WorldWideScience

Sample records for chirped pulse amplification

  1. Hybrid Chirped Pulse Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I; Barty, C P J

    2002-05-07

    We present a novel chirped pulse amplification method which combines optical parametric amplification and laser amplification. We have demonstrated this hybrid CPA concept with a combination of beta-barium borate and Ti:sapphire. High-efficiency, multi-terawatt compatible amplification is achieved without gain narrowing and without electro-optic modulators using a simple commercial pump laser.

  2. Next generation Chirped Pulse Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nees, J.; Biswal, S.; Mourou, G. [Univ. Michigan, Center for Ultrafast Optical Science, Ann Arbor, MI (United States); Nishimura, Akihiko; Takuma, Hiroshi

    1998-03-01

    The limiting factors of Chirped Pulse Amplification (CPA) are discussed and experimental results of CPA in Yb:glass regenerative amplifier are given. Scaling of Yb:glass to the petawatt level is briefly discussed. (author)

  3. Hybrid chirped pulse amplification system

    Science.gov (United States)

    Barty, Christopher P.; Jovanovic, Igor

    2005-03-29

    A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

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

    OpenAIRE

    Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten; Galili, Michael; Peucheret, Christophe

    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.

  5. 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....

  6. Dispersion compensation in chirped pulse amplification systems

    Science.gov (United States)

    Bayramian, Andrew James; Molander, William A.

    2014-07-15

    A chirped pulse amplification system includes a laser source providing an input laser pulse along an optical path. The input laser pulse is characterized by a first temporal duration. The system also includes a multi-pass pulse stretcher disposed along the optical path. The multi-pass pulse stretcher includes a first set of mirrors operable to receive input light in a first plane and output light in a second plane parallel to the first plane and a first diffraction grating. The pulse stretcher also includes a second set of mirrors operable to receive light diffracted from the first diffraction grating and a second diffraction grating. The pulse stretcher further includes a reflective element operable to reflect light diffracted from the second diffraction grating. The system further includes an amplifier, a pulse compressor, and a passive dispersion compensator disposed along the optical path.

  7. Hyper dispersion pulse compressor for chirped pulse amplification systems

    Energy Technology Data Exchange (ETDEWEB)

    Barty, Christopher P. J. (Hayward, CA)

    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.

  8. 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.

  9. Millijoule pulse energy picosecond fiber chirped-pulse amplification system

    Institute of Scientific and Technical Information of China (English)

    Zhi Yang; Xiaohong Hu; Yishan Wang; Wei Zhang; Wei Zhao

    2011-01-01

    @@ The efficient generation of a 1.17-mJ laser pul8e with 360 ps duration using an ytterbium (Yb)-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally.A specially designed figure-of-eight fiber laser acts as the seed source of a chirped-pulse amplification (CPA) system and generates mode-locked pulse8 with hundreds of picosecond widths.Two kinds of large-mode-area (LMA) double-clad Yb-doped fibers are employed to construct the pre-amplifier and main amplifier, All of the adopted instruments help avoid severe nonlinearity in fibers to raise sub-nanosecond pulse energy with acceptable signal-to-noise ratio (SNR).The output spectrum of this fiber-based CPA system shows that amplified spontaneous emission (ASE) is suppressed to better than 30 dB, and the onset of stimulated Raman scattering is excluded.%The efficient generation of a 1.17-mJ laser pulse with 360 ps duration using an ytterbium (Yb)-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally. A specially designed figure-of-eight fiber laser acts as the seed source of a chirped-pulse amplification (CPA) system and generates mode-locked pulses with hundreds of picosecond widths. Two kinds of large-mode-area (LMA) double-clad Yb-doped fibers are employed to construct the pre-amplifier and main amplifier. All of the adopted instruments help avoid severe nonlinearity in fibers to raise sub-nanosecond pulse energy with acceptable signal-to-noise ratio (SNR). The output spectrum of this fiber-based CPA system shows that amplified spontaneous emission (ASE) is suppressed to better than 30 dB, and the onset of stimulated Raman scattering is excluded.

  10. 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

  11. 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....

  12. 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

  13. 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)

  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.

  15. 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

  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. 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).

  18. 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.

  19. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    Science.gov (United States)

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

  20. 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.

  1. 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

  2. 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)

  3. 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....

  4. 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.

  5. Compensation of high-order phase distortions in chirped-pulse amplification system

    Science.gov (United States)

    Zhou, Bing; Jiang, Yong-Liang; Leng, Yu-xin; Chen, Xiao-Wei; Li, Ru-Xin; Xu, Zhi-Zhan

    2007-01-01

    Chirped-pulse amplification (CPA) technique has been widely used to generate ultra-intense femto-second pulses. In this scheme the seed pulses from an oscillator are stretched before amplification. The stretched pulses can support more energy extraction and effectively decrease the nonlinear effects in the gain media. The subsequent amplification in a CPA chain will result in a broadening of the output compressed pulses in temporal domain due to the gain narrowing and uncompensated phase distortions. In our experiment, using spectral modulation and phase pre-compensation system (Acoustic-Optics Programmable Dispersive Filter) between the oscillator and the stretcher, the effects of gain narrowing and high-order dispersions on the pulse duration in kHz chirped-pulse amplification system have been pre-compensated, and the spectral FWHM is expanded from 30nm to 50nm. The effects of GDD, TOD and FOD were investigated by scanning the four dispersion parameters respectively. By pre-compensating the high-order phase distortions with the phase measured by SPIDER, we successfully optimize the output duration from 51fs to 30fs, which is 1.07 times Fourier-transform-limitation.

  6. 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.

  7. Optical chirped beam amplification and propagation

    Science.gov (United States)

    Barty, Christopher P.

    2004-10-12

    A short pulse laser system uses dispersive optics in a chirped-beam amplification architecture to produce high peak power pulses and high peak intensities without the potential for intensity dependent damage to downstream optical components after amplification.

  8. 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.

  9. 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

  10. Spectral Phase Modulation and chirped pulse amplification in High Gain Harmonic Generation

    CERN Document Server

    Wu, Zilu; Krinsky, Sam; Loos, Henrik; Murphy, James; Shaftan, Timur; Sheehy, Brian; Shen, Yuzhen; Wang, Xijie; Yu Li Hua

    2004-01-01

    High Gain Harmonic Generation (HGHG), because it produces longitudinally coherent pulses derived from a coherent seed, presents remarkable possibilities for manipulating FEL pulses. If spectral phase modulation imposed on the seed modulates the spectral phase of the HGHG in a deterministic fashion, then chirped pulse amplification, pulse shaping, and coherent control experiments at short wavelengths become possible. In addition, the details of the transfer function will likely depend on electron beam and radiator dynamics and so prove to be a useful tool for studying these. Using the DUVFEL at the National Synchrotron Light Source at Brookhaven National Laboratory, we present spectral phase analyses of both coherent HGHG and incoherent SASE ultraviolet FEL radiation, applying Spectral Interferometry for Direct Electric Field Reconstruction (SPIDER), and assess the potential for employing compression and shaping techniques.

  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. 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.

  13. 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)

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    Marta Fajardo

    2013-07-01

    Full Text Available 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 study the transposition to soft X-rays of the Chirped Pulse Amplification (CPA technique. Soft X-ray pulses with energy of 6 mJ and 200 fs duration are reachable by seeding plasmas pumped by compact 100 J, sub-ns, 1 shot/min lasers. These soft X-ray lasers would reach GW power, corresponding to an increase of 100 times as compared to the highest peak power achievable nowadays in the soft X-ray region (30 eV–1 keV. X-ray CPA is opening new horizon for soft x-ray ultra-intense sources.

  18. Energy and average power scalable optical parametric chirped-pulse amplification in yttrium calcium oxyborate.

    Science.gov (United States)

    Liao, Zhi M; Jovanovic, Igor; Ebbers, Chris A; Fei, Yiting; Chai, Bruce

    2006-05-01

    Optical parametric chirped-pulse amplification (OPCPA) in nonlinear crystals has the potential to produce extremes of peak and average power but is limited either in energy by crystal growth issues or in average power by crystal thermo-optic characteristics. Recently, large (7.5 cm diameter x 25 cm length) crystals of yttrium calcium oxyborate (YCOB) have been grown and utilized for high-average-power second-harmonic generation. Further, YCOB has the necessary thermo-optic properties required for scaling OPCPA systems to high peak and average power operation for wavelengths near 1 microm. We report what is believed to be the first use of YCOB for OPCPA. Scalability to higher peak and average power is addressed.

  19. 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.

  20. High and Stable Conversion Efficiency Obtaining in Single-Stage Multi-Crystal Optical Parametric Chirped Pulse Amplification System

    Institute of Scientific and Technical Information of China (English)

    JIANG Yong-Liang; LENG Yu-Xin; ZHAO Bao-Zhen; WANG Cheng; LIANG Xiao-Yan; LU Hai-He; XU Zhi-Zhan

    2005-01-01

    @@ An optical parametric chirped-pulse amplification system is demonstrated to provide 32.9% pump-to-signal con-version efficiency. Special techniques are used to make the signal and pump pulses match with each other inboth spectral and temporal domains. The broadband 9.5-mJ pulses are produced at the repetition rate of 1 Hzwith the gain of over 1.9 × 108. The output energy fluctuation of 7.8% is achieved for the saturated amplificationprocess against the pump fluctuation of 10%.

  1. 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.

  2. 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...

  3. 200 TW 45 fs laser based on optical parametric chirped pulse amplification.

    Science.gov (United States)

    Lozhkarev, V V; Freidman, G I; Ginzburg, V N; Katin, E V; Khazanov, E A; Kirsanov, A V; Luchinin, G A; Mal'shakov, A N; Martyanov, M A; Palashov, O V; Poteomkin, A K; Sergeev, A M; Shaykin, A A; Yakovlev, I V; Garanin, S G; Sukharev, S A; Rukavishnikov, N N; Charukhchev, A V; Gerke, R R; Yashin, V E

    2006-01-01

    200 TW peak power has been achieved experimentally using a Cr:forsterite master oscillator at 1250 nm, a stretcher, three optical parametrical amplifiers based on KD*P (DKDP) crystals providing 14.5 J energy in the chirped pulse at 910 nm central wavelength, and a vacuum compressor. The final parametrical amplifier and the compressor are described in detail. Scaling of such architecture to multipetawatt power is discussed.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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...

  9. 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)

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

    OpenAIRE

    He, F.; Price, J.H.V.; De Malinowski, A.; Piper, A.; Ibsen, M; D.J.Richardson; 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.

  11. High contrast, 86  fs, 35  mJ pulses from a diode-pumped, Yb:glass, double-chirped-pulse amplification laser system.

    Science.gov (United States)

    Liebetrau, Hartmut; Hornung, Marco; Keppler, Sebastian; Hellwing, Marco; Kessler, Alexander; Schorcht, Frank; Hein, Joachim; Kaluza, Malte C

    2016-07-01

    We demonstrate the generation of 86 fs, 35 mJ, high-contrast laser pulses at 1030 nm with a repetition rate of 1 Hz from a diode-pumped double chirped-pulse amplification setup. The pulses exhibit a spectral bandwidth exceeding 27 nm full width at half-maximum. This could be achieved by using a laser architecture comprising two stages of chirped pulse amplification with a cross-polarized wave generation filter in between, by applying spectral shaping and by increasing the spectral hard-clip of the second stretcher. These are, to the best of our knowledge, the shortest pulses at the mJ level with ultra-high contrast generated with a diode-pumped front end at 1030 nm.

  12. Demonstration of a double chirped-pulse-amplification front-end system to improve the temporal contrast at a sub-petawatt laser

    Science.gov (United States)

    Xie, Na; Zhou, Kainan; Huang, Wanqing; Wang, Xiaodong; Sun, Li; Guo, Yi; Li, Qing

    2012-02-01

    The temporal contrast is an important factor affecting the application of ultra-intense and ultra-short lasers. In this paper, we develop a double chirped-pulse-amplification (CPA) front-end system with an intermediate nonlinear temporal pulse filter to improve the temporal contrast at a sub-petawatt Ti:sapphire laser facility, i.e. the super intense laser for experiment on the extremes (SILEX-I). The temporal pulse filter employs cross-polarized wave (XPW) generation to suppress the amplified spontaneous emission (ASE). The design output energy is 320 mJ for the front-end system. The experimental results show that the output energy of the double CPA system is 360 mJ. The ASE pedestal is suppressed significantly and the temporal contrast is improved by around three orders of magnitude.

  13. Ionization of atoms by chirped attosecond pulses

    Institute of Scientific and Technical Information of China (English)

    Tan Fang; Peng Liang-You; Gong Qi-Huang

    2009-01-01

    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.

  14. 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

  15. Ion Acceleration by Short Chirped Laser Pulses

    Directory of Open Access Journals (Sweden)

    Jian-Xing Li

    2015-02-01

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

  16. 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.

  17. 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%.

  18. 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

  19. 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.

  20. 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)

  1. 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.

  2. 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.

  3. 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...

  4. 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.

  5. Dispersion management for a sub-10-fs, 10 TW optical parametric chirped-pulse amplifier.

    Science.gov (United States)

    Tavella, Franz; Nomura, Yutaka; Veisz, Laszlo; Pervak, Vladimir; Marcinkevicius, Andrius; Krausz, Ferenc

    2007-08-01

    We report the amplification of three-cycle, 8.5 fs optical pulses in a near-infrared noncollinear optical parametric chirped-pulse amplifier (OPCPA) up to energies of 80 mJ. Improved dispersion management in the amplifier by means of a combination of reflection grisms and a chirped-mirror stretcher allowed us to recompress the amplified pulses to within 6% of their Fourier limit. The novel ultrabroad, ultraprecise dispersion control technology presented in this work opens the way to scaling multiterawatt technology to even shorter pulses by optimizing the OPCPA bandwidth.

  6. Charged particle interaction with a chirped electromagnetic pulse

    NARCIS (Netherlands)

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

    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.

  7. Surface-reflection-initiated pulse-contrast degradation in an optical parametric chirped-pulse amplifier.

    Science.gov (United States)

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

    2013-07-01

    We study a novel mechanism of pre-pulse generation in an optical parametric chirped-pulse amplification (OPCPA) system through an analytical approach together with numerical simulations. The acquired pre-pulses are initiated from the surface-reflection-induced modulation of the seed spectrum and occur as a consequence of high-order distortion of such modulated spectrum due to the instantaneous gain saturation effect. We demonstrate that the intensities of pre-pulses increase quadratically with the initial temporal modulation-depth of the stretched signal pulse as well as the conversion efficiency prior to substantial pump-depletion. Explicit formulas for estimating the contrast limit due to surface reflections are present. We also discuss the impact of group-velocity mismatch on the pre-pulse generation. The results of this work may deepen our cognition on the complexity of the pulse-contrast problem in OPCPA systems. PMID:23842344

  8. 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.

  9. 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)

  10. Chirp of monolithic colliding pulse mode-locked diode lasers

    DEFF Research Database (Denmark)

    Hofmann, M.; Bischoff, S.; Franck, Thorkild;

    1997-01-01

    Spectrally resolved streak camera measurements of picosecond pulses emitted by hybridly colliding pulse mode-locked (CPM) laser diodes are presented in this letter. Depending on the modulation frequency both blue-chirped (upchirped) and red-chirped (downchirped) pulses can be observed. The two...... different regimes and the transition between them are characterized experimentally and the behavior is explained on the basis of our model for the CPM laser dynamics. (C) 1997 American Institute of Physics....

  11. Highly stable ultrabroadband mid-IR optical parametric chirped-pulse amplifier optimized for superfluorescence suppression.

    Science.gov (United States)

    Moses, J; Huang, S-W; Hong, K-H; Mücke, O D; Falcão-Filho, E L; Benedick, A; Ilday, F O; Dergachev, A; Bolger, J A; Eggleton, B J; Kärtner, F X

    2009-06-01

    We present a 9 GW peak power, three-cycle, 2.2 microm optical parametric chirped-pulse amplification source with 1.5% rms energy and 150 mrad carrier envelope phase fluctuations. These characteristics, in addition to excellent beam, wavefront, and pulse quality, make the source suitable for long-wavelength-driven high-harmonic generation. High stability is achieved by careful optimization of superfluorescence suppression, enabling energy scaling.

  12. 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

  13. Analysis of ultra-broadband high-energy optical parametric chirped pulse amplifier based on YCOB crystal

    Institute of Scientific and Technical Information of China (English)

    Meizhi Sun; Lailin Ji; Qunyu Bi; Nannan Wang; Jun Kang; Xinglong Xie; Zunqi Lin

    2011-01-01

    A new type of optical parametric chirped pulse amplifier is designed and analyzed for the amplification of pulse centered at 808 nm.A novel crystal,yttrium calcium oxyborate YCa4O(BO3)3 (YCOB),is utilized in the power amplification stage of optical parametric amplification (OPA).Noncollinear phase matching parameters in the xoz principle plane of YCOB,compared with those in BBO and DKDP,are analyzed by numerical simulation.The results show that YCOB rather than DKDP can be used in the power amplification stage of OPA to realize the amplification of chirped pulse to several joules with a gain bandwidth exceeding 100 nm.This can be used to gain a high intensity pulse of ~10 fs after the compressor.The amplification of the femtosecond pulse is an important branch of ultra-intense laser technology,with Ti:sapphire as the medium for its large gain bandwidth.From the perspective of technical features and applications,such femtosecond pulses are used to study high field physics and other related areas in ultrashort time[1,2];however,the pursuit of higher energy femtosecond pulse should not be abandoned.Optical parametric chirped pulse amplification (OPCPA) has been successfully used in the front end of high intensity lasers[3-8],indicating the possibility of femtosecond pulse amplification.This has been verified by an increasing number of fine crystals being invented,such as YCa4O(BO3)3 (YCOB)[9-12].%A new type of optical parametric chirped pulse amplifier is designed and analyzed for the amplification of pulse centered at 808 nm. A novel crystal, yttrium calcium oxyborate YCa4O(BO3)3 (YCOB), is utilized in the power amplification stage of optical parametric amplification (OPA). Noncollinear phase matching parameters in the xoz principle plane of YCOB, compared with those in BBO and DKDP, are analyzed by numerical simulation. The results show that YCOB rather than DKDP can be used in the power amplification stage of OPA to realize the amplification of chirped pulse to

  14. 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.

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

    Science.gov (United States)

    Lali-Dastjerdi, Zohreh; Cristofori, Valentina; Rottwitt, Karsten; Galili, Michael; Peucheret, Christophe

    2015-03-01

    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.

  16. 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)

  17. Spectral Analysis using Linearly Chirped Gaussian Pulse Stacking

    Institute of Scientific and Technical Information of China (English)

    ZHENG Huan; WANG An-Ting; XU Li-Xin; MING Hai

    2009-01-01

    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.

  18. Periodic compression of chirped femtosecond pulses in silicon waveguides under fourth-order dispersion

    Science.gov (United States)

    Mandeng Mandeng, Lucien; Ibraid Fewo, Serge; Tchawoua, Clément; Crépin Kofané, Timoléon

    2014-08-01

    We report the analysis of the compression mechanism for chirped femtosecond pulses in silicon-on-insulator waveguides under the effect of fourth-order dispersion (FOD) using the modified variational approach that involves Rayleigh's dissipation function (RDF). Our results show that the nonlinear compression in these waveguides is input pulse dependent. Moreover, this study leads to a nearly periodic-like dynamic induced by the interplay between self-phase modulation and FOD in a normal group-velocity dispersion. In addition, when large values of the initial chirp and absorption coefficients present in these waveguides are considered, the compression mechanism is completely destroyed, with the observation of at least one pulse amplification over a short distance of propagation prior to pulse broadening.

  19. 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...

  20. 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.

  1. 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...

  2. Interaction of free charged particles with a chirped electromagnetic pulse

    NARCIS (Netherlands)

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

    2004-01-01

    We study the effect of chirp on electromagnetic (EM) pulse interaction with a charged particle. Both the one-dimensional (1D) and 3D cases are considered. It is found that, in contrast to the case of a nonchirped pulse, the charged particle energy can be changed after the interaction with a 1D EM ch

  3. 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.

  4. 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.

  5. Chirped pulse inverse free-electron laser vacuum accelerator

    Science.gov (United States)

    Hartemann, Frederic V.; Baldis, Hector A.; Landahl, Eric C.

    2002-01-01

    A chirped pulse inverse free-electron laser (IFEL) vacuum accelerator for high gradient laser acceleration in vacuum. By the use of an ultrashort (femtosecond), ultrahigh intensity chirped laser pulse both the IFEL interaction bandwidth and accelerating gradient are increased, thus yielding large gains in a compact system. In addition, the IFEL resonance condition can be maintained throughout the interaction region by using a chirped drive laser wave. In addition, diffraction can be alleviated by taking advantage of the laser optical bandwidth with negative dispersion focusing optics to produce a chromatic line focus. The combination of these features results in a compact, efficient vacuum laser accelerator which finds many applications including high energy physics, compact table-top laser accelerator for medical imaging and therapy, material science, and basic physics.

  6. Thomson scattering in high-intensity chirped laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Holkundkar, Amol R., E-mail: amol.holkundkar@pilani.bits-pilani.ac.in [Department of Physics, Birla Institute of Technology and Science, Pilani, Rajasthan 333031 (India); Harvey, Chris, E-mail: christopher.harvey@chalmers.se; Marklund, Mattias, E-mail: mattias.marklund@chalmers.se [Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg (Sweden)

    2015-10-15

    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.

  7. A direct digital synthesis chirped pulse Fourier transform microwave spectrometer.

    Science.gov (United States)

    Finneran, Ian A; Holland, Daniel B; Carroll, P Brandon; Blake, Geoffrey A

    2013-08-01

    Chirped pulse Fourier transform microwave (CP-FTMW) spectrometers have become the instrument of choice for acquiring rotational spectra, due to their high sensitivity, fast acquisition rate, and large bandwidth. Here we present the design and capabilities of a recently constructed CP-FTMW spectrometer using direct digital synthesis (DDS) as a new method for chirped pulse generation, through both a suite of extensive microwave characterizations and deep averaging of the 10-14 GHz spectrum of jet-cooled acetone. The use of DDS is more suited for in situ applications of CP-FTMW spectroscopy, as it reduces the size, weight, and power consumption of the chirp generation segment of the spectrometer all by more than an order of magnitude, while matching the performance of traditional designs. The performance of the instrument was further improved by the use of a high speed digitizer with dedicated signal averaging electronics, which facilitates a data acquisition rate of 2.1 kHz.

  8. Effects of chirp of pump pulses on broadband terahertz pulse spectra generated by optical rectification

    Science.gov (United States)

    Hamazaki, Junichi; Furusawa, Kentaro; Sekine, Norihiko; Kasamatsu, Akifumi; Hosako, Iwao

    2016-11-01

    The effects of the chirp of the pump pulse in broadband terahertz (THz) pulse generation by optical rectification (OR) in GaP were systematically investigated. It was found that the pre-compensation for the dispersion of GaP is important for obtaining smooth and single-peaked THz spectra as well as high power-conversion efficiency. It was also found that an excessive amount of chirp leads to distortions in THz spectra, which can be quantitatively analyzed by using a simple model. Our results highlight the importance of accurate control over the chirp of the pump pulse for generating broadband THz pulses by OR.

  9. 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.

  10. 2-μm wavelength, high-energy Ho:YLF chirped-pulse amplifier for mid-infrared OPCPA.

    Science.gov (United States)

    Hemmer, M; Sánchez, D; Jelínek, M; Smirnov, Vadim; Jelinkova, H; Kubeček, V; Biegert, J

    2015-02-15

    A 2-μm wavelength laser delivering up to 39-mJ energy, ∼10  ps duration pulses at 100-Hz repetition rate is reported. The system relies on chirped pulse amplification (CPA): a modelocked Er:Tm:Ho fiber-seeder is followed by a Ho:YLF-based regenerative amplifier and a cryogenically cooled Ho:YLF single pass amplifier. Stretching and compressing are performed with large aperture chirped volume Bragg gratings (CVBG). At a peak power of 3.3 GW, the stability was <1%  rms over 1 h, confirming high suitability for OPCPA and extreme nonlinear optics applications. PMID:25680122

  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. 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.

  13. 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.

  14. 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.

  15. 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

  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.

  17. Time-Resolved Radiography using Chirp-Pulse Proton Beams

    Institute of Scientific and Technical Information of China (English)

    TENG Jian; ZHAO Zong-Qing; ZHU Bin; HONG Wei; CAO Lei-Feng; ZHOU Wei-Min; SHAN Lian-Qiang; GU Yu-Qiu

    2011-01-01

    Protons accelerated by the target normal sheath acceleration(TNSA)mechanism have a wide energy spectrum and are called chirp-pulse protons. The numerical simulation of chirp-pulse proton radiography in an implosion process with single shot is carried out using the Monte Carlo method.Two different methods are proposed.The first method, proton framing radiography ,uses a stack of radiochromic film layers as the detector. Each layer deposits protons with energy corresponding to the Bragg peak, which can record the transient state of the implosion process. The second method, proton streak radiography, uses an external magnetic field to deflect protons. Different energies correspond to different times. By using a slit before the magnetic field, one-dimensional spatial resolution and temporal resolution can be obtained. This method is more suitable for the diagnosis of the implosion process.

  18. Coherent chirped pulse laser network with Mickelson phase-conjugator

    CERN Document Server

    Okulov, A Yu

    2013-01-01

    The mechanisms of nonlinear phase-locking of a large fiber amplifier array are analyzed. The preference is given to configuration most suitable for a coherent coupling of a thousands of a fundamental spatial mode fiber beams into a single smooth beam ready for chirped pulse compression. It is shown that Michelson phase conjugating configuration with double passage through array of fiber amplifiers have the definite advantages compared to one-way fiber array coupled in a Mach-Zehnder configuration. Regardless to amount of synchronized fiber amplifiers Michelson phase-conjugating interferometer is expected to do a perfect compensation of the phase-piston errors and collimation of backwardly amplified fiber beams on entrance/output beamsplitter. In both configurations the nonlinear transformation of the stretched pulse envelope due to gain saturation is capable to randomize the position of chirp inside envelope thus it may reduce the visibility of interference pattern at output beamsplitter. A certain advantages...

  19. 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.

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

    Institute of Scientific and Technical Information of China (English)

    ZHANG LiFu; FU XiQuan; FENG ZeHu; YANG Hua; WEN ShuangChun

    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.

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Highly Efficient Tabletop Optical Parametric Chirped Pulse Amplifier at 1 (micron)m

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I.; Ebbers, C.A.; Comaskey, B.J.; Bonner, R.A.; Morse, E.C.

    2001-12-04

    Optical parametric chirped pulse amplification (OPCPA) is a scalable technology, for ultrashort pulse amplification. Its major advantages include design simplicity, broad bandwidth, tunability, low B-integral, high contrast, and high beam quality. OPCPA is suitable both for scaling to high peak power as well as high average power. We describe the amplification of stretched 100 fs oscillator pulses in a three-stage OPCPA system pumped by a commercial, single-longitudinal-mode, Q-switched Nd:YAG laser. The stretched pulses were centered around 1054 nm with a FWHM bandwidth of 16.5 nm and had an energy of 0.5 nJ. Using our OPCPA system, we obtained an amplified pulse energy of up to 31 mJ at a 10 Hz repetition rate. The overall conversion efficiency from pump to signal is 6%, which is the highest efficiency obtained With a commercial tabletop pump laser to date. The overall conversion efficiency is limited due to the finite temporal overlap of the seed (3 ns) with respect to the duration of the pump (8.5 ns). Within the temporal window of the seed pulse the pump to signal conversion efficiency exceeds 20%. Recompression of the amplified signal was demonstrated to 310 fs, limited by the aberrations initially present in the low energy seed imparted by the pulse stretcher. The maximum gain in our OPCPA system is 6 x 10{sup 7}, obtained through single passing of 40 mm of beta-barium borate. We present data on the beam quality obtained from our system (M{sup 2}=1.1). This relatively simple system replaces a significantly more complex Ti:sapphire regenerative amplifier based CPA system used in the front end of a high energy short pulse laser. Future improvement will include obtaining shorter amplified pulses and higher average power.

  9. 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)

  10. 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

  11. 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

  12. 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.

  13. 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...

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. Generation of attosecond pulse pair in polar media by chirped few-cycle pulses

    Science.gov (United States)

    Hu, Pidong; Niu, Yueping; Wang, Xiangxin; Gong, Shangqing; Liu, Chengpu

    2016-09-01

    The high-order harmonic generation in a polar medium driven by an initially chirped few-cycle laser pulse is investigated via numerically solving the nonlinear Bloch or Maxwell-Bloch equations based on whether propagation effects are taken into account or not. As a result of the reduction of quantum trajectories number due to the introduction of chirps, an attosecond pulse pair (APP) is generated instead of a general attosecond pulse train. Moreover, the time delay between the two attosecond pulses is tunable. When propagation effects take roles, the peak intensities of the APP can be enhanced at suitable propagation distances without observable duration broadening, and such an enhancement can be modulated by changing medium density.

  20. 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.

  1. 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.

  2. Influence of Initial Pulse Chirp on Rainbow-Like Supercontinuum Generation from Filamentation in Air

    Institute of Scientific and Technical Information of China (English)

    HAO Zuo-Qiang; ZHANG Jie; ZHANG Zhe; LU Xin; JIN Zhan; ZHONG Jia-Yong; LIU Yun-Quan; WANG Zhao-Hua

    2008-01-01

    @@ Supercontinuum (SC) generation from laser filamentation in air is found to depend strongly on the pulse duration.Rainbow-like SC generation is observed only for a pulse of appropriate negative chirp that agrees with the predictions put forward by Golubtsov et al. [Quantum Electron. 33 (2003) 525]. The conversion efficiency of an 800-nm laser light to rainbow-like SC is found to be the highest for 257fs pulses with an initial negative chirp.A larger chirp will lead to ffiamentation surviving at longer distance.

  3. 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.

  4. 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.

  5. Chirp-dependent spectral distribution for few-cycle pulses propagating through nano-semiconductor devices

    Science.gov (United States)

    Zhang, Chaojin; Liu, Chengpu

    2016-09-01

    The propagation of an initially chirped incident few-cycle pulse through an ensemble of quantum wells is numerically investigated. It is found that the distribution characteristic of the transmitted spectrum sensitively depends on the incident laser parameters, especially its positive or negative chirp property. As for the incident pulse with a positive initial chirp, beyond the obvious spectral blue-shift, the transmitted spectral distribution is discrete. In contrast, as for a negative initial chirp, the spectral distribution is continuous instead. In addition, the insensitivity of chirp-dependent spectral distribution to medium symmetry character is also tested and the intensity of high-frequency spectral components enhances obviously due to the nonlinear propagation effects.

  6. 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/)

  7. 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.

  8. 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...

  9. 16.6 J chirped femtosecond laser pulses from a diode-pumped Yb:CaF2 amplifier.

    Science.gov (United States)

    Kessler, Alexander; Hornung, Marco; Keppler, Sebastian; Schorcht, Frank; Hellwing, Marco; Liebetrau, Hartmut; Körner, Jörg; Sävert, Alexander; Siebold, Mathias; Schnepp, Matthias; Hein, Joachim; Kaluza, Malte C

    2014-03-15

    We report the amplification of laser pulses at a center wavelength of 1034 nm to an energy of 16.6 J from a fully diode-pumped amplifier using Yb:CaF2 as the active medium. Pumped by a total optical power of 300 kW from high-power laser diodes, a gain factor of g=6.1 was achieved in a nine-pass amplifier configuration agreeing with numerical simulations. A measured spectral bandwidth of 10 nm full width at half-maximum promises a bandwidth-limited compression of the pulses down to a duration of 150 fs. These are, to our knowledge, the most energetic laser pulses achieved from a diode-pumped chirped-pulse amplifier so far.

  10. 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)

  11. 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)

  12. Dynamics of linear compression of chirped femtosecond optical pulses under fourth-order dispersion

    Science.gov (United States)

    Mandeng Mandeng, Lucien; Ibraid Fewo, Serge; Tchawoua, Clément; Crépin Kofané, Timoléon

    2014-05-01

    In a linear dispersive optical medium under fourth-order dispersion (FOD), we study the dynamics of the chirped pulse compression with the help of trial Gaussian and raised-cosine (RC) ansätze pulses. The analysis based on the variational approach leads to the occurrence of compression conditions, highlighting the cases where both the group-velocity dispersion (GVD) and the chirp could have the same sign or the case where both the FOD and the GVD have the same sign. Furthermore, we show that the compression process is dependent on the considered input profile. Particularly, a condition supposing that the GVD, the FOD and the chirp have the same sign leads to a compression only for the RC pulse in comparison to the previous results obtained for the Gaussian pulse. Numerical simulations, which confirm these features, are presented for the 380-fs input pulses undergoing ? value in the FOD.

  13. 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.

  14. 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.

  15. Cpuf: Chirped-Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    Science.gov (United States)

    Suits, Arthur; Abeysekera, Chamara; Zack, Lindsay N.; Joalland, Baptiste; Ariyasingha, Nuwandi M.; Park, Barratt; Field, Robert W.; Sims, Ian

    2015-06-01

    Chirped-pulse Fourier-transform microwave spectroscopy has stimulated a resurgence of interest in rotational spectroscopy owing to the dramatic reduction in spectral acquisition time it enjoys when compared to cavity-based instruments. This suggests that it might be possible to adapt the method to study chemical reaction dynamics and even chemical kinetics using rotational spectroscopy. The great advantage of this would be clear, quantifiable spectroscopic signatures for polyatomic products as well as the possibility to identify and characterize new radical reaction products and transient intermediates. To achieve this, however, several conditions must be met: 1) products must be thermalized at low temperature to maximize the population difference needed to achieve adequate signal levels and to permit product quantification based on the rotational line strength; 2) a large density and volume of reaction products is also needed to achieve adequate signal levels; and 3) for kinetics studies, a uniform density and temperature is needed throughout the course of the reaction. These conditions are all happily met by the uniform supersonic flow produced from a Laval nozzle expansion. In collaboration with the Field group at MIT we have developed a new instrument we term a CPUF (Chirped-pulse/Uniform Flow) spectrometer in which we can study reaction dynamics, photochemistry and kinetics using broadband microwave and millimeter wave spectroscopy as a product probe. We will illustrate the performance of the system with a few examples of photodissociation and reaction dynamics, and also discuss a number of challenges unique to the application of chirped-pulse microwave spectroscopy in the collisional environment of the flow. Future directions and opportunities for application of CPUF will also be explored.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Factorization of numbers with Gauss sums: II. Suggestions for implementation with chirped laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Merkel, W; Woelk, S; Schleich, W P [Institut fuer Quantenphysik, Universitaet Ulm, Albert-Einstein-Allee 11, D-89081 Ulm (Germany); Averbukh, I Sh [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Girard, B [Laboratoire de Collisions, Agregats, Reactivite, IRSAMC (Universite de Toulouse/UPS, CNRS), Toulouse (France); Paulus, G G, E-mail: sabine.woelk@uni-ulm.de [Institut fuer Optik und Quantenelektronik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)

    2011-10-15

    We propose three implementations of the Gauss sum factorization schemes discussed in part I of this series (Woelk et al 2011 New J. Phys. 13 103007): (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 appropriate Gauss sum. We provide rules on how to encode the number N to be factored in our system and how to identify the factors of N in the fluorescence signal of the excited state.

  1. 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)

  2. 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.

  3. 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.

  4. Effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    Song Rui; Hou Jing; Wang Ze-Feng; Xiao Rui; Lu Qi-Sheng

    2013-01-01

    Theoretical and experimental research on the effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier is carried out.The complex Ginzburg-Landau equation is used to simulate the propagation of the pulse in the fiber amplifier and the results show that pulses with negative initial chirp produce the widest supercontinuum and pulses with positive initial chirp produce the narrowest supercontinuum when the central wavelength of the pump lies in the normal dispersion region of the gain fiber.A self-made line width narrowing system is utilized to control the initial chirp of the nanosecond pump pulse and a four-stage master oscillator power amplifier configuration is adopted to produce a high power near-infrared suppercontinuum.The experimental results are in good agreement with simulations which can provide some guidance on further optimization of the system in future work.

  5. Perspective: The first ten years of broadband chirped pulse Fourier transform microwave spectroscopy.

    Science.gov (United States)

    Park, G Barratt; Field, Robert W

    2016-05-28

    Since its invention in 2006, the broadband chirped pulse Fourier transform spectrometer has transformed the field of microwave spectroscopy. The technique enables the collection of a ≥10 GHz bandwidth spectrum in a single shot of the spectrometer, which allows broadband, high-resolution microwave spectra to be acquired several orders of magnitude faster than what was previously possible. We discuss the advantages and challenges associated with the technique and look back on the first ten years of chirped pulse Fourier transform spectroscopy. In addition to enabling faster-than-ever structure determination of increasingly complex species, the technique has given rise to an assortment of entirely new classes of experiments, ranging from chiral sensing by three-wave mixing to microwave detection of multichannel reaction kinetics. However, this is only the beginning. Future generations of microwave experiments will make increasingly creative use of frequency-agile pulse sequences for the coherent manipulation and interrogation of molecular dynamics.

  6. Chirped self-healing Airy pulses compression in silicon waveguides under fourth-order dispersion

    Science.gov (United States)

    Mandeng Mandeng, Lucien; Tchawoua, Clément

    2013-03-01

    We present the compression of Airy pulses in silicon-on-insulator (SOI) waveguides under the fourth-order dispersion (FOD) using the variational approach that involves Rayleigh's dissipation function (RDF). All the pulse characteristics are under the influence of the two-photon and the frequency-carrier absorptions. In a quasi-linear approximation, the pulse compression conditions induced by the interaction of the group-velocity dispersion (GVD), the chirp and the FOD are derived. In the nonlinear case, the self-phase modulation (SPM), the two-photon absorption (TPA) and the free-carrier absorption (FCA) reduce the length of compression in a propagation regime of normal GVD, positive chirp and a negative value of FOD. The TPA reduces the maximal power reached than the SPM while the FCA rather increases its value. These results are confirmed in the general case where they all interact with the linear dispersion terms of the SOI waveguide.

  7. Perspective: The first ten years of broadband chirped pulse Fourier transform microwave spectroscopy

    Science.gov (United States)

    Park, G. Barratt; Field, Robert W.

    2016-05-01

    Since its invention in 2006, the broadband chirped pulse Fourier transform spectrometer has transformed the field of microwave spectroscopy. The technique enables the collection of a ≥10 GHz bandwidth spectrum in a single shot of the spectrometer, which allows broadband, high-resolution microwave spectra to be acquired several orders of magnitude faster than what was previously possible. We discuss the advantages and challenges associated with the technique and look back on the first ten years of chirped pulse Fourier transform spectroscopy. In addition to enabling faster-than-ever structure determination of increasingly complex species, the technique has given rise to an assortment of entirely new classes of experiments, ranging from chiral sensing by three-wave mixing to microwave detection of multichannel reaction kinetics. However, this is only the beginning. Future generations of microwave experiments will make increasingly creative use of frequency-agile pulse sequences for the coherent manipulation and interrogation of molecular dynamics.

  8. Simulation of the relativistic electron dynamics and acceleration in a linearly-chirped laser pulse

    CERN Document Server

    Jisrawi, Najeh M; Salamin, Yousef I

    2014-01-01

    Theoretical investigations are presented, and their results are discussed, of the laser acceleration of a single electron by a chirped pulse. Fields of the pulse are modeled by simple plane-wave oscillations and a $\\cos^2$ envelope. The dynamics emerge from analytic and numerical solutions to the relativistic Lorentz-Newton equations of motion of the electron in the fields of the pulse. All simulations have been carried out by independent Mathematica and Python codes, with identical results. Configurations of acceleration from a position of rest as well as from injection, axially and sideways, at initial relativistic speeds are studied.

  9. 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...

  10. 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

  11. Characterization of electrons and x-rays produced using chirped laser pulses in a laser wakefield accelerator

    Science.gov (United States)

    Zhao, T. Z.; Behm, K.; He, Z.-H.; Maksimchuk, A.; Nees, J. A.; Yanovsky, V.; Thomas, A. G. R.; Krushelnick, K.

    2016-11-01

    The electron injection process into a plasma-based laser wakefield accelerator can be influenced by modifying the parameters of the driver pulse. We present an experimental study on the combined effect of the laser pulse duration, pulse shape, and frequency chirp on the electron injection and acceleration process and the associated radiation emission for two different gas types—a 97.5% He and 2.5% N2 mixture and pure He. In general, the shortest pulse duration with minimal frequency chirp produced the highest energy electrons and the most charge. Pulses on the positive chirp side sustained electron injection and produced higher charge, but lower peak energy electrons, compared with negatively chirped pulses. A similar trend was observed for the radiant energy. The relationship between the radiant energy and the electron charge remained linear over a threefold change in the electron density and was independent of the drive pulse characteristics. X-ray spectra showed that ionization injection of electrons into the wakefield generally produced more photons than self-injection for all pulse durations/frequency chirp and had less of a spread in the number of photons around the peak x-ray energy.

  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

    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...

  13. Combined Yb/Nd driver for optical parametric chirped pulse amplifiers.

    Science.gov (United States)

    Michailovas, Kirilas; Baltuska, Andrius; Pugzlys, Audrius; Smilgevicius, Valerijus; Michailovas, Andrejus; Zaukevicius, Audrius; Danilevicius, Rokas; Frankinas, Saulius; Rusteika, Nerijus

    2016-09-19

    We report on the developed front-end/pump system for optical parametric chirped pulse amplifiers. The system is based on a dual output fiber oscillator/power amplifier which seeds and assures all-optical synchronization of femtosecond Yb and picosecond Nd laser amplifiers operating at a central wavelength of 1030 nm and 1064 nm, respectively. At the central wavelength of 1030 nm, the fiber oscillator generates partially stretched 4 ps pulses with the spectrum supporting a scaling currently is prevented by limited dimensions of the diffraction gratings, which, because of the fast progress in MLD grating manufacturing technologies is only a temporary obstacle.

  14. 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.

  15. 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.

  16. Photoelectron sidebands induced by a chirped laser field for shot-by-shot temporal characterization of FEL pulses

    Science.gov (United States)

    Liu, Chien-Nan; Morishita, Toru; Fushitani, Mizuho; Hishikawa, Akiyoshi

    2016-02-01

    We theoretically investigate the laser-assisted photoionization of He by an extreme ultra violet (XUV) pulse in the presence of a linearly chirped intense laser pulse by solving the time-dependent Schrödinger equation within the single-active-electron approximation. Analysis based on the time-dependent perturbation theory is also carried out to provide more physical insights. A new scheme is shown to be capable of extracting the arrival time of an XUV free-electron laser (FEL) pulse relative to an external laser pulse as well as the XUV pulse duration from the photoelectron sidebands resulting from XUV ionization in the presence of a chirped laser pulse. This scheme is independent of the energy fluctuation and the timing jittering of the FEL pulse. Therefore it can be implemented in a non-invasive way to characterize FEL pulses on a shot-by-shot basis in time-resolved spectroscopy.

  17. A chirped-pulse Fourier-transform microwave/pulsed uniform flow spectrometer. I. The low-temperature flow system.

    Science.gov (United States)

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

    2014-10-21

    We report the development of a new instrument that combines chirped-pulse microwave spectroscopy with a pulsed uniform supersonic flow. This combination promises a nearly universal detection method that can deliver isomer and conformer specific, quantitative detection and spectroscopic characterization of unstable reaction products and intermediates, product vibrational distributions, and molecular excited states. This first paper in a series of two presents a new pulsed-flow design, at the heart of which is a fast, high-throughput pulsed valve driven by a piezoelectric stack actuator. Uniform flows at temperatures as low as 20 K were readily achieved with only modest pumping requirements, as demonstrated by impact pressure measurements and pure rotational spectroscopy. The proposed technique will be suitable for application in diverse fields including fundamental studies in spectroscopy, kinetics, and reaction dynamics.

  18. A chirped-pulse Fourier-transform microwave/pulsed uniform flow spectrometer. II. Performance and applications for reaction dynamics.

    Science.gov (United States)

    Abeysekera, Chamara; Zack, Lindsay N; Park, G Barratt; Joalland, Baptiste; Oldham, James M; Prozument, Kirill; Ariyasingha, Nuwandi M; Sims, Ian R; Field, Robert W; Suits, Arthur G

    2014-12-01

    This second paper in a series of two reports on the performance of a new instrument for studying chemical reaction dynamics and kinetics at low temperatures. Our approach employs chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy to probe photolysis and bimolecular reaction products that are thermalized in pulsed uniform flows. Here we detail the development and testing of a new K(a)-band CP-FTMW spectrometer in combination with the pulsed flow system described in Paper I [J. M. Oldham, C. Abeysekera, B. Joalland, L. N. Zack, K. Prozument, I. R. Sims, G. B. Park, R. W. Field, and A. G. Suits, J. Chem. Phys. 141, 154202 (2014)]. This combination delivers broadband spectra with MHz resolution and allows monitoring, on the μs timescale, of the appearance of transient reaction products. Two benchmark reactive systems are used to illustrate and characterize the performance of this new apparatus: the photodissociation of SO2 at 193 nm, for which the vibrational populations of the SO product are monitored, and the reaction between CN and C2H2, for which the HCCCN product is detected in its vibrational ground state. The results show that the combination of these two well-matched techniques, which we refer to as chirped-pulse in uniform flow, also provides insight into the vibrational and rotational relaxation kinetics of the nascent reaction products. Future directions are discussed, with an emphasis on exploring the low temperature chemistry of complex polyatomic systems.

  19. 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.

  20. 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.

  1. Pulsed single-photon spectrograph by frequency-to-time mapping using chirped fiber Bragg gratings

    CERN Document Server

    Davis, Alex O C; Karpinski, Michal; Smith, Brian J

    2016-01-01

    A fiber-integrated spectrograph for single-photon pulses based upon frequency-to-time mapping, implemented by chromatic group delay dispersion (GDD), and precise temporally-resolved single photon counting is presented. A chirped fiber Bragg grating provides low-loss GDD mapping the frequency distribution of an input pulse onto the temporal envelope of the output pulse. Time-resolved detection with fast single-photon-counting modules enables the monitoring of the 825 nm to 835 nm wavelength range with nearly uniform efficiency with 55 pm resolution (24 GHz at 830 nm). To demonstrate the versatility of this technique spectral interference of heralded single photons and the joint spectral intensity distribution of a photon-pair source are measured. This approach to single-photon-level spectral measurements provides a route to realize applications of time-frequency quantum optics at visible and near-infrared wavelengths, where multiple spectral channels must be simultaneously monitored.

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

    Science.gov (United States)

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

    2011-06-20

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

  3. Ultrafast double-pulse parametric amplification for precision Ramsey metrology

    NARCIS (Netherlands)

    Kandula, D.Z.; Renault, A.A.L.; Gohle, C.; Wolf, A.L.; Witte, S.; Hogervorst, W.; Ubachs, W.M.G.; Eikema, K.S.E.

    2008-01-01

    We demonstrate phase stable, mJ-level parametric amplification of pulse pairs originating from a Ti: Sapphire frequency comb laser. The amplifier-induced phase shift between the pulses has been determined interferometrically with an accuracy of approximate to 10 mrad. Typical phase shifts are on the

  4. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  6. 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.

  7. 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 ...

  8. 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

  9. 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.

  10. Negatively-chirped laser enables nonlinear excitation and nanoprocessing with sub-20-fs pulses

    Science.gov (United States)

    Uchugonova, A.; Müller, J.; Bückle, R.; Tempea, G.; Isemann, A.; Stingl, A.; König, K.

    2008-02-01

    It has long been considered that the advantages emerging from employing chirp pre-compensation in nonlinear microscopy were overweighed by the complexity of prism- or grating-based compressors. These concerns were refuted with the advent of dispersive-mirrors-based compressors that are compact, user-friendly and sufficiently accurate to support sub-20-fs pulse delivery. Recent advances in the design of dispersive multilayer mirrors resulted in improved bandwidth (covering now as much as half of the gain bandwidth of Ti:Sapphire) and increased dispersion per bounce (one reflection off a state-of-the-art dispersive mirror pre-compensates the dispersion corresponding to >10mm of glass). The compressor built with these mirrors is sufficiently compact to be integrated in the housing of a sub-12-fs Ti:Sapphire oscillator. A complete scanning nonlinear microscope (FemtOgene, JenLab GmbH) equipped with highly-dispersive, large-NA objectives (Zeiss EC Plan-Neofluoar 40x/1.3, Plan-Neofluar 63x/1,25 Oil) was directly seeded with this negatively chirped laser. The pulse duration was measured at the focus of the objectives by inserting a scanning autocorrelator in the beam path between the laser and the microscope and recording the second order interferometric autocorrelation traces with the detector integrated in the microscope. Pulse durations stem cells. Here we report on the successful transfection of human stem cells by transient optoporation of the cell membrane with a low mean power of cells were able to reproduce. The daughter cell expressed also green fluorescent proteins (GFP) indicating the successful modification of the cellular DNA.

  11. 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....

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

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2010-04-01

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

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

    Science.gov (United States)

    Im, Song-Jin

    2015-03-01

    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 µJ by broad-band chirped idler pulses at 830 nm and MW pump pulses with narrow-band at 277 nm. The 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 a kagome-lattice hollow-core PCF filled with noble gas of high pressure with core diameter less than 40 µm, which would enable technically simple or highly efficient coupling to the fundamental mode of the fiber.

  14. 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.

  15. 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)

  16. Robust and Efficient Population Transfer in Ultracold Rubidium Using A Single Linearly Chirped Laser Pulse With a Novel Pulse Envelope

    Science.gov (United States)

    Collins, Thomas; Malinovskaya, Svetlana

    2012-06-01

    The ability to manipulate the state of a quantum system is the at very heart of the field of quantum control. As quantum control is an essential aspect of the emerging field of quantum computing, it is necessary to find techniques for manipulating quantum systems that are both robust and efficient to implement industrially. In this work the population dynamics of the valence electron of Rubidium, interacting with a single linearly chirped laser pulse, are studied. The pulse envelope is constructed from overlapping Gaussian waveforms and is described analytically by the formula: E0∑β=-n^nExp-[t-(T-n*ɛ)]^22τ0^2 with the parameter ɛ being the separation in time between each peak with the oscillating electric field is phase locked to the central peak. The response of the quantum yield obtained at the end of the pulse to changes in the parameters of the oscillating electric field and pulse envelope are studied. For certain values of these parameters, achievement of a transfer of over 99% of the population to a desired quantum state within the hyperfine structure of the 5S shell via adiabatic passage using beam intensities which are on the order of 100W/cm^2 is demonstrated. Results are robust in the adiabatic regime.

  17. Zero-Chirp Return-to-Zero Pulses Generation with Two Single-Driver z-Cut Mach-Zehnder Modulators

    Institute of Scientific and Technical Information of China (English)

    QIN Xi; CAO Ji-Hong; ZHANG Feng; WANG Mu-Guang; ZHANG Jian-Yong; JIAN Shui-Sheng

    2007-01-01

    A novel method is proposed to suppress the frequency chirp of single-driver z-cut Mach-Zehnder modulators.Theoretical analysis shows that by multiplying the output pulses of a half clock frequency driving single-driver z-cut modulator with the one delayed odd multiple bit duration,the frequency chirp can be removed entirely,and return-to-zero(RZ)pulses with duty cycles of about 25% and 56% are obtained.An experimental scheme is proposed to validate the proposed method.The experimental results show that perfect 40 GHz zero-chirp RZ pulses can be obtained by using this scheme.

  18. Cooling of relativistic electron beams in intense laser pulses: Chirps and radiation

    Science.gov (United States)

    Yoffe, S. R.; Noble, A.; Macleod, A. J.; Jaroszynski, D. A.

    2016-09-01

    Next-generation high-power laser facilities (such as the Extreme Light Infrastructure) will provide unprecedented field intensities, and will allow us to probe qualitatively new physical regimes for the first time. One of the important fundamental questions which will be addressed is particle dynamics when radiation reaction and quantum effects play a significant role. Classical theories of radiation reaction predict beam cooling in the interaction of a relativistic electron bunch and a high-intensity laser pulse, with final-state properties only dependent on the laser fluence. The observed quantum suppression of this cooling instead exhibits a dependence on the laser intensity directly. This offers the potential for final-state properties to be modified or even controlled by tailoring the intensity profile of the laser pulse. In addition to beam properties, quantum effects will be manifest in the emitted radiation spectra, which could be manipulated for use as radiation sources. We compare predictions made by classical, quasi-classical and stochastic theories of radiation reaction, and investigate the influence of chirped laser pulses on the observed radiation spectra.

  19. 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...

  20. High-energy femtosecond Yb-doped all-fiber monolithic chirped-pulse amplifier at repetition rate of 1 MHz

    Science.gov (United States)

    Lv, Zhi-Guo; Teng, Hao; Wang, Li-Na; Wang, Jun-Li; Wei, Zhi-Yi

    2016-09-01

    A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification (CPA) technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillator is studied. We find that the compressed pulse duration is dependent on the amplified energy, the pulse duration of 804 fs corresponds to the maximum amplified energy of 10.5 μJ, while the shortest pulse duration of 424 fs corresponds to the amplified energy of 6.75 μJ. The measured energy fluctuation is approximately 0.46% root mean square (RMS) over 2 h. The low-cost femtosecond fiber laser source with super-stability will be widely used in industrial micromachines, medical therapy, and scientific studies. Project supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2012BAC23B03), the National Key Basic Research Program of China (Grant No. 2013CB922401), and the National Natural Science Foundation of China (Grant No. 11474002).

  1. 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.

  2. 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.

  3. 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...

  4. 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...

  5. 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.

  6. 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.

  7. Pulse train amplification and regeneration based on semiconductor quantum dots waveguide

    DEFF Research Database (Denmark)

    Chen, Yaohui; Öhman, Filip; Mørk, Jesper

    2008-01-01

    We numerical analyze pulse train amplification up to 200 Gbit/s in quantum dot amplifiers and present regeneration properties with saturable absorber based on semiconductor quantum dot waveguides.......We numerical analyze pulse train amplification up to 200 Gbit/s in quantum dot amplifiers and present regeneration properties with saturable absorber based on semiconductor quantum dot waveguides....

  8. 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

  9. 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.

  10. Chirped solitary pulses for a nonic nonlinear Schrödinger equation on a continuous-wave background

    Science.gov (United States)

    Triki, Houria; Porsezian, K.; Choudhuri, Amitava; Dinda, P. Tchofo

    2016-06-01

    A class of derivative nonlinear Schrödinger equation with cubic-quintic-septic-nonic nonlinear terms describing the propagation of ultrashort optical pulses through a nonlinear medium with higher-order Kerr responses is investigated. An intensity-dependent chirp ansatz is adopted for solving the two coupled amplitude-phase nonlinear equations of the propagating wave. We find that the dynamics of field amplitude in this system is governed by a first-order nonlinear ordinary differential equation with a tenth-degree nonlinear term. We demonstrate that this system allows the propagation of a very rich variety of solitary waves (kink, dark, bright, and gray solitary pulses) which do not coexist in the conventional nonlinear systems that have appeared so far in the literature. The stability of the solitary wave solution under some violation on the parametric conditions is investigated. Moreover, we show that, unlike conventional systems, the nonlinear Schrödinger equation considered here meets the special requirements for the propagation of a chirped solitary wave on a continuous-wave background, involving a balance among group velocity dispersion, self-steepening, and higher-order nonlinearities of different nature.

  11. 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.

  12. Sub-picosecond chirped return-to-zero nonlinear optical pulse propagating in dense dispersion-managed fibre

    Science.gov (United States)

    Guo, Shuqin; Le, Zichun; Quan, Bisheng

    2006-01-01

    By numerical simulation, we show that the fourth-order dispersion (FOD) makes sub-picosecond optical pulse broaden as second-order dispersion (SOD), makes optical pulse oscillate simultaneously as third-order dispersion (TOD). Based on above two reasons, sub-picosecond optical pulse will be widely broaden and lead to emission of continuum radiation during propagation. Here, resemble to two- and third-order dispersion compensation, fourth-order dispersion compensation is also suggested in a dispersion-managed optical fiber link, which is realized by arranging two kinds of fiber with opposite dispersion sign in each compensation cell. For sake of avoiding excessively broadening, ultra short scale dispersion compensation cell is required in ultra high speed optical communication system. In a full dispersion compensation optical fiber system which path average dispersion is zero about SOD, TOD, and FOD, even suffering from affection of high order nonlinear like self-steep effect and self-frequency shift, 200 fs gauss optical pulse can stable propagate over 1000 km with an optimal initial chirp. When space between neighboring optical pulse is only 2 picoseconds corresponding to 500 Gbit/s transmitting capacity, eye diagram is very clarity after 1000 km. The results demonstrate that ultra short scale dispersion compensation including FOD is need and effective in ultra-high speed optical communication.

  13. 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

  14. 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

  15. Self-similar propagation and amplification of parabolic pulses in optical fibers.

    Science.gov (United States)

    Fermann, M E; Kruglov, V I; Thomsen, B C; Dudley, J M; Harvey, J D

    2000-06-26

    Ultrashort pulse propagation in high gain optical fiber amplifiers with normal dispersion is studied by self-similarity analysis of the nonlinear Schrödinger equation with gain. An exact asymptotic solution is found, corresponding to a linearly chirped parabolic pulse which propagates self-similarly subject to simple scaling rules. The solution has been confirmed by numerical simulations and experiments studying propagation in a Yb-doped fiber amplifier. Additional experiments show that the pulses remain parabolic after propagation through standard single mode fiber with normal dispersion.

  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...... chirp-to-intensity conversion. We also experimentally achieve propagation through a 20 km nonzero dispersion shifted fiber with no degradation of the signal at the receiver. Our method constitutes a prospective low-cost solution and offers integration capabilities with fiber...

  17. Amplification of stimulated Brillouin scattering of two collinear pulsed laser beams with orthogonal polarizations.

    Science.gov (United States)

    Shi, Jinwei; Chen, Xudong; Ouyang, Min; Liu, Juan; Liu, Dahe

    2009-06-10

    A polarization-controlling device was developed based on the fact that there can be a time delay between the seeder and the pumping beams during the amplification of a stimulated Brillouin scattering signal. The device causes two coaxially transmitted pulsed beams with orthogonal polarizations to have the same polarization in order to implement amplification by the pumping effect. An experiment showed that good pumping amplification can be achieved by using this technique. PMID:19516374

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

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

    CERN Document Server

    Konoplev, O A

    2000-01-01

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

  4. 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.

  5. Near-Nyquist optical pulse generation with fiber optical parametric amplification.

    Science.gov (United States)

    Vedadi, Armand; Shoaie, Mohammad Amin; Brès, Camille-Sophie

    2012-12-10

    A novel method using optical fiber parametric amplification and phase modulation is proposed in order to generate Nyquist pulses. Using parabolic pulses as a pump, we show theoretically that it is possible to generate Nyquist pulses. Furthermore, we show that by using a sinusoidal pump (pump intensity modulated by an RF tone), it is possible to obtain pulses with characteristics that are close to Nyquist limited pulses. We demonstrate experimentally the generation of bandwidth limited pulses with full width half maximum of 14 ps at 10 GHz repetition rate. We also discuss limitations of this method and means to overcome these limitations.

  6. 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 clearly show the dependence of the maximum bit rate on material and device parameters. A comparative analysis of QD, quantum well (QW), and bulk SOAs shows that QD SOAs may have superior properties; calculations predict patterning-free amplification up to bit rates of 150–200 Gb/s with pulse output...

  7. 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.

  8. Exawatt-Zettawatt Pulse Generation and Applications

    CERN Document Server

    Mourou, G A; Malkin, V M; Toroker, Z; Khazanov, E A; Sergeev, A M; Tajima, T

    2011-01-01

    A new amplification method, weaving the three basic compression techniques, Chirped Pulse Amplification (CPA), Optical Parametric Chirped Pulse Amplification (OPCPA) and Plasma Compression by Backward Raman Amplification (BRA) in plasma, is proposed. It is called C3 for Cascaded Conversion Compression. It has the capability to compress with good efficiency kilojoule to megajoule, nanosecond laser pulses into femtosecond pulses, to produce exawatt and beyond peak power. In the future, C3 could be used at large-scale facilities such as the National Ignition Facility (NIF) or the Laser Megajoule (LMJ) and open the way to zettawatt level pulses. The beam will be focused to a wavelength spot size with a f#1. The very small beam size, i.e. few centimeters, along with the low laser repetition rate laser system will make possible the use of inexpensive, precision, disposable optics. The resulting intensity will approach the Schwinger value, thus opening up new possibilities in fundamental physics.

  9. Wavelength-dependent femtosecond pulse amplification in wideband tapered-waveguide quantum well semiconductor optical amplifiers.

    Science.gov (United States)

    Xia, Mingjun; Ghafouri-Shiraz, H

    2015-12-10

    In this paper, we study the wavelength-dependent amplification in three different wideband quantum well semiconductor optical amplifiers (QWAs) having conventional, exponentially tapered, and linearly tapered active region waveguide structures. A new theoretical model for tapered-waveguide QWAs considering the effect of lateral carrier density distribution and the strain effect in the quantum well is established based on a quantum well transmission line modeling method. The temporal and spectral characteristics of amplified femtosecond pulse are analyzed for each structure. It was found that, for the amplification of a single femtosecond pulse, the tapered-waveguide QWA provides higher saturation gain, and the output spectra of the amplified pulse in all three structures exhibit an apparent redshift and bandwidth narrowing due to the reduction of carrier density; however, the output spectrum in the tapered-waveguide amplifier is less distorted and exhibits smaller bandwidth narrowing. For the simultaneous amplification of two femtosecond pulses with different central frequencies, in all the three structures, two peaks appear in the output spectra while the peak at the frequency closer to the peak frequency of the QWA gain spectrum receives higher amplification due to the frequency (wavelength) dependence of the QWA gain. At a low peak power level of the input pulse, the bandwidth of each window in the tapered structure is larger than that of the conventional waveguide structure, which aggravates the spectrum alias in the amplification of femtosecond pulses with different central frequencies. As the peak powers of the two pulses increase, the spectrum alias in the conventional waveguide becomes more serious while there are small changes in the tapered structures. Also, we have found that in the amplification of a femtosecond pulse train, the linear-tapered QWAs exhibit the fastest gain recovery as compared with the conventional and exponentially tapered QWAs.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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

  15. Optical amplification and pulse interleaving for low noise photonic microwave generation

    CERN Document Server

    Quinlan, Franklyn; Fortier, Tara M; Zhou, Qiugui; Cross, Allen; Campbell, Joe C; Diddams, Scott A

    2013-01-01

    We investigate the impact of pulse interleaving and optical amplification on the spectral purity of microwave signals generated by photodetecting the pulsed output of an Er:fiber-based optical frequency comb. It is shown that the microwave phase noise floor can be extremely sensitive to delay length errors in the interleaver, and the contribution of the quantum noise from optical amplification to the phase noise can be reduced ~10 dB for short pulse detection. We exploit optical amplification, in conjunction with high power handling modified uni-traveling carrier photodetectors, to generate a phase noise floor on a 10 GHz carrier of -175 dBc/Hz, the lowest ever demonstrated in the photodetection of a mode-locked fiber laser. At all offset frequencies, the photodetected 10 GHz phase noise performance is comparable to or better than the lowest phase noise results yet demonstrated with stabilized Ti:sapphire frequency combs.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    CERN Document Server

    Wang, Zhen; Zhao, Zhentang

    2016-01-01

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

  2. 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.

  3. High repetition rate tunable femtosecond pulses and broadband amplification from fiber laser pumped parametric amplifier.

    Science.gov (United States)

    Andersen, T V; Schmidt, O; Bruchmann, C; Limpert, J; Aguergaray, C; Cormier, E; Tünnermann, A

    2006-05-29

    We report on the generation of high energy femtosecond pulses at 1 MHz repetition rate from a fiber laser pumped optical parametric amplifier (OPA). Nonlinear bandwidth enhancement in fibers provides the intrinsically synchronized signal for the parametric amplifier. We demonstrate large tunability extending from 700 nm to 1500 nm of femtosecond pulses with pulse energies as high as 1.2 muJ when the OPA is seeded by a supercontinuum generated in a photonic crystal fiber. Broadband amplification over more than 85 nm is achieved at a fixed wavelength. Subsequent compression in a prism sequence resulted in 46 fs pulses. With an average power of 0.5 W these pulses have a peak-power above 10 MW. In particular, the average power and pulse energy scalability of both involved concepts, the fiber laser and the parametric amplifier, will enable easy up-scaling to higher powers.

  4. 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...

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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...... 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 compatibility of FOPAs with fiber...... optical systems and high gain over broad bandwidths. In particular, the amplification of 400 fs pulses is investigated in a single-pump fiber optical chirped pulse amplification sc heme. First, a dynamic characterization is carried out both in unsaturated and saturated regimes and, then, amplification...

  11. 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.

  12. 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

  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. 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

  15. 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.

  16. 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).

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

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, N. S., E-mail: ginzburg@appl.sci-nnov.ru; Zaslavsky, V. Yu. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul' yanov Str., 603950 Nizhny Novgorod (Russian Federation); Nizhny Novgorod State University, 23 Gagarin Ave., 603950 Nizhny Novgorod (Russian Federation); Zotova, I. V.; Sergeev, A. S.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul' yanov Str., 603950 Nizhny Novgorod (Russian Federation)

    2015-11-15

    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.

  18. 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.

  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. Nonlinear temporal pulse cleaning techniques and application

    Institute of Scientific and Technical Information of China (English)

    Yi; Xu; Jianzhou; Wang; Yansui; Huang; Yanyan; Li; Xiaomin; Lu; Yuxin; Leng

    2013-01-01

    Two different pulse cleaning techniques for ultra-high contrast laser systems are comparably analysed in this work.The first pulse cleaning technique is based on noncollinear femtosecond optical-parametric amplification(NOPA)and second-harmonic generation(SHG)processes.The other is based on cross-polarized wave(XPW)generation.With a double chirped pulse amplifier(double-CPA)scheme,although temporal contrast enhancement in a high-intensity femtosecond Ti:sapphire chirped pulse amplification(CPA)laser system can be achieved based on both of the techniques,the two different pulse cleaning techniques still have their own advantages and are suitable for different contrast enhancement requirements of different laser systems.

  2. 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.

  3. 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.

  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.

  5. 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

  6. 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.

  7. Diffraction of Ultrashort Pulse on a Nanoscale Conductive Cone

    CERN Document Server

    Golovinski, P A; Manuylovich, E S

    2015-01-01

    Surface plasmon polariton is collective oscillation of the free electrons at metal dielectric interface. As a wave phenomenon, surface plasmon polaritons can be focused using appropriate excitation geometry of metallic structures. We theoretically demonstrate the possibility of controlling nanoscale short pulse superfocusing based on the generation of radially polarized surface plasmon polariton mode of conical metallic tip. Numerical simulation for femtosecond pulse propagation along a silver nano-needle is discussed. The spatial distribution for a near field strongly depends on a linear chirp of the laser pulse which can partially compensate the wave dispersion. Field distribution is calculated for different chirp values, opening angles and distances. For a pulse with a negative chirp, pulse duration becomes shorter with amplification ~40.

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Evolution of sum-chirp in polarization multiplexed communication system

    Institute of Scientific and Technical Information of China (English)

    Wang Jing; Wang Zhen-Li

    2004-01-01

    The evolution of sum-chirp for an initially chirped Gaussian pulse is studied in the polarization multiplexed communication system, with fibre attenuation considered. The sum-chirp is found to have the character of saturation.Its value appears different along the two different polarization axes, determined by the incidence polarization angle. We also find that sum-chirp is dominated by the initial chirp at a short distance, and by the cross-phase modulation effect at long distance. And it is influenced apparently by a wavevector mismatch parameter below 10 ps/km. Further, its saturation results from the effective distance determined by fibre attenuation.

  15. 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...

  16. A Study of the Monohydrate and Dihydrate Complexes of Perfluoropropionic Acid Using Chirped-Pulse Fourier Transform Microwave (CP-FTMW) Spectroscopy.

    Science.gov (United States)

    Grubbs, G S; Obenchain, Daniel A; Frank, Derek S; Novick, Stewart E; Cooke, S A; Serrato, Agapito; Lin, Wei

    2015-10-22

    This work reports the first known spectroscopic observation of the monohydrate and dihydrate complexes of perfluoropropionic acid (PFPA). The spectra have been observed using a chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer in the 7750 to 14,250 MHz region. The structures of the species have been confirmed with the aid of ab initio quantum chemical calculations. Rotational constants A, B, and C have been determined and reported for both species along with centrifugal distortion constants ΔJ, ΔJK, ΔK, δJ, δK for H2O-PFPA and ΔJ, ΔJK, and δJ for (H2O)2-PFPA. Effects due to large amplitude motions were not observable in these experiments. Structures of the complexes have been determined using a combination of experimental second moment values and ab initio results. The complexation of the -OH of one or two water molecules has been found to occur in the plane of the carboxylic acid group forming a six- or eight-member ring.

  17. 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...

  18. Intensity noise reduction of a high-power nonlinear femtosecond fiber amplifier based on spectral-breathing self-similar parabolic pulse evolution

    Science.gov (United States)

    Wang, Sijia; Liu, Bowen; Song, Youjian; Hu, Minglie

    2016-04-01

    We report on a simple passive scheme to reduce the intensity noise of high-power nonlinear fiber amplifiers by use of the spectral-breathing parabolic evolution of the pulse amplification with an optimized negative initial chirp. In this way, the influences of amplified spontaneous emission (ASE) on the amplifier intensity noise can be efficiently suppressed, owing to the lower overall pulse chirp, shorter spectral broadening distance, as well as the asymptotic attractive nature of self-similar pulse amplification. Systematic characterizations of the relative intensity noise (RIN) of a free-running nonlinear Yb-doped fiber amplifier are performed over a series of initial pulse parameters. Experiments show that the measured amplifier RIN increases respect to the decreased input pulse energy, due to the increased amount of ASE noise. For pulse amplification with a proper negative initial chirp, the increase of RIN is found to be smaller than with a positive initial chirp, confirming the ASE noise tolerance of the proposed spectral-breathing parabolic amplification scheme. At the maximum output average power of 27W (25-dB amplification gain), the incorporation of an optimum negative initial chirp (-0.84 chirp parameter) leads to a considerable amplifier root-mean-square (rms) RIN reduction of ~20.5% (integrated from 10 Hz to 10 MHz Fourier frequency). The minimum amplifier rms RIN of 0.025% (integrated from 1 kHz to 5 MHz Fourier frequency) is obtained along with the transform-limited compressed pulse duration of 55fs. To our knowledge, the demonstrated intensity noise performance is the lowest RIN level measured from highpower free-running femtosecond fiber amplifiers.

  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. 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

  1. Compression of realistic laser pulses in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, John

    2009-01-01

    Dispersive compression of chirped few-picosecond pulses at the microjoule level in a hollow-core photonic bandgap fiber is studied numerically. The performance of ideal parabolic input pulses is compared to pulses from a narrowband picosecond oscillator broadened by self-phase modulation during...... amplification. It is shown that the parabolic pulses are superior for compression of high-quality femtosecond pulses up to the few-megawatts level. With peak powers of 5-10 MW or higher, there is no significant difference in power scaling and pulse quality between the two pulse types for comparable values...

  2. Pulse compression and beam focusing with segmented diffraction gratings in a high-power chirped-pulse amplification glass laser system

    OpenAIRE

    Habara, Hideaki; Xu, Guang; Jitsuno, Takahisa; Kodama, Ryosuke; Suzuki, Kenji; Sawai, Kiyonobu; Kondo, Kiminori; Miyanaga, Noriaki; Tanaka, Kazuo A.; Mima, Kunioki; Rushford, Michael C.; Britten, Jerald A.; Barty, Christopher P.J.

    2010-01-01

    This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.35.001783 Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

  3. Femtosecond Laser Pumped Conical Emission and Seeded Ring Amplification in BBO Crystals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-Sen; LI Feng-Ming; WANG Shu-Feng; GONG Qi-Huang

    2005-01-01

    @@ The characteristics of femtosecond laser pumped conical emission in quadratic media of β-barium borate (BBO)crystals are analysed. A minimized dispersion phase-matching angle, by which a wide-range spectrum can be obtained, is used for broadband amplification. When a seed of a chirped supercontinuum pulse is input, it is found that the seed in wavelength 500nm-750nm is amplified and time resolved.

  4. Comparative typing of Pseudomonas aeruginosa by random amplification of polymorphic DNA or pulsed-field gel electrophoresis of DNA macrorestriction fragments

    NARCIS (Netherlands)

    N. Renders (Nicole); Y. Romling; A.F. van Belkum (Alex); H.A. Verbrugh (Henri)

    1996-01-01

    textabstractEighty-seven strains of Pseudomonas aeruginosa were typed by random amplification of polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) of macrorestriction fragments. Stains were clustered on the basis of interpretative criteria as presented

  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. 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)

  7. 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.

  8. 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.

  9. Solid-State Source of Subcycle Pulses in the Midinfrared.

    Science.gov (United States)

    Stepanov, E A; Lanin, A A; Voronin, A A; Fedotov, A B; Zheltikov, A M

    2016-07-22

    We demonstrate a robust, all-solid-state approach for the generation of microjoule subcycle pulses in the midinfrared through a cascade of carefully optimized parametric-amplification, difference-frequency-generation, spectral-broadening, and chirp-compensation stages. This method of subcycle waveform generation becomes possible due to an unusual, ionization-assisted solid-state pulse self-compression dynamics, where highly efficient spectral broadening is enabled by ultrabroadband four-wave parametric amplification phase matched near the zero-group-velocity wavelength of the material.

  10. 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

  11. 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.

  12. 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

  13. Modeling and optimizing of low-repetition-rate high-energy pulse amplification in high-concentration erbium-doped fiber amplifiers

    Science.gov (United States)

    Li, Jianfeng; Dai, Zhiyong; Ou, Zhonghua; Zhang, Lixun; Liu, Yongzhi; Liu, Yong

    2009-09-01

    Starting from the modeling of isolated ions and ion-pairs, a closed form rate and power evolution equations for pulse amplification in high-concentration erbium-doped fiber amplifiers (EDFAs) are constructed. According to the equations, the effects of ion-pairs on the performance of a high-concentration EDFA in steady state including upper-state population, ASE powers without input signal are analyzed numerically. Furthermore, the effects of ion-pairs on the dynamic characteristics of low-repetition-rate pulse amplification in the EDFA including the storied energy, output pulse energy and evolution of pulse waveform distortion are systematically studied by using the finite-difference method. The results show that the presence of the ion-pairs deteriorates amplifier performance, such as the upper-state population, ASE power, storied energy, output pulse energy, and saturated gain, etc. For the high-concentration EDFA, the optimum fiber length should be modified to achieve a better performance. The relations between the evolution of pulse waveform distortion or output pulse energy and the input pulse peak power are also discussed. The results can provide important guide for the design and optimization of the low-repetition-rate pulse amplification in high-concentration EDFAs.

  14. 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.

  15. 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

  16. Enhancement of Ultracold Molecule Formation Using Shaped Nanosecond Frequency Chirps

    CERN Document Server

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

    2016-01-01

    We demonstrate that judicious shaping of a nanosecond-time-scale frequency chirp can dramatically enhance the formation rate of ultracold $^{87}$Rb$_{2}$ molecules. Starting with ultracold $^{87}$Rb atoms, we apply pulses of frequency-chirped light to first photoassociate the atoms into excited molecules and then, later in the chirp, de-excite these molecules into a high vibrational level of the lowest triplet state, $a \\, ^{3}\\Sigma_{u}^{+}$. The enhancing chirp shape passes through the absorption and stimulated emission transitions relatively slowly, thus increasing their adiabaticity, but jumps quickly between them to minimize the effects of spontaneous emission. Comparisons with quantum simulations for various chirp shapes support this enhancement mechanism.

  17. Enhancement of Ultracold Molecule Formation Using Shaped Nanosecond Frequency Chirps

    Science.gov (United States)

    Carini, Jennifer; Kallush, Shimshon; Kosloff, Ronnie; Gould, Phillip

    2016-05-01

    We demonstrate that judicious shaping of a nanosecond-time-scale frequency chirp can dramatically enhance the formation rate of ultracold molecules. Starting with ultracold 87 Rb atoms, we apply pulses of frequency-chirped light to first photoassociate the atoms into excited molecules and then, later in the chirp, de-excite these molecules into a high vibrational level of the lowest triplet state. The enhancing chirp shape passes through the absorption and stimulated emission transitions relatively slowly, thus increasing their adiabaticity, but jumps quickly between them to minimize the effects of spontaneous emission. Comparisons with quantum simulations for various chirp shapes support this enhancement mechanism. Schemes for further improvements of the formation rate will also be presented. This work is supported by DOE and BSF.

  18. A single-shot spatial chirp method for measuring initial AC conductivity evolution of femtosecond laser pulse excited warm dense matter

    Science.gov (United States)

    Chen, Z.; Hering, P.; Brown, S. B.; Curry, C.; Tsui, Y. Y.; Glenzer, S. H.

    2016-11-01

    To study the rapid evolution of AC conductivity from ultrafast laser excited warm dense matter (WDM), a spatial chirp single-shot method is developed utilizing a crossing angle pump-probe configuration. The pump beam is shaped individually in two spatial dimensions so that it can provide both sufficient laser intensity to excite the material to warm dense matter state and a uniform time window of up to 1 ps with sub-100 fs FWHM temporal resolution. Temporal evolution of AC conductivity in laser excited warm dense gold was also measured.

  19. 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.

  20. 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.

  1. Three-Dimensional Analysis of Frequency-Chirped FELs

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.; Ding, Y.; Wu, J.; /SLAC

    2010-09-14

    Frequency-chirped free-electron lasers (FELs) are useful to generate a large photon bandwidth or a shorter x-ray pulse duration. In this paper, we present a three-dimensional analysis of a high-gain FEL driven by the energy-chirped electron beam. We show that the FEL eigenmode equation is the same for a frequency-chirped FEL as for an undulator-tapered FEL. We study the transverse effects of such FELs including mode properties and transverse coherence.

  2. 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)

  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...

  4. Brillouin optical time-domain analysis sensor with pump pulse amplification.

    Science.gov (United States)

    Mompó, Juan José; Urricelqui, Javier; Loayssa, Alayn

    2016-06-13

    We demonstrate a simple technique to provide conventional Brillouin optical time-domain analysis sensors with mitigation for pump pulse attenuation. The technique is based on operating the sensor in loss configuration so that energy is transferred from the probe wave to the pump pulse that becomes amplified as it counter-propagates with the probe wave. Furthermore, the optical frequency of the probe wave is modulated along the fiber so that the pump pulse experiences a flat total gain spectrum that equally amplifies all the spectral components of the pulse, hence, preventing distortion. This frequency modulation of the probe brings additional advantages because it provides increased tolerance to non-local effects and to spontaneous Brillouin scattering noise, so that a probe power above the Brillouin threshold of the fiber can be safely deployed, hence, increasing the signal-to-noise ratio of the measurement. The method is experimentally demonstrated in a 100-km fiber link, obtaining a measurement uncertainty of 1 MHz at the worst-contrast position. PMID:27410288

  5. 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.

  6. Generating nonlinear FM chirp radar signals by multiple integrations

    Science.gov (United States)

    Doerry, Armin W.

    2011-02-01

    A phase component of a nonlinear frequency modulated (NLFM) chirp radar pulse can be produced by performing digital integration operations over a time interval defined by the pulse width. Each digital integration operation includes applying to a respectively corresponding input parameter value a respectively corresponding number of instances of digital integration.

  7. 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...

  8. Frequency comb based on a narrowband Yb-fiber oscillator: pre-chirp management for self-referenced carrier envelope offset frequency stabilization.

    Science.gov (United States)

    Lim, Jinkang; Chen, Hung-Wen; Chang, Guoqing; Kärtner, Franz X

    2013-02-25

    Laser frequency combs are normally based on mode-locked oscillators emitting ultrashort pulses of ~100-fs or shorter. In this paper, we present a self-referenced frequency comb based on a narrowband (5-nm bandwidth corresponding to 415-fs transform-limited pulses) Yb-fiber oscillator with a repetition rate of 280 MHz. We employ a nonlinear Yb-fiber amplifier to both amplify the narrowband pulses and broaden their optical spectrum. To optimize the carrier envelope offset frequency (fCEO), we optimize the nonlinear pulse amplification by pre-chirping the pulses at the amplifier input. An optimum negative pre-chirp exists, which produces a signal-to-noise ratio of 35 dB (100 kHz resolution bandwidth) for the detected fCEO. We phase stabilize the fCEO using a feed-forward method, resulting in 0.64-rad (integrated from 1 Hz to 10 MHz) phase noise for the in-loop error signal. This work demonstrates the feasibility of implementing frequency combs from a narrowband oscillator, which is of particular importance for realizing large line-spacing frequency combs based on multi-GHz oscillators usually emitting long (>200 fs) pulses. PMID:23481986

  9. Production and characterisation of periodic and chirped La/B{sub 4}C-multilayer-mirrors for the reflection of ultra short XUV-pulses

    Energy Technology Data Exchange (ETDEWEB)

    Lass, Maike; Hendel, Stefan; Bienert, Florian; Sacher, Marc D.; Hachmann, Wiebke; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Schaefers, Franz [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Elektronenspeicherring BESSY II (Germany)

    2009-07-01

    The applicability of reflective optical components for the soft X-ray region depends upon the existence of multilayer-optics. For the photon energy range of 100-190eV Lanthanum (La) is favoured as the absorber material and boroncarbide (B{sub 4}C) as the spacer material. Thin periodic and aperiodic (chirped) layer systems of those materials with double layer periods of 3.5 nm have been produced by UHV electron beam evaporation combined with ion polishing to decrease the interface roughness and thus to increase the reflectivity. In-situ layer thickness control is done by X-ray reflectometry and single-wavelength ellipsometry. The characterisation of the layer purity is done by ex-situ sputter Auger spectroscopy, whilst structural analysis is performed by X-ray diffraction, transmission electron microscopy and at-wavelength reflectivity measurements with synchrotron radiation at the BESSY II facility. We report on reflectivities of periodic and aperiodic multilayer-mirrors.

  10. 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 ...

  11. 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

  12. 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.

  13. 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

  14. Experimental demonstration of spatially coherent beam combining using optical parametric amplification.

    Science.gov (United States)

    Kurita, Takashi; Sueda, Keiichi; Tsubakimoto, Koji; Miyanaga, Noriaki

    2010-07-01

    We experimentally demonstrated coherent beam combining using optical parametric amplification with a nonlinear crystal pumped by random-phased multiple-beam array of the second harmonic of a Nd:YAG laser at 10-Hz repetition rate. In the proof-of-principle experiment, the phase jump between two pump beams was precisely controlled by a motorized actuator. For the demonstration of multiple-beam combining a random phase plate was used to create random-phased beamlets as a pump pulse. Far-field patterns of the pump, the signal, and the idler indicated that the spatially coherent signal beams were obtained on both cases. This approach allows scaling of the intensity of optical parametric chirped pulse amplification up to the exa-watt level while maintaining diffraction-limited beam quality.

  15. Parabolic similariton Yb-fiber laser with triangular pulse evolution

    Science.gov (United States)

    Wang, Sijia; Wang, Lei

    2016-04-01

    We propose a novel mode-locked fiber laser design which features a passive nonlinear triangular pulse formation and self-similar parabolic pulse amplification intra cavity. Attribute to the nonlinear reshaping progress in the passive fiber, a triangular-profiled pulse with negative-chirp is generated and paved the way for rapid and efficient self-similar parabolic evolution in a following short-length high-gain fiber. In the meanwhile, the accompanied significantly compressed narrow spectrum from this passive nonlinear reshaping also gives the promise of pulse stabilization and gain-shaping robustness without strong filtering. The resulting short average intra-cavity pulse duration, low amplified spontaneous emission (ASE) and low intra-cavity power loss are essential for the low-noise operation. Simulations predict this modelocked fiber laser allows for high-energy ultra-short transform-limited pulse generation exceeding the gain bandwidth. The output pulse has a de-chirped duration (full-width at half maximum, FWHM) of 27 fs. In addition to the ultrafast laser applications, the proposed fiber laser scheme can support low-noise parabolic and triangular pulse trains at the same time, which are also attractive in optical pulse shaping, all-optical signal processing and high-speed communication applications.

  16. 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...

  17. 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...

  18. 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.

  19. 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.)

  20. 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.)

  1. 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.

  2. Broadband Asymmetric Conical Emission via Cascaded Second-Order Nonlinear Polarization during the Propagation of Femtosecond Laser Pulses in a BBO Crystal

    Institute of Scientific and Technical Information of China (English)

    WEN Jing; JIANG Hong-Bing; YU Jing; YANG Hong; GONG Qi-Huang

    2011-01-01

    @@ 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.

  3. 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...

  4. 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.

  5. Broadband mid-infrared pulses from potassium titanyl arsenate/zinc germanium phosphate optical parametric amplifier pumped by Tm, Ho-fiber-seeded Ho:YAG chirped-pulse amplifier.

    Science.gov (United States)

    Malevich, Pavel; Kanai, Tsuneto; Hoogland, Heinar; Holzwarth, Ronald; Baltuška, Andrius; Pugžlys, Audrius

    2016-03-01

    We present a concept of a white-light-seeded-cascaded mid-infrared (mid-IR) optical parametric amplifier (OPA) based on potassium titanyl arsenate and zinc germanium phosphate nonlinear optical crystals and producing 100-μJ level pulses centered at 5300 nm, with the spectrum supporting four-optical-cycle pulse duration. The OPA is pumped by 2090-nm master oscillator/power amplifier based on a Tm,Ho-fiber laser seeder and a Ho:YAG regenerative amplifier delivering 3.8-mJ sub-ps pulses at a repetition rate of 1 kHz. We validate that output parameters of the OPA are scalable by means of increasing the pulse energy, decreasing the pulse duration and redshifting the central wavelength. PMID:26974083

  6. 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)

  7. 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

  8. 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.

  9. Chirped mirrors with low dispersion ripple.

    Science.gov (United States)

    Pervak, V; Naumov, S; Krausz, F; Apolonski, A

    2007-10-17

    We demonstrate a chirped dielectric multilayer mirror (CM) with controlled reflectivity and dispersion in the wavelength range 760-840 nm. It exhibits a reflectivity of >99.9% and a mean group delay dispersion (GDD) of about -30 fs(2) with a theoretical GDD ripple of less than 0.5 fs(2) in the working spectral range. Deviations of the measured GDD from the calculated one are restricted to less than +/- 3 fs(2), limited by our measurement system. Simulations reveal that a dispersive delay line composed of 120 bounces off these mirrors introduces negligible distortion to a femtosecond pulse and largely preserves its contrast. The mirrors constitute an ideal tool for precision intracavity or extracavity dispersion control in the range of several thousand fs(2), particularly if pulses with high contrast are to be generated.

  10. Simple ps microchip Nd:YVO4 laser with 3.3-ps pulses at 0.2 to 1.4 MHz and single-stage amplification to the microjoule level

    Science.gov (United States)

    Türkyilmaz, Erdal; Lohbreier, Jan; Günther, Christian; Mehner, Eva; Kopf, Daniel; Giessen, Harald; Braun, Bernd

    2016-06-01

    Commercial picosecond sources have found widespread applications. Typical system parameters are pulse widths below 20 ps, repetition rates between 0.1 and 2 MHz, and microjoule level pulse energies. Most systems are based on short pulse mode-locked oscillators, regenerative amplifiers, and pockel cells as active beam switches. In contrast, we present a completely passive system, consisting of a passively Q-switched microchip laser, a single-stage amplifier, and a pulse compressor. The Q-switched microchip laser has a 50-μm-long Nd:YVO4 gain material optically bonded to a 4.6-mm-thick undoped YVO4 crystal. It delivers pulse widths of 40 ps and repetition rates of 0.2 to 1.4 MHz at a wavelength of 1.064 μm. The pulse energy is a few nanojoule. These 40-ps pulses are spectrally broadened in a standard single-mode fiber and then compressed in a 24-mm-long chirped Bragg grating to as low as 3.3 ps. The repetition rate can be tuned from ˜0.2 to 1.4 MHz by changing the pump power, while the pulse width and the pulse energy from the microchip laser are unchanged. The spectral broadening in the fiber is observed throughout the pulse repetition rate, supporting sub-10-ps pulses. Finally, the pulses are amplified in a single-stage Nd:YVO4 amplifier up to the microjoule level (up to 4 μJ pulse energy). As a result, the system delivers sub-10-ps pulses at a microjoule level with about 1 MHz repetition rate, and thus fulfills the requirements for ps-micromachining. It does not contain any active switching elements and can be integrated in a very compact setup.

  11. Simple ps microchip Nd:YVO4 laser with 3.3 ps pulses at 0.2 - 1.4 MHz and single-stage amplification to the microjoule level

    Science.gov (United States)

    Türkyilmaz, Erdal; Lohbreier, Jan; Günther, Christian; Mehner, Eva; Kopf, Daniel; Giessen, Harald; Braun, Bernd

    2016-03-01

    Commercial picosecond sources have found widespread applications. Typical system parameters are pulse widths below 20 ps, repetition rates between 0.1 to 2 MHz, and micro Joule level pulse energies. Most systems are based on short pulse modelocked oscillators, regenerative amplifiers, and pockel cells as active beam switches. In contrast we present a completely passive system, consisting of a passively Q-switched microchip laser, a single-stage amplifier, and a pulse compressor. The Q-switched microchip laser has a 50 μm long Nd:YVO4-gain material optically bonded to a 4.6 mm thick undoped YVO4-crystal. It delivers pulse widths of 40 ps and repetition rates of 0.2 - 1.4 MHz at a wavelength of 1.064 μm. The pulse energy is a few nJ. These 40-ps pulses are spectrally broadened in a standard single mode fibre and then compressed in a 24 mm long chirped Bragg grating to as low as 3.3 ps. The repetition rate can be tuned from app. 0.2 to 1.4 MHz by changing the pump power while the pulse width and the pulse energy from the microchip laser are unchanged. The spectral broadening in the fibre is observed throughout the pulse repetition rate, supporting sub-10- ps pulses. Finally, the pulses are amplified in a single-stage Nd:YVO4-amplifier up to the microjoule level (up to 4 μJ pulse energy). As a result the system delivers sub-10-ps pulses at a microjoule level with about 1 MHz repetition rate, and thus fulfills the requirements for ps-micromachining. It does not contain any active switching elements and can be integrated in a very compact setup.

  12. Generation of high-energy self-phase-stabilized pulses by difference-frequency generation followed by optical parametric amplification.

    Science.gov (United States)

    Manzoni, C; Vozzi, C; Benedetti, E; Sansone, G; Stagira, S; Svelto, O; De Silvestri, S; Nisoli, M; Cerullo, G

    2006-04-01

    We produce ultrabroadband self-phase-stabilized near-IR pulses by a novel approach where a seed pulse, obtained by difference-frequency generation of a hollow-fiber broadened supercontinuum, is amplified by a two-stage optical parametric amplifier. Energies up to 20 microJ with a pulse spectrum extending from 1.2 to 1.6 microm are demonstrated, and a route for substantial energy scaling is indicated.

  13. 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.

  14. 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.

  15. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Galow, Benjamin J.; Keitel, Christoph H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Salamin, Yousef I. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Department of Physics, American University of Sharjah, POB 26666, Sharjah (United Arab Emirates); Liseykina, Tatyana V. [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany); Harman, Zoltan [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); ExtreMe Matter Institute EMMI, Planckstrasse 1, 64291 Darmstadt (Germany)

    2012-07-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. Feasibility of generating ultra-intense (10{sup 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{sup 21} W/cm{sup 2}.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianxing; Galow, Benjamin J.; Keitel, Christoph H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Salamin, Yousef I. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); Department of Physics, American University of Sharjah, POB 26666, Sharjah (United Arab Emirates); Harman, Zoltan [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, Heidelberg (Germany); ExtreMe Matter Institute EMMI, Planckstrasse 1, 64291 Darmstadt (Germany)

    2013-07-01

    Interactions of linearly and radially polarized frequency-chirped laser pulses with single protons and hydrogen gas targets are studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultra-intense (10{sup 7} particles per bunch) and phase-space collimated beams of protons 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{sup 21} W/cm{sup 2}.

  18. Post-compression of high energy terawatt-level femtosecond pulses and application to high order harmonic generation

    CERN Document Server

    Hort, Ondřej; Cabasse, Amélie; Petit, Stéphane; Mével, Eric; Descamps, Dominique; Constant, Eric

    2015-01-01

    We perform a post-compression of high energy pulses by using optical-field ionization of low pressure helium gas in a guided geometry. We apply this approach to a TW chirped-pulse-amplification based Ti:Sapphire laser chain and show that spectral broadening can be controlled both with the input pulse energy and gas pressure. Under optimized conditions, we generate 10 fs pulses at TW level directly under vacuum and demonstrate a high stability of the post compressed pulse duration. These high energy post-compressed pulses are thereafter used to perform high harmonic generation in a loose focusing geometry. The XUV beam is characterized both spatially and spectrally on a single shot basis and structured continuous XUV spectra are observed.

  19. 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.

  20. 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.

  1. 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.

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

    Science.gov (United States)

    Charpak, G.; Benaben, P.; Breuil, P.; Peskov, V.

    2008-02-01

    Ionization chambers working in ambient air in current detection mode are attractive due to their simplicity and low cost and are widely used in several applications such as smoke detection, dosimetry, therapeutic beam monitoring and so on. 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 which potentially offers the highest possible sensitivity in applications like alpha particle detection or high energy X-ray photon or electron detection. 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 one (pulse ionization chamber). This detector was readout by a custom made wide -band charge sensitive amplifier able to deal with slow induced signals generated by slow motion of negative and positive ions. The multiwire detector was able to detect alpha particles with an efficiency close to 22%. The second type of an alpha detector was an innovative GEM-like detector with resistive electrodes operating in air in avalanche mode at high gas gains (up to 104). This detector can also operate in a cascaded mode or being combined with other detectors, for example with MICROMEGAS. This detector was readout by a conventional charge -sensitive amplifier and was able to detect alpha particles with 100% efficiency. This detector could also detect X-ray photons or fast electrons. A detailed comparison between these two detectors is given as well as a comparison with 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 applications of these new detectors is alpha particle background monitors which, due to their low cost can find wide application not only in houses, but

  3. 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.

  4. 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

  5. A note on ultra-short pulses compression in silicon optical waveguides under fourth-order dispersion

    Science.gov (United States)

    Mandeng Mandeng, L.; Fewo Ibraid, S.; Tchawoua, C.; Kofané, T. C.

    2014-08-01

    We present an overview of the pulse compression phenomenon obtained during the propagation of ultra-short pulses in common used optical waveguides. In the case of the silicon-on-insulator (SOI) waveguides, using the modified and realistic variational approach (MVA) that involves the Rayleigh's dissipation function (RDF), we conduct the analysis of the compression mechanism on different input profiles. This study allows to show the effects of fourth-order dispersion (FOD), the nonlinear coefficients of absorption (nonlinear absorption) and the chirp, not only on symmetric and compact pulses but also on those with asymmetric profile as the Airy pulses. Indeed, considering the case of linear compression, the conditions of their occurrence are obtained. A relation between the FOD, the group-velocity dispersion (GVD) and the chirp is proposed in this way. In the nonlinear case, using the symmetric profiles as input pulses, we demonstrate a periodic compression induced by the interplay between the self-phase modulation (SPM) and the FOD. This appears as a new mode to generate the pulse compression phenomenon. Then, we show that when large values of the initial chirp and absorption coefficients as the two-photon absorption (TPA) present in these waveguides are considered, the compression mechanism is completely destroyed with at least the observation of one pulse amplification over a short distance of propagation before the pulse broadening. Finally, the study relating to the Airy pulses, leads rather to the reduction of the compression length induced by the SPM, the TPA and the free-carrier absorption (FCA) showing the pulse asymmetry influence.

  6. Amplification of noise-like pulses generated from a graphene-based Tm-doped all-fiber laser.

    Science.gov (United States)

    Sobon, Grzegorz; Sotor, Jaroslaw; Przewolka, Aleksandra; Pasternak, Iwona; Strupinski, Wlodek; Abramski, Krzysztof

    2016-09-01

    We report on the generation of noise-like pulse (NLP) trains in a Tm-doped fiber laser mode-locked by multilayer graphene saturable absorber. The spectral bandwidth obtained directly from the oscillator exceeds 60 nm, centered at 1950 nm, with 23.5 MHz repetition rate. The pulses were also amplified in a fully fiberized amplifier based on a double-cladding Tm-doped fiber. The system was capable of delivering 1.21 W of average power, which corresponds to 51.5 nJ energy stored in the noise-like bundle. We believe that the presented source might serve as a pump for supercontinuum generation in highly nonlinear fibers. PMID:27607642

  7. 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.

  8. 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.

  9. 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

  10. 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.

  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. 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.

  13. Generation of Ultra-high Intensity Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    N.J. Fisch; V.M. Malkin

    2003-06-10

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

  14. 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.

  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. Coherent white light amplification

    Science.gov (United States)

    Jovanovic, Igor; Barty, Christopher P.

    2004-05-25

    A system for coherent simultaneous amplification of a broad spectral range of light that includes an optical parametric amplifier and a source of a seed pulse is described. A first angular dispersive element is operatively connected to the source of a seed pulse. A first imaging telescope is operatively connected to the first angular dispersive element and operatively connected to the optical parametric amplifier. A source of a pump pulse is operatively connected to the optical parametric amplifier. A second imaging telescope is operatively connected to the optical parametric amplifier and a second angular dispersive element is operatively connected to the second imaging telescope.

  17. Generation of 9.5 fs pulse by use of chirped mirrors in Ti: sapphire laser cavity%钛宝石激光器9.5fs脉冲输出中的啁啾镜色散补偿

    Institute of Scientific and Technical Information of China (English)

    王胭脂; 柴路; 王清月; 邵建达; 董洪成; 晋云霞; 贺洪波; 易葵; 范正修; 宋有建; 胡明列

    2011-01-01

    根据钛宝石激光器的要求,实验设计了中心波长800 nm带宽200 nm的啁啾镜,在700-900 nm波长范围内提供约-60 fs2群延迟色散(group delay dispersion,GDD).采用双射频离子束溅射方法进行制备,用实验室搭建的白光干涉仪进行色散性能测试,从测试结果可以看出,制备的啁啾镜的性能和设计值符合得比较好.制备得到的非成对啁啾镜在钛宝石激光谐振腔中进行色散补偿,锁模后分别获得了12fs和9.5 fs的激光脉冲输出.这是目前报道的使用国产啁啾镜获得的最短的飞秒激光脉冲输出.%According to the requirement of Ti: sapphire laser, the optimized chirped mirrors (CM) are designed to provide group delay dispersion (GDD) of around - 60 fs2 with bandwidth 200 nm at a center wavelength of 800 nm. The CMs are manufactured by time controlled ion beam sputtering. The GDD is determined by using a home-built white light interferometer. The measurement results show that the manufactured CM can meat our requirement. By balancing the intra-cavity dispersion with our manufactured chirped mirrors, 12 fs and 9.5 fs pulses have been obtained respecitively.

  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. 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.

  20. Experimental study on the chirped structure of the white-light continuum generation by femtosecond laser spectroscopy

    Institute of Scientific and Technical Information of China (English)

    全冬晖; 刘世林; 张蕾; 杨健; 汪力; 杨国桢; 翁羽翔

    2003-01-01

    The chirped structure of the white-light continuum generation(WLCG)pulse produced by focusing 800nm laser pulse with a pulse duration of 150fs(FWHM:full-width-at-half-maximum)onto a 2.4 mm thick sapphire plate was investigated by the optical Kerr gate technique with normal hexane as the optical Kerr gate medium.The observed WLCG was positively chirped,the measured anti-Stokes spectrum of WLCG ranges from 449 to 580nm with a temporal span of 2.56ps.When using metal reflecting mirrors to eliminate the group velocity dispersion(GVD)effect,we found that a span of 1.3ps still remained,indicating that the chirped pulse cannot be accounted for simply by GVD of the pulse propagation in the dispersive media.Our results suggest that the light-induced refractive index change due to the third-order nonlinear optical effect leads to an additional positive group velocity dispersion,which contributes to an important portion of the observed temporal broadening of the chirped WLCG.In addition to using reflective optical elements instead of dispersive optical elements,an effective way of reducing the chirp is to minimize the optical path length of the WLCG medium.

  1. Detection and frequency tracking of chirping signals

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, G.R.; Stearns, S.D.

    1990-08-01

    This paper discusses several methods to detect the presence of and track the frequency of a chirping signal in broadband noise. The dynamic behavior of each of the methods is described and tracking error bounds are investigated in terms of the chirp rate. Frequency tracking and behavior in the presence of varying levels of noise are illustrated in examples. 11 refs., 29 figs.

  2. Focal spot measurement in ultra-intense ultra-short pulse laser facility

    Science.gov (United States)

    Liu, Lanqin; Peng, Hansheng; Zhou, Kainan; Wang, Xiaodong; Wang, Xiao; Zeng, Xiaoming; Zhu, Qihua; Huang, Xiaojun; Wei, Xiaofeng; Ren, Huan

    2005-06-01

    A peak power of 286-TW Ti:sapphire laser facility referred to as SILEX-I was successfully built at China Academy of Engineering Physics, for a pulse duration of 30 fs in a three-stage Ti:sapphire amplifier chain based on chirped-pulse amplification. The beam have a wavefront distortion of 0.63μm PV and 0.09μm RMS, and the focal spot with an f/2.2 OAP is 5.7μm, to our knowledge, this is the best far field obtained for high-power ultra-short pulse laser systems with no deformable mirror wavefront correction. The peak focused intensity of ~1021W /cm2 were expected.

  3. Effect of frequency variation on electromagnetic pulse interaction with charges and plasma

    NARCIS (Netherlands)

    Khachatryan, A.G.; Goor, van F.A.; Verschuur, J.W.J.; Boller, K.-J.

    2005-01-01

    The effect of frequency variation (chirp) in an electromagnetic (EM) pulse on the pulse interaction with a charged particle and plasma is studied. Various types of chirp and pulse envelopes are considered. In vacuum, a charged particle receives a kick in the polarization direction after interaction

  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. 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.

  6. Flux amplification in SSPX

    Science.gov (United States)

    Lodestro, Lynda; Hooper, E. B.; Jayakumar, R. J.; Pearlstein, L. D.; Wood, R. D.; McLean, H. S.

    2007-11-01

    Flux amplification---the ratio of poloidal flux enclosed between the magnetic and geometric axes to that between the separatrix and the geometric axis---is a key measure of efficiency for edge-current-driven spheromaks. With the new, modular capacitor bank, permitting flexible programming of the gun current, studies of flux amplification under various drive scenarios can be performed. Analysis of recent results of pulsed operation with the new bank finds an efficiency ˜ 0.2, in selected shots, of the conversion of gun energy to confined magnetic energy during the pulses, and suggests a route toward sustained efficiency at 0.2. Results of experiments, a model calculation of field build-up, and NIMROD simulations exploring this newly suggested scenario will be presented.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Parametric Techniques for Extreme-Contracts, High-Energy Petawatt Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I; Wattellier, B; Barty, C P J

    2003-09-05

    Prepulses are of great concern in high-power lasers: if their intensity is sufficiently high, they can heat and/or destroy a target before the arrival of the main pulse. For ultrahigh peak power lasers, for which focused intensity can exceed 10{sup 21} W/cm{sup 2}, a contrast of at least 10{sup 8} is the minimum requirement to avoid preionization of solid targets. Conventional preamplification stages do not meet this requirement, primarily due to prepulse originating from regenerative amplification. Optical parametric amplification (OPA) is well-known to generate pulses with a prepulse contrast equal to the gain of the amplifier, but it does not remove pre-existing prepulses. In this paper we describe a novel technique for contrast enhancement in cascaded optical parametric amplifiers (COPA). Based on cascaded idler utilization, COPA represents a versatile technique with a potentially infinite prepulse contrast enhancement. We have experimentally demonstrated COPA, producing a prepulse contrast of 10{sup 8}, limited by the sensitivity of measurement. A simple modification of the front end of a petawatt-type laser that utilizes optical parametric chirped pulse amplification (OPCPA) can yield unprecedented levels of prepulse contrast.

  12. 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

  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. Pulse Pressure in Clinical Practice

    Directory of Open Access Journals (Sweden)

    Jiri Parenica

    2012-02-01

    Full Text Available The review presents basic information about the pulse pressure. The variables related to pulse pressure are briefly explained - arterial stiffness, arterial compliance, pulse wave velocity, pulse pressure amplification and augmentation index. We present some recent trials and observational studies that show the importance of pulse pressure in clinical practice. Briefly the possibilities of influencing the pulse pressure are discussed.

  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. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  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. Chirp-driven giant phase space vortices

    Science.gov (United States)

    Trivedi, Pallavi; Ganesh, Rajaraman

    2016-06-01

    In a collisionless, unbounded, one-dimensional plasma, modelled using periodic boundary conditions, formation of steady state phase space coherent structures or phase space vortices (PSV) is investigated. Using a high resolution one-dimensional Vlasov-Poisson solver based on piecewise-parabolic advection scheme, the formation of giant PSV is addressed numerically. For an infinitesimal external drive amplitude and wavenumber k, we demonstrate the existence of a window of chirped external drive frequency that leads to the formation of giant PSV. The linear, small amplitude, external drive, when chirped, is shown to couple effectively to the plasma and increase both streaming of "untrapped" and "trapped" particle fraction. The steady state attained after the external drive is turned off and is shown to lead to a giant PSV with multiple extrema and phase velocities, with excess density fraction, defined as the deviation from the Maxwellian background, Δ n / n 0 ≃ 20 % - 25 % . It is shown that the process depends on the chirp time duration Δt. The excess density fraction Δn/n0, which contains both trapped and untrapped particle contribution, is also seen to scale with Δt, only inhibited by the gradient of the distribution in velocity space. Both single step drive and multistep chirp processes are shown to lead to steady state giant PSV, with multiple extrema due to embedded holes and clumps, long after the external drive is turned off.

  5. 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.

  6. 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...

  7. Time Delay Estimation of Chirp Signals Based on Doubl e-Channel DFRFT Cross-Spectrum%基于双通道 DFRFT 互谱法的 Chirp 信号时延估计

    Institute of Scientific and Technical Information of China (English)

    李昕

    2014-01-01

    针对脉冲Chirp类信号的时延估计问题,理论推导了基于离散分数阶Fourier变换的脉冲Chirp信号的特性,分析了当时延参量等效的分数阶Fourier域的频率大于采样率时,脉冲Chirp信号的分数阶Fourier域谱产生混叠,造成时延估计模糊的问题,并提出基于离散分数阶Fourier变换(DFRFT )双通道互谱法进行时延估计,给出两个通道采样率选取的原则及算法的性能分析,实验结果表明,在一定的采样率下,算法能够快速精确地估计脉冲Chirp信号的时延参数。%For the problem of time-delay estimation for Chirp pulse signals ,the characteristics of Chirp pulse signals based on the discrete fractional Fourier transform was theoretically derived .When time-delay equivalent frequency parameter was greater than the sampling rate in fractional Fourier domain ,the spectrum of Chirp pulse signals in fractional Fourier domain produced aliasing , which caused the delay estimation ambiguity problem .In order to solve this problem ,the time-delay estimation of Chirp signal based on double-channel DFRFT cross-spectral method was proposed ,then the principles of the two-channel sampling rate selection and the performance analysis was given .The experimental results show that ,in a certain sampling rate ,the proposed algorithm is able to quickly and accurately estimate the time-delay parameters of Chirp pulse signals .

  8. 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.

  9. 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.

  10. 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.

  11. Numerical analysis of double chirp effect in tapered and linearly chirped fiber Bragg gratings.

    Science.gov (United States)

    Markowski, Konrad; Jedrzejewski, Kazimierz; Osuch, Tomasz

    2016-06-10

    In this paper, a theoretical analysis of recently developed tapered chirped fiber Bragg gratings (TCFBG) written in co-directional and counter-directional configurations is presented. In particular, the effects of the synthesis of chirps resulting from both a fused taper profile and a linearly chirped fringe pattern of the induced refractive index changes within the fiber core are extensively examined. For this purpose, a numerical model based on the transfer matrix method (TMM) and the coupled mode theory (CMT) was developed for such a grating. The impact of TCFBG parameters, such as grating length and steepness of the taper transition, as well as the effect of the fringe pattern chirp rate on the spectral properties of the resulting gratings, are presented. Results show that, by using the appropriate design process, TCFBGs with reduced or enhanced resulting chirp, and thus with widely tailored spectral responses, can be easily achieved. In turn, it reveals a great potential application of such structures. The presented numerical approach provides an excellent tool for TCFBG design. PMID:27409005

  12. 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)

  13. Positioning of Littrow mounted gratings in pulse compressors

    Science.gov (United States)

    Kalinchenko, Galina; Vyhlidka, Stepan; Kramer, Daniel; Lerer, Alexander; Rus, Bedrich

    2015-09-01

    The development of chirped pulse amplification lasers toward multi-PetaWatt power imposes more demands on laser system elements. To make the spectral band of pulse compressors wider, laser designers began to consider Littrow mounted grating setups. In this study we investigate two Littrow type configurations. The first one is roll - a grating is rotated in the grating plane by a small angle. The second configuration is pitch - a grating is rotated by small angle about an axis perpendicular to the grating grooves. In this paper we experimentally measured diffraction efficiency of rolled and pitched dielectric grating, and simulated it with two methods: numerical Fourier Modal Method in LightTrans Virtual Lab and semi-analytical Volume Integral Equation Method. Here we claim that roll is more preferable for dielectric diffraction gratings with high groove density. It is shown that the energy of laser pulse compressed by a Littrow-roll configured compressor is 2 to 5% higher than Littrow-pitch configured one.

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  18. 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)

  19. 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.

  20. Chirp- and random-based coded ultrasonic excitation for localized blood-brain barrier opening

    Science.gov (United States)

    Kamimura, HAS; Wang, S; Wu, S-Y; Karakatsani, ME; Acosta, C; Carneiro, AAO; Konofagou, EE

    2015-01-01

    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 mm3 and 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. PMID:26394091

  1. Near-field diffraction of chirped gratings.

    Science.gov (United States)

    Sanchez-Brea, Luis Miguel; Torcal-Milla, Francisco Jose; Morlanes, Tomas

    2016-09-01

    In this Letter, we analyze the near-field diffraction pattern produced by chirped gratings. An intuitive analytical interpretation of the generated diffraction orders is proposed. Several interesting properties of the near-field diffraction pattern can be determined, such as the period of the fringes and its visibility. Diffraction orders present different widths and also, some of them present focusing properties. The width, location, and depth of focus of the converging diffraction orders are also determined. The analytical expressions are compared to numerical simulation and experimental results, showing a high agreement. PMID:27607980

  2. 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...

  3. 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.

  4. A novel cognitive ISAR imaging method with random stepped frequency chirp signal

    Institute of Scientific and Technical Information of China (English)

    ZHU Feng; ZHANG Qun; LUO Ying; LI KaiMing; GU FuFei

    2012-01-01

    The random stepped frequency chirp signal (RSFCS) has better performance in anti-jamming than that of conventional stepped frequency chirp signal (SFCS).In combination with the theory of compressing sensing (CS),a novel ISAR imaging method is proposed based on RSFCS,in which the high resolution range profile (HRRP) is reconstructed by using the conventional OMP algorithm,whereas the cognitive approach is introduced to further reduce the number of sub-pulse in RSFCS.In the proposed method,via cognizing the characteristics of moving targets,the number of sub-pulse in each burst can be adjusted adaptively.Finally,in the cross-range direction,the accurate reconstruction of ISAR image by using CS theory is implemented,which can effectively accomplish unwrapping.With the proposed method,high quality HRRP and ISAR image can be achieved with fewer sub-pulses of RSFCS and lower burst repetition frequency (BRF).Some simulation results are given to validate the effectiveness and robustness of the proposed algorithm.

  5. Progress on developing a PW ultrashort laser facility with ns, ps, and fs outputting pulses

    Science.gov (United States)

    Zhu, Qihua; Huang, Xiaojun; Wang, Xiao; Zeng, Xiaoming; Xie, Xudong; Wang, Fang; Wang, Fengrui; Lin, Donghui; Wang, Xiaodong; Zhou, Kainan; Jiang, Dongbin; Deng, Wu; Zuo, Yanlei; Zhang, Ying; Deng, Ying; Wei, Xiaofeng; Zhang, Xiaomin; Fan, Dianyuan

    2008-03-01

    A petawatt laser facility with three beams for fast ignition research and strong-field physics applications has been designed and is being constructed. The first beam (referred as SILEX-I) is a Ti:sapphire femto-second laser which pulse width is 30 fs, and till now, output power has reached to 330 TW. The other two beams are Nd 3+:glass lasers which output energy are larger than 1kJ and pulse width are about 1ps and 1ns respectively. By using the technology of OPA pumped by 800nm femtosecond laser and seeded by super-continuum spectrum white light, the three beams are synchronized with each other without jitter time. By using the seeds from OPA pumped by femtosecond laser, and by using the pre-amplification stage of OPCPA, the signal to noise ratio of the Nd 3+:glass petawatt laser will reach to 10 8. Active methods are taken to control the gain narrowing effect of the Nd 3+:glass amplifiers, giving the option to compress the chirped pulse to ultrashort pulse with width less than 400fs. Tiled multilayer dielectric coating gratings are used for the compressor of the PW beam, which has been successfully demonstrated on a 100J picosecond Nd 3+:glass laser system.

  6. 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.

  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. 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).

  9. 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.

  10. 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.

  11. 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.

  12. Can Anomalous Amplification be Attained Without Postselection?

    CERN Document Server

    Martínez-Rincón, Julián; Viza, Gerardo I; Howell, John C

    2015-01-01

    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 the need of postselection, 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, and a phase controls the amplification response. We experimentally demonstrate the proposed technique by measuring polarization rotations in a linearly polarized laser pulse. The effective sensitivity and precision of a split detector is increased when compared to a conventional continuous-wave balanced detection technique...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-15

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

  14. 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.

  15. 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.

  16. Patterning effects in multi-purpose amplification by a quantum dot amplifier

    DEFF Research Database (Denmark)

    Poel, Mike van der; Berg, Tommy Winther; Mørk, Jesper;

    2006-01-01

    The potential for ultrafast signal processing in a quantum dot amplifier is investigated by observing the gain dynamics during amplification of femtosecond pulses in rapid succession. Significant patterning is seen at picosecond pulse separation....

  17. 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...

  18. 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.

  19. Suppression of a parasitic pump side-scattering in backward Raman amplifiers of laser pulses in plasmas

    Science.gov (United States)

    Solodov, Andrei; Malkin, Vladimir; Fisch, Nathaniel

    2003-10-01

    In backward Raman amplifiers (BRA), the pump laser pulse can be prematurely depleted through Raman scattering, seeded by the plasma noise, as the pump encounters plasma before reaching the counter-propagating seed pulse. It was shown previously that detuning of the Raman resonance, either by a plasma density gradient or a pump frequency chirp, can prevent the premature pump backscattering, even while the desired amplification of the seed pulse persists with a high efficiency. However, parasitic pump side-scattering is not automatically suppressed together with the parasitic backscattering, and might be even more dangerous for BRA. What we show here is that by combining the above two detuning mechanisms one can suppress parasitic pump side-scattering as well. Apart from the simplest counterpropagating geometry, we examine BRA for arbitrary angles between the directions of pump and seed propagation. We show that, by selecting an appropriate direction of the plasma density gradient, one can favorably minimize the detuning in the direction of the seed pulse propagation, while strongly suppressing the parasitic pump side-scattering in all the other directions. This work was supported in part by DOE and DARPA.

  20. 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.

  1. 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...

  2. 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

  3. 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.

  4. 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)

  5. 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.

  6. Single-Shot Measurement of Broad Bandwidth Terahertz Pulses

    Institute of Scientific and Technical Information of China (English)

    ZHOU Mu-Lin; LU Xin; DONG Quan-Li; ZHANG Jie; LIU Feng; LI Chun; DU Fei; LI Yu-Tong; WANG Wei-Min; SHENG Zheng-Ming; CHEN Li-Ming; MA Jing-Long

    2012-01-01

    We propose a new single-shot method for measuring terahertz pulses using a linearly chirped optical pulse interferogram.Modulated frequency domain phase information can be extracted by the interferogram recorded on imaging spectrographs.The terahertz pulse waveform is obtained from the phase information.We overcome the energy fluctuation problem by using the phase information,making a reference shot unnecessary and the terahertz detection more flexible and convincing.%We propose a new single-shot method for measuring terahertz pulses using a linearly chirped optical pulse interferogram. Modulated frequency domain phase information can be extracted by the interferogram recorded on imaging spectrographs. The terahertz pulse waveform is obtained from the phase information. We overcome the energy fluctuation problem by using the phase information, making a reference shot unnecessary and the terahertz detection more flexible and convincing.

  7. 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

  8. 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.

  9. Tomographic measurement of temperature change in phantoms of the human body by chirp radar-type microwave computed tomography.

    Science.gov (United States)

    Miyakawa, M

    1993-07-01

    The chirp radar-type microwave computed tomograph (CT) measures the temperature change in a human body noninvasively. The paper examines its feasibility. A chirp pulse signal between 1 and 2 GHz is radiated from the transmitting antenna to the phantom. The transmitted waves are detected by the receiving antenna, which is placed on the opposite side of the object, and the beat signal between the incident wave and the transmitted wave is produced by the mixer. By spectral analysis of the beat signal, only those signals transmitted on the straight line between the transmitting antenna and the receiving antenna are discriminated from multipath signals. The microwave tomogram can therefore be reconstructed easily using the conventional algorithms for an X-ray CT image. The microwave CT can use the chirp signal to remove the influence of multipath signals caused by diffraction and reflection. The imaging of dielectric materials with complicated structures is thus possible. The experimental results using phantoms show that the spatial resolution of this microwave CT is about 10 mm and that a two-dimensional distribution of temperature change can be measured.

  10. A High-Energy, Ultrashort-Pulse X-Ray System for the Dynamic Study of Heavy, Dense Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, David Jeremy [Univ. of California, Davis, CA (United States)

    2004-01-01

    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 1018 photons • s-1 • mm-2 • mrad-2 • 0.01% bandwidth-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 in high

  11. 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

  12. Single-Shot Broad Bandwidth Terahertz Pulse Measurement

    Institute of Scientific and Technical Information of China (English)

    周木林; 刘峰; 李春; 杜飞; 李玉同; 王伟民; 鲁欣; 董全力; 张杰

    2012-01-01

    A new method based on a chirped optical pulse interferogram has been proposed to measure terahertz radiation. The frequency domain phase information of the interferogram is used to extract the time-domain terahertz pulse waveform. In principle, the resolution of our method can be as high as the unchirped probe pulse duration, with the advantages of relatively simple measurement setup and signal extracting techniques.

  13. 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.

  14. Excitation of Chirping Whistler Waves in a Laboratory Plasma.

    Science.gov (United States)

    Van Compernolle, B; An, X; Bortnik, J; Thorne, R M; Pribyl, P; Gekelman, W

    2015-06-19

    Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, 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 beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density, and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified.

  15. Excitation of Chirping Whistler Waves in a Laboratory Plasma

    Science.gov (United States)

    Van Compernolle, B.; An, X.; Bortnik, J.; Thorne, R. M.; Gekelman, W. N.; Pribyl, P.

    2015-12-01

    Whistler mode chorus emissions with a characteristic frequency chirp are an important magnetospheric wave, 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 beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified. The research was funded by NSF/DOE Plasma Partnership program by grant DE-SC0010578. Work was done at the Basic Plasma Science Facility (BAPSF) also funded by NSF/DOE.

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

  17. 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.

  18. Quantum state engineering with flux-biased Josephson phase qubits by Stark-chirped rapid adiabatic passages

    CERN Document Server

    Nie, W; Shi, X; Wei, L F

    2010-01-01

    In this paper, the scheme of quantum computing based on Stark chirped rapid adiabatic passage (SCRAP) technique [L. F. Wei et al., Phys. Rev. Lett. 100, 113601 (2008)] is extensively applied to implement the quantum-state manipulations in the flux-biased Josephson phase qubits. The broken-parity symmetries of bound states in flux-biased Josephson junctions are utilized to conveniently generate the desirable Stark-shifts. Then, assisted by various transition pulses universal quantum logic gates as well as arbitrary quantum-state preparations could be implemented. Compared with the usual PI-pulses operations widely used in the experiments, the adiabatic population passage proposed here is insensitive the details of the applied pulses and thus the desirable population transfers could be satisfyingly implemented. The experimental feasibility of the proposal is also discussed.

  19. The Seneca Amplification Construction

    Directory of Open Access Journals (Sweden)

    Wallace Chafe

    2012-01-01

    Full Text Available The polysynthetic morphology of the Northern Iroquoian languages presents a challenge to studies of clause combining. The discussion here focuses on a Seneca construction that may appear within a single clause but may also straddle clause boundaries. It amplifies the information provided by a referent, here called the trigger, that is introduced by the pronominal prefix within a verb or occasionally in some other way. The particle neh signals that further information about that referent will follow. This construction is found at four levels of syntactic complexity. At the first level the trigger and its amplification occur within the same prosodic phrase and the amplification is a noun. At the second level the amplification occurs in a separate prosodic phrase but remains a noun. At the third level the amplification exhibits verb morphology but has been lexicalized with a nominal function. At the fourth level the amplification functions as a full clause and neh serves as a marker of clause combining. Several varieties of amplification are discussed, as are cases in which the speaker judges that no amplification is needed. It is suggested that the typologically similar Caddo language illustrates a situation in which this construction could never arise, simply because Caddo verbs lack the pronominal element that triggers the construction in Seneca.

  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. 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.

  2. 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.

  3. Bloch oscillations in chirped layered structures with metamaterials.

    Science.gov (United States)

    Davoyan, Arthur R; Shadrivov, Ilya V; Sukhorukov, Andrey A; Kivshar, Yuri S

    2008-03-01

    We analyze the Bloch oscillations of electromagnetic waves in chirped layered structures with alternating layers of negative-index metamaterial and conventional dielectric under the condition of the zero average refractive index. We consider the case when the chirp is introduced by varying the thickness of the layers linearly across the structure. We demonstrate that such structures can support three different types of the Bloch oscillations for electromagnetic waves associated with either propagating or evanescent guided modes. In particular, we predict a novel type of the Bloch oscillations associated with coupling between surface waves excited at the interfaces separating the layers of negative-index metamaterial and the layers of the conventional dielectric.

  4. Design of chirped fiber gratings for optical beamforming networks

    Institute of Scientific and Technical Information of China (English)

    YE Ying-bo; SHI Pei-ming; HUANG Shan-guo; ZHOU Jing

    2011-01-01

    The properties of the linear chirped fiber grating (CFG) which is used in the true time delay unit of the optical beamforming networks (OBFNs) are studied intensively through theoretical analyses and numerical calculations.It is concluded that the dispersion of the CFG is equal to 1/(3Gc),where G is the chirp coefficient of CFG and c is the light speed.Based on this relationship,a simplified designing process of a CFG which satisfies the requirements of the OB FN is given.The simulation results are coincident with the theoretical conclusions.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Pulse-shaping mechanism in colliding-pulse mode-locked laser diodes

    DEFF Research Database (Denmark)

    Bischoff, Svend; Sørensen, Mads Peter; Mørk, J.;

    1995-01-01

    The large signal dynamics of passively colliding pulse mode-locked laser diodes is studied. We derive a model which explains modelocking via the interplay of gain and loss dynamics; no bandwidth limiting element is necessary for pulse formation. It is found necessary to have both fast and slow...... absorber dynamics to achieve mode-locking. Significant chirp is predicted for pulses emitted from long lasers, in agreement with experiment. The pulse width shows a strong dependence on both cavity and saturable absorber length. (C) 1995 American Institute of Physics....

  10. Adaptive Light Modulation for Improved Resolution and Efficiency in All-Optical Pulse-Echo Ultrasound.

    Science.gov (United States)

    Alles, Erwin J; Colchester, Richard J; Desjardins, Adrien E

    2016-01-01

    In biomedical all-optical pulse-echo ultrasound systems, ultrasound is generated with the photoacoustic effect by illuminating an optically absorbing structure with a temporally modulated light source. Nanosecond range laser pulses are typically used, which can yield bandwidths exceeding 100 MHz. However, acoustical attenuation within tissue or nonuniformities in the detector or source power spectra result in energy loss at the affected frequencies and in a reduced overall system efficiency. In this work, a laser diode is used to generate linear and nonlinear chirp optical modulations that are extended to microsecond time scales, with bandwidths constrained to the system sensitivity. Compared to those obtained using a 2-ns pulsed laser, pulse-echo images of a phantom obtained using linear chirp excitation exhibit similar axial resolution (99 versus 92 μm, respectively) and signal-to-noise ratios (SNRs) (10.3 versus 9.6 dB). In addition, the axial point spread function (PSF) exhibits lower sidelobe levels in the case of chirp modulation. Using nonlinear (time-stretched) chirp excitations, where the nonlinearity is computed from measurements of the spectral sensitivity of the system, the power spectrum of the imaging system was flattened and its bandwidth broadened. Consequently, the PSF has a narrower axial extent and still lower sidelobe levels. Pulse-echo images acquired with time-stretched chirps as optical modulation have higher axial resolution (64 μm) than those obtained with linear chirps, at the expense of a lower SNR (6.8 dB). Using a linear or time-stretched chirp, the conversion efficiency from optical power to acoustical pressure improved by a factor of 70 or 61, respectively, compared to that obtained with pulsed excitation.

  11. 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.

  12. 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.

  13. Aerosol Lidar for the Relative Backscatter Amplification Measurements

    Directory of Open Access Journals (Sweden)

    Razenkov Igor A.

    2016-01-01

    Full Text Available 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.

  14. Optical Nyquist pulse generation using a time lens with spectral slicing.

    Science.gov (United States)

    Wang, Dong; Huo, Li; Xing, Yanfei; Jiang, Xiangyu; Lou, Caiyun

    2015-02-23

    Optical Nyquist pulse generation based on a time lens with subsequent optical filtering is proposed. A nearly chirp-free 10-GHz 8.1-ps Nyquist pulse generator is experimentally demonstrated. By inserting group velocity dispersion (GVD) between cascaded phase and amplitude modulators, 11 tones ultraflat optical frequency comb (OFC) of 10-GHz frequency spacing within 0.9 dB power variation is obtained. The quasi-rectangular shape spectrum is then filtered out with a tunable rectangular-shaped optical band-pass filter (OBPF) and the quasi-linear chirp is compensated by a segment of standard single mode fiber (SSMF). By changing the wavelength of the continuous wave (CW) light, nearly chirp-free Nyquist pulses over C band are obtained. Furthermore, simultaneous dual-wavelength pulse generation is also demonstrated.

  15. 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...

  16. 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.

  17. Optimization of Apodized Chirped Fiber Bragg Grating for Dispersion Compensation

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Multiwavelength chirped fiber Bragg grating (MCFBG) is a more valuable approach to chromatic dispersion compensation. And adjusting the structure of FBG will optimize the performance of dispersion compensator in 8×10Gb/s DWDM network, which is proved by simulating calculation.

  18. 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.

  19. 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 repetition...... back from a Tucker Davies Technologies System II, and a Matlab program controlled the test setup. The results are specified in dB peak-to-peak equivalent threshold sound pressure levels (dB peETSPL). Study sample: The test group consisted of 25 otologically-normal young adults (age 18–25 years......). Results: The results are in good agreement with the results from another investigation of hearing thresholds using the same chirp stimuli, and the values for the octave-band chirps are in line with the standardized reference values for corresponding tone bursts (ISO 389-6, 2007). Conclusions: The results...

  20. 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

  1. 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

  2. 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

  3. 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...

  4. 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...

  5. 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.

  6. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...

  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. 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.

  9. Limits of Femtosecond Fiber Amplification by Parabolic Pre-Shaping

    CERN Document Server

    Fu, Walter; McComb, Timothy S; Lowder, Tyson L; Wise, Frank W

    2016-01-01

    We explore parabolic pre-shaping as a means of generating and amplifying ultrashort pulses. We develop a theoretical framework for modeling the technique and use its conclusions to design a femtosecond fiber amplifier. Starting from 9 ps pulses, we obtain 4.3 $\\mu$J, nearly transform-limited pulses 275 fs in duration, simultaneously achieving over 40 dB gain and 33-fold compression. Finally, we show that this amplification scheme is limited by Raman scattering, and outline a method by which the pulse duration and energy may be further improved and tailored for a given application.

  10. 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.

  11. Optical pulse compression using the combination of phase modulation and high-order dispersion compensation

    Science.gov (United States)

    Deng, Guo; Pan, Wei; Zou, Xihua

    2010-09-01

    Optical pulse compression using high-order dispersion compensation is proposed and theoretically analyzed. Firstly, the required dispersion profile for the high-order dispersion compensation is derived, according to the linear chirp and the nonlinear chirp of a phase-modulated continuous-wave (CW) laser source. With the use of the high-order dispersion compensation, such as the combination compensation of the second order dispersion (SOD) and the fourth order dispersion (FOD), an efficient pulse compression having a less time-bandwidth product and a greater peak power is realized. A sampled fiber Bragg grating (FBG) with both the SOD and the FOD is then designed using the equivalent chirp and the reconstruction algorithm. Finally, in the numerical simulation an optical pulse with a time-bandwidth product of 0.79 is generated via high-order dispersion compensation that is performed by using the sampled FBG.

  12. 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.

  13. 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.

  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. Chirp Z-transform spectral zoom optimization with MATLAB.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Grant D.

    2005-11-01

    The MATLAB language has become a standard for rapid prototyping throughout all disciplines of engineering because the environment is easy to understand and use. Many of the basic functions included in MATLAB are those operations that are necessary to carry out larger algorithms such as the chirp z-transform spectral zoom. These functions include, but are not limited to mathematical operators, logical operators, array indexing, and the Fast Fourier Transform (FFT). However, despite its ease of use, MATLAB's technical computing language is interpreted and thus is not always capable of the memory management and performance of a compiled language. There are however, several optimizations that can be made within the chirp z-transform spectral zoom algorithm itself, and also to the MATLAB implementation in order to take full advantage of the computing environment and lower processing time and improve memory usage. To that end, this document's purpose is two-fold. The first demonstrates how to perform a chirp z-transform spectral zoom as well as an optimization within the algorithm that improves performance and memory usage. The second demonstrates a minor MATLAB language usage technique that can reduce overhead memory costs and improve performance.

  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. Fabrication of High Quality Broadband Type IIA Chirped Fiber Bragg Gratings

    Institute of Scientific and Technical Information of China (English)

    SANG Xin-zhu; YU Chong-xiu; YAN Bin-bin; MA Jian-xin; LU Nai-guang

    2006-01-01

    Chirped fiber Bragg gratings have found many applications in optical communication and sensing systems. High quality filters based on chirped fiber Bragg gratings with reflection bandwidth of 2.6 and 32nm and high reflectivity are demonstrated experimentally with 2 and 4cm long phase masks, respectively. These filters with flat reflection band and high reflectivity are achieved by writing type IIA chirped Bragg gratings.

  20. Reduction of energy chirp by the wake of coherent synchrotron radiation

    Science.gov (United States)

    Bosch, R. A.

    2010-11-01

    When an energy-chirped bunch is undercompressed in a magnetic chicane, the compressed bunch also has an energy chirp. The chirp may be decreased by sending the bunch through bending magnets, since the largest energy loss from the wake of coherent synchrotron radiation occurs in the tail of a typical bunch. We obtain formulas for the dechirping of a rectangular bunch by short magnets, and apply this dechirping technique in a design for a free-electron laser.

  1. 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.

  2. Interrogation of a linearly chirped fiber Bragg grating sensor with high resolution using a linearly chirped optical waveform.

    Science.gov (United States)

    Wang, Yiping; Zhang, Jiejun; Coutinho, Olympio; Yao, Jianping

    2015-11-01

    An approach to the interrogation of a linearly chirped fiber Bragg grating (LCFBG) sensor using a linearly frequency-modulated (or chirped) optical waveform (LFMOW) with a high resolution is proposed and experimentally demonstrated. An LFMOW is generated at a laser diode through linear frequency modulation. The generated LFMOW is then launched into an LCFBG pair consisting of two identical LCFBGs, with one serving as a sensing LCFBG and the other as a reference LCFBG. The reflection of the LFMOW from the two LCFBGs would lead to two time delayed LFMOWs. By beating the LFMOWs at a photodetector, a microwave signal with a beat frequency that is proportional to the time delay difference between the two reflected LFMOWs is generated. By measuring the frequency change of the beat signal, the strain applied to the sensing LCFBG is estimated. The proposed approach is experimentally evaluated. An LCFBG sensor with a resolution of 0.25 με is experimentally demonstrated. PMID:26512484

  3. Interrogation of a linearly chirped fiber Bragg grating sensor with high resolution using a linearly chirped optical waveform.

    Science.gov (United States)

    Wang, Yiping; Zhang, Jiejun; Coutinho, Olympio; Yao, Jianping

    2015-11-01

    An approach to the interrogation of a linearly chirped fiber Bragg grating (LCFBG) sensor using a linearly frequency-modulated (or chirped) optical waveform (LFMOW) with a high resolution is proposed and experimentally demonstrated. An LFMOW is generated at a laser diode through linear frequency modulation. The generated LFMOW is then launched into an LCFBG pair consisting of two identical LCFBGs, with one serving as a sensing LCFBG and the other as a reference LCFBG. The reflection of the LFMOW from the two LCFBGs would lead to two time delayed LFMOWs. By beating the LFMOWs at a photodetector, a microwave signal with a beat frequency that is proportional to the time delay difference between the two reflected LFMOWs is generated. By measuring the frequency change of the beat signal, the strain applied to the sensing LCFBG is estimated. The proposed approach is experimentally evaluated. An LCFBG sensor with a resolution of 0.25 με is experimentally demonstrated.

  4. 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)

  5. 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

  6. 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.

  7. Analytic solutions of self-similar pulse based on Ginzburg-Landau equation with constant coefficients

    Institute of Scientific and Technical Information of China (English)

    FENG Jie; XU WenCheng; LI ShuXian; LIU SongHao

    2008-01-01

    Based on the constant coefficients of Ginzburg-Landau equation that considers the influence of the doped fiber retarded time on the evolution of self-similar pulse, the parabolic asymptotic self-similar solutions were obtained by the symmetry reduc-tion algorithm.The parabolic asymptotic amplitude function, phase function, strict linear chirp function and the effective temporal pulse width of self-similar pulse are given in this paper.And these theoretical results are consistent with the numerical simulations.

  8. Strengthening weak value amplification with recycled photons

    CERN Document Server

    Dressel, Justin; Jordan, Andrew N; Graham, Trent M; Kwiat, Paul G

    2013-01-01

    We consider the use of cyclic weak measurements to improve the sensitivity of weak-value amplification precision measurement schemes. Previous weak-value experiments have used only a small fraction of events, while discarding the rest through the process of "post-selection". We extend this idea by considering recycling of events which are typically unused in a weak measurement. Here we treat a sequence of polarized laser pulses effectively trapped inside an interferometer using a Pockels cell and polarization optics. In principle, all photons can be post-selected, which will improve the measurement sensitivity. We first provide a qualitative argument for the expected improvements from recycling photons, followed by the exact result for the recycling of collimated beam pulses, and numerical calculations for diverging beams. We show that beam degradation effects can be mitigated via profile flipping or Zeno reshaping. The main advantage of such a recycling scheme is an effective power increase, while maintainin...

  9. Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique

    Science.gov (United States)

    Li, Lihua; Coon, Michael; McLinden, Matthew

    2013-01-01

    technique could bring significant impact on future radar development. The novel feature of this innovation is the non-linear FM (NLFM) waveform design. The traditional linear FM has the limit (-20 log BT -3 dB) for achieving ultra-low-range sidelobe in pulse compression. For this study, a different combination of 20- or 40-microsecond chirp pulse width and 2- or 4-MHz chirp bandwidth was used. These are typical operational parameters for airborne or spaceborne weather radars. The NLFM waveform design was then implemented on a FPGA board to generate a real chirp signal, which was then sent to the radar transceiver simulator. The final results have shown significant improvement on sidelobe performance compared to that obtained using a traditional linear FM chirp.

  10. 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....

  11. 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.

  12. Photonic generation of linearly chirped millimeter wave based on comb-spacing tunable optical frequency comb

    Science.gov (United States)

    Xia, Zongyang; Xie, Weilin; Sun, Dongning; Shi, Hongxiao; Dong, Yi; Hu, Weisheng

    2013-12-01

    We demonstrated a photonic approach to generate a phase-continuous frequency-linear-chirped millimeter-wave (mm-wave) signal with high linearity based on continuous-wave phase modulated optical frequency comb and cascaded interleavers. Through linearly sweeping the frequency of the radio frequency (RF) driving signal, high-order frequency-linear-chirped optical comb lines are generated and then extracted by the cascaded interleavers. By beating the filtered high-order comb lines, center frequency and chirp range multiplied linear-chirp microwave signals are generated. Frequency doubled and quadrupled linear-chirp mm-wave signals of range 48.6 to 52.6 GHz and 97.2 to 105.2 GHz at chirp rates of 133.33 and 266.67 GHz/s are demonstrated with the ±1st and ±2nd optical comb lines, respectively, while the RF driving signal is of chirp range 24.3 to 26.3 GHz and chirp time 30 ms.

  13. 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

  14. Chirped Peregrine solitons in a class of cubic-quintic nonlinear Schrödinger equations

    Science.gov (United States)

    Chen, Shihua; Baronio, Fabio; Soto-Crespo, Jose M.; Liu, Yi; Grelu, Philippe

    2016-06-01

    We shed light on the fundamental form of the Peregrine soliton as well as on its frequency chirping property by virtue of a pertinent cubic-quintic nonlinear Schrödinger equation. An exact generic Peregrine soliton solution is obtained via a simple gauge transformation, which unifies the recently-most-studied fundamental rogue-wave species. We discover that this type of Peregrine soliton, viable for both the focusing and defocusing Kerr nonlinearities, could exhibit an extra doubly localized chirp while keeping the characteristic intensity features of the original Peregrine soliton, hence the term chirped Peregrine soliton. The existence of chirped Peregrine solitons in a self-defocusing nonlinear medium may be attributed to the presence of self-steepening effect when the latter is not balanced out by the third-order dispersion. We numerically confirm the robustness of such chirped Peregrine solitons in spite of the onset of modulation instability.

  15. Realizing Ultrafast Electron Pulse Self-Compression by Femtosecond Pulse Shaping Technique.

    Science.gov (United States)

    Qi, Yingpeng; Pei, Minjie; Qi, Dalong; Yang, Yan; Jia, Tianqing; Zhang, Shian; Sun, Zhenrong

    2015-10-01

    Uncorrelated position and velocity distribution of the electron bunch at the photocathode from the residual energy greatly limit the transverse coherent length and the recompression ability. Here we first propose a femtosecond pulse-shaping method to realize the electron pulse self-compression in ultrafast electron diffraction system based on a point-to-point space-charge model. The positively chirped femtosecond laser pulse can correspondingly create the positively chirped electron bunch at the photocathode (such as metal-insulator heterojunction), and such a shaped electron pulse can realize the self-compression in the subsequent propagation process. The greatest advantage for our proposed scheme is that no additional components are introduced into the ultrafast electron diffraction system, which therefore does not affect the electron bunch shape. More importantly, this scheme can break the limitation that the electron pulse via postphotocathode static compression schemes is not shorter than the excitation laser pulse due to the uncorrelated position and velocity distribution of the initial electron bunch. PMID:26722884

  16. 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.

  17. Spontaneous parametric down conversion in chirped, aperiodically-poled crystals

    CERN Document Server

    Sanchez-Lozano, X; U'Ren, Alfred

    2014-01-01

    We present a theoretical analysis of the process of spontaneous parametric down conversion (SPDC) in a non-linear crystal characterized by a linearly-chirped X(2) grating along the direction of propagation. Our analysis leads to an expression for the joint spectral amplitude, based on which we can derive various spectral-temporal properties of the photon pairs and of the heralded single photons obtained from the photon pairs, including: the single photon spectrum, the chronocyclic Wigner function and the Schmidt number. The simulations that we present are for the specific case of a collinear SPDC source based on a PPLN crystal with the signal and idler photons emitted close to the telecom window. We discuss the mechanism for spectral broadening due to the presence of a linearly chirped X(2) grating, showing that not only the width but also to some extent the shape of the SPDC spectrum maybe controlled. Also, we discuss how the fact that the different spectral components are emitted on different planes in the ...

  18. Bandwidth enhancement for parametric amplifiers operated in chirped multi-beam mode

    CERN Document Server

    Terranova, F; Pegoraro, F

    2008-01-01

    In this paper we discuss the bandwidth enhancement that can be achieved in multi-Joule OPCPA systems exploiting the tunability of parametric amplification. In particular, we consider a pair of single pass amplifiers based on DKDP, pumped by the second harmonic of Nd:glass and tuned to amplify adjacent regions of the signal spectrum. We demonstrate that a bandwidth enhancement up to 50% is possible in two configurations; in the first case, one of the two amplifiers is operated near its non-collinear broadband limit; to allow for effective recombination and recompression of the outgoing signals this configuration requires filtering and phase manipulation of the spectral tail of the amplified pulses. In the second case, effective recombination can be achieved simply by spectral filtering: in this configuration, the optimization of the parameters of the amplifiers (pulse, crystal orientation and crystal length) does not follow the recipes of non-collinear OPCPA.

  19. Superfocusing of an ultrashort plasmon pulse by a conducting cone

    Science.gov (United States)

    Manuilovich, E. S.; Astapenko, V. A.; Golovinskii, P. A.

    2016-01-01

    We have shown theoretically the possibility of controlling nanoscale superfocusing of plasmons in a metal conical tip by modulating the carrier frequency of the pulse. The propagation of an ultrashort plasmon pulse in a metal nanoneedle is simulated numerically. The calculation is based on an asymptotic analytical solution of Maxwell's equations for electromagnetic wave propagation in a conical conductor in the vicinity of its apex, obtained by the approximate separation of variables in spherical coordinates. The dependence the field superfocusing on the conductor material, pulse chirp and propagation length is studied.

  20. Pulse compression by parametric beating with a prepared Raman coherence

    International Nuclear Information System (INIS)

    We present a general analysis for the interaction of a probe-laser radiation with a coherently prepared molecular Raman medium. We describe a general formalism that includes dispersive effects, such as group velocity and group-velocity dispersion (GVD). When dispersion is negligible, the analysis is especially simple and insightful. We show that molecular oscillations result in a modulated instantaneous susceptibility of the medium. The effect of the time-varying susceptibility on a probe-laser pulse is twofold: the output frequency becomes modulated because of the time-varying phase velocity, and the pulse shape becomes deformed because of the time-varying group velocity. We identify two mechanisms for pulse compression: (1) Frequency chirping with subsequent pulse compression by normal linear GVD (possibly in the same medium) and (2) Compression due to the time-varying group velocity. We analyze various aspects of pulse compression in the coherent Raman medium and derive conservation relations for this process. When we consider a probe-laser pulse that is much shorter than the molecular oscillation period, we observe frequency chirping, compression, or stretching of this pulse, depending on its relative timing with respect to the molecular oscillations. Based on our analysis, we propose a method for selective compression or frequency conversion of single ultrashort pulses

  1. 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 extens...

  2. 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)

  3. LASERS: Efficient source of femtosecond pulses and its use for broadband supercontinuum generation

    Science.gov (United States)

    Tausenev, Anton V.; Kryukov, P. G.; Bubnov, M. M.; Likhachev, M. E.; Romanova, E. Yu; Yashkov, M. V.; Khopin, V. F.; Salganskii, M. Yu

    2005-07-01

    A femtosecond Er3+-doped fibre laser system is developed and studied. The system contains a master oscillator operating in the pulse stretching regime, an amplifier of chirped pulses, and a device for pulse compression. The laser emits 1.55-μm, 100-fs, 90-mW pulses with a pulse repetition rate of 25 MHz. The setup was used for supercontinuum generation in an optical fibre heavily doped with GeO2. The width of the generated supercontinuum was close to an octave.

  4. Intensity Modulation of Hybrid Soliton Pulsed Source with Fibre Bragg Grating External Cavity

    Institute of Scientific and Technical Information of China (English)

    Nuran Dogru; M.Sadettin Ozyazici

    2004-01-01

    Resonance peak spectral splitting (RPSS) in the intensity modulation of a hybrid soliton pulsed source, where fibre Bragg gratings are used as an external cavity, can be suppressed by introducing a suitable linear chirp rate in a Gaussian apodized grating. Antireflection-coated reflectivity and gain suppression factor does not strongly affect the RPSS.

  5. 40 Gb/s Pulse Generation Using Gain Switching of a Commercially Available Laser Module

    DEFF Research Database (Denmark)

    Nørregaard, Jesper; Hanberg, Jesper; Franck, Thorkild;

    1999-01-01

    , and a photodiode for optical power monitoring.The RF input port was connected to the driver circuit using a coplanar microwave probe. A DC bias and a large signal modulation at 10 GHz was applied to the module to generate chirped pulses. A linear as well as a non-linear soliton compression was used with optical...

  6. Theory of deep ultraviolet generation at maximum coherence assisted by Stark-chirped two-photon resonance

    CERN Document Server

    Myslivets, S A; Kimberg, V V; George, T F; George, Thomas F.

    2003-01-01

    A scheme is analyzed for effcient generation of vacuum ultraviolet radiation through four-wave mixing processes assisted by the technique of Stark-chirped rapid adiabatic passage. These opportunities are associated with pulse excitation of laddertype short-wavelength two-photon atomic or molecular transitions so that relaxation processes can be neglected. In this three-laser technique, a delayed-pulse of strong oR-resonant infrared radiation sweeps the laser-induced Stark-shift of a two-photon transition in a such way that facilitates robust maximum two-photon coherence induced by the first ultraviolet laser. A judiciously delayed third pulse scatters at this coherence and generates short-wavelength radiation. A theoretical analysis of these problems based on the density matrix is performed. A numerical model is developed to carry out simulations of a typical experiment. The results illustrate a behavior of populations, coherence and generated radiation along the medium as well as opportunities of effcient ge...

  7. Self-deflecting plasmonic lattice solitons and sur-face modes in chirped plasmonic arrays

    CERN Document Server

    Li, Chunyan; Ye, Fangwei; Kartashov, Yaroslav V; Torner, Lluis; Chen, Xianfeng

    2015-01-01

    We show that chirped metal-dielectric waveguide arrays with focusing cubic nonlinearity can support plasmonic lattice solitons that undergo self-deflection in the transverse plane. Such lattice solitons are deeply-subwavelength self-sustained excitations, although they cover several periods of the array. Upon propagation,the excitations accelerate in the transverse plane and follow trajectories curved in the direction in which the separation between neighboring metallic layers decreases, a phenomenon that yields considerable deflection angles. The deflection angle can be controlled by varying the array chirp. We also reveal the existence of surface modes at the boundary of truncated plasmonic chirped arraythat form even in the absence of nonlinearity.

  8. Automated Chirp Detection with Diffusion Entropy: Application to Infrasound from Sprites

    CERN Document Server

    Ignaccolo, M; Farges, T; Fullekrug, M

    2005-01-01

    We study the performance of three different methods to automatically detect a chirp in background noise. (1) The standard deviation detector uses the computation of the signal to noise ratio. (2) The spectral covariance detector is based on the recognition of the chirp in the spectrogram. (3) The CASSANDRA detector uses diffusion entropy analysis to detect periodic patterns in noise. All three detectors are applied to an infrasound recording for detecting chirps produced by sprites. The CASSANDRA detector provides the best trade off between the false alarm rate and the detection efficiency.

  9. Effect of Initial Frequency Chirp on Supercontinuum Generation in Dispersion-flattened Fibers

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-zhu; LI Yong-yao; YU Zhi-qiang Yu; FENG Ming-neng

    2009-01-01

    . Supercontinuum generation in dispersion-flattened fibers is studied theoretically. It is found that the flat spectral width of the supercontinuum generation in normal dispersion-flattened fiber can be increased from 66 nm to over 100 nm when the absolute value of the initial frequency chirps is increased from zero to 10. It is further found that initial frequency chirps are adverse to flat and wideband supercontinuum generation in anomalous dispersion-flattened fiber, and when the absolute value of the frequency chirps is increased to a certain degree, supercontinuum spectrum even can not be achieved.

  10. Coupling dynamics for a photonic crystal fib er femtosecond laser nonlinear amplification system%光子晶体光纤飞秒激光非线性放大系统的耦合动力学过程研究∗

    Institute of Scientific and Technical Information of China (English)

    石俊凯; 柴路; 赵晓薇; 李江; 刘博文; 胡明列; 栗岩锋; 王清月

    2015-01-01

    构建了掺镱大模场面积单偏振光子晶体光纤飞秒激光非线性放大系统.讨论了腔内净色散量和抽运功率对振荡级输出参数的影响和振荡级参数对放大级输出参数的影响.在本实验条件下,当腔内净色散量取较大负色散时,振荡级直接输出的脉冲更宽,且携带更少的啁啾.当振荡级抽运4.53 W时,选择最接近变换极限的脉冲作为种子脉冲,放大级在60 W抽运时输出压缩后无基底的短脉冲,宽度为45.7 fs,平均功率28 W.振荡级抽运功率增加到5.08 W,放大级抽运70 W时,获得最高输出功率34.5 W,对应脉宽53.5 fs.%A femtosecond laser single-stage nonlinear amplification system composed of Yb-doped large-mode-area single-polarization photonic crystal fibers is demonstrated. Effects of net cavity dispersion and pump power on oscillator output parameters and the evolution dynamics of the amplified pulse after compression are discussed for different seed pulse parameters. Under the experimental conditions in this paper, the longer and less chirped pulses are obtained with a larger negative net intracavity dispersion in the oscillator. When a nearly-transform-limited pulse is chosen as seed pulse nder the condition of oscillator pump power of 4.53 W, the shortest nearly-pedestal-free amplified pulse is achieved under the amplifier pump power of 60 W after the dispersion is compensated by a grating pair, in which the pulse duration is 45.7 fs with an average power of 28 W at a repetition frequency of 42 MHz. When the oscillator pump power is increased to 5.08 W and most nearly-transform-limited pulses under the pump condition are selected as the seed pulses, the maximum average power of 34.5 W with a duration of 53.5 fs is obtained at an amplifier pump power of 70 W.

  11. Chirped-Frequency Excitation of Gravitationally Bound Ultracold Neutrons

    CERN Document Server

    Manfredi, Giovanni; Friedland, Lazar

    2015-01-01

    Ultracold neutrons confined in the Earth's gravitational field display quantized energy levels that have been observed for over a decade. In recent resonance spectroscopy experiments [T. Jenke et al., Nature Phys. 7, 468 (2011)], the transition between two such gravitational quantum states was driven by the mechanical modulation of one of the plates that confines the neutrons. Here we show that, by applying a sinusoidal modulation with slowly varying frequency (chirp), the neutrons can be brought to any excited state, however large its energy, by climbing the energy levels one by one. This technique should make it possible to observe the quantum-classical transition that occurs at high energies. The proposed experiment is realizable using current technology and could significantly improve the sensitivity of future tests of gravitational physics.

  12. Broadband sum frequency generation via chirped quasi-phase-matching

    CERN Document Server

    Rangelov, A A

    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 the phase match occur for \\omega 3 and then for \\omega 4 SFG processes then the energy is converted adiabatically to the \\omega 4 field. Efficient SFG of the \\omega 4 field is also possible by the opposite direction of the local modulation sweep; then transient SFG of the \\omega 3 field is strongly reduced. Most of these features remain valid in the nonlinear regime of depleted pump.

  13. The receiving of chirp signals with frequency invariant beam response

    Institute of Scientific and Technical Information of China (English)

    GUO Yuan-xi; WANG Ji-sheng; SANG En-fang

    2006-01-01

    A frequency invariant response algorithm is proposed for getting over the signal distortion in high frequency when the beamformer receives the broadband signals. In this method, the weight vector of the reference beam pattern is designed firstly, then the weight vectors when the beam response in the frequency sub-bands approaching the reference response mostly are computed by optimized method or adaptive method. By this method, the beam pattern in each sub-band can be almost kept invariable. As a result, the receiving chirp signal can be improved. Owing to the adoption of the adaptive method to approach the optimized vectors, it has no restricting of the array format and the element directivity, and the method can be used widely.

  14. A Matrix Formulation of Discrete Chirp Fourier Transform Algorithms

    Institute of Scientific and Technical Information of China (English)

    Juan Pablo Soto Quiros; Domingo Rodriguez

    2014-01-01

    This work presents a computational matrix framework in terms of tensor signal algebra for the formulation of discrete chirp Fourier transform algorithms. These algorithms are used in this work to estimate the point target functions (impulse response functions) of multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) systems. This estimation technique is being studied as an alternative to the estimation of point target functions using the discrete cross-ambiguity function for certain types of environmental surveillance applications. The tensor signal algebra is presented as a mathematics environment composed of signal spaces, finite dimensional linear operators, and special matrices where algebraic methods are used to generate these signal transforms as computational estimators. Also, the tensor signal algebra contributes to analysis, design, and implementation of parallel algorithms. An instantiation of the framework was performed by using the MATLAB Parallel Computing Toolbox, where all the algorithms presented in this paper were implemented.

  15. Chirped photonic crystal with different symmetries for asymmetric light propagation

    Science.gov (United States)

    Singh, Brahm Raj; Rawal, Swati; Sinha, R. K.

    2016-06-01

    In the present paper, we have carried out analysis of asymmetric light propagation in a chirped photonic crystal waveguide. The designed structures have hexagonal arrangement and square arrangement of silicon rods in air substrate. Dimensions of the defect rods are tailored, so that the proposed design structure works as an optical isolator. The transmission analysis of the structure reveals that it can act as an optical diode. We have plotted the extinction ratio and transmission analysis graphs for the structure, and it has been observed that the maximum output is obtained for telecom wavelength of 1.55 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using finite element method. The proposed structures are applicable for photonic integrated circuits due to their simple and clear operating principle.

  16. Short optical pulse generation at 40 GHz with a bulk electro-absorption modulator packaged device

    Science.gov (United States)

    Langlois, Patrick; Moore, Ronald; Prosyk, Kelvin; O'Keefe, Sean; Oosterom, Jill A.; Betty, Ian; Foster, Robert; Greenspan, Jonathan; Singh, Priti

    2003-12-01

    Short optical pulse generation at 40GHz and 1540nm wavelength is achieved using fully packaged bulk quaternary electro-absorption modulator modules. Experimental results obtained with broadband and narrowband optimized packaged modules are presented and compared against empirical model predictions. Pulse duty cycle, extinction ratio and chirp are studied as a function of sinusoidal drive voltage and detuning between operating wavelength and modulator absorption band edge. Design rules and performance trade-offs are discussed. Low-chirp pulses with a FWHM of ~12ps and sub-4ps at a rate of 40GHz are demonstrated. Optical time-domain demultiplexing of a 40GHz to a 10GHz pulse train is also demonstrated with better than 20dB extinction ratio.

  17. Reaching white-light radiation source of ultrafast laser pulses with tunable peak power using nonlinear self-phase modulation in neon gas

    Science.gov (United States)

    Tawfik, Walid

    2016-08-01

    A source of white-light radiation that generates few-cycle pulses with controlled peak power values has been developed. These ultrafast pulses have been observed by spectral broadening of 32 fs pulses through nonlinear self-phase modulation in a neon-filled hollow-fiber then compressed with a pair of chirped mirrors for dispersion compensation. The observed pulses reached transform-limited duration of 5.77 fs and their peak power values varied from 57 GW up to 104 GW at repetition rate of 1 kHz. Moreover, the applied method is used for a direct tuning of the peak power of the output pulses through varying the chirping of the input pulses at different neon pressures. The observed results may give an opportunity to control the ultrafast interaction dynamics on the femtosecond time scale and facilitate the regeneration of attosecond pulses.

  18. High-temperature ultrafast polariton parametric amplification in semiconductor microcavities

    Science.gov (United States)

    Saba, M.; Ciuti, C.; Bloch, J.; Thierry-Mieg, V.; André, R.; Dang, Le Si; Kundermann, S.; Mura, A.; Bongiovanni, G.; Staehli, J. L.; Deveaud, B.

    2001-12-01

    Cavity polaritons, the elementary optical excitations of semiconductor microcavities, may be understood as a superposition of excitons and cavity photons. Owing to their composite nature, these bosonic particles have a distinct optical response, at the same time very fast and highly nonlinear. Very efficient light amplification due to polariton-polariton parametric scattering has recently been reported in semiconductor microcavities at liquid-helium temperatures. Here we demonstrate polariton parametric amplification up to 120K in GaAlAs-based microcavities and up to 220K in CdTe-based microcavities. We show that the cut-off temperature for the amplification is ultimately determined by the binding energy of the exciton. A 5-µm-thick planar microcavity can amplify a weak light pulse more than 5,000 times. The effective gain coefficient of an equivalent homogeneous medium would be 107cm-1. The subpicosecond duration and high efficiency of the amplification could be exploited for high-repetition all-optical microscopic switches and amplifiers. 105 polaritons occupy the same quantum state during the amplification, realizing a dynamical condensate of strongly interacting bosons which can be studied at high temperature.

  19. Femtosecond parabolic pulse shaping in normally dispersive optical fibers.

    Science.gov (United States)

    Sukhoivanov, Igor A; Iakushev, Sergii O; Shulika, Oleksiy V; Díez, Antonio; Andrés, Miguel

    2013-07-29

    Formation of parabolic pulses at femtosecond time scale by means of passive nonlinear reshaping in normally dispersive optical fibers is analyzed. Two approaches are examined and compared: the parabolic waveform formation in transient propagation regime and parabolic waveform formation in the steady-state propagation regime. It is found that both approaches could produce parabolic pulses as short as few hundred femtoseconds applying commercially available fibers, specially designed all-normal dispersion photonic crystal fiber and modern femtosecond lasers for pumping. The ranges of parameters providing parabolic pulse formation at the femtosecond time scale are found depending on the initial pulse duration, chirp and energy. Applicability of different fibers for femtosecond pulse shaping is analyzed. Recommendation for shortest parabolic pulse formation is made based on the analysis presented.

  20. Self-Focusing/Defocusing of Chirped Gaussian Laser Beam in Collisional Plasma with Linear Absorption

    Science.gov (United States)

    Wani, Manzoor Ahmad; Kant, Niti

    2016-09-01

    This paper presents an investigation on the self-focusing/defocusing of chirped Gaussian laser beam in collisional plasma with linear absorption. We have derived the differential equation for the beam width parameter by using WKB and paraxial approximations and solved it numerically. The effect of chirp and other laser plasma parameters is seen on the behavior of beam width parameter with dimensionless distance of propagation. The results are discussed and presented graphically. Our simulation results show that the amplitude of oscillations decreases with the distance of propagation. Due to collisional frequency, the laser beam shows fast divergence which can be minimized by the introduction of chirp parameter. The chirp decreases the effect of defocusing and increases the ability of self-focusing of laser beam in collisional plasma. Supported by a financial grant from CSIR, New Delhi, India, under Project No. 03(1277)/13/EMR-II