2015-12-01

    Full Text Available The biomechanical properties of soft tissues vary with pathological phenomenon. Ultrasound elasticity imaging is a noninvasive method used to analyze the local biomechanical properties of soft tissues in clinical diagnosis. However, the echo signal-to-noise ratio (eSNR is diminished because of the attenuation of ultrasonic energy by soft tissues. Therefore, to improve the quality of elastography, the eSNR and depth of ultrasound penetration must be increased using chirp-coded excitation. Moreover, the low axial resolution of ultrasound images generated by a chirp-coded pulse must be increased using an appropriate compression filter. The main aim of this study is to develop an ultrasound elasticity imaging system with chirp-coded excitation using a Tukey window for assessing the biomechanical properties of soft tissues. In this study, we propose an ultrasound elasticity imaging system equipped with a 7.5-MHz single-element transducer and polymethylpentene compression plate to measure strains in soft tissues. Soft tissue strains were analyzed using cross correlation (CC and absolution difference (AD algorithms. The optimal parameters of CC and AD algorithms used for the ultrasound elasticity imaging system with chirp-coded excitation were determined by measuring the elastographic signal-to-noise ratio (SNRe of a homogeneous phantom. Moreover, chirp-coded excitation and short pulse excitation were used to measure the elasticity properties of the phantom. The elastographic qualities of the tissue-mimicking phantom were assessed in terms of Young’s modulus and elastographic contrast-to-noise ratio (CNRe. The results show that the developed ultrasound elasticity imaging system with chirp-coded excitation modulated by a Tukey window can acquire accurate, high-quality elastography images.

  7. Interband photorefractive effect in beta-BBO crystal due to multiphoton excitation by intense ultrashort optical pulses.

    Science.gov (United States)

    Xu, Shixiang; Cai, Hua; Zeng, Heping

    2007-08-20

    This paper presents the first experimental observation of interband photo- refractive (PR) effects in beta-BBO crystal due to multiphoton excitation with intense ultrashort pulses. In order to fully characterize the PR effects, a sensitive intracavity scheme is developed to magnify the dynamics of nonlinear lenses induced by the PR effects. The reproducible PR phenomena depend strongly on the power, wavelength, and spatial intensity profile of the intense laser pulses and the electro-optic coefficient of the optical materials. Its response time is from tens of seconds to several minutes. The results may be very helpful for us to find a solution to overcome the deleterious influence of multiphoton induced photo-charges on nonlinear optical frequency conversions, e.g. optical parametric chirped pulse amplification. PMID:19547410

  8. Sub 100-fs, 5.2-$\\mu$m ZGP Parametric Amplifier Driven by a ps Ho:YAG Chirped Pulse Amplifier and its application to high harmonic generation

    CERN Document Server

    Kanai, Tsuneto; Kangaparambil, Sarayoo Sasidharan; Hoogland, Heinar; Holzwarth, Ronald; Pugžlys, Audrius; Baltuška, Andrius

    2016-01-01

    We report a 1 kHz repetition-rate mid-IR (MIR) optical parametric amplifier (OPA) system operating at a central wavelength of 5.2 $\\mu$m with the tail-to-tail spectrum extending over 1.5 $\\mu$m and delivering 40 $\\mu$J pulses that are compressed to 99 fs (5.6 optical cycles). Also we develop a novel pulse compression scheme for further pulse compression and wavelength tunability. As the first application of this laser system, we generated high harmonics in bulk ZnSe above the bandgap, dense exciton generation after 10-photon absorption, high order sum- and difference-frequency generation, ultrafast transition in the conduction band, which reflects the structure of conduction bands.

  9. Controlling condensed-phase vibrational excitation with tailored infrared pulses

    Science.gov (United States)

    Kleiman, V. D.; Arrivo, S. M.; Melinger, J. S.; Heilweil, E. J.

    1998-08-01

    Vibrational population distributions within the CO-stretching T 1u manifold of W(CO) 6 in room-temperature n-hexane were created by using near-transform limited and linearly chirped picosecond infrared excitation pulses. These pulses were characterized using the second harmonic FROG (frequency-resolved optical gating) algorithm to determine the ˜8 cm -1/ps chirp for both positively- and negatively-chirped 2 ps pulses. FROG and time-resolved transient difference spectra were obtained with an InSb focal plane array detector. While unchirped and positively-chirped excitation leads predominantly to v=1 population, negatively-chirped pulses produce excess population in the v=2 level. These results are compared to predictions from density matrix calculations for a model potential.

  10. Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

    International Nuclear Information System (INIS)

    Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5x1017 W/cm2) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime

  11. RF-photonic chirp encoder and compressor for seamless analysis of information flow.

    Science.gov (United States)

    Zalevsky, Zeev; Shemer, Amir; Zach, Shlomo

    2008-05-26

    In this paper we realize an RF photonic chirp compression system that compresses a continuous stream of incoming RF data (modulated on top of an optical carrier) into a train of temporal short pulses. Each pulse in the train can be separated and treated individually while being sampled by low rate optical switch and without temporal loses of the incoming flow of information. Each such pulse can be filtered and analyzed differently. The main advantage of the proposed system is its capability of being able to handle, seamlessly, high rate information flow with all-optical means and with low rate optical switches. PMID:18545501

  12. Amplification of high power short pulse excimer laser with beam smoothing%平滑化窄脉冲高功率准分子激光放大技术

    Institute of Scientific and Technical Information of China (English)

    赵学庆; 黄坷; 黄超; 于力; 刘晶儒; 易爱平; 薛全喜; 华恒祺; 钱航; 郑国鑫; 胡云; 张永生

    2011-01-01

    The combination of optical angular mutiplexing and Echelon Free Induced Spatial Incoherence (EFISI) is a best choice for the pulse compression and beam smoothing in a high power excimer laser system, which relates to the transportation and amplification of smoothed narrow laser pulse mainly. In this paper, the construction of a partial coherence oscillator by scattering method was described and primary results for pulse shaping were provided. Then, the gain characteristics for five laser amplifiers by single-pass amplifications and simulations of different output couplings were discussed, and measures to control over Amplification Spontaneous Emission (ASE) in the short laser pulse amplification was described. Finally, the Main Oscilation Power Amplifer (MOPA) chain of a single-beam XeCl laser and primary results were introduced. Obtained results show that the final output energy is 5-6 J with a pulsewidth around 10 ns and the focal spot is around 300 μm in the diameter. These results indicate that the laser chain and optical design are reasonable, which can be used as a good guide for the specific design of full scale angular multiplexed laser MOPA system.%对于高功率准分子激光,光学角多路和诱导空间非相干(EFISI)光束平滑是高功率准分子激光压缩脉宽、提高功率密度和实现靶面均匀辐照的有效途径,其应用涉及前端至靶前的各个环节,主要体现为平滑化窄脉冲激光的传输放大问题.首先介绍了基于散射法开展的部分相千源前端技术及脉冲整形的初步研究结果,利用直接法和反射率耦合方法,研究了5台激光放大器增益特性.然后,讨论了窄脉宽激光放大时的自发辐射放大(ASE)控制技术,最后,介绍了窄脉冲激光放大实验系统.实验获得了预期的实验结果,输出能量为5~6 J,激光脉宽约10 ns,聚焦光斑约Φ300 μm.单路系统实验结果表明,系统放大链和光学设计合理,基本满足角多路MOPA系统的

  13. Theoretical exploration of harmonic emission and attosecond pulse generation from H2+ in the presence of terahertz pulse

    Science.gov (United States)

    Liu, Hang; Feng, Liqiang

    2016-06-01

    Harmonic generation spectra from H2+ molecule ion driven by the chirped pulse combined with a terahertz (THz) pulse have been theoretically investigated by numerically solving the non-Born-Oppenheimer time-dependent Schrödinger equation (NBO-TDSE). The results show that with the introduction of the chirp, the harmonic cutoff is extended, resulting in a smooth supercontinuum. Further, when the initial vibrational state is prepared as v = 3, and by properly adding a THz controlling pulse, the harmonic yield is enhanced by almost six orders of magnitude compared with the single chirped pulse case. Quantum analyses are shown to explain the harmonic extension and enhancement. Furthermore, through the investigation of the isotopic effect, we find that more intense harmonics are generated in the lighter nucleus. Finally, by properly superposing the harmonics, a series of intense 35 as XUV pulses can be obtained, which are almost six orders of magnitude improvement in comparison with the single chirped pulse case.

  14. Raw Knudsen 320B/R CHIRP Subbottom Profiler - CHIRP Subbottom Profiler data for the Arctic Ocean ECS survey.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knudsen 320B/R CHIRP Subbottom Profiler - CHIRP Subbottom Profiler data were collected in Raw Knudsen SEG-Y Datagram format.

  15. Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier for high-energy femtosecond pulses at 1.55 microm.

    Science.gov (United States)

    Shirakawa, Akira; Ota, Jun; Musha, Mitsuru; Nakagawa, Ken'ichi; Ueda, Ken-Ichi; Folkenberg, Jacob Riis; Broeng, Jes

    2005-02-21

    We report a high-energy femtosecond fiber amplifier based on an air-cladded single-transverse-mode erbium-ytterbium-codoped photonic-crystal fiber with a 26-microm mode-field-diameter. 700-fs, 47-MHz pulses at 1557 nm were amplified and compressed to near-transform-limited 100-fs, 7.4-nJ pulses with 54-kW peak powers without chirped-pulse amplification. A linearly polarized output with an extinction ratio exceeding 42 dB was obtained by double-pass configuration. As an application, supercontinuum spanning from 1000 to 2500 nm was generated by a successive 2-m high-nonlinear fiber with a 140-mW average power. PMID:19494992

  16. Large-mode-area erbium-ytterbium-doped photonic-crystal fiber amplifier for high-energy femtosecond pulses at 1.55 µm

    Science.gov (United States)

    Shirakawa, Akira; Ota, Jun; Musha, Mitsuru; Nakagawa, Ken'Ichi; Ueda, Ken-Ichi; Riis Folkenberg, Jacob; Broeng, Jes

    2005-02-01

    We report a high-energy femtosecond fiber amplifier based on an air-cladded single-transverse-mode erbium-ytterbium-codoped photonic-crystal fiber with a 26-µm mode-field-diameter. 700-fs, 47-MHz pulses at 1557 nm were amplified and compressed to near-transform-limited 100-fs, 7.4-nJ pulses with 54-kW peak powers without chirped-pulse amplification. A linearly polarized output with an extinction ratio exceeding 42 dB was obtained by double-pass configuration. As an application, supercontinuum spanning from 1000 to 2500 nm was generated by a successive 2-m high-nonlinear fiber with a 140-mW average power.

  17. Generation of 1.5 cycle 0.3 TW laser pulses using a hollow-fiber pulse compressor.

    Science.gov (United States)

    Park, Juyun; Lee, Jae-Hwan; Nam, Chang Hee

    2009-08-01

    Pulse compression in a differentially pumped neon-filled hollow fiber was used to generate high-power few-cycle laser pulses. The pulse compression process was optimized by adjusting gas pressure and laser chirp to produce the shortest laser pulses. Precise dispersion control enabled the generation of laser pulses with duration of 3.7 fs and energy of 1.2 mJ. This corresponds to an output of 1.5 cycle, 0.3 TW pulses at a 1 kHz repetition rate using positively chirped 33 fs laser pulses. PMID:19649091

  18. Synchronously pumped femtosecond optical parametric oscillator with broadband chirped mirrors

    Science.gov (United States)

    Stankevičiūte, Karolina; Melnikas, Simas; Kičas, Simonas; Trišauskas, Lukas; Vengelis, Julius; Grigonis, Rimantas; Vengris, Mikas; Sirutkaitis, Valdas

    2015-05-01

    We present results obtained during investigation of synchronously pumped optical parametric oscillator (SPOPO) with broadband complementary chirped mirror pairs (CMP). The SPOPO based on β-BBO nonlinear crystal is pumped by second harmonic of femtosecond Yb:KGW laser and provides signal pulses tunable over spectral range from 625 to 980 nm. More than 500 mW are generated in the signal beam, giving up to 27 % pump power to signal power conversion efficiency. The plane SPOPO cavity mirror pairs were specially designed to provide 99 % reflection in broad spectral range corresponding to signal wavelength tuning (630-1030 nm) and to suppress group delay dispersion (GDD) oscillations down to +/-10 fs2. Dispersion properties of designed mirrors were tested with white light interferometer (WLI) and attributed to the SPOPO tuning behaviour.

  19. Performance of chirped-fsk and chirped-psk in the presence of partial-band interference

    NARCIS (Netherlands)

    Dutta, Ramen; Kokkeler, André B.J.; Zee, van der Ronan; Bentum, Mark J.

    2011-01-01

    To improve interference robustness of wireless communication, spread spectrum techniques are often used. We use the chirp spreading technique along with FSK and PSK binary modulation schemes to obtain interference robust radio communication. The performance of chirped-FSK and chirped- PSK modulation

  20. Morphology of ablation craters generated by ultra-short laser pulses in dentin surfaces: AFM and ESEM evaluation

    International Nuclear Information System (INIS)

    In this study, the surface morphology and structure of dentin after ablation by ultra-short pulses were evaluated using environmental scanning electron microscopy (ESEM) and atomic force microscopy (AFM). The dentin specimens examined were irradiated by a chirped-pulse-amplification (CPA) Ti:sapphire laser (800 nm) and the optimal conditions for producing various nanostructures were determined. Based on the ESEM results, it was possible to identify an energy density range as the ablation threshold for dentin. The laser-induced damage was characterized over the fluence range 1.3-2.1 J/cm2. The results demonstrate that by selecting suitable parameters one can obtain efficient dentin surface preparation without evidence of thermal damage, i.e., with minimized heat affected zones and reduced collateral damage, the latter being normally characterized by formation of microcracks, grain growth and recrystallization in the heat affected zones.

  1. Morphology of ablation craters generated by ultra-short laser pulses in dentin surfaces: AFM and ESEM evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Daskalova, A., E-mail: a_daskalova@code.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Bashir, S.; Husinsky, W. [IAP, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna (Austria)

    2010-11-15

    In this study, the surface morphology and structure of dentin after ablation by ultra-short pulses were evaluated using environmental scanning electron microscopy (ESEM) and atomic force microscopy (AFM). The dentin specimens examined were irradiated by a chirped-pulse-amplification (CPA) Ti:sapphire laser (800 nm) and the optimal conditions for producing various nanostructures were determined. Based on the ESEM results, it was possible to identify an energy density range as the ablation threshold for dentin. The laser-induced damage was characterized over the fluence range 1.3-2.1 J/cm{sup 2}. The results demonstrate that by selecting suitable parameters one can obtain efficient dentin surface preparation without evidence of thermal damage, i.e., with minimized heat affected zones and reduced collateral damage, the latter being normally characterized by formation of microcracks, grain growth and recrystallization in the heat affected zones.

  2. Raw ODEC Bathy2000 CHIRP subbottom profiler - CHIRP high-resolution Seismic Profile data for the Chukchi Cap and Arctic Ocean.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — ODEC Bathy2000 CHIRP subbottom profiler - CHIRP high-resolution Seismic Profile data were collected in Raw ODEC Bathy2000 CHIRP dat Datagram Format.

  3. Raw ODEC Bathy2000 CHIRP subbottom profiler - CHIRP high-resolution Seismic Profile data for the U.S. Arctic Continental Margin.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — ODEC Bathy2000 CHIRP subbottom profiler - CHIRP high-resolution Seismic Profile data were collected in Raw ODEC Bathy2000 CHIRP dat Datagram Format.

  4. Photorefractive surface nonlinearly chirped waveguide arrays

    Science.gov (United States)

    Qi, Pengfei; Feng, Tianrun; Wang, Sainan; Han, Rong; Hu, Zhijian; Zhang, Tianhao; Tian, Jianguo; Xu, Jingjun

    2016-05-01

    We report an alternate type of nonlinear waveguides, photorefractive surface nonlinearly chirped waveguide arrays, which can be directly induced by photorefractive surface waves in virtue of diffusion and drift nonlinearities. The amplitude of such nonlinearly chirped waveguide arrays has an apodized envelope owing to the diffusion nonlinearity. The refractive-index change of the apodized tails converges to a nonzero value which can be handily adjusted by an external electric field. Moreover, the chirp parameters such as amplitude, sign (positive or negative), and initial position can be conveniently adjusted by an external electric field, background illumination, incident beam, etc. Then the guided-wave properties of this type of waveguide arrays are analyzed by using the transfer matrix method. Owing to the flexible tail and the nonlinear chirp, the dispersion curves of the index-guided modes can be tailored by an external electric field and the dispersion curves of ordinary and extraordinary Bragg guided modes couple, intertwine, and anticross with each other. Meanwhile, there is a clear "competition" in the coupling hybrid mode near anticrossing.

  5. Scattering of relativistic electron beam by two counter-propagating laser pulses: A new approach to Raman X-ray amplification

    Directory of Open Access Journals (Sweden)

    Andriyash I.A.

    2013-11-01

    Full Text Available We present a detailed study of the properties of electron beam injected and trapped in an high intensity optical lattice. By using the hydrodynamic and kinetic approaches, we identified the beam trapping conditions, the high-frequency longitudinal beam eigenmodes and their dependence on the electron angular and energy spread. The coupling of these beam eigenmodes to the laser waves is also considered. This corresponds to the convective parametric instability: a stimulated scattering of two laser beams creating the optical lattice on the trapped electron beam mode. The amplification coefficients for the up-scattered Raman modes propagating parallel to the electron beam are calculated and their dependence on the beam characteristics is analyzed.

  6. Complete temporal reconstruction of attosecond high-harmonic pulse trains

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Taec; Ko, Dong Hyuk; Park, Juyun; Tosa, Valer; Nam, Chang Hee, E-mail: chnam@kaist.ac.k [Department of Physics and Coherent X-ray Research Center, KAIST, Daejeon 305-701 (Korea, Republic of)

    2010-08-15

    The method of complete reconstruction of attosecond bursts has been demonstrated for attosecond high-harmonic pulse trains. The retrieved harmonic field provided detailed information about the envelope and the individual attosecond pulses contained in the attosecond pulse train. The time-frequency analysis revealed complicated spectral chirp structures and the contribution of different quantum paths to attosecond pulse formation.

  7. High-energy fibered amplification for large-scale laser facilities

    International Nuclear Information System (INIS)

    This work concerns the development of a double-clad ytterbium-doped single-mode micro-structured flexible fiber-based amplifier, in the nanosecond, multi-kilohertz and milli-Joule regime, for large-scale laser facilities seeding. We have used a multi-stage master oscillator power amplifier fibered architecture. A numerical model of ytterbium-doped double-clad fiber-based amplification, including amplified spontaneous emission, was developed in order to study the behaviour of such amplifier and to correctly design the experimental set-up. This model was completed by a feed-back algorithm to numerically predict the optimal temporal shape to compensate the gain saturation process. We demonstrated experimental results in good agreement with numerical simulations, with the following performances: 0.5 mJ pulse energy, at a frequency repetition from 1 kHz to 10 kHz, with a narrow bandwidth spectrum centred at 1053 nm wavelength, with 10 ns pulse duration on a perfect super-Gaussian temporal profile, an optical signal-to-noise ratio better than 50 dB and a polarization extinction ratio of 20 dB. We checked that the beam quality was diffraction limited, with an M2 measurement of 1.1. Moreover, the system can deliver energies up to 1.5 mJ. Then, we took the advantage of such results to amplify chirped pulses. We demonstrated 0.7 mJ pulse energy, with 570 fs duration at 10 kHz repetition frequency. (author)

  8. Reference hearing threshold levels for chirp signals delivered by an ER-3A insert earphone

    DEFF Research Database (Denmark)

    Gøtsche-Rasmussen, Kristian; Poulsen, Torben; Elberling, Claus

    2012-01-01

    Objective: To establish reference hearing threshold levels for chirps and frequency-specific chirps. Design: Hearing thresholds were determined monaurally for broad-band chirps and octave-band chirps using the Etymotic Research, ER-3A insert earphone. The chirps were presented using two repetitio...

  9. Coherent control of bond making: The performance of rationally phase-shaped femtosecond laser pulses

    CERN Document Server

    Levin, Liat; Kosloff, Ronnie; Koch, Christiane P; Amitay, Zohar

    2015-01-01

    The first step in the coherent control of a photoinduced binary reaction is bond making or photoassociation. We have recently demonstrated coherent control of bond making in multi-photon femtosecond photoassociation of hot magnesium atoms, using linearly chirped pulses [Levin et al., arXiv:1411.1542]. The detected yield of photoassociated magnesium dimers was enhanced by positively chirped pulses which is explained theoretically by a combination of purification and chirp-dependent Raman transitions. The yield could be further enhanced by pulse optimization resulting in pulses with an effective linear chirp and a sub-pulse structure, where the latter allows for exploiting vibrational coherences. Here, we systematically explore the efficiency of phase-shaped pulses for the coherent control of bond making, employing a parametrization of the spectral phases in the form of cosine functions. We find up to an order of magnitude enhancement of the yield compared to the unshaped transform-limited pulse. The highly per...

  10. A bright, cold, velocity-controlled molecular beam by frequency-chirped laser slowing

    CERN Document Server

    Truppe, S; Hambach, M; Fitch, N; Wall, T E; Hinds, E A; Sauer, B E; Tarbutt, M R

    2016-01-01

    Using frequency-chirped radiation pressure slowing we precisely control the velocity of a pulsed CaF molecular beam down to a few m/s, compressing its velocity spread by a factor of 10 while retaining its high brightness. When the final velocity is 15 m/s the flux, measured 1.3 m from the source, is $8 \\times 10^5$ molecules per cm$^2$ per shot in a single rovibrational state. The beam is suitable for loading a magneto-optical trap of molecules. Our method, when combined with transverse laser cooling, can improve the precision of spectroscopic measurements that test fundamental physics. We compare the frequency-chirped slowing method with slowing using frequency-broadened light.

  11. First observation of multi-pulse X-ray train via multi-collision laser Compton scattering

    International Nuclear Information System (INIS)

    A compact hard X-ray source via laser Compton scattering (LCS) has been developed for biological and medical applications at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan. The multi-collision LCS has been investigated in order to enhance the X-ray yields. The first observation of multi-pulse X-ray train with 6 pulses via the multi-collision LCS has been successfully demonstrated between the multi-bunch electron train with 6 bunches and the multi-pulse Ti:Sa laser train with 6 pulses. The 32 MeV electron train was generated from a Cs2Te photocathode rf gun with a multi-pulse UV laser and the S-band linac. The Ti:Sa laser train was obtained with the chirp pulse amplification (CPA) including the modified regenerative amplifier. The X-ray train with 6 pulses with 12.6 ns spacing was observed with the micro-channel plate (MCP). The maximum energy of the X-ray is analytically estimated to be about 24 keV and the total number of generated photons was calculated to be about 1.8x106 photons/train.

  12. Role of wavefront aberrations of amplified femtosecond pulses in nonlinear optics

    OpenAIRE

    Borrego Varillas, Rocío

    2012-01-01

    [ES] Desde la primera demostración experimental en 1960, el láser ha revolucionado campos tan diversos como la Física, la Química o la Medicina. La atención se centró pronto en conseguir pulsos cada vez más cortos y energéticos. Con este propósito surgieron varias técnicas como el Q-switching o el mode locking, hasta la aparición en 1985 de la tecnología CPA (chirped pulse amplification). La potencia pico alcanzada por los sistemas CPA abrió nuevas fronteras en el procesado de materiales, la ...

  13. Study of the transverse lasing in big size crystals of Ti:Sa. Application to the design of the peta-watt high-energy amplifier of the pilot laser of the LASERIX facility; Etude de l'amplification parasite transverse de la fluorescence dans les cristaux de Ti:Sa de grandes dimensions. Application a la realisation de l'amplificateur petawatt haute energie du laser pilote de la station LASERIX

    Energy Technology Data Exchange (ETDEWEB)

    Ple, F

    2007-11-15

    This manuscript presents experimental and theoretical works accomplished for the development of the LASERIX laser driver. The main goal of this thesis work was to design a high energy and high repetition rate titanium doped sapphire amplifier (Ti:Sa) allowing to reach an energy of 40 J at a repetition rate of 0.1 Hz before compression. After a general description of amplification in chirped pulse amplification Ti:Sa laser systems (Chapter 1), I present the two particular developments we made during this work for high energy amplification (Chapter 2). First, the spatial shaping and the homogenization based on micro-lens array (MLA) systems of the eight Nd-Glass pump lasers dedicated to the pumping of the last booster amplifier.Secondly, the suppression of parasitic effects due to transverse amplification of the fluorescence in the last booster amplifier Ti:Sa crystal. The developments performed as part of this thesis allowed us to amplify an impulsion of 2 J of energy up to 39 J in a crystal of 10 cm diameter. I also present the simulation program I developed (Chapter 3) in order to simulate the three dimensional parasitic lasing effect and fluorescence transverse amplification phenomena in large Ti:Sa crystals. A parametric study of these parasitic effects is also presented. Finally, the last part of this manuscript (Chapter 4) gives prospects of this work as part of the large future ELI and ILE projects. (author)

  14. Click- and chirp-evoked human compound action potentials

    OpenAIRE

    Chertoff, Mark; Lichtenhan, Jeffery; Willis, Marie

    2010-01-01

    In the experiments reported here, the amplitude and the latency of human compound action potentials (CAPs) evoked from a chirp stimulus are compared to those evoked from a traditional click stimulus. The chirp stimulus was created with a frequency sweep to compensate for basilar membrane traveling wave delay using the O-Chirp equations from Fobel and Dau [(2004). J. Acoust. Soc. Am. 116, 2213–2222] derived from otoacoustic emission data. Human cochlear traveling wave delay estimates were obta...

  15. Tapered and linearly chirped fiber Bragg gratings with co-directional and counter-directional resultant chirps

    Science.gov (United States)

    Osuch, Tomasz

    2016-05-01

    A method of spectral width tailoring of tapered fiber Bragg gratings is theoretically analyzed and experimentally verified. This concept is based on inscription grating structures in which synthesis of chirps comes from both taper profile and a linearly chirped phase mask used for grating inscription. It is shown that under UV exposure and depending on the orientation of the optical fiber taper relative to the variable-pitch phase mask, tapered and linearly chirped fiber Bragg gratings (TCFBG) with resultant co-directional or counter-directional chirps are achieved. Thus, both effects, those of reduction and enhancement of the grating chirp, as well as their influence on the grating spectral response, are presented. In particular, using the above approach TCFBG with significantly narrowed spectral width are shown. Moreover, fused tapered chirped FBG with relatively large waist diameter are shown having broad spectrum, something that prior to now was not attainable using previously developed techniques.

  16. Whispering Gallery Pulse Compressor

    International Nuclear Information System (INIS)

    A barrel-like cavity resonant at a whispering gallery mode is known as capable to provide a SLED-like rf pulse compression. To enhance the power handling capacity of the compressor, we propose to use a coupler based on a wave tunneling through a continuous slot. A modeling low power 11.4 GHz experiment proved to be consistent with theory. A preliminary technical design for an evacuated high-power compressor has also been developed. According to a theory, a twin-cavity version of the device can efficiently compress microwave pulses produced with sources of limited bandwidth, in particular frequency-chirped pulses

  17. Effect of chromatic-dispersion-induced chirp on the temporal coherence properties of individual beams from spontaneous four-wave mixing

    International Nuclear Information System (INIS)

    Temporal coherence of individual signal or idler beam, determined by the spectral correlation property of photon pairs, is important for realizing quantum interference among independent sources. Based on spontaneous four-wave mixing in optical fibers, we study the effect of chirp on the temporal coherence property by introducing a different amount of chirp into either the pulsed pump or individual signal (idler) beam. The investigation shows that the pump chirp induces additional frequency correlation into photon pairs; the mutual spectral correlation of photon pairs and the coherence of individual beam can be characterized by measuring the intensity correlation function g(2) of the individual beam. To improve the coherence degree, the pump chirp should be minimized. Moreover, a Hong-Ou-Mandel-type two-photon interference experiment with the signal beams generated in two different fibers illustrates that the chirp of the individual signal (idler) beam does not change the temporal coherence degree, but affects the temporal mode matching. To achieve high visibility among multiple sources, apart from improving the coherence degree, mode matching should be optimized by managing the chirps of individual beams.

  18. What We Can Learn about Ultrashort Pulses by Linear Optical Methods

    Directory of Open Access Journals (Sweden)

    Karoly Osvay

    2013-04-01

    Full Text Available Spatiotemporal compression of ultrashort pulses is one of the key issues of chirped pulse amplification (CPA, the most common method to achieve high intensity laser beams. Successful shaping of the temporal envelope and recombination of the spectral components of the broadband pulses need careful alignment of the stretcher-compressor stages. Pulse parameters are required to be measured at the target as well. Several diagnostic techniques have been developed so far for the characterization of ultrashort pulses. Some of these methods utilize nonlinear optical processes, while others based on purely linear optics, in most cases, combined with spectrally resolving device. The goal of this work is to provide a review on the capabilities and limitations of the latter category of the ultrafast diagnostical methods. We feel that the importance of these powerful, easy-to-align, high-precision techniques needs to be emphasized, since their use could gradually improve the efficiency of different CPA systems. We give a general description on the background of spectrally resolved linear interferometry and demonstrate various schematic experimental layouts for the detection of material dispersion, angular dispersion and carrier-envelope phase drift. Precision estimations and discussion of potential applications are also provided.

  19. Intraband effects on ultrafast pulse propagation in semiconductor optical amplifier

    Indian Academy of Sciences (India)

    K Hussain; S K Varshney; P K Datta

    2010-11-01

    High bit-rate (>10 Gb/s) signals are composed of very short pulses and propagation of such pulses through a semiconductor optical amplifier (SOA) requires consideration of intraband phenomena. Due to the intraband effects, the propagating pulse sees a fast recovering nonlinear gain which introduces less distortion in the pulse shape and spectrum of the output pulse but introduces a positive chirping at the trailing edge of the pulse.

  20. Chirp- and random-based coded ultrasonic excitation for localized blood-brain barrier opening

    Science.gov (United States)

    Kamimura, H. A. S.; Wang, S.; Wu, S.-Y.; Karakatsani, M. E.; Acosta, C.; Carneiro, A. A. O.; Konofagou, E. E.

    2015-10-01

    Chirp- and random-based coded excitation methods have been proposed to reduce standing wave formation and improve focusing of transcranial ultrasound. However, no clear evidence has been shown to support the benefits of these ultrasonic excitation sequences in vivo. This study evaluates the chirp and periodic selection of random frequency (PSRF) coded-excitation methods for opening the blood-brain barrier (BBB) in mice. Three groups of mice (n  =  15) were injected with polydisperse microbubbles and sonicated in the caudate putamen using the chirp/PSRF coded (bandwidth: 1.5-1.9 MHz, peak negative pressure: 0.52 MPa, duration: 30 s) or standard ultrasound (frequency: 1.5 MHz, pressure: 0.52 MPa, burst duration: 20 ms, duration: 5 min) sequences. T1-weighted contrast-enhanced MRI scans were performed to quantitatively analyze focused ultrasound induced BBB opening. The mean opening volumes evaluated from the MRI were 9.38+/- 5.71 mm3, 8.91+/- 3.91 mm3and 35.47+/- 5.10 mm3 for the chirp, random and regular sonications, respectively. The mean cavitation levels were 55.40+/- 28.43 V.s, 63.87+/- 29.97 V.s and 356.52+/- 257.15 V.s for the chirp, random and regular sonications, respectively. The chirp and PSRF coded pulsing sequences improved the BBB opening localization by inducing lower cavitation levels and smaller opening volumes compared to results of the regular sonication technique. Larger bandwidths were associated with more focused targeting but were limited by the frequency response of the transducer, the skull attenuation and the microbubbles optimal frequency range. The coded methods could therefore facilitate highly localized drug delivery as well as benefit other transcranial ultrasound techniques that use higher pressure levels and higher precision to induce the necessary bioeffects in a brain region while avoiding damage to the surrounding healthy tissue.

  1. Attosecond pulse shaping using partial phase matching

    International Nuclear Information System (INIS)

    We propose a method for programmable shaping of the amplitude and phase of the extreme ultraviolet and x-ray attosecond pulses produced by high-order harmonic generation. It overcomes the bandwidth limitations of existing spectral filters and enables removal of the intrinsic attosecond chirp as well as the synthesis of pulse sequences. It is based on partial phase matching using a longitudinally addressable modulation. Although the method is in principle applicable to any form of partial phase matching, we focus on quasi-phase matching using a counterpropagating pulse train. We present simulations of the production of isolated attosecond pulses at 250 eV, including a 31 as transform-limited pulse, tunably chirped pulses and double pulses. (paper)

  2. Can Anomalous Amplification be Attained without Postselection?

    Science.gov (United States)

    Martínez-Rincón, Julián; Liu, Wei-Tao; Viza, Gerardo I.; Howell, John C.

    2016-03-01

    We present a parameter estimation technique based on performing joint measurements of a weak interaction away from the weak-value-amplification approximation. Two detectors are used to collect full statistics of the correlations between two weakly entangled degrees of freedom. Without discarding of data, the protocol resembles the anomalous amplification of an imaginary-weak-value-like response. The amplification is induced in the difference signal of both detectors allowing robustness to different sources of technical noise, and offering in addition the advantages of balanced signals for precision metrology. All of the Fisher information about the parameter of interest is collected. A tunable phase controls the strength of the amplification response. We experimentally demonstrate the proposed technique by measuring polarization rotations in a linearly polarized laser pulse. We show that in the presence of technical noise the effective sensitivity and precision of a split detector is increased when compared to a conventional continuous-wave balanced detection technique.

  3. Explanatory Model for Sound Amplification in a Stethoscope

    Science.gov (United States)

    Eshach, H.; Volfson, A.

    2015-01-01

    In the present paper we suggest an original physical explanatory model that explains the mechanism of the sound amplification process in a stethoscope. We discuss the amplification of a single pulse, a continuous wave of certain frequency, and finally we address the resonant frequencies. It is our belief that this model may provide students with…

  4. Coherent control in room-temperature quantum dot semiconductor optical amplifiers using shaped pulses

    CERN Document Server

    Karni, Ouri; Eisenstein, Gadi; Ivanov, Vitalii; Reithmaier, Johann Peter

    2016-01-01

    We demonstrate the ability to control quantum coherent Rabi-oscillations in a room-temperature quantum dot semiconductor optical amplifier (SOA) by shaping the light pulses that trigger them. The experiments described here show that when the excitation is resonant with the short wavelength slope of the SOA gain spectrum, a linear frequency chirp affects its ability to trigger Rabi-oscillations within the SOA: A negative chirp inhibits Rabi-oscillations whereas a positive chirp can enhance them, relative to the interaction of a transform limited pulse. The experiments are confirmed by a numerical calculation that models the propagation of the experimentally shaped pulses through the SOA.

  5. Femtosecond soliton amplification in nonlinear dispersive traps and soliton dispersion management

    OpenAIRE

    Vladimir N. Serkin; Hasegawa, Akira

    2000-01-01

    The nonlinear pulse propagation in an optical fibers with varying parameters is investigated. The capture of moving in the frequency domain femtosecond colored soliton by a dispersive trap formed in an amplifying fiber makes it possible to accumulate an additional energy and to reduce significantly the soliton pulse duration. Nonlinear dynamics of the chirped soliton pulses in the dispersion managed systems is also investigated. The methodology developed does provide a systematic way to gener...

  6. Chirped photonic crystals: a natural strategy for broadband reflectance

    CERN Document Server

    Cook, Caleb Q

    2016-01-01

    One-dimensional photonic crystals with slowly varying, i.e. "chirped", lattice period are responsible for broadband light reflectance in many diverse biological contexts, ranging from the shiny coatings of various beetles to the eyes of certain butterflies. We present a quantum scattering analogy for light reflection from these adiabatically chirped photonic crystals (ACPCs) and apply a WKB-type approximation to obtain a closed-form expression for the reflectance. From this expression we infer several design principles, including a differential equation for the chirp pattern required to elicit a given reflectance spectrum and the minimal number of bilayers required to exceed a desired reflectance threshold. Comparison of the number of bilayers found in ACPCs throughout nature and our predicted minimal required number also gives a quantitative measure of the optimality of chirped biological reflectors. Together these results elucidate the design principles of chirped reflectors in nature and their possible app...

  7. Analysis of dispersion compensation for position-dependence in externally modulated CATV lightwave systems by using chirped fiber grating

    Institute of Scientific and Technical Information of China (English)

    Qing Ye; Feng Liu; Haiwen Cai; Ronghui Qu; Zujie Fang

    2005-01-01

    The dispersion compensation characteristics of the chirped fiber grating (CFG) for different dispersion compensation positions are analyzed in externally modulated cable television (CATV) lightwave system and the analytic expression of the composite second order (CSO) distortion is derived. The analyses give a reasonable explanation for the position-dependent effect of CFG dispersion compensator, which was found in practical systems. Moreover, the theoretical result is also verified by an experiment. It is believed that the theory will be helpful in designing optical CATV fiber links with nodes at proper positions both for intensity amplification and dispersion compensation.

  8. Electron-yield enhancement in a Laser-Wakefield accelerator driven by asymmetric laser pulses

    CERN Document Server

    Leemans, W P; Esarey, E; Geddes, C G R; Toth, C; Trines, R; Schroeder, C B; Shadwick, B A; Tilborg, J V; Faure, J

    2002-01-01

    The effect of asymmetric laser pulses on electron yield from a laser Wakefield accelerator has been experimentally studied using > 10 sup 1 sup 9 cm sup - sup 3 plasmas and a 10 TW, >45 fs, Ti:Al sub 2 O sub 3 laser. The laser pulse shape was controlled through nonlinear chirp with a grating pair compressor. Pulses (76 fs FWHM) with a steep rise and positive chirp were found to significantly enhance the electron yield compared to pulses with a gentle rise and negative chirp. Theory and simulation show that fast rising pulses can generate larger amplitude wakes that seed the growth of the self-modulation instability, and that frequency chirp is of minimal importance for the experimental parameters.

  9. Chirped Auger electron emission due to field-assisted post-collision interaction

    Directory of Open Access Journals (Sweden)

    Bonitz M.

    2013-03-01

    Full Text Available We have investigated the Auger decay in the temporal domain by applying a terahertz streaking light field. Xenon and krypton atoms were studied by implementing the free-electron laser in Hamburg (FLASH as well as a source of high-order harmonic radiation combined with terahertz pulses from an optical rectification source. The observed linewidth asymmetries in the streaked spectra suggest a chirped Auger electron emission which is understood in terms of field-assisted post-collision interaction. The experimentally obtained results agree well with model calculations.

  10. Pulse retiming based on XPM using parabolic pulses formed in a fiber Bragg grating

    OpenAIRE

    Parmigiani, F.; Petropoulos, P.; Ibsen, M.; Richardson, D.J.

    2006-01-01

    We experimentally demonstrate a novel all-optical all-fiberized pulse retiming scheme incorporating parabolic pulses generated in a linear fashion through pulse shaping in a superstructured fiber Bragg grating. The scheme relies on chirping the signal to be retimed using cross-phase modulation with the broader parabolic clock pulses, and subsequently retiming it through linear propagation in a dispersive medium. We demonstrate the cancellation of up to 4-ps root-mean-square timing jitter for ...

  11. Fast Decompression Of Ultra-Thin Targets For High-Energy, High-Contrast Laser Pulses

    Science.gov (United States)

    Antici, P.; Fuchs, J.; Lefebvre, E.; Gremillet, L.; Brambrink, E.; Audebert, P.; Pépin, H.

    2010-02-01

    In the laser-plasma interaction process, for ultra-high temporal contrast laser pulses, experimental measurements show that reducing the thickness of solid targets increases the laser-to-fast electrons energy conversion and the hot electron temperature. We have performed an experiment using the LULI 100 TW laser facility working in the chirped pulse amplification (CPA) mode at a wavelength λ0 = 1.057 μm, pulse duration 320 fs, laser spot size FWHM ˜6 μm and intensity ˜1×1018 W/cm2 in which the laser pulses were temporal-contrast enhanced by the use of two plasma mirrors. Shots were performed on Si3N4 aluminum coated targets of thickness 30 nm to 500 nm. Spectra of the laser-accelerated electrons were recorded with a spectrometer and are compared to PIC simulations performed with the CALDER code. The simulations allow an insight into the electron heating process during the laser-matter interaction.

  12. Investigation of temporal contrast effects in femtosecond pulse laser micromachining of metals.

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Benjamin (Pennsylvania State University, Freeport, PA); Palmer, Jeremy Andrew

    2006-06-01

    Femtosecond pulse laser drilling has evolved to become a preferred process for selective (maskless) micromachining in a variety of materials, including metals, polymers, semiconductors, ceramics, and living tissue. Manufacturers of state-of-the-art femtosecond laser systems advertise the inherent advantage of micromachining with ultra short pulses: the absence of a heat affected zone. In the ideal case, this leads to micro and nano scale features without distortion due to melt or recast. However, recent studies have shown that this is limited to the low fluence regime in many cases. High dynamic range autocorrelation studies were performed on two commercial Ti:sapphire femtosecond laser systems to investigate the possible presence of a nanosecond pedestal in the femtosecond pulse produced by chirped pulse amplification. If confirmed, nanosecond temporal phenomena may explain many of the thermal effects witnessed in high fluence micromachining. The material removal rate was measured in addition to feature morphology observations for percussion micro drilling of metal substrates in vacuum and ambient environments. Trials were repeated with proposed corrective optics installed, including a variable aperture and a nonlinear frequency doubling crystal. Results were compared. Although the investigation of nanosecond temporal phenomena is ongoing, early results have confirmed published accounts of higher removal rates in a vacuum environment.

  13. Chirped-Superlattice, Blocked-Intersubband QWIP

    Science.gov (United States)

    Gunapala, Sarath; Ting, David; Bandara, Sumith

    2004-01-01

    An Al(x)Ga(1-x)As/GaAs quantum-well infrared photodetector (QWIP) of the blocked-intersubband-detector (BID) type, now undergoing development, features a chirped (that is, aperiodic) superlattice. The purpose of the chirped superlattice is to increase the quantum efficiency of the device. A somewhat lengthy background discussion is necessary to give meaning to a brief description of the present developmental QWIP. A BID QWIP was described in "MQW Based Block Intersubband Detector for Low-Background Operation" (NPO-21073), NASA Tech Briefs Vol. 25, No. 7 (July 2001), page 46. To recapitulate: The BID design was conceived in response to the deleterious effects of operation of a QWIP at low temperature under low background radiation. These effects can be summarized as a buildup of space charge and an associated high impedance and diminution of responsivity with increasing modulation frequency. The BID design, which reduces these deleterious effects, calls for a heavily doped multiple-quantum-well (MQW) emitter section with barriers that are thinner than in prior MQW devices. The thinning of the barriers results in a large overlap of sublevel wave functions, thereby creating a miniband. Because of sequential resonant quantum-mechanical tunneling of electrons from the negative ohmic contact to and between wells, any space charge is quickly neutralized. At the same time, what would otherwise be a large component of dark current attributable to tunneling current through the whole device is suppressed by placing a relatively thick, undoped, impurity-free AlxGa1 x As blocking barrier layer between the MQW emitter section and the positive ohmic contact. [This layer is similar to the thick, undoped Al(x)Ga(1-x)As layers used in photodetectors of the blocked-impurity-band (BIB) type.] Notwithstanding the aforementioned advantage afforded by the BID design, the responsivity of a BID QWIP is very low because of low collection efficiency, which, in turn, is a result of low

  14. Stretched pulse Yb3+:silica fibre laser

    OpenAIRE

    Cautaerts, V.; Richardson, D.J.; Paschotta, R.; Hanna, D.C.

    1997-01-01

    We report what we believe to be the first results on short-pulse generation in Yb3+:silica fiber. By applying the stretched pulse technique in a unidirectional, polarization-switch Yb3+ fiber laser incorporating a prism-based dispersive delay line, we obtain self-start mode locking and 100pJ pulses that can be compressed to give clean chirp-free

  15. Perambatan Gelombang Optik pada Grating Sinusoidal dengan Chirp dan Taper

    Directory of Open Access Journals (Sweden)

    Isnani Darti

    2009-11-01

    menggunakan MIL, dipelajari perubahan respon optik pada grating sinusoidal akibat variasi amplitudo modulasi indeks (taper dan variasi frekuensi spasial grating (chirp. Hasil simulasi menunjukkan bahwa taper menyebabkan adanya fenomena penghilangan side-lobe pada spektrum transmitansi. Adanya chirp menyebabkan penghalusan side-lobe pada spektrum transmitansi dengan semakin besar parameter chirp menyebabkan peningkatan transmitansi di sekitar pusat band-gap dari grating homogen. Selain implementasi integrasi numerik (Runge-Kutta, MIL merupakan metode eksak sehingga dapat digunakan untuk mengevaluasi validitas metode yang sering digunakan yaitu Persamaan Moda Tergandeng (PMT. Dari hasil perbandingan dapat disimpulkan bahwa secara umum PMT kurang akurat dalam menganalisis struktur grating sinusoidal baik homogen maupun tak-homogen.

  16. Controlling the formation of excited neutral D* fragments of D2 using intense ultrashort laser pulses

    Science.gov (United States)

    Feizollah, Peyman; Berry, Ben; Severt, T.; Jochim, Bethany; Zohrabi, M.; Kanaka Raju, P.; Rajput, Jyoti; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.

    2016-05-01

    Excited neutral D* fragments (n >> 1) are produced by the interaction of strong-field laser pulses with D2 molecules. In this work, we focus on the formation of low kinetic energy release (KER) D* fragments, which are relatively unstudied, using NIR (800-nm) and UV (400-nm) laser pulses. The KER spectrum is found to be very sensitive to the laser parameters, including laser chirp. By changing the chirp of the UV laser pulses, two separate low-KER peaks are generated instead of a single peak. Moreover, the ratio between these peaks can be controlled with the chirp. Similarly, by chirping the NIR pulses, the low-KER peak is attenuated and shifted to lower energy. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy. BJ was also supported in part by DOE-SCGF (DE-AC05-06OR23100).

  17. Strictly all-fiber picosecond Ytterbium fiber laser utilizing chirped-fiber-Bragg-gratings for dispersion control

    OpenAIRE

    KATZ, Ori; Sintov, Yoav

    2008-01-01

    A compact, strictly all-fiber, picosecond pulse source based on ytterbium (Yb) doped fiber is described. Stable solitary mode-locking is obtained in a fiber-oscillator utilizing a carefully designed chirped fiber-Bragg-grating (C-FBG) for both dispersion control and spectral filtering. Self-starting is assured through the use of a fiber-coupled semiconductor-saturable-absorber-mirror (SESAM). The oscillator's 50MHz 3.8ps pulse-train output at 1064nm wavelength is amplified to 1.2W average pow...

  18. Amplification of cylindrically polarized laser beams in single crystal fiber amplifiers

    OpenAIRE

    Piehler, Stefan; Délen, Xavier; Rumpel, Martin; Didierjean, Julien; Aubry, Nicolas; Graf, Thomas; Balembois, François; Georges, Patrick; Abdou Ahmed, Marwan

    2013-01-01

    Yb:YAG single crystal fiber (SCF) amplifiers have recently drawn much attention in the field of amplification of ultra-short pulses. In this paper, we report on the use of SCF amplifiers for the amplification of cylindrically polarized laser beams, as such beams offer promising properties for numerous applications. While the amplification of cylindrically polarized beams is challenging with other amplifier designs due to thermally induced depolarization, we demonstrate the amplification of 32...

  19. Simulation of Novel Tunable Nonlinear Chirped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; ZHANG Xiao-guang; YU Li; YANG Bo-jun

    2003-01-01

    A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic field, the period of the grating can be changed with the strain imposed on it by the magnetostrictive effect .The chirped characteristics can be tuned by changing the magnetic filed which is very flexible in designing.

  20. Theoretical and experimental investigation of photopolymer chirped gratings formation

    OpenAIRE

    Dovolnov, Eugene A.; Sharangovich, Sergey N.; Sheridan, John T.

    2005-01-01

    In the work an analytical model of transmission holographic grating formation by light beams with non-uniform phase-amplitude profiles is presented. The model takes into consideration influence of light absorption of a photopolymer with dye-sensitizer and nonlinearity of photo-polymerization on the spatial profiles and diffraction properties of the chirped grating. The model of diffraction efficiency and selective properties of chirped gratings is also presented. The results of fi...

  1. Iterative direction-of-arrival estimation with wideband chirp signals

    Science.gov (United States)

    Wang, Genyuan; Xia, Xiang-Gen; Chen, Victor C.

    1999-11-01

    Amin et. al. recently developed a time-frequency MUSIC algorithm with narrow band models for the estimation of direction of arrival (DOA) when the source signals are chirps. In this research, we consider wideband models. The joint time-frequency analysis is first used to estimate the chirp rates of the source signals and then the DOA is estimated by the MUSIC algorithm with an iterative approach.

  2. Optical pulse compression using a nonlinear optical loop mirror constructed from dispersion decreasing fiber

    Institute of Scientific and Technical Information of China (English)

    CAO Wenhua; LIU Songhao

    2004-01-01

    A novel scheme to compress optical pulses is proposed and demonstrated numerically, which is based on a nonlinear optical loop mirror constructed from dispersion decreasing fiber (DDF). We show that, in contrast to the conventional soliton-effect pulse compression in which compressed pulses are always accompanied by pedestals and frequency chirps owning to nonlinear effects, the proposed scheme can completely suppress pulse pedestals and frequency chirps. Unlike the adiabatic compression technique in which DDF length must increase exponentially with input pulsewidth, the proposed scheme does not require adiabatic condition and therefore can be used to compress long pulses by using reasonable fiber lengths. For input pulses with peak powers higher than a threshold value, the compressed pulses can propagate like fundamental solitons. Furthermore, the scheme is fairly insensitive to small variations in the loop length and is more robust to higher-order nonlinear effects and initial frequency chirps than the adiabatic compression technique.

  3. Copper ESEEM and HYSCORE through ultra-wideband chirp EPR spectroscopy.

    Science.gov (United States)

    Segawa, Takuya F; Doll, Andrin; Pribitzer, Stephan; Jeschke, Gunnar

    2015-07-28

    The main limitation of pulse electron paramagnetic resonance (EPR) spectroscopy is its narrow excitation bandwidth. Ultra-wideband (UWB) excitation with frequency-swept chirp pulses over several hundreds of megahertz overcomes this drawback. This allows to excite electron spin echo envelope modulation (ESEEM) from paramagnetic copper centers in crystals, whereas up to now, only ESEEM of ligand nuclei like protons or nitrogens at lower frequencies could be detected. ESEEM spectra are recorded as two-dimensional correlation experiments, since the full digitization of the electron spin echo provides an additional Fourier transform EPR dimension. Thus, UWB hyperfine-sublevel correlation experiments generate a novel three-dimensional EPR-correlated nuclear modulation spectrum. PMID:26233121

  4. Tuning characteristics of femtosecond optical parametric oscillator with broadband chirped mirrors

    Science.gov (United States)

    Stankevičiūtė, Karolina; Vengris, Mikas; Melnikas, Simas; Kičas, Simonas; Grigonis, Rimantas; Sirutkaitis, Valdas

    2015-12-01

    We present the investigation of a synchronously pumped optical parametric oscillator (SPOPO) based on beta barium borate (BBO) nonlinear crystal with broadband complementary chirped mirror pairs (CMPs). Three SPOPO cavity configurations with slightly different intracavity dispersion were explored. Dispersion properties of cavity mirrors were characterized using a white light interferometer and found to be the key factor determining the gap-free tuning range as well as simultaneous multiwavelength generation. The SPOPO is pumped by the second harmonic of a Yb:KGW oscillator and provides signal pulses tunable over a spectral range from 625 to 980 nm. Signal pulse duration ranges from 102 to 268 fs in various intracavity dispersion regimes. In addition, signal beam power in excess of 500 mW is demonstrated, corresponding to 27% conversion efficiency from pump to signal wave.

  5. Excitation of chirping whistler waves in a laboratory plasma

    Science.gov (United States)

    An, Xin

    2015-11-01

    Whistler mode chorus emissions with a characteristic frequency chirp largely control the dynamic variability of the Earth's outer radiation belt. They are responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a gyrating beam of energetic electrons injected into a cold plasma. It is shown that there is an optimal beam density for frequency chirps, which indicates the existence of optimum wave amplitude for the generation of chirps. Also, frequency chirps only occur for a very narrow range of ratio of fpe /fce , similar to that observed in space. Strong magnetic field gradient, which prohibits the formation of phase space electron hole, disrupts frequency chirps as expected. Broadband whistler waves similar to magnetospheric hiss are also observed at relatively high plasma density. Their mode structures are identified by the phase-correlation technique. It is demonstrated that broadband whistlers are excited through Landau resonance, cyclotron resonance and anomalous cyclotron resonance. Wave growth rate and wave normal angle given by linear theory are consistent with experimental results in general. Preliminary particle-in-cell simulation captures the linear theory prediction of broadband whistlers and also gives important information on the evolution of electron distribution function. Supported by NSF/DOE Plasma Partnership grant DE-SC0010578.

  6. Temporal Characterization of individual Harmonics of an attosecond pulse train by THz Streaking

    CERN Document Server

    Ardana-Lamas, F; Stepanov, A; Gorgisyan, I; Juranic, P; Abela, R; Hauri, C P

    2015-01-01

    We report on the global temporal pulse characteristics of individual harmonics in an attosecond pulse train by means of photo-electron streaking in a strong low-frequency transient. The scheme allows direct retrieval of pulse durations and first order chirp of individual harmonics without the need of temporal scanning. The measurements were performed using an intense THz field generated by tilted phase front technique in LiNbO_3 . Pulse properties for harmonics of order 23, 25 and 27 show that the individual pulse durations and linear chirp are decreasing by the harmonic order.

  7. Ambiguity function and accuracy of the hyperbolic chirp: comparison with the linear chirp

    OpenAIRE

    Balleri, A.; Farina, A.

    2016-01-01

    In this paper, we derive the Ambiguity Function (AF) of a narrowband and a wideband hyperbolic chirp. We calculate the second derivatives of the squared amplitude of the narrowband Complex Ambiguity Function (CAF) and use them to calculate the Fisher Information Matrix (FIM) of the estimators of the target range and velocity. The FIM is then used to calculate the Cramer-Rao Lower Bounds (CRLB) of the variance of the estimators and to ´ carry out an analysis of estimation performance and a com...

  8. Nonlinear pulse compression

    OpenAIRE

    Grün, Alexander

    2014-01-01

    In this thesis I investigate two methods for generating ultrashort laser pulses in spectral regions which are ordinarily difficult to achieve by the existing techniques. These pulses are specially attractive in the study of ultrafast (few femtosecond) atomic and molecular dynamics. The first involves Optical Parametric Amplification (OPA) mediated by four-wave-mixing in gas and supports the generation of ultrashort pulses in the Near-InfraRed (NIR) to the Mid-InfraRed (MIR) spectral regio...

  9. Time-domain analysis of a dynamically tuned signal recycled interferometer for the detection of chirp gravitational waves from coalescing compact binaries

    CERN Document Server

    Simakov, D A

    2013-01-01

    In this article we study a particular method of detection of chirp signals from coalescing compact binary stars -- the so-called dynamical tuning, i.e. amplification of the signal via tracking of its instantaneous frequency by the tuning of the signal-recycled detector. A time-domain consideration developed for signal-recycled interferometers, in particular GEO\\,600, describes the signal and noise evolution in the non-stationary detector. Its non-stationarity is caused by motion of the signal recycling mirror, whose position defines the tuning of the detector. We prove that the shot noise from the dark port and optical losses remains white. The analysis of the transient effects shows that during the perfect tracking of the chirp frequency only transients from amplitude changes arise. The signal-to-noise-ratio gain, calculated in this paper, is $\\sim 16$ for a shot-noise limited detector and $\\sim 4$ for a detector with thermal noise.

  10. Amplification for the Adolescent.

    Science.gov (United States)

    Wilber, Laura Ann

    1978-01-01

    Explored are various means of amplification for aurally handicapped adolescents, including behind-the-ear hearing aids, "custom ear" (or in-the-ear) hearing aids, as well as aural rehabilitation. (BD)

  11. Amplification of fluorescence using collinear picosecond optical parametric amplification at degeneracy

    Institute of Scientific and Technical Information of China (English)

    Zhang Jing; Zhang Qiu-Lin; Jiang Man; Zhang Dong-Xiang; Feng Bao-Hua; Zhang Jing-Yuan

    2012-01-01

    We demonstrate the output characteristic of broadband parametric amplification of incoherent light pulses in a 355-nm pumped degenerate picosecond optical parametric amplification with either saturated or unsaturated amplification.The optical parametric amplifier is seeded by the fluorescence generated in a solution of pyridine-1 dye in ethanol.With the saturated amplification,we can obtain high energy incoherent light pulses,whose full widtth at half maximum bandwidth varies from 16 nm to 53 nm for the different phase matching angles near degeneracy.Moreover,the unsaturated bandwidth of the amplified pulses fits well to the calculated result at degeneracy.Selecting s-polarized fluorescence with a Glan-Taylor prism,the maximum bandwidth of the amplified fluorescence is found to be 59 nm for a purely s-polarized seed.The maximum output energy is 0.67 mJ for the optical parametric amplifier.By using an optical filter and compressor,the generated high energy incoherent light has great potential as the incoherent pump,signal or idler wave of a parametric down-conversion process,so that a wave with a high degree of coherence can be generated from an incoherent pump light.

  12. Optimization of noncollinear optical parametric amplification

    Science.gov (United States)

    Schimpf, D. N.; Rothardt, J.; Limpert, J.; Tünnermann, A.

    2007-02-01

    Noncollinearly phase-matched optical parametric amplifiers (NOPAs) - pumped with the green light of a frequency doubled Yb-doped fiber-amplifier system 1, 2 - permit convenient generation of ultrashort pulses in the visible (VIS) and near infrared (NIR) 3. The broad bandwidth of the parametric gain via the noncollinear pump configuration allows amplification of few-cycle optical pulses when seeded with a spectrally flat, re-compressible signal. The short pulses tunable over a wide region in the visible permit transcend of frontiers in physics and lifescience. For instance, the resulting high temporal resolution is of significance for many spectroscopic techniques. Furthermore, the high magnitudes of the peak-powers of the produced pulses allow research in high-field physics. To understand the demands of noncollinear optical parametric amplification using a fiber pump source, it is important to investigate this configuration in detail 4. An analysis provides not only insight into the parametric process but also determines an optimal choice of experimental parameters for the objective. Here, the intention is to design a configuration which yields the shortest possible temporal pulse. As a consequence of this analysis, the experimental setup could be optimized. A number of aspects of optical parametric amplifier performance have been treated analytically and computationally 5, but these do not fully cover the situation under consideration here.

  13. Acetylene measurement in flames by chirp-based quantum cascade laser spectrometry.

    Science.gov (United States)

    Quine, Zachary R; McNesby, Kevin L

    2009-06-01

    We have designed and characterized a mid-IR spectrometer built around a pulsed distributed-feedback quantum cascade laser using the characteristic frequency down-chirp to scan through the spectral region 6.5 cm(-1) spectral region. The behavior of this chirp is extensively measured. The accuracy and detection limits of the system as an absorption spectrometer are demonstrated first by measuring spectra of acetylene through a single pass 16 cm absorption cell in real time at low concentrations and atmospheric pressure. The smallest detectable peak is measured to be approximately 1.5 x 10(-4) absorbance units, yielding a minimum detectable concentration length product of 2.4 parts per million meter at standard temperature and pressure. This system is then used to detect acetylene within an ethylene-air opposed flow flame. Measurements of acetylene content as a function of height above the fuel source are presented, as well as measurements of acetylene produced in fuel breakdown as a function of preinjection fuel temperature. PMID:19488121

  14. Chirp-coded robust synthetic aperture technique for medical endoscopic ultrasonography

    Institute of Scientific and Technical Information of China (English)

    LIMing; CHEN Xiaodong; LI Yan; WANG Yi; YU Daoyin

    2012-01-01

    A chirp-coded robust synthetic aperture (CRSA) technique for medical endoscopic ultrasonography is presented. The technique uses chirp-coded excitation and pulse compression to enhance the robustness of synthetic aperture technique. The effect of resolution enhancement by the CRSA technique is demonstrated by both Field II simulation and practical experiment. Data for 6 point targets is simulated and the performance of CRSA is compared with that of conventional barker-coded synthetic aperture technique (BSA). Nylon ropes are examined by a single element transducer centered at 8 MHz. Both simulation and experimental results indicated that CRSA can improve resolution of ultrasound images with good robustness as compared with the conventional BSA technique. The lateral resolution is upgraded to 1.4 mm from 1.8 mm. The main-lobe broadening and SNR degradation are 0.04 mm and 0.2 dB respectively, which are 0.95 mm and 3.6 dB lower than those of BSA, when the sound speed error is 6% of the true value 1540 m/s. It therefore can be concluded that CRSA has more robustness than BSA against the disturbance caused by sound speed errors.

  15. Aerosol Lidar for the Relative Backscatter Amplification Measurements

    Science.gov (United States)

    Razenkov, Igor A.; Banakh, Victor A.; Nadeev, Alexander I.

    2016-06-01

    Backscatter amplification presents only in a turbulent atmosphere, when the laser beam is propagates twice through the same inhomogeneities. We proposed technical solution to detect backscatter amplification. An aerosol micro pulse lidar with a beam expansion via receiving telescope was built to study this effect. Our system allows simultaneous detection of two returns from the same scattering volume: exactly on the axis of the laser beam and off the axis.

  16. Attosecond pulse shaping using partial phase matching

    OpenAIRE

    Austin, Dane R.; Biegert, Jens

    2014-01-01

    We propose a method for programmable shaping of the amplitude and phase of the XUV and x-ray attosecond pulses produced by high-order harmonic generation. It overcomes the bandwidth limitations of existing spectral filters and enables removal of the intrinsic attosecond chirp as well as the synthesis of pulse sequences. It is based on partial phase matching, such as quasi-phase matching, using a longitudinally addressable modulation.

  17. Frequency conversion of high-intensity, femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Banks, P S

    1997-06-01

    Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated

  18. Early amplification options.

    Science.gov (United States)

    Gabbard, Sandra Abbott; Schryer, Jennifer

    2003-01-01

    Children with permanent hearing loss have been remediated with hearing amplification devices for decades. The influx of young infants identified with hearing loss through successful newborn hearing screening programs has established a need for amplification resources for infants within the first six months of life. For the approximately two of every 1000 infants born who are identified with bilateral hearing loss [Mehl and Thomson, 1998, Pediatrics 101, p. e4], the use of amplification is commonly the first step in treating the sequella of their loss. The use of hearing aids, combined with early intervention, has been shown to significantly improve the speech and language skills of young children with hearing loss [Yoshinaga-Itano, 2000, Seminars in Hearing 21, p. 309]. Speech and language delays have contributed to compromised academic performance of school aged children with hearing loss [Johnson et al., 1997, Educational Audiology Handbook, Singular Publishing, San Diego]. Most hard-of-hearing and deaf children use hearing aids and other assistive listening devices every day throughout their lifetime and the life expectancy of a hearing aid is only five to eight years. The current challenge for pediatric audiologists is selecting and evaluating the available amplification to provide the best options for children and their families. Amplification technology has seen an explosion in growth the past few years and the options continue to expand rapidly. This article examines currently available amplification technology and reviews the selection criteria that may be used for infants and young children. Issues such as style, type, amplification features, signal processing strategies, and verification and validation tools are also discussed. PMID:14648816

  19. Time-frequency signature sparse reconstruction using chirp dictionary

    Science.gov (United States)

    Nguyen, Yen T. H.; Amin, Moeness G.; Ghogho, Mounir; McLernon, Des

    2015-05-01

    This paper considers local sparse reconstruction of time-frequency signatures of windowed non-stationary radar returns. These signals can be considered instantaneously narrow-band, thus the local time-frequency behavior can be recovered accurately with incomplete observations. The typically employed sinusoidal dictionary induces competing requirements on window length. It confronts converse requests on the number of measurements for exact recovery, and sparsity. In this paper, we use chirp dictionary for each window position to determine the signal instantaneous frequency laws. This approach can considerably mitigate the problems of sinusoidal dictionary, and enable the utilization of longer windows for accurate time-frequency representations. It also reduces the picket fence by introducing a new factor, the chirp rate α. Simulation examples are provided, demonstrating the superior performance of local chirp dictionary over its sinusoidal counterpart.

  20. Chirped-cavity dispersion-compensation filter design

    Science.gov (United States)

    Li, Ya-Ping; Chen, Sheng-Hui; Lee, Cheng-Chung

    2006-03-01

    A new basic structure of a dispersive-compensation filter, called a chirped-cavity dispersion-compensator (CCDC) filter, was designed to offer the advantages of small ripples in both reflectance and group-delay dispersion (GDD). This filter provides a high dispersion compensation, like the Gires-Tournois interferometer (GTI) filter, and a wide working bandwidth, like the chirped mirror (CM). The structure of the CCDC is a cavity-type Fabry-Perot filter with a spacer layer (2 mH or 2 mL) and a chirped high reflector. The CCDC filter can provide a negative GDD of -50 fs2 over a bandwidth of 56 THz with half the optical thickness of the CM or the GTI.

  1. Curvature aided long range propagation of short laser pulses in the atmosphere

    International Nuclear Information System (INIS)

    The pre-filamentation regime of propagation of a short and intense laser pulse in the atmosphere is considered. Spatiotemporal self-focusing dynamics of the laser beam are investigated by calculating the coupled differential equations for spot size, pulse length, phase, curvature, and chirp functions of a Gaussian laser pulse via a variational technique. The effect of initial curvature parameter on the propagation of the laser pulse is taken into consideration. A method relying on the adjustment of the initial curvature parameter can expand the filamentation distance of a laser beam of given power and chirp is proposed.

  2. A High-Energy, Ultrashort-Pulse X-Ray System for the Dynamic Study of Heavy, Dense Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, D J

    2004-09-17

    Thomson-scattering based x-ray radiation sources, in which a laser beam is scattered off a relativistic electron beam resulting in a high-energy x-ray beam, are currently being developed by several groups around the world to enable studies of dynamic material properties which require temporal resolution on the order of tens of femtoseconds to tens of picoseconds. These sources offer pulses that are shorter than available from synchrotrons, more tunable than available from so-called Ka sources, and more penetrating and more directly probing than ultrafast lasers. Furthermore, Thomson-scattering sources can scale directly up to x-ray energies in the few MeV range, providing peak brightnesses far exceeding any other sources in this regime. This dissertation presents the development effort of one such source at Lawrence Livermore National Laboratory, the Picosecond Laser-Electron InterAction for the Dynamic Evaluation of Structures (PLEIADES) project, designed to target energies from 30 keV to 200 keV, with a peak brightness on the order of 10{sup 18} photons {center_dot} s{sup -1} {center_dot} mm{sup -2} {center_dot} mrad{sup -2} {center_dot} 0.01% bandwidth{sup -1}. A 10 TW Ti:Sapphire based laser system provides the photons for the interaction, and a 100 MeV accelerator with a 1.6 cell S-Band photoinjector at the front end provides the electron beam. The details of both these systems are presented, as is the initial x-ray production and characterization, validating the theory of Thomson scattering. In addition to the systems used to enable PLEIADES, two alternative systems are discussed. An 8.5 GHz X-Band photoinjector, capable of sustaining higher accelerating gradients and producing lower emittance electron beams in a smaller space than the S-Band gun, is presented, and the initial operation and commissioning of this gun is presented. Also, a hybrid chirped-pulse amplification system is presented as an alternative to the standard regenerative amplifier technology

  3. Coherent control of atoms and diatomic molecules with shaped ultrashort pulses

    International Nuclear Information System (INIS)

    This thesis deals with the theoretical and experimental study of coherent control of atomic and molecular systems with shaped pulses. At first, we present several experiments of control of coherent transients in rubidium. These transients appear when a two-level system is excited by a perturbative chirped pulse, and are characterized by oscillations in the excited state population. For a strong chirp, we show that a phase step in the spectrum modifies the phase of the oscillations. Then, by direct analogy with Fresnel zone lens, we conceive a chirped pulse with a highly modulated amplitude, allowing to suppress destructive contributions to the population transfer. In a second set of experiments, we focus on quantum path interferences in two-photon transitions excited by linearly chirped pulses. Owing to the broad bandwidth of ultrashort pulses, sequential and direct excitation paths contribute to the excited state population. Oscillations resulting from interferences between these two paths are observed in atomic sodium. Moreover, we show that they are observable whatever the sign of chirp. Theoretically, we study the control of the predissociation of a benchmark diatomic molecule: NaI. Predissociation leads to matter wave interferences in the fragments distribution. First, we show that a suitably chosen probe pulse allows the observation of theses interferences. Next, using a sequence of control pulse inducing electronic transition, we demonstrate the possibility to manipulate fragment energy distribution. (author)

  4. Non-diffracting chirped Bessel waves in optical antiguides

    CERN Document Server

    Chremmos, Ioannis

    2015-01-01

    Chirped Bessel waves are introduced as stable (non-diffracting) solutions of the paraxial wave equation in optical antiguides with a power-law radial variation in their index of refraction. Through numerical simulations, we investigate the propagation of apodized (finite-energy) versions of such waves, with or without vorticity, in antiguides with practical parameters. The new waves exhibit a remarkable resistance against the defocusing effect of the unstable index potentials, outperforming standard Gaussians with the same full width at half maximum. The chirped profile persists even under conditions of eccentric launching or antiguide bending and is also capable of self-healing like standard diffraction-free beams in free space.

  5. Observation and explanation of the JET n=0 chirping mode

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, C.J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)]. E-mail: christopher.boswell@navy.mil; Berk, H.L. [Institute for Fusion Studies, University of Texas at Austin, Austin, TX 78712-1060 (United States); Borba, D.N. [Centro de Fusao Nuclear Associacao Euratom-IST, Instituto Superior Tecnico, 1049001 Lisbon (Portugal); EFDA Close Support Unit, Culham Science Centre, OX14 3DB (United Kingdom); Johnson, T. [Alfven Laboratory, KTH, Euratom-VR Association (Sweden); Pinches, S.D. [Max-Planck Institute for Plasma Physics, EURATOM Association, D-85748 Garching (Germany); Sharapov, S.E. [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2006-10-09

    Persistent rapid up and down frequency chirping modes with a toroidal mode number of zero (n=0) have been observed in the JET tokamak when energetic ions, with a mean energy {approx}500keV, were created by high field side ion cyclotron resonance frequency heating. This heating method enables the formation of an energetically inverted ion distribution function that allows ions to spontaneously excite the observed instability, identified as a global geodesic acoustic mode. The interpretation is that phase space structures form and interact with the fluid zonal flow to produce the pronounced frequency chirping.

  6. Wavelength-encoding/temporal-spreading optical code division multiple-access system with in-fiber chirped moiré gratings.

    Science.gov (United States)

    Chen, L R; Smith, P W; de Sterke, C M

    1999-07-20

    We propose an optical code division multiple-access (OCDMA) system that uses in-fiber chirped moiré gratings (CMG's) for encoding and decoding of broadband pulses. In reflection the wavelength-selective and dispersive nature of CMG's can be used to implement wavelength-encoding/temporal-spreading OCDMA. We give examples of codes designed around the constraints imposed by the encoding devices and present numerical simulations that demonstrate the proposed concept. PMID:18323934

  7. Quantum Feedback Amplification

    Science.gov (United States)

    Yamamoto, Naoki

    2016-04-01

    Quantum amplification is essential for various quantum technologies such as communication and weak-signal detection. However, its practical use is still limited due to inevitable device fragility that brings about distortion in the output signal or state. This paper presents a general theory that solves this critical issue. The key idea is simple and easy to implement: just a passive feedback of the amplifier's auxiliary mode, which is usually thrown away. In fact, this scheme makes the controlled amplifier significantly robust, and furthermore it realizes the minimum-noise amplification even under realistic imperfections. Hence, the presented theory enables the quantum amplification to be implemented at a practical level. Also, a nondegenerate parametric amplifier subjected to a special detuning is proposed to show that, additionally, it has a broadband nature.

  8. Relations between chirp transform and Fresnel diffraction, Wigner distribution function and a fast algorithm for chirp transform

    International Nuclear Information System (INIS)

    Two physical interpretations of chirp transform related to Fresnel diffraction and Wigner distribution function are given. The chirp transform can be regarded as a Fresnel diffraction observed on a spherical tangent to the diffraction plane, or a rotation and stretching transformation of the Wigner distribution function space. A general fast algorithm for the numerical calculation of chirp transform is developed by employing two fast Fourier transform algorithms. The algorithm, by which a good evaluation can be achieved, unifies the calculations of Fresnel diffraction, arbitrary fractional-order Fourier transforms and other scalar diffraction systems. The algorithm is used to calculate the Fourier transform of a Gaussian function and the Fourier transform, the Fresnel transform, the Fractional-order Fourier transforms of a rectangle function to evaluate the performance of this algorithm. The calculated results are in good agreement with the analytical results, both in the amplitude and phase. (classical areas of phenomenology)

  9. Chirped InAs/InP quantum-dash laser with enhanced broad spectrum of stimulated emission

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-03-01

    We report on the demonstration of 50 nm (full-width at half-maximum) broadband stimulated emission from a chirped AlGaInAs barrier thickness multi-stack InAs/InP quantum dash (Qdash) laser. The 2 ?m wide uncoated Fabry-Perot (FP) ridge-waveguide laser exhibits a total power of 0.18 W, corresponding to an average spectral power density of 3.5 mW/nm, under pulsed current conditions. Intentional extended inhomogeneity across the Qdash stacks have been attributed to the enhancement of broadband emission. © 2013 American Institute of Physics.

  10. Femtosecond-Laser-Pulse Characterization and Optimization for CARS Microscopy.

    Directory of Open Access Journals (Sweden)

    Vincenzo Piazza

    Full Text Available We present a simple method and its experimental implementation to determine the pulse durations and linear chirps of the pump-and-probe pulse and the Stokes pulse in a coherent anti-Stokes Raman scattering microscope at sample level without additional autocorrelators. Our approach exploits the delay line, ubiquitous in such microscopes, to perform a convolution of the pump-and-probe and Stokes pulses as a function of their relative delay and it is based on the detection of the photons emitted from an appropriate non-linear sample. The analysis of the non-resonant four-wave-mixing and sum-frequency-generation signals allows for the direct retrieval of the pulse duration on the sample and the linear chirp of each pulse. This knowledge is crucial in maximizing the spectral-resolution and contrast in CARS imaging.

  11. Femtosecond-Laser-Pulse Characterization and Optimization for CARS Microscopy

    Science.gov (United States)

    Piazza, Vincenzo; de Vito, Giuseppe; Farrokhtakin, Elmira; Ciofani, Gianni; Mattoli, Virgilio

    2016-01-01

    We present a simple method and its experimental implementation to determine the pulse durations and linear chirps of the pump-and-probe pulse and the Stokes pulse in a coherent anti-Stokes Raman scattering microscope at sample level without additional autocorrelators. Our approach exploits the delay line, ubiquitous in such microscopes, to perform a convolution of the pump-and-probe and Stokes pulses as a function of their relative delay and it is based on the detection of the photons emitted from an appropriate non-linear sample. The analysis of the non-resonant four-wave-mixing and sum-frequency-generation signals allows for the direct retrieval of the pulse duration on the sample and the linear chirp of each pulse. This knowledge is crucial in maximizing the spectral-resolution and contrast in CARS imaging. PMID:27224203

  12. Deterministic implementations of quantum gates with circuit QEDs via Stark-chirped rapid adiabatic passages

    International Nuclear Information System (INIS)

    Highlights: • A specific SCRAP technique is proposed to realize quantum gates in the circuit QED. • These quantum gates are insensitive to the durations of the applied pluses. • The implemented quantum gates are robustness against the operational imperfections. - Abstract: We show that a set of universal quantum gates could be implemented robustly in a circuit QED system by using Stark-chirped rapid adiabatic passage (SCRAP) technique. Under the adiabatic limit we find that the population transfers could be deterministically passaged from one selected quantum states to the others, and thus the desired quantum gates can be implemented. The proposed SCRAP-based gates are insensitive to the details of the operations and thus relax the designs of the applied pulses, operational imperfections, and the decoherence of the system

  13. Generation of 3D ellipsoidal laser beams by means of a profiled volume chirped Bragg grating

    Science.gov (United States)

    Mironov, S. Yu; Poteomkin, A. K.; Gacheva, E. I.; Andrianov, A. V.; Zelenogorskii, V. V.; Vasiliev, R.; Smirnov, V.; Krasilnikov, M.; Stephan, F.; Khazanov, E. A.

    2016-05-01

    A method for shaping photocathode laser driver pulses into 3D ellipsoidal form has been proposed and implemented. The key idea of the method is to use a chirped Bragg grating recorded within the ellipsoid volume and absent outside it. If a beam with a constant (within the grating reflection band) spectral density and uniform (within the grating aperture) cross-section is incident on such a grating, the reflected beam will be a 3D ellipsoid in space and time. 3D ellipsoidal beams were obtained in experiment for the first time. It is expected that such laser beams will allow the electron bunch emittance to be reduced when applied at R± photo injectors.

  14. Deterministic implementations of quantum gates with circuit QEDs via Stark-chirped rapid adiabatic passages

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingwei [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Wei, L.F., E-mail: weilianfu@gmail.com [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China)

    2015-10-23

    Highlights: • A specific SCRAP technique is proposed to realize quantum gates in the circuit QED. • These quantum gates are insensitive to the durations of the applied pluses. • The implemented quantum gates are robustness against the operational imperfections. - Abstract: We show that a set of universal quantum gates could be implemented robustly in a circuit QED system by using Stark-chirped rapid adiabatic passage (SCRAP) technique. Under the adiabatic limit we find that the population transfers could be deterministically passaged from one selected quantum states to the others, and thus the desired quantum gates can be implemented. The proposed SCRAP-based gates are insensitive to the details of the operations and thus relax the designs of the applied pulses, operational imperfections, and the decoherence of the system.

  15. Stretching of Picosecond Laser Pulses with Uniform Reflecting Volume Bragg Gratings

    Science.gov (United States)

    Mokhov, Sergiy

    It is shown that a uniform reflecting volume Bragg grating (VBG) can be used as a compact monolithic stretcher of high-power picosecond laser pulses in cases when chirped Bragg gratings with an appropriate chirp rate are difficult to fabricate. A chirp-free reflected stretched pulse is generated of almost rectangular shape when incident short pulse propagates along a grating and experiences local Bragg diffraction. The increase in duration of the reflected pulse is approximately equal to twice the propagation times along the grating. We derived the analytic expression for diffraction efficiency, which incorporates incident pulse duration, grating thickness, and amplitude of refractive index modulation, enabling an optimum selection of the grating for pulse stretching. The typical expected theoretical value of diffraction efficiency is about 10% after taking into account the spectral narrowing of the reflected emission. We believe that the relatively low energy efficiency of the proposed method is more than offset by a number of advantages, which are chirp-free spectrum of a stretched pulse, compactness, robustness, preservation of setup alignment and beam quality, and tolerance to high power. Obtained pulses of several tens of picoseconds can be amplified by standard methods which are not requiring special measures to avoid undesirable non-linear effects. We propose a simple and reliable method to control the temporal parameters of the high-power picosecond pulses using the same laser source and the VGB of variable thickness that can significantly simplify the experiments requiring different pulse durations.

  16. Analytic expression of the chirped sampled function used to produce the equal chirp in the specific reflection channel in uniform period fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; YANG Hong-bo; ZHANG Na

    2005-01-01

    The general analytic expression of the chirped sampled function is derived based on coupled mode theory. This function can be used to describe how to use uniform period fiber Bragg grating to produce the equal chirp at will in the specific reflection channel. As an example,the exact sampled function expression that produces a linear chirped at the +4 channel is given. The simulation results by using the transfer-matrix show that the theory is correct.

  17. Attosecond laser pulse ionization of atoms and molecules

    International Nuclear Information System (INIS)

    Ionization dynamics of atoms and molecules under attosecond laser pulses with various photon energies and peak intensities have been investigated using the Time-Dependent Close-Coupling (TDCC) method. We predict the chirp effects on the triply differential probabilities for the ionized electrons of He produced by 450 and 135 asec pulses. In addition, we shall apply our generalized TDCC method to examine the four-body breakup dynamics of molecular hydrogen induced by these ultrashort pulses.

  18. On soliton amplification

    Science.gov (United States)

    Leibovich, S.; Randall, J. D.

    1979-01-01

    The paper considers a modified Korteweg-de Vries equation that permits wave amplification or damping. A 'terminal similarity' solution is identified for large times in amplified systems. Numerical results are given which confirm that the terminal similarity solution is a valid local approximation for mu t sufficiently large and positive, even though the approximation is not uniformly valid in space.

  19. Chirped microlens arrays for diode laser circularization and beam expansion

    Science.gov (United States)

    Schreiber, Peter; Dannberg, Peter; Hoefer, Bernd; Beckert, Erik

    2005-08-01

    Single-mode diode lasers are well-established light sources for a huge number of applications but suffer from astigmatism, beam ellipticity and large manufacturing tolerances of beam parameters. To compensate for these shortcomings, various approaches like anamorphic prism pairs and cylindrical telescopes for circularization as well as variable beam expanders based on zoomed telescopes for precise adjustment of output beam parameters have been employed in the past. The presented new approach for both beam circularization and expansion is based on the use of microlens arrays with chirped focal length: Selection of lenslets of crossed cylindrical microlens arrays as part of an anamorphic telescope enables circularization, astigmatism correction and divergence tolerance compensation of diode lasers simultaneously. Another promising application of chirped spherical lens array telescopes is stepwise variable beam expansion for circular laser beams of fiber or solid-state lasers. In this article we describe design and manufacturing of beam shaping systems with chirped microlens arrays fabricated by polymer-on-glass replication of reflow lenses. A miniaturized diode laser module with beam circularization and astigmatism correction assembled on a structured ceramics motherboard and a modulated RGB laser-source for photofinishing applications equipped with both cylindrical and spherical chirped lens arrays demonstrate the feasibility of the proposed system design approach.

  20. Magnetostatic-Wave-Based Magneto-Optic Pulse Compression by Control of Phase Mismatching

    Institute of Scientific and Technical Information of China (English)

    WU Bao-Jian; GAO Xiang

    2008-01-01

    Microwave magnetostatic waves (MSWs) as moving gratings in magneto-optic (MO) film can lead to the Bragg diffraction of guided optical waves (GOWs). The MO coupling characteristics are responsible for the amplitude and phase frequency spectra of diffracted pulses and even result in the compression of chirped optical pulses in time domain. We theoretically investigate the noncollinear diffraction of linearly chirped Gaussian optical pulses by continuous magnetostatic forward volume waves in detail. For a given chirped optical pulse, with the increase of phase-mismatching slopes, the compression efficiency (CE) is gradually improved up to the maximum followed by the transition of diffracted pulses from single peak to multi peaks. The larger the chirp parameter is,the smaller the required phase-mismatching slope to achieve the maximal CE is. However, the rise of the chirp parameter or phase-mismatching slope reduces the relative peak intensity of the diffracted pulse. Lastly, it is pointed out that the phase-mismatching slope can be greatly increased by using the high-order modes of MSWs and GOWs.

  1. MGL1109 Chirp - US Extended Continental Shelf Project: Gulf of Alaska CHIRP high-resolution Seismic Profile data.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Knudsen 2620 acquired sub-bottom profiles continuously throughout the cruise. The Knudsen was operated in 3.5 kHz Chirp mode, emitting a 1.5 kHz to 5 kHz (3 kHz...

  2. MGL111 Chirp - US Extended Continental Shelf Project: Bering Sea CHIRP high-resolution Seismic Profile data.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Knudsen 2620 acquired sub-bottom profiles continuously throughout the cruise. The Knudsen was operated in 3.5 kHz Chirp mode, emitting a 1.5 kHz to 5 kHz (3 kHz...

  3. Optimization of the idler wavelength tunable cascaded optical parametric oscillator based on chirp-assisted aperiodically poled lithium niobate crystal

    Science.gov (United States)

    Tao, Chen; Rong, Shu; Ye, Ge; Zhuo, Chen

    2016-01-01

    We present the numerical results for the optimization of the pump-to-idler conversion efficiencies of nanosecond idler wavelength tunable cascaded optical parametric oscillators (OPO) in different wavelength tuning ranges, where the primary signals from the OPO process are recycled to enhance the pump-to-idler conversion efficiencies via the simultaneous difference frequency generation (DFG) process by monolithic aperiodically poled, magnesium oxide doped lithium niobate (APMgLN) crystals. The APMgLN crystals are designed with different chirp parameters for the DFG process to broaden their thermal acceptance bandwidths to different extents. The idler wavelength tuning of the cascaded OPO is realized by changing the temperature of the designed APMgLN crystal and the cascaded oscillation is achieved in a single pump pass singly resonant linear cavity. The pump-to-idler conversion efficiencies with respect to the pump pulse duration and ratio of OPO coefficient to DFG coefficient are calculated by numerically solving the coupled wave equations. The optimal working conditions of the tunable cascaded OPOs pumped by pulses with energies of 350 μJ and 700 μJ are compared to obtain the general rules of optimization. It is concluded that the optimization becomes the interplay between the ratio of OPO coefficient to DFG coefficient and the pump pulse duration when the idler wavelength tuning range and the pump pulse energy are fixed. Besides, higher pump pulse energy is beneficial for reaching higher optimal pump-to-idler conversion efficiency as long as the APMgLN crystal is optimized according to this pump condition. To the best of our knowledge, this is the first numerical analysis of idler wavelength tunable cascaded OPOs based on chirp-assisted APMgLN crystals. Project supported by the National Natural Science Foundation of China (Grant No. 61505236), the Innovation Program of Shanghai Institute of Technical Physics, China (Grant No. CX-2), and the Program of Shanghai

  4. Nanosecond Pulse Shaping with Fiber-Based Electro-Optical Modulators and a Double-Pass Tapered Amplifier

    CERN Document Server

    Rogers, Charles E

    2015-01-01

    We describe a system for generating frequency-chirped and amplitude-shaped pulses on time scales from sub-nanosecond to ten nanoseconds. The system starts with cw diode-laser light at 780 nm and utilizes fiber-based electro-optical phase and intensity modulators, driven by an arbitrary waveform generator, to generate the shaped pulses. These pulses are subsequently amplified to several hundred mW with a tapered amplifier in a delayed double-pass configuration. Frequency chirps up to 5 GHz in 2 ns and pulse widths as short as 0.15 ns have been realized.

  5. Propagation characteristics of two-color laser pulses in homogeneous plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hemlata,; Saroch, Akanksha; Jha, Pallavi [Department of Physics, University of Lucknow, Lucknow 226007 (India)

    2015-11-15

    An analytical and numerical study of the evolution of two-color, sinusoidal laser pulses in cold, underdense, and homogeneous plasma has been presented. The wave equations for the radiation fields driven by linear as well as nonlinear contributions due to the two-color laser pulses have been set up. A variational technique is used to obtain the simultaneous equations describing the evolution of the laser spot size, pulse length, and chirp parameter. Numerical methods are used to graphically analyze the simultaneous evolution of these parameters due to the combined effect of the two-color laser pulses. Further, the pulse parameters are compared with those obtained for a single laser pulse. Significant focusing, compression, and enhanced positive chirp is obtained due to the combined effect of simultaneously propagating two-color pulses as compared to a single pulse propagating in plasma.

  6. Propagation characteristics of two-color laser pulses in homogeneous plasma

    International Nuclear Information System (INIS)

    An analytical and numerical study of the evolution of two-color, sinusoidal laser pulses in cold, underdense, and homogeneous plasma has been presented. The wave equations for the radiation fields driven by linear as well as nonlinear contributions due to the two-color laser pulses have been set up. A variational technique is used to obtain the simultaneous equations describing the evolution of the laser spot size, pulse length, and chirp parameter. Numerical methods are used to graphically analyze the simultaneous evolution of these parameters due to the combined effect of the two-color laser pulses. Further, the pulse parameters are compared with those obtained for a single laser pulse. Significant focusing, compression, and enhanced positive chirp is obtained due to the combined effect of simultaneously propagating two-color pulses as compared to a single pulse propagating in plasma

  7. 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.

  8. Influence of the cubic spectral phase of high-power laser pulses on their self-phase modulation

    Science.gov (United States)

    Ginzburg, V. N.; Kochetkov, A. A.; Yakovlev, I. V.; Mironov, S. Yu; Shaykin, A. A.; Khazanov, E. A.

    2016-02-01

    Spectral broadening of high-power transform-limited laser pulses under self-phase modulation in a medium with cubic nonlinearity is widely used to reduce pulse duration and to increase its power. It is shown that the cubic spectral phase of the initial pulse leads to a qualitatively different broadening of its spectrum: the spectrum has narrow peaks and broadening decreases. However, the use of chirped mirrors allows such pulses to be as effectively compressed as transform-limited pulses.

  9. Chirping for large-scale maritime archaeological survey

    DEFF Research Database (Denmark)

    Grøn, Ole; Boldreel, Lars Ole

    2014-01-01

    -resolution subbottom profilers. This paper presents a strategy for cost-effective, large-scale mapping of previously undetected sediment-embedded sites and wrecks based on subbottom profiling with chirp systems. The mapping strategy described includes (a) definition of line spacing depending on the target; (b......) interactive surveying, for example, immediate detailed investigation of potential archaeological anomalies on detection with a denser pattern of subbottom survey lines; (c) onboard interpretation during data acquisition; (d) recognition of nongeological anomalies. Consequently, this strategy differs from...... those employed in several detailed studies of known wreck sites and from the way in which geologists map the sea floor and the geological column beneath it. The strategy has been developed on the basis of extensive practical experience gained during the use of an off-the-shelf 2D chirp system and, given...

  10. SAW chirp Fourier transform for MB-OFDM UWB receiver

    Institute of Scientific and Technical Information of China (English)

    HE Peng-fei; L(U) Ying-hua; ZHANG Hong-xin; WANG Ye-qiu; XU Yong

    2006-01-01

    In the conventional multiband orthogonal frequency division multiplexing ultra wideband (MB-OFDM UWB )receiver, the fast Fourier transform (FFT) algorithm is realized by the expensive and power-consuming digital signal processor (DSP) chips. In this article, the lower power, lower cost, and lower complexity real-time analog surface acoustic wave (SAW)chirp Fourier transform devices were used to replace the DSP part. A MB-OFDM UWB receiver based on the M-C-M SAW chirp Fourier transform was presented, and the step of signal transformation from input signals was also depicted. The simulation results show that the proposed receiver provides similar bit error performance compared to the fully digital receiver when used in the channel environments proposed by the IEEE 802.15SG3a.

  11. Improved chirp scaling algorithm for parallel-track bistatic SAR

    Institute of Scientific and Technical Information of China (English)

    Li Feng; Li Shu; Zhao Yigong

    2009-01-01

    The curvature factor of the parallel-track bistatic SAR is range dependent, even without variation of the effective velocity. Accounting for this new characteristic, a parallel-track chirp scaling algorithm (CSA) is derived, by introducing the method of removal of range walk (RRW) in the time domain. Using the RRW before the CSA, this method can reduce the varying range of the curvature factor, without increasing the computation load obviously. The azimuth dependence of the azimuth-FM rate, resulting from the RRW, is compensated by the nonlinear chirp scaling factor. Therefore, the algorithm is extended into stripmap imaging. The realization of the method is presented and is verified by the simulation results.

  12. Nonlinear Brillouin amplification of finite-duration seeds in the strong coupling regime

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, G.; Spatschek, K. H. [Institut für Theoretische Physik, Heinrich-Heine-Universität Düsseldorf, D–40225 Düsseldorf (Germany)

    2013-07-15

    Parametric plasma processes received renewed interest in the context of generating ultra-intense and ultra-short laser pulses up to the exawatt-zetawatt regime. Both Raman as well as Brillouin amplifications of seed pulses were proposed. Here, we investigate Brillouin processes in the one-dimensional (1D) backscattering geometry with the help of numerical simulations. For optimal seed amplification, Brillouin scattering is considered in the so called strong coupling (sc) regime. Special emphasis lies on the dependence of the amplification process on the finite duration of the initial seed pulses. First, the standard plane-wave instability predictions are generalized to pulse models, and the changes of initial seed pulse forms due to parametric instabilities are investigated. Three-wave-interaction results are compared to predictions by a new (kinetic) Vlasov code. The calculations are then extended to the nonlinear region with pump depletion. Generation of different seed layers is interpreted by self-similar solutions of the three-wave interaction model. Similar to Raman amplification, shadowing of the rear layers by the leading layers of the seed occurs. The shadowing is more pronounced for initially broad seed pulses. The effect is quantified for Brillouin amplification. Kinetic Vlasov simulations agree with the three-wave interaction predictions and thereby affirm the universal validity of self-similar layer formation during Brillouin seed amplification in the strong coupling regime.

  13. Pulse-width compression based on photonic crystal fiber

    Institute of Scientific and Technical Information of China (English)

    WANG Jing; WANG Zhen-li; SHI Yan-mei

    2006-01-01

    According to the characteristics of high-order solitons,compressed picosecond pulses are numerically simulated in the photonic crystal fiber (PCF),by means of split-step Fourier method. The results show that,PCF enables input pulse with lower peak power to form high-order solitons for the purpose of femtosecond pulse-width compression. For example,60- femtosecond pulse width was made for 1-ps initial pulse width only over the distance of 2.2 m.Besides,shorter optimum fiber length for compression and higher compression ratio could be obtained on the premise of pre-chirp technique.

  14. Broadband sum frequency generation via chirped quasi-phase-matching

    OpenAIRE

    Rangelov, A. A.; Vitanov, N. V.

    2011-01-01

    An efficient broadband sum frequency generation (SFG) technique using the two collinear optical parametric processes \\omega 3=\\omega 1+\\omega 2 and \\omega 4=\\omega 1+\\omega 3 is proposed. The technique uses chirped quasi-phase-matched gratings, which, in the undepleted pump approximation, make SFG analogous to adiabatic population transfer in three-state systems with crossing energies in quantum physics. If the local modulation period %for aperiodically poled quasi-phase-matching first makes ...

  15. Precise Location Technology Based on Chirp Spread Spectrum

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2011-06-01

    Full Text Available This article introduces chirp spread spectrum technology (CSS for short and optimized location algorithm. Symmetric double-sided two way ranging technique (SDS–TWR for short is applied to improve accuracy and range of measurement. Linear frequency modulation ranging technology utilizes protocols combining CSMA / CA and TDMA, and adjusts dynamically transmission rate and frame length according to noise, interference and multipath to ensure optimal throughput and accurate distance information. System has anti-jamming capability and covers great distance.

  16. Shear wave speed and dispersion measurements using crawling wave chirps.

    Science.gov (United States)

    Hah, Zaegyoo; Partin, Alexander; Parker, Kevin J

    2014-10-01

    This article demonstrates the measurement of shear wave speed and shear speed dispersion of biomaterials using a chirp signal that launches waves over a range of frequencies. A biomaterial is vibrated by two vibration sources that generate shear waves inside the medium, which is scanned by an ultrasound imaging system. Doppler processing of the acquired signal produces an image of the square of vibration amplitude that shows repetitive constructive and destructive interference patterns called "crawling waves." With a chirp vibration signal, successive Doppler frames are generated from different source frequencies. Collected frames generate a distinctive pattern which is used to calculate the shear speed and shear speed dispersion. A special reciprocal chirp is designed such that the equi-phase lines of a motion slice image are straight lines. Detailed analysis is provided to generate a closed-form solution for calculating the shear wave speed and the dispersion. Also several phantoms and an ex vivo human liver sample are scanned and the estimation results are presented. PMID:24658144

  17. Overview of Spontaneous Frequency Chirping in Confined Plasmas

    Science.gov (United States)

    Berk, Herbert

    2012-10-01

    Spontaneous rapid frequency chirping is now a commonly observed phenomenon in plasmas with an energetic particle component. These particles typically induce so called weak instabilities, where they excite background waves that the plasma can support such as shear Alfven waves. The explanation for this phenomenon attributes the frequency chirping to the formation of phase space structures in the form of holes and clumps. Normally a saturated mode, in the presence of background dissipation, would be expected decay after saturation as the background plasma absorbs the energy of the excited wave. However the phase space structures take an alternate route, and move to a regions of phase space that are lower energy states of the energetic particle distribution. Through the wave-resonant particle interaction, this movement is locked to the frequency observed by the wave. This phenomenon implies that alternate mechanisms for plasma relaxation need to be considered for plasma states new marginal stability. It is also possible that these chirping mechanisms can be used to advantage to externally control states of plasma.

  18. Fully programmable spectrum sliced chirped microwave photonic filter.

    Science.gov (United States)

    Leitner, Peter; Yi, Xiaoke; Li, Liwei; Huang, Thomas X H

    2015-02-23

    A novel chirped microwave photonic filter (MPF) capable of achieving a large radio frequency (RF) group delay slope and a single passband response free from high frequency fading is presented. The design is based upon a Fourier domain optical processor (FD-OP) and a single sideband modulator. The FD-OP is utilized to generate both constant time delay to tune the filter and first order dispersion to induce the RF chirp, enabling full software control of the MPF without the need for manual adjustment. An optimized optical parameter region based on a large optical bandwidth >750 GHz and low slicing dispersion < ± 1 ps/nm is introduced, with this technique greatly improving the RF properties including the group delay slope magnitude and passband noise. Experimental results confirm that the structure simultaneously achieves a large in-band RF chirp of -4.2 ns/GHz, centre frequency invariant tuning and independent reconfiguration of the RF amplitude and phase response. Finally, a stochastic study of the device passband noise performance under tuning and reconfiguration is presented, indicating a low passband noise <-120 dB/Hz. PMID:25836442

  19. Amplification of cylindrically polarized laser beams in single crystal fiber amplifiers.

    Science.gov (United States)

    Piehler, Stefan; Délen, Xavier; Rumpel, Martin; Didierjean, Julien; Aubry, Nicolas; Graf, Thomas; Balembois, Francois; Georges, Patrick; Ahmed, Marwan Abdou

    2013-05-01

    Yb:YAG single crystal fiber (SCF) amplifiers have recently drawn much attention in the field of amplification of ultra-short pulses. In this paper, we report on the use of SCF amplifiers for the amplification of cylindrically polarized laser beams, as such beams offer promising properties for numerous applications. While the amplification of cylindrically polarized beams is challenging with other amplifier designs due to thermally induced depolarization, we demonstrate the amplification of 32 W cylindrically polarized beams to an output power of 100 W. A measured degree of radial polarization after the SCF of about 95% indicates an excellent conservation of polarization. PMID:23669994

  20. Spectral characteristics of draw-tower step-chirped fiber Bragg gratings

    Science.gov (United States)

    Idrisov, Ravil F.; Varzhel, Sergey V.; Kulikov, Andrey V.; Meshkovskiy, Igor K.; Rothhardt, Manfred; Becker, Martin; Schuster, Kay; Bartelt, Hartmut

    2016-06-01

    This paper presents research results on the spectral properties of step-chirped fiber Bragg grating arrays written during the fiber drawing process into a birefringent optical fiber with an elliptical stress cladding. The dependences of resonance shift of the step-chirped fiber Bragg grating on bending, on applied tensile stress and on temperature have been investigated. A usage of such step-chirped fiber Bragg gratings in fiber-optic sensing elements creation has been considered.

  1. Few-cycle fiber pulse compression and evolution of negative resonant radiation

    CERN Document Server

    McLenaghan, Joanna

    2013-01-01

    We present numerical simulations and experimental observations of the spectral expansion of fs-pulses compressing in optical fibers. Using the input pulse frequency chirp we are able to scan through the pulse compression spectra and observe in detail the emergence of negative-frequency resonant radiation (NRR), a recently discovered pulse instability coupling to negative frequencies [Rubino et al., PRL 108, 253901 (2012)]. We observe how the compressing pulse is exciting NRR as long as it overlaps spectrally with the resonant frequency. Furthermore, we observe that optimal pulse compression can be achieved at an optimal input chirp and for an optimal fiber length. The results are important for Kerr-effect pulse compressors, to generate novel light sources, as well as for the observation of quantum vacuum radiation.

  2. Nonlinear polarization rotation-induced pulse shaping in a stretched-pulse ytterbium-doped fiber laser

    Science.gov (United States)

    Bai, Dong-Bi; Li, Wen-Xue; Yang, Kang-Wen; Shen, Xu-Ling; Chen, Xiu-Liang; Zeng, He-Ping

    2014-10-01

    We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of ~ 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.

  3. Broadband multilayer mirror and diffractive optics for attosecond pulse shaping in the 280-500 eV photon energy range

    Directory of Open Access Journals (Sweden)

    Schmidt J.

    2013-03-01

    Full Text Available Chirped broadband multilayer mirrors are key components to shape attosecond pulses in the XUV range. Compressing high harmonic pulses to their Fourier limit is the major goal for attosecond physics utilizing short pulse pump-probe experiments. Here, we report about the first implementation of multilayers and diffractive optics fulfilling these requirements in the “water-window” spectral range.

  4. Molecular Alignment Effects in Ammonia at 6.14 μm, Using a Down-Chirped Quantum Cascade Laser Spectrometer

    Science.gov (United States)

    Hay, K. G.; Duxbury, G.; Langford, N.

    2009-06-01

    In recent intra-pulse experiments in acetylene we have seen the generation of short emission pulses using the fast frequency down-chirp of a pulsed quantum cascade (QC)laser. These follow the absorptive part of rapid passage signals and are caused by the effects of molecular alignment in low pressure gases. These effects occur when the sweep rate of a laser through a Doppler broadened line is much faster than the collisional relation rate. At higher pressures of the pure gas, a series of free induction decay signals may often be observed. In our current spectrometer using a 6.14 μm, laser, in which both the bandwidth of the detection system and the temperature stabilisation of the QC laser itself have been greatly improved, we have been able to study the time dependence of rapid passage effects in ammonia. Using pulses of duration up to 2 microseconds, within which the chirp rate varies from about 100 MHz/ns at the beginning to very slow rate approaching 6 MHz/ns at the end, we can study the interplay between chirp rate and collision processes. By using the base temperature tuning of the laser we can set the centre of the chosen line at the appropriate position within the scan. The absorption path length within our astigmatic Herriott cell is 60 m, so that the gas pressures used are very low. As the QC emission bandwidth chosen lies close to the centre of the ν _4 band of ammonia, a large number of low J transitions may be studied in detail. K. G. Hay,G. Duxbury, and N. Langford J. Mod. Opt. 55, 3293 2008.

  5. Evidence of high-elevation amplification versus Arctic amplification

    Science.gov (United States)

    Wang, Qixiang; Fan, Xiaohui; Wang, Mengben

    2016-01-01

    Elevation-dependent warming in high-elevation regions and Arctic amplification are of tremendous interest to many scientists who are engaged in studies in climate change. Here, using annual mean temperatures from 2781 global stations for the 1961-2010 period, we find that the warming for the world’s high-elevation stations (>500 m above sea level) is clearly stronger than their low-elevation counterparts; and the high-elevation amplification consists of not only an altitudinal amplification but also a latitudinal amplification. The warming for the high-elevation stations is linearly proportional to the temperature lapse rates along altitudinal and latitudinal gradients, as a result of the functional shape of Stefan-Boltzmann law in both vertical and latitudinal directions. In contrast, neither altitudinal amplification nor latitudinal amplification is found within the Arctic region despite its greater warming than lower latitudes. Further analysis shows that the Arctic amplification is an integrated part of the latitudinal amplification trend for the low-elevation stations (≤500 m above sea level) across the entire low- to high-latitude Northern Hemisphere, also a result of the mathematical shape of Stefan-Boltzmann law but only in latitudinal direction.

  6. Raman amplification in the broken-wave regime

    CERN Document Server

    Farmer, John P

    2015-01-01

    In regimes far beyond the wavebreaking theshold of Raman amplification, we show that significant amplifcation can occur after the onset of wavebreaking, before phase mixing destroys the coupling between pump and probe. The amplification efficiency in this regime is therefore strongly dependent on the energy-transfer rate when wavebreaking occurs, and is, as such, sensitive to both the probe amplitude and profile. In order to access the higher-efficiency broken-wave regime, a short, intense probe is required. Parameter scans show the marked difference in behaviour compared to below wavebreaking, where longer, more energetic pulses lead to improved efficiencies.

  7. Efficient audio power amplification - challenges

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Michael A.E.

    2005-07-01

    For more than a decade efficient audio power amplification has evolved and today switch-mode audio power amplification in various forms are the state-of-the-art. The technical steps that lead to this evolution are described and in addition many of the challenges still to be faced and where extensive research and development are needed is covered. (au)

  8. Gene amplification during myogenic differentiation

    Science.gov (United States)

    Fischer, Ulrike; Ludwig, Nicole; Raslan, Abdulrahman; Meier, Carola; Meese, Eckart

    2016-01-01

    Gene amplifications are mostly an attribute of tumor cells and drug resistant cells. Recently, we provided evidence for gene amplifications during differentiation of human and mouse neural progenitor cells. Here, we report gene amplifications in differentiating mouse myoblasts (C2C12 cells) covering a period of 7 days including pre-fusion, fusion and post-fusion stages. After differentiation induction we found an increase in copy numbers of CDK4 gene at day 3, of NUP133 at days 4 and 7, and of MYO18B at day 4. The amplification process was accompanied by gamma-H2AX foci that are indicative of double stand breaks. Amplifications during the differentiating process were also found in primary human myoblasts with the gene CDK4 and NUP133 amplified both in human and mouse myoblasts. Amplifications of NUP133 and CDK4 were also identified in vivo on mouse transversal cryosections at stage E11.5. In the course of myoblast differentiation, we found amplifications in cytoplasm indicative of removal of amplified sequences from the nucleus. The data provide further evidence that amplification is a fundamental mechanism contributing to the differentiation process in mammalians. PMID:26760505

  9. Efficient Audio Power Amplification - Challenges

    DEFF Research Database (Denmark)

    Andersen, Michael Andreas E.

    2005-01-01

    For more than a decade efficient audio power amplification has evolved and today switch-mode audio power amplification in various forms are the state-of-the-art. The technical steps that lead to this evolution are described and in addition many of the challenges still to be faced and where...

  10. Coherent control of atoms and diatomic molecules with shaped ultrashort pulses; Manipulation coherente d'atomes et de molecules diatomiques avec des impulsions mises en forme

    Energy Technology Data Exchange (ETDEWEB)

    Degert, J

    2002-12-15

    This thesis deals with the theoretical and experimental study of coherent control of atomic and molecular systems with shaped pulses. At first, we present several experiments of control of coherent transients in rubidium. These transients appear when a two-level system is excited by a perturbative chirped pulse, and are characterized by oscillations in the excited state population. For a strong chirp, we show that a phase step in the spectrum modifies the phase of the oscillations. Then, by direct analogy with Fresnel zone lens, we conceive a chirped pulse with a highly modulated amplitude, allowing to suppress destructive contributions to the population transfer. In a second set of experiments, we focus on quantum path interferences in two-photon transitions excited by linearly chirped pulses. Owing to the broad bandwidth of ultrashort pulses, sequential and direct excitation paths contribute to the excited state population. Oscillations resulting from interferences between these two paths are observed in atomic sodium. Moreover, we show that they are observable whatever the sign of chirp. Theoretically, we study the control of the predissociation of a benchmark diatomic molecule: NaI. Predissociation leads to matter wave interferences in the fragments distribution. First, we show that a suitably chosen probe pulse allows the observation of theses interferences. Next, using a sequence of control pulse inducing electronic transition, we demonstrate the possibility to manipulate fragment energy distribution. (author)

  11. Ultrashort-pulse lasers and their applications

    International Nuclear Information System (INIS)

    A revolution has occurred over the past ten years in our ability to generate, manipulate, and amplify ultrashort pulses. Laser pulses can be as short as a few femtoseconds (few optical cycles) and possess extreme power up to several terawatts. The applications of these pulses are numerous in physics, chemistry, and biology, where they can be used to time resolve ultrafast events. We review in this article the state of the art in short pulse generation and amplification. (author)

  12. 1-J white-light continuum from 100-TW laser pulses

    International Nuclear Information System (INIS)

    We experimentally measured the supercontinuum generation using 3-J, 30-fs laser pulses and measured white-light generation at the level of 1 J. Such high energy is allowed by a strong contribution to the continuum by the photon bath, as compared to the self-guided filaments. This contribution due to the recently observed congestion of the filament number density in the beam profile at very high intensity also results in a wider broadening for positively chirped pulses rather than for negatively chirped ones, similar to broadening in hollow-core fibers.

  13. Intensity improvement in the attosecond pulse generation with the coherent superposition initial state

    Science.gov (United States)

    Feng, Liqiang; Chu, Tianshu

    2012-03-01

    We investigate the coherent superposition initial state effect and found that when the initial active electron state is prepared in the coherent superposition of the 1s and 2s states of the He+ ion and the chirp parameter of the fundamental field in the two-color scheme is chosen to be β=0.3, the harmonic cutoff energy is remarkably extended and the harmonic yield is enhanced by at least 6 orders of magnitude compared with the case of the single 1s ground state with chirp-free pulse. An ultrabroad supercontinuum with a 458 eV bandwidth is formed, directly producing an intense isolated 34 as pulse.

  14. Bandwidth and chirp characterisation of wavelength conversion based on electroabsorption modulators

    DEFF Research Database (Denmark)

    Xu, Lin; Oxenløwe, Leif Katsuo; Chi, Nan;

    2002-01-01

    It is demonstrated experimentally that the frequency chirp of a data modulated signal can be reduced and the modulation bandwidth increased through wavelength conversion in an electroabsorption modulator.......It is demonstrated experimentally that the frequency chirp of a data modulated signal can be reduced and the modulation bandwidth increased through wavelength conversion in an electroabsorption modulator....

  15. A novel tunable polarization mode dispersion compensator with strain chirped fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    Yumin Liu(刘玉敏); Zhongyuan Yu(俞重远); Yuan Zheng(郑远); Xiaoguang Zhang(张晓光); Bojun Yang(杨伯君)

    2004-01-01

    A tunable polarization mode dispersion (PMD) compensator based on strain-chirped fiber Bragg gratings (FBGs) is proposed. It natures in flexible designing, large tuning range, without using linear or nonlinear chirped phase mask, fast tuning response time, continuously adjustable, all-fiber based, compact, and cheap.

  16. Evidence of high-elevation amplification versus Arctic amplification

    OpenAIRE

    Qixiang Wang; Xiaohui Fan; Mengben Wang

    2016-01-01

    Elevation-dependent warming in high-elevation regions and Arctic amplification are of tremendous interest to many scientists who are engaged in studies in climate change. Here, using annual mean temperatures from 2781 global stations for the 1961–2010 period, we find that the warming for the world’s high-elevation stations (>500 m above sea level) is clearly stronger than their low-elevation counterparts; and the high-elevation amplification consists of not only an altitudinal amplification b...

  17. Experimental demonstration of a multi-wavelength distributed feedback semiconductor laser array with an equivalent chirped grating profile based on the equivalent chirp technology.

    Science.gov (United States)

    Li, Wangzhe; Zhang, Xia; Yao, Jianping

    2013-08-26

    We report, to the best of our knowledge, the first realization of a multi-wavelength distributed feedback (DFB) semiconductor laser array with an equivalent chirped grating profile based on equivalent chirp technology. All the lasers in the laser array have an identical grating period with an equivalent chirped grating structure, which are realized by nonuniform sampling of the gratings. Different wavelengths are achieved by changing the sampling functions. A multi-wavelength DFB semiconductor laser array is fabricated and the lasing performance is evaluated. The results show that the equivalent chirp technology is an effective solution for monolithic integration of a multi-wavelength laser array with potential for large volume fabrication. PMID:24105542

  18. SBS pulse compression for excimer inertial fusion energy drivers

    International Nuclear Information System (INIS)

    A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, λ ca. 250 nm, pulse duration, τp ca. 6 ns, bandwidth, Δλ ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, τpp, is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, τpp which falls in the range, 30 τpppp. As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration τp. These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ''chirped,'' self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF6 at a density, ρ ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at λ=248 nm. In order to avoid the generation of output pulses substantially shorter than τp, the optical power in the chirped input SBS ''seed'' beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of τp ca. ns

  19. Accurate determination of the absolute phase and temporal-pulse phase of few-cycle laser pulses

    Institute of Scientific and Technical Information of China (English)

    Xia Ke-Yu; Gong Shang-Qing; Niu Yue-Ping; Li Ru-Xin; Xu Zhi-Zhan

    2007-01-01

    A Fourier analysis method is used to accurately determine not only the absolute phase but also the temporalpulse phase of an isolated few-cycle (chirped) laser pulse. This method is independent of the pulse shape and can fully characterize the light wave even though only a few samples per optical cycle are available. It paves the way for investigating the absolute phase-dependent extreme nonlinear optics, and the evolutions of the absolute phase and the temporal-pulse phase of few-cycle laser pulses.

  20. Pulse compression by nonlinear pulse evolution with reduced optical wave breaking in erbium-doped fiber amplifiers.

    Science.gov (United States)

    Tamura, K; Nakazawa, M

    1996-01-01

    Nonlinear pulse evolution is studied for a fiber with normal dispersion (ND) and gain. Numerical simulations show that under certain conditions the pulse evolves into a parabolic shape, which has been shown to reduce optical wave breaking. Much as with the square pulse that forms in passive fibers with ND, the interplay of ND and self-phase modulation creates a highly linear chirp, which can be efficiently compressed. Application to an amplifying fiber/grating (prism) pair pulse compressor is considered, with an experimental demonstration of compression from 350 to 77 fs at a gain of 18 dB in an erbium-doped fiber amplifier. PMID:19865307