共查询到20条相似文献,搜索用时 656 毫秒
1.
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
2.
Focusing 800-nm pulses of 10–20 fs and ≤0.4 mJ into atmospheric-pressure argon gives rise to a supercontinuum extending down to 250 nm. We show that spectral cuts from this radiation can be shortened by a simple prism compressor down to 30 fs even near the UV cut-off. The resulting pulses have enough energy (several hundred nanojoules) to serve as a simple and rugged broadly tunable pump source in ultra-fast transient spectroscopy. Such an application is demonstrated for the first time, using pulses tuned over 280–320 nm to excite Cr(CO)6; probing it by intense-field ionization at 800 nm, we determine the lifetime of initially populated states to be as short as 14 fs.PACS 42.65.Jx; 42.65.Ky; 42.65.Re; 42.72.Bj; 82.20.-w; 82.53.-k 相似文献
3.
T. Imahoko K. Takasago T. Sumiyoshi H. Sekita K. Takahashi M. Obara 《Applied physics. B, Lasers and optics》2007,87(4):629-634
We have developed a 6–12 μm mid-infrared (MIR) femtosecond laser source for glyco-protein structure analysis. The MIR femtosecond
laser pulses are generated by a differential frequency generation (DFG) configuration with a combination of Ti:sapphire based
regeneratively amplified femtosecond laser pulses (780 nm, 160 fs, 1 mJ) and a β-BaB2O4 (BBO) based optical parametric amplifier (OPA). The MIR pulse energy exceeds 4.5 μJ, where a glyco-protein molecule has resonant
absorption lines due to the vibrational–rotational transitions. The pulse width is estimated to be less than 1 ps according
to the cross correlation measurement between the two OPA output pulses. Using the MIR femtosecond laser pulses, we demonstrated
photo-dissociation of the sialyl Lewis X (sLeX) proton added ion, which is the first time to the best of our knowledge.
PACS 42.65.Re; 42.62.-b; 42.60.-b; 42.65.-k; 87.50 相似文献
4.
A 50 cm silver coated hollow fiber with inner diameter of 250 μm and filled with argon has been used to compress optical pulses
from a Ti:sapphire laser at 800 nm. Input pulses with energy of 250 μJ and duration of 110 fs were used and compressed pulses
with energy of 220 μJ and duration of 20 fs were generated by using a prism compressor. Numerical and experimental results
are compared. There is good agreement between the measured beam diameters of the hollow-fiber output pulse and the calculated
values obtained from propagation of the HE11 mode into free space. For comparison, a similar uncoated fused-silica hollow fiber was also used to obtain 20 fs compressed
pulses with an energy of 190 μJ.
Received: 7 September 2002 / Published online: 26 March 2003
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ID="*"Corresponding author. Fax: +1-780/492-1811, E-mail: mohebbi@ee.ualberta.ca 相似文献
5.
E. Riedle M. Beutter S. Lochbrunner J. Piel S. Schenkl S. Spörlein W. Zinth 《Applied physics. B, Lasers and optics》2000,71(3):457-465
Noncollinearly phase-matched optical parametric amplifiers (NOPAs) pumped by the blue light of a frequency-doubled Ti:sapphire
regenerative amplifier are a convenient source of continuously tunable ultrashort pulses in the visible and near infrared
for spectroscopic experiments. We present the underlying principles, report recent improvements and describe the experiences
gained from the routine use of a number of NOPAs in our laboratories. We find that the setup can easily be optimized for the
given experimental requirements. Typical output-pulse energies in the visible are 5 to 10 μJ and a few μJ in the NIR from
200 μJ regenerative-amplifier pulses at 800 nm. From 460 to 700 nm, pulse lengths between 10 and 20 fs are routinely achieved,
while the length increases monotonically from about 20 fs at 900 nm to just below 50 fs at 1600 nm. In all cases this corresponds
to a dramatic shortening compared to the length of the pump pulses of around 100 fs. First results show that the 700 to 900 nm
region can be accessed with sub-50-fs pulse lengths by use of an intermediate white-light generator in a two-stage setup.
Received: 29 November 1999 / Published online: 5 July 2000 相似文献
6.
7.
Wang X. Li P. Yang H. Jiang T. Ma Y. Fan Z. Niu G. Yu J. Wang A. Zhang Z. 《Laser Physics》2011,21(11):1941-1944
An all-fiber high-energy nonlinear chirped-pulse amplification system with two-stage double-cladding fiber amplifiers is presented
in this paper. It generates pulses with the energy up to 10 μJ at 20 kHz repetition rate and total accumulated nonlinear phase
shift as large as 12.8π. The pulses can be compressed to 137 fs with the compensation of mismatched third-order dispersion
by self-phase modulation in the fiber amplifiers. 相似文献
8.
