共查询到20条相似文献,搜索用时 31 毫秒
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V. S. Belyaev D. V. Kovkov A. P. Matafonov G. F. Karabadzhak G. G. Raikunov A. Ya. Faenov S. A. Pikuz Jr. I. Yu. Skobelev T. A. Pikuz D. A. Fokin V. E. Fortov G. N. Ignat’ev S. V. Kapitanov P. S. Krapiva K. E. Korotkov 《JETP Letters》2013,97(12):681-685
It is proposed to use a high rate of collisional ionization in a superdense laser plasma to generate incoherent femtosecond X-ray pulses. The calculations indicate that the use of picosecond laser pulses with a contrast of about 1010 will allow the generation of an X-ray pulse with a duration of about 10 fs. The adequacy of the proposed model of the excitation of linear X-ray radiation from the plasma has been tested in the experiments with a picosecond laser of a moderately high contrast. 相似文献
3.
本文利用交叉偏振波产生技术(XPW)对800 nm波段钛宝石飞秒激光器输出的激光脉冲进行时域净化, 提高脉冲时域对比度, 并测量验证了1011对比度的脉冲, 达到测量仪器的动态范围极限, 比初始脉冲时域对比度有三个量级的提高, XPW的效率为22%. 同时发现净化后脉冲光谱宽度也得到一定展宽, 进一步利用啁啾镜对和补偿片对净化后的脉冲进行色散补偿, 得到25 fs脉宽的脉冲. 利用该净化后的激光脉冲作为种子注入已有的太瓦级钛宝石啁啾脉冲放大系统中, 在输出脉冲能量250 mJ, 宽度50 fs, 对应峰值功率5 TW的情况下, 在主脉冲前100 ps以外的范围内测量验证了1011的脉冲对比度. 相似文献
4.
We report on the implementation of intensity-dependent filter for picosecond pulse temporal cleaning based on an effect of
pulse polarization rotation during the unbalanced phase matched second harmonic generation. The pulse contrast enhancement
by more than two orders of magnitude and filter transmission of ∼25% has been demonstrated at pulse intensities of <1 GW/cm2. A simple and reliable all-solid-state filter scheme was integrated in a two-stage picosecond Nd:YAG regenerative amplifier
seeded with pJ-energy femtosecond pulses of the Yb:KGW oscillator, and allowed us to reduce the ASE intensity level down to
1.5×10−8 with reference to the intensity of main 100 ps and 100 μJ pulse. 相似文献
5.
Tunable wavelength conversion for picosecond pulses is proposed and demonstrated exploiting cascaded sum- and difference-frequency generation in quasi-phase-matched LiNbO3 waveguides. The influences of initial pulse widths and injected pulse powers on the conversion efficiency and converted pulse width are theoretically analyzed. Arbitrarily tunable wavelength conversion is performed for the signal pulse with the temporal width of 1.57 ps and repetition rate of 40 GHz. Approximately −18.9 dB conversion efficiency and 25 nm variable region of the input signal are achieved under the lower launched signal power. The results imply that simultaneous wavelength conversion and pulse compression can be potentially obtained by using the pulsed control wave or designing longer waveguides. 相似文献
6.
采用常规透镜设计了适用于非真空环境中交叉偏振波(XPW)产生的双透镜聚焦系统,在相对较短的距离实现了长焦透镜聚焦的效果,并测量了聚焦后的激光脉冲,发现其没有显著的非线性相位积累,保证了激光光束质量.在非真空中采用双BaF_2晶体得到了XPW系统转换效率22%,光谱1.78倍展宽的净化脉冲输出,双透镜组合聚焦形式使得双BaF_2晶体间距在13—22 cm内可保证20%以上的XPW转换效率,双晶体间距的调节冗余度提高了两个量级,极大地降低了双晶转换效率对晶体间距的依赖.这种正负透镜组合聚焦的光路设计在非真空中实现了高效稳定的XPW输出,为后续的放大应用提供了高对比度、宽光谱的高质量种子源. 相似文献
7.
H. M. Liang H. B. Wang X. Y. Zhao J. L. Du J. G. Yang Y. Ma J. B. Li S. L. Hu 《Laser Physics》2009,19(3):424-427
In this paper, the Stimulated Raman Scattering (SRS) Stokes wave pumped by a picosecond pulse laser in cyclohexane (C6H12) enhanced by the fluorescence of 4-(Dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) is studied in the experiment. 249 ps pulse laser from Nd:YAG laser second harmonic generation at 532 nm is used as the pumping source. The results indicate that the energy conversion efficiency is raised by the increase of the pumping energy, and the high conversion efficiency depends on the proper selection of the DCM concentration. The high energy conversion efficiency of the first Stokes enhanced by fluorescence of 37.3% is obtained. The fluorescence enhancing mechanism of the picosecond SRS Stokes wave is discussed. 相似文献
8.
W. Leupacher A. Penzkofer B. Runde K. H. Drexhage 《Applied physics. B, Lasers and optics》1987,44(2):133-140
The phase-matched collinear third harmonic generation of picosecond laser pulses in a 0.0825 molar hexafluoroisopropanol solution of a pyrimidonecarbocyanine dye is studied. The fundamental pulses are generated in a passively mode-locked Nd-phosphate glass laser. The saturation of third harmonic generation at high intensities is investigated. The influences of two-photon absorption, excited-state absorption, and amplified spontaneous emission are discussed. For input peak intensities above 1011 W/cm2 a third harmonic energy conversion of about 2×10–4 is achieved. 相似文献
9.
Transient stimulated Raman scattering is used for the generation of a frequency shifted picosecond light pulse; part of this Raman shifted pulse is subsequently coherently scattered at a material excitation of a second Raman cell. Starting with the second harmonic pulse (tp = 4 ps) of a mode-locked Nd : glass laser system, both the stimulated and the coherently produced pulses have durations of 2.3 ps at different wavelengths. By the appropriate choice of the Raman medium pulses between 13 000 and 21 000 cm-1 can be generated. The coherent generation process minimizes the temporal jitter between the two pulses and allows to obtain a high time resolution of better than 0.3 ps in excite and probe experiments. 相似文献
10.
We present a chirped pulse amplification (CPA) Ti:Sa laser generating sub-15 fs pulses with expected high temporal quality. Gain-narrowing in the pre-amplifier is balanced by a variable spectral reflectivity mirror and by a fine adaptation of the saturation conditions. A crossed polarized wave generation (XPW) filter is introduced to enhance the contrast, reduce the pulse duration and improve the spectral quality. The pulses are generated at 10 Hz repetition rate, with pulse energy of 110 μJ and very clean Gaussian spectrum. The temporal contrast is evaluated by a measurement before the XPW filter and calculations of the enhancement by the filter. The potential temporal incoherent contrast is 1012 and the coherent contrast 1010. The performance of the system makes it suitable as an injector for petawatt lasers operating in the double-CPA scheme. 相似文献
11.
We demonstrate the generation of high harmonics (up to the 65th order, λ=12.24 nm) of a Ti:sapphire laser radiation after
the propagation of femtosecond laser pulses through the low-excited plasma produced by a picosecond prepulse radiation on
the surface of different targets. High-order harmonics generated from the surface plasma of most targets showed a plateau
pattern. It is assumed that the harmonic generation in these conditions occurs due to the interaction of the femtosecond pulses
with the ions. The conversion efficiencies at the plateau region were varied between 1×10-7 to 8×10-6, depending on the target. The main contribution to the limitation of harmonic generation efficiency and cutoff energy was
attributed to the self-defocusing of main pulse. A considerable restriction of the 27th harmonic generation was observed at
different focusing conditions in the case of chromium plasma. Our observation of the resonance-induced enhancement of a single
harmonic (λ=61.2 nm) at a plateau region with the efficiency of 8×10-5 in the case of In plasma can offer some expectation that analogous processes can be realized in other plasma samples in the
shorter wavelength range where the highest harmonics were achieved.
PACS 42.65.Ky; 52.35.Mw; 52.38.-r 相似文献
12.
Spectral-Phase-Modulated Cross-Polarized Wave for Chirped Pulse Amplifier with High Contrast Ratio 下载免费PDF全文
《中国物理快报》2017,(2)
We demonstrate a high-quality cross-polarized-wave filter based on spectral phase modulation. Driven by wellcompressed spectral-phase fully-compensated fundamental laser pulses, the filter stretches the pulse bandwidth from 35 nm to 70 nm with a conversion efficiency of 20%. After implementing the filter into a femtosecond TW Ti:sapphire laser system, we generate 40 mJ output pulse energy with pulse duration of 18.9 fs. The temporal contrast of the compressed pulse is enhanced to 10~9. 相似文献
13.
N.E. Karatzas 《Optics Communications》2006,267(2):498-504
Calculations are presented for the first four (odd and even) harmonics of an 800 nm laser from a gold surface, with pulse widths ranging from 100 down to 14 fs. For peak laser intensities above 1 GW/cm2 the harmonics are enhanced because of a partial depletion of the initial electron states. At 1011 W/cm2 of peak laser intensity the calculated conversion efficiency for 2nd-harmonic generation is 3 × 10−9, while for the 5th-harmonic it is 10−10. The generated harmonic pulses are broadened and delayed relative to the laser pulse because of the finite relaxation times of the excited electronic states. The finite electron relaxation times cause also the broadening of the autocorrelations of the laser pulses obtained from surface harmonic generation by two time-delayed identical pulses. Comparison with recent experimental results shows that the response time of an autocorrelator using nonlinear optical processes in a gold surface is shorter than the electron relaxation times. This seems to indicate that for laser pulses shorter than ∼30 fs, the fast nonresonant channel for multiphoton excitation via continuum-continuum transitions in metals becomes important as the resonant channel becomes slow (relative to the laser pulse) and less efficient. 相似文献
14.
H. Ishizuki T. Suhara M. Fujimura H. Nishihara 《Optical and Quantum Electronics》2001,33(7-10):953-961
We report picosecond all-optical switching in optical communication band using a LiNbO3 waveguide quasi-phase matched second-harmonic generation/difference-frequency generation device. Analysis based on the beam propagation method showed that 1 ps switching with 3.1% efficiency is feasible with 10 W peak control pulse power. Switching efficiency of ?22 dB was demonstrated using control pulses of 10 ps width and 2 W peak power. 相似文献
15.
Chih-Hsuan Lin Yi-Jing You Chia-Chun Chung Alexey Zaytsev Feng-Hua Tsai Chi-Luen Wang 《Fiber and Integrated Optics》2014,33(1-2):68-84
AbstractThis article presents an experimental and theoretical study of the generation of picosecond bursts by a non-polarization-maintaining ytterbium-doped fiber master oscillator fiber amplifier system. The peak power and pulse energy of the burst are higher than 45 kW and 350 nJ at 700 kHz, respectively. The master oscillator fiber amplifier was used to generate 3 W of green and 200 mW of UV light with conversion efficiencies of 16% and 8%, respectively. The enhancement of conversion efficiency by the pulse burst compared with regular pulses was analyzed and attributed to dynamically saturated gain of the pump-power-limited fiber amplifier. 相似文献
16.
Hiromitsu Kiriyama Michiaki Mori Yoshiki Nakai Takuya Shimomura Manabu Tanoue Atushi Akutsu Hajime Okada Tomohiro Motomura Shuji Kondo Shuhei Kanazawa Akito Sagisaka Jinglong Ma Izuru Daito Hideyuki Kotaki Hiroyuki Daido Sergei Bulanov Toyoaki Kimura Toshiki Tajima 《Optics Communications》2009,282(4):625-2346
We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 1010 within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 1020 W/cm2. 相似文献
17.
Shifeng Du Dongxiang Zhang Baohua Feng Jing-Yuan Zhang Jing-Cun Zang 《Optics Communications》2009,282(14):2960-12186
We report the generation of high-peak power multi-wavelength picosecond laser pulses using optical parametric amplification (OPA) in BBO seeded with pulses generated in a 5-mm length BaWO4 crystal by stimulated Raman scattering of 18-ps laser pulses at 532 nm. The maximum output energy of the amplified first-Stokes component at 559.7 nm was about 1.76 mJ. The corresponding maximum peak power, pulse duration and spectral line width were measured to be 117.3 MW, 15 ps and 18.0 cm−1, respectively. The multi-wavelength picosecond laser pulses were in the visible and near infrared ranges. Using this Raman-seeded OPA technique, the beam quality of the stimulated Raman scattering pulses can be improved. 相似文献
18.
Optical rectification of ultrashort near-IR laser pulses with tilted pulse fronts and pulse energies of a few J in Mg-doped stoichiometric LiNbO3 cooled to low temperature is a powerful technique for efficient generation of THz pulses. The pulse energy critically depends on the Mg doping (necessary for preventing photorefractive damage) and can be easily increased by a factor of three if the MgO content is reduced. Pulse energies up to 400 pJ at repetition rates of 200 kHz and 3.4% quantum conversion efficiency are achieved at 77 K. At 10 K, changing the tilt angle of the pump pulse front results in continuous tuning of the frequency across the 1.0–4.4 THz range. The temporal pulse shapes measured by electro-optic sampling are in good agreement with the signal calculated by a simple theory. This model predicts tunability on a considerably broader range and narrower spectra even at room temperature if GaSe is used instead of LiNbO3. The advantages of the velocity matching technique utilizing tilted pulse fronts are analyzed in comparison with quasi-phase-matching in periodically poled LiNbO3 crystals. The first method provides a ten times higher pulse energy conversion efficiency. PACS 42.65.Ky; 42.70.Mp; 42.72.Ai 相似文献
19.
V. S. Belyaev V. I. Vinogradov A. P. Matafonov A. M. Chekmarev A. G. Karabadzhak 《Laser Physics》2006,16(3):477-487
The interaction of high-power picosecond laser radiation with solid targets is experimentally studied for the first time at various spectral distributions of a chirped laser pulse. The interaction of the high-power laser radiation with the target is studied at four regimes of the experimental setup: (i) at a relatively high contrast (103) in the picosecond (Δt ~ 25 ps) range, (ii) at a relatively low contrast (3 × 101) in the picosecond (Δt ~ 25 ps) range, (iii) with spectral distortions of the chirped pulse, and (iv) with a strongly modulated spectrum of the chirped pulse. The results obtained reveal a strong dependence of the atomic and nuclear processes in the laser picosecond plasma on the spectral distribution of the chirped laser pulse. The prospects for the application of the spectral interferometry of chirped pulses for the online control of the parameters of the high-power laser radiation are demonstrated. 相似文献
20.
K. Osvay I.N. Ross J.M.D. Lister C.J. Hooker 《Applied physics. B, Lasers and optics》1999,69(1):19-23
This paper presents an experimental technique for measurement of the contrast ratio of ultrashort UV pulses. As a multiple-shot
device based on the scheme of difference frequency generation this is, to our knowledge, the only cross correlator in the
UV so far, which offers a dynamic range of 107 and operates with input pulse energies as low as 5 μJ. By changing the cross correlator into single-shot mode, the temporal
shape of the UV pulse can be measured.
Received: 26 October 1998 / Revised version: 13 January 1998 / Published online: 28 April 1999 相似文献