共查询到20条相似文献,搜索用时 31 毫秒
1.
S. A. Skobelev D. I. Kulagin A. N. Stepanov A. V. Kim A. M. Sergeev N. E. Andreev 《JETP Letters》2009,89(11):540-546
A mechanism of the ionization-induced self-compression of femtosecond laser pulses propagating in a gas-filled hollow dielectric capillary has been investigated both experimentally and theoretically. In particular, the double self-compression of a laser pulse from 76 to 40 fs has been experimentally demonstrated. A theoretical model that explains the mechanism of such a self-compression and provides a good agreement with the experimental data has been developed. The model also predicts that a laser pulse shorter than 10 fs can be generated in the optimal regime with an energy efficiency exceeding the efficiency of self-compression on a filament widely discussed at present. 相似文献
2.
We calculate pulse self-compression of a 30 fs laser pulse traversing gas with different pressure gradients. We show that an appropriate density profile brings significant improvement to the self-compression by filamentation. Under an optimal pressure gradient, the pulse duration is reduced to the single optical cycle limit over a long distance, allowing easy extraction into an interaction chamber. 相似文献
3.
We demonstrate a novel technique for pulse compression of few-millijoule pulses with shorter than 10 fs duration. Our technique relies on spectral broadening in a white-light filament generated in a noble gas. In this filament we observe self-compression of 45 fs pulses down to below 8 fs duration without the need for any additional dispersion compensation. Using input pulses of 5 mJ, we generate compressed pulses with up to 3.8 mJ pulse energy. Therefore this method is much more efficient than previously demonstrated compression schemes. The generated peak powers of more than 100 GW at a kilohertz repetition rate open up a perspective for compression of few-cycle pulses with energies well beyond the capacity of hollow-fiber compressors. 相似文献
4.
Comparison of the filamentation and the hollow-core fiber characteristics for pulse compression into the few-cycle regime 总被引:1,自引:0,他引:1
L. Gallmann T. Pfeifer P.M. Nagel M.J. Abel D.M. Neumark S.R. Leone 《Applied physics. B, Lasers and optics》2007,86(4):561-566
The gas-filled hollow-core fiber compression and the optical filamentation technique are compared experimentally in a parameter
regime suitable for intense few-cycle pulse generation. In particular, pointing stability, spectral properties, and spatial
chirp are investigated. It is found that in the case of filamentation, the critical parameter for pointing stability is gas
pressure inside the generation cell whereas for the hollow-core fiber it is alignment that plays this role. The hollow-core
fiber technique yields spectra that are better suited for chirped-mirror pulse compression whereas filamentation offers higher
throughput and prospects for easy-to-implement self-compression. We present spectral phase interferometry for direct electric-field
reconstruction (SPIDER) measurements that directly show the transition in the spectral phase of the output continua into the
self-compression regime as the gas pressure is increased.
PACS 42.65.Re; 42.65.Jx; 42.65.Tg 相似文献
5.
实验研究了正色散固体介质中的激光脉冲自压缩现象,证明了无需任何外加色散补偿情况下,固体透明介质中的自聚焦传输过程可使高功率飞秒激光脉冲实现时域脉冲压缩,并详细研究了输出脉冲的时域和频域特性随入射脉冲强度的演化规律.实验结果表明脉冲自压缩量随入射脉冲强度的增加呈递增趋势,然而当入射光强增大到足以引起超连续谱及锥形辐射产生时,脉冲时域形状会发生分裂.此外还发现发散光束入射情况下同样可以观察到脉冲自压缩现象.
关键词:
超短激光脉冲
脉冲压缩
非线性传输 相似文献
6.
E. Schulz T. Binhammer D. S. Steingrube S. Rausch M. Kovacev U. Morgner 《Applied physics. B, Lasers and optics》2009,95(2):269-272
Sub-10-fs-pulses are generated by self-compression in a noble gas filament. Using input pulses from a Ti:sapphire amplifier
system with an energy of about 1.5 mJ at a repetition rate of 3 kHz and a pulse duration of 30 fs self-compressed sub-10-fs
pulses with energies of about 0.3 mJ have been generated. These pulses are characterized with spectral phase interferometry
for direct electrical-field reconstruction (SPIDER). Depending on the laser parameters, we observe a significant change in
the chirp of the white-light. The spectral distribution of the outcoming beam profile is measured to distinguish the white-light
core from the surrounding halo. 相似文献
7.
Application of the hollow-fiber pulse compression technique to 100 fs DUV pulses at 248 nm is reported. Sub-20 fs pulses with up to 20 μJ energy were obtained by using krypton in a 65 cm long fiber of 138 μm core radius. The physical process of the spectral broadening is modeled by a nonlinear propagation equation. The experimental data is in good agreement with the results of the model calculations. PACS 42.65.Re; 42.65.Jx; 42.65.-k 相似文献
8.
A. Za¨ır O. Tcherbakoff E. Mével E. Constant R. Lopez-Martens J. Mauritsson P. Johnsson A. L’Huillier 《Applied physics. B, Lasers and optics》2004,78(7-8):869-872
We investigate the temporal confinement of high order harmonic pulses generated by a femtosecond (fs) infrared (IR) pulse with a time varying polarization. We use a set of two birefringent quartz plates to modulate the IR polarization. It produces a short temporal gate of linear polarization where harmonics are efficiently generated during a small fraction of the IR pulse. By rotating one of the plates, the gate width can be continuously varied between 70 fs down to 7 fs. The XUV pulse duration is measured by cross-correlation with a probe IR pulse of 12 fs. When the gate width is decreased, a clear temporal confinement of the XUV emission is observed through the cross correlation signal. This experiment is the first direct experimental evidence in the temporal domain that the polarization gating technique can be used to significantly shorten the harmonic pulse duration. PACS 32.80.Wr; 42.65.Ky; 42.65.Re 相似文献
9.
G. Sansone G. Steinmeyer C. Vozzi S. Stagira M. Nisoli S. De Silvestri K. Starke D. Ristau B. Schenkel J. Biegert A. Gosteva U. Keller 《Applied physics. B, Lasers and optics》2004,78(5):551-555
Ultrabroadband chirped mirrors with a bandwidth of 270 THz have been manufactured using the BASIC design approach. These mirrors were used to compress the supercontinuum of cascaded hollow fibers down to 4.6 fs. The pulse duration was measured with spectral phase interferometry for direct electric-field reconstruction (SPIDER). PACS 42.65.Re; 42.65.Wi; 42.79.Fm 相似文献
10.
Self-transformation of a powerful femtosecond laser pulse into a white-light laser pulse in bulk optical media (or supercontinuum generation) 总被引:2,自引:0,他引:2
V.P. Kandidov O.G. Kosareva I.S. Golubtsov W. Liu A. Becker N. Akozbek C.M. Bowden S.L. Chin 《Applied physics. B, Lasers and optics》2003,77(2-3):149-165
We present experimental and theoretical results on white-light generation in the filamentation of a high-power femtosecond laser pulse in water and atmospheric air. We have shown that the high spatio-temporal localization of the light field in the filament, which enables the supercontinuum generation, is sustained due to the dynamic transformation of the light field on the whole transverse scale of the beam, including its edges. We found that the sources of the supercontinuum blue wing are in the rings, surrounding the filament, as well as at the back of the pulse, where shock-wave formation enhanced by self-steepening takes place. We report on the first observation and demonstration of the interference of the supercontinuum spectral components arising in the course of multiple filamentation in a terawatt laser pulse. We demonstrate that the conversion efficiency of an initially narrow laser pulse spectrum into the supercontinuum depends on the length of the filament with high intensity gradients and can be increased by introducing an initial chirp. PACS 42.65.Jx; 42.65.Re; 42.25.Bs; 42.50.Hz 相似文献
11.
Y. Chen F. Théberge C. Marceau H. Xu N. Aközbek O. Kosareva S.L. Chin 《Applied physics. B, Lasers and optics》2008,91(2):219-222
We observed a new filamentation nonlinear process: continuous self-frequency down shift inside the filament zone during the
propagation of a femtosecond laser pulse in air. The frequency shift depends strongly on the length of the self-guided column
(filament).
PACS 42.65.Dr; 42.65.Jx; 52.35.Mw 相似文献
12.
V. Strelkov A. Zair O. Tcherbakoff R. López-Martens E. Cormier E. Mével E. Constant 《Applied physics. B, Lasers and optics》2004,78(7-8):879-884
We have studied experimentally and theoretically high-order harmonic generation using a laser field with a time-dependent ellipticity. We show that the harmonic emission can be confined into a narrow temporal window, in which the fundamental polarization is quasi-linear. This allows a single attosecond pulse (200 as) with a fundamental field obtained from 10 fs pulse to be generated. PACS 42.65.Ky; 42.65.Re; 32.80.Wr 相似文献
13.
A.J. Verhoef J. Seres K. Schmid Y. Nomura G. Tempea L. Veisz F. Krausz 《Applied physics. B, Lasers and optics》2006,82(4):513-517
High intensity contrast ratio, pre-pulse free pulses with pulse duration of 5 fs and pulse energy of 1 mJ were generated at a repetition rate of 1 kHz by compressing the output pulses of a multi-stage Ti:sapphire laser amplifier system in a Ne-gas-filled hollow fibre. The spatial and temporal properties of the output laser beam were fully characterised. PACS 42.60.Jf; 42.65.Re; 42.81.Qb 相似文献
14.
M. Delaigue I. Manek-Hönninger F. Salin C. Hönninger P. Rigail A. Courjaud E. Mottay 《Applied physics. B, Lasers and optics》2006,84(3):375-378
We report a diode-pumped high-repetition-rate chirped-pulse Yb:KGW regenerative amplifier delivering tens of microjoules pulse energy at repetition rates of up to 300 kHz. High repetition rates are obtained by using an acousto-optic modulator as switching element in the regenerative amplifier cavity. The output pulses were compressed down to 600 fs pulse duration. Even shorter pulses in the 100 fs range are obtained using an amplifier configuration without chirped pulse amplification. PACS 42.55.Xi; 42.60.Da; 42.65 Re 相似文献
15.
F. Théberge J. Filion N. Aközbek Y. Chen A. Becker S.L. Chin 《Applied physics. B, Lasers and optics》2007,87(2):207-210
Self-stabilization of the laser pulse parameters is demonstrated during the two-color filamentation of ultrashort and intense
laser pulses in gases. Experimental data and results of numerical simulations show, in good qualitative agreement, that the
root-mean-square values of the intensity fluctuations decrease below the initial value for the near-infrared pump pulse and
the perturbative limit for the third-harmonic pulse in the filament. It is found that the stabilization of the third-harmonic
intensity and energy are due to intensity clamping of the pump pulse and a constant ‘volume’ of the laser pulse during the
nonlinear propagation inside the filament.
PACS 42.65.Ky; 42.65.Jx; 52.35.Mw 相似文献
16.
通过数值求解一维非线性薛定谔方程,研究了圆偏振入射激光脉冲在初始密度范围为1/4到略低于1倍临界密度的等离子体中的自压缩和分裂现象. 提高等离子体密度和入射激光强度以及减小脉冲宽度可以在更短的传输距离获得有效的激光脉冲压缩,压缩后的脉冲半高宽度可达到初始脉冲半高宽度的1/35,甚至更小. 这种压缩是激光脉冲在等离子体中形成高阶孤子的过程中产生的,可以获得比在稀薄等离子体中更好的压缩比例. 数值计算的结果给出了该情况下激光脉冲在等离子体中自压缩后形成的高阶孤子分裂. 利用一维粒子数值模拟程序(particle-in-cell,PIC)也观察到了脉冲的压缩和分裂现象,得到了与数值计算一致的结果.
关键词:
非线性薛定谔方程
自压缩
脉冲分裂
粒子模拟 相似文献
17.
18.
D. Walter S. Eyring J. Lohbreier R. Spitzenpfeil C. Spielmann 《Applied physics. B, Lasers and optics》2007,88(2):175-178
We demonstrate the spatial homogenization of intense laser pulses by adaptive minimization of spatial chirp of the spectrally
broadened output pulses of a filament. A liquid-crystal-based two-dimensional spatial light modulator is used to control the
spatial phase of the driver pulse. An evolutionary algorithm finds the optimal spatial laser phase distribution that introduces
minimal distortions during filamentation and enhances the beam quality of the output pulse. A homogeneous intensity distribution
favours efficient temporal compression close to the bandwidth limit without the need for spatial filtering after the filament.
PACS 42.65.-k; 42.65.Re; 41.85.Ct 相似文献
19.
J.S. Robinson C.A. Haworth H. Teng R.A. Smith J.P. Marangos J.W.G. Tisch 《Applied physics. B, Lasers and optics》2006,85(4):525-529
We have investigated experimentally the energy transmission and spectral broadening of 30-fs, 700-μJ laser pulses in a neon-filled, 250-μm inner diameter hollow fibre. We implement a differentially pumped fibre, where a vacuum is maintained at the fibre entrance, and compare this to a statically filled fibre. We obtain significantly higher transmission and increased spectral broadening in the differentially pumped case due to a reduction of ionisation defocusing at the fibre entrance. This arrangement provides a method for the generation of near-transform- limited pulses with smoothly varying pulse duration whilst maintaining constant pulse energy, by simple adjustment of the gas pressure. Compression of ∼450-μJ pulses from the differentially pumped fibre to a duration of 6.5 fs has been achieved for pulses with spectra spanning 650–900 nm, by use of negatively dispersive chirped mirrors. PACS 42.65.Re; 42.65.Jx; 42.65.-k 相似文献
20.
Systematic study of highly efficient white light generation in transparent materials using intense femtosecond laser pulses 总被引:1,自引:0,他引:1
We report the results of a systematic study of white light generation in different high band-gap optical media (BaF2, acrylic, water and BK-7 glass) using ultrashort (45 fs) laser pulses. We have investigated the influence of different parameters, such as focal position of the incident laser light within the medium, the polarization state of the incident laser radiation and the pulse duration of the incident laser beam on the white light generation. Our results indicate that for intense, ultrashort pulses, the position of physical focus inside the media is crucial in the generation, with high efficiency, of white light spectra over the wavelength range 400–1100 nm. Linearly polarized incident laser light generates white light with higher intensity in the blue region than circularly polarized light. Ultrashort (45 fs) pulses generate a flatter spectrum with higher white light conversion efficiency than longer (300 fs) pulses of the same laser power. We believe that a flat response over a wide range of wavelengths in the continuum may be efficiently compressed for generation of sub-10 fs pulses. PACS 52.38.Hb; 42.65.Jx; 42.65.Tg; 33.80.Wz; 52.35.Mw 相似文献