The hard X-ray yield generated with femtosecond laser pulses is studied for differently chirped irradiating laser pulses.
The radiation of a Ti:sapphire CPA laser system (29 fs, 750 μJ, 1 kHz) is focused onto an iron containing solid state target
producing incoherent hard X-ray radiation, Bremsstrahlung as well as target-specific Kα and Kβ lines. The hard X-ray yield has been optimized by introducing negative and positive group delay dispersion (GDD) and third
order dispersion (TOD) to the femtosecond laser pulse. The Kα yield could be enhanced by a factor of 1.7 and reached 1.9×108 Fe Kα photons/s in 4π with the laser pulse positively chirped, and 1.5×108 Fe Kα photons/s with the pulse negatively chirped. When the pulse energy is lowered to about 400 μJ the yield maximum at negative
chirp vanishes and only the maximum at positive chirp remains. We explain this behavior with an increased electron temperature
caused by the induced GDD and TOD in the pulse.
PACS 42.65.Re; 52.38.Ph; 52.50.Jm 相似文献
9.
D. Krennrich R. Knappe B. Henrich R. Wallenstein J.A. L’huillier 《Applied physics. B, Lasers and optics》2008,92(2):175-183
This paper reports on the generation of picosecond (ps) laser pulses by self-phase-adjusting additive-pulse-mode-locking (PSA)
at wavelengths of 0.9 and 1.3 μm. The main objective of this work was to investigate and compare the characteristic optical
properties of ps lasers based on different Nd-doped laser crystals like Nd:YAG, Nd:YAlO3, Nd:YVO4 and Nd:GdVO4. As a result of these investigations a mode-locked Nd:YVO4 laser for example, generated, ps pulses at 1.3 μm with a duration of 7 ps, a repetition rate of 160 MHz and an average power
of 4.7 W. At 0.9 μm pulses with a duration of 1.9 ps were obtained at a repetition rate of 158 MHz and an average power of
2.8 W.
PACS 42.70.Hj; 42.65.Re; 42.65.Ky 相似文献
10.
A.B. Sugiharto C.M. Johnson H.B. de Aguiar L. Alloatti S. Roke 《Applied physics. B, Lasers and optics》2008,91(2):315-318
We present a novel high power femtosecond infrared laser source, based on a three-stage chirped-pulse amplification scheme.
Owing to the high power output of the Ti:sapphire amplifiers, it becomes routinely possible to produce femtosecond infrared
laser pulses in the wavelength region of 2.6–20 μm with minimum pulse energies of 15 μJ, to our knowledge roughly an improvement
of an order of magnitude. With such pulses we have performed femtosecond second-order nonlinear optical surface spectroscopy
in the fingerprint region. We have probed the skeletal modes of the first few monolayers of a polymer/air interface in a femtosecond
vibrational sum frequency generation experiment. This development opens up new possibilities to investigate surface structures
and dynamics of, e.g., organo-metallic compounds, proteins, and peptides.
PACS 42.65.-k; 68.35.-Ja; 82.35.Ps 相似文献
11.
T. Eidam F. Röser O. Schmidt J. Limpert A. Tünnermann 《Applied physics. B, Lasers and optics》2008,92(1):9-12
We report on the generation of 27 fs pulses with an average output power of 57 W and a repetition rate of 78 MHz. The pulses
are generated by combining a high average power fiber chirped pulse amplification (FCPA) system with a microstructured large-mode-area
fiber for nonlinear compression. The FCPA system delivers 270 fs pulses in a linearly polarized beam with diffraction-limited
quality. Nonlinear compression is achieved by launching the pulses into a short (few cm) piece of microstructured fiber and
subsequent compression by a pair of chirped mirrors.
PACS 42.55.Wd; 42.55.Xi, 42.65.Re 相似文献
12.
Ultraviolet pulses with a duration of 7 fs are efficiently generated by frequency doubling the output of a noncollinear optical parametric amplifier. The ultraviolet pulses are tunable between 275 to 335 nm. The acceptance bandwidth of the doubling crystal is increased by a factor of 80 through high-order achromatic phase matching. The chirp of the visible pulses and the dispersion introduced along the beam path are compensated partially before and partially after the doubling crystal. For the design of the dispersion management, we investigate the second harmonic generation of pulses with mixed orders of chirp and explicitly discuss the transfer of the spectral phase in frequency doubling. A simple analytic theory is derived that correctly describes frequently observed spectral narrowing effects. We find that chirped SHG avoids spectral narrowing and allows for precompression of dispersion encountered in the ultraviolet beam path. We apply chirped SHG to generate 18.7 fs ultraviolet pulses in an extremely simple setup. PACS 42.65.Re; 42.65.Ky; 42.65.Yj 相似文献
13.
O. Paul A. Quosig T. Bauer M. Nittmann J. Bartschke G. Anstett J.A. L’huillier 《Applied physics. B, Lasers and optics》2007,88(1):111-115
We present a temperature-dependent Sellmeier equation for the extraordinary refractive index of 5 mol % MgO doped congruent lithium niobate. This equation is adapted for wavelengths in the range of 1.3–5 μm and temperatures between 40 °C and 200 °C. The calculation of the appropriate Sellmeier coefficients is based on the wavelengths of the signal and idler radiation measured for quasi-phase-matched optical parametric generators excited by 10-ns-long, 1064-nm pulses of a Q-switched Nd:YVO4 laser. PACS 42.65.Ky; 42.70.Mp; 42.65.Yj 相似文献
14.
V.L. Kalashnikov E. Podivilov A. Chernykh A. Apolonski 《Applied physics. B, Lasers and optics》2006,83(4):503-510
Theory of chirped-pulse oscillators operating in the positive dispersion regime is presented. It is found that the chirped pulses can be described analytically as solitary pulse solutions of the nonlinear cubic-quintic complex Ginzburg–Landau equation. Due to the closed form of the solution, basic characteristics of the regime under consideration are easily traceable. Numerical simulations validate the analytical technique and the chirped-pulse stability. Experiments with 10 MHz Ti:Sa oscillator providing up to 150 nJ chirped pulses, which are compressible down to 30 fs, are in agreement with the theory. PACS 42.65.Re; 42.65.Tg; 42.55.Rz 相似文献
15.
A scheme for the construction of fiber laser systems for the generation of tunable ultrashort optical pulses is proposed.
The scheme is based on the self-Raman shift of the soliton frequency in dispersion-decreasing fibers with the subsequent spectral
broadening owing to the supercontinuum generation in a short highly nonlinear fiber and the compression in the corresponding
fiber compressor. An all-fiber laser system for the generation of ultrashort laser pulses in the wavelength range 1.6–2.0
μm is experimentally demonstrated. In particular, the shortest pulses with a duration of 24 fs are generated at wavelengths
of 1.8–1.9 μm, which corresponds to less than four optical cycles. 相似文献
16.
V. A. Donchenko A. I. Yakimov A. A. Zemlyanov V. V. Kirienko 《Russian Physics Journal》2010,53(5):504-507
Results of investigations into the time characteristics of photosensitive layers based on Ge/Si nanoheterostructures excited
by femtosecond laser pulses with a wavelength of 1.55 μm are given. It is demonstrated that the leading front duration of
the photoresponse pulse for the examined specimens excited by laser pulses of 120 fs duration does not exceed 30–40 пs. 相似文献
17.
S. Banerjee K. Miyata K. Kato N. Saito S. Wada 《Applied physics. B, Lasers and optics》2007,87(1):101-103
AgGa1-xInxS2 with x=0.14±0.01 was found to be 90° phase-matchable for type-I difference-frequency generation (DFG) by mixing the dual-wavelength
pulses emitted from an electronically tuned Ti:sapphire laser. Infrared radiation continuously tunable over the range of 4.80–6.98 μm
was generated by independently varying the two wavelengths in the 705–932 nm spectral range, and 4.04 μm radiation by mixing
a Nd:YAG laser with the Ti:sapphire laser. In addition, this material was found to be noncritically phase-matchable for the
second harmonic generation (SHG) of CO2 laser radiation at 10.591 μm at 203 °C. Sellmeier equations that reproduce well these experimental data are presented.
PACS 42.65.-k; 42.65.ky 相似文献
18.
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
19.
V. Shcheslavskiy V. Petrov F. Noack N. Zhavoronkov 《Applied physics. B, Lasers and optics》1999,69(2):167-169
Frequency doubling the output of a high-power femtosecond Cr:forsterite regenerative amplifier with >50% conversion efficiency
in a temperature-tuned noncritically phase-matched LBO crystal produces femtosecond pulses of >100 μJ energy in the visible
range near 625 nm at a pulse duration of about 200 fs or >65 μJ at <170 fs.
Received: 29 March 1999 / Revised version: 27 April 1999 / Published online: 24 June 1999 相似文献
20.
M. Tiihonen V. Pasiskevicius A. Fragemann C. Canalias F. Laurell 《Applied physics. B, Lasers and optics》2006,85(1):73-77
An optical parametric gain bandwidth of 115 THz at full-width half maximum is generated from a picosecond Ti:sapphire pumped degenerate optical parametric generator. This ultrabroad bandwidth could be obtained by first identifying the wavelength where the nonlinear optical material has zero group-velocity dispersion (GVD). By pumping at half this wavelength the degenerate signal–idler pairs can accommodate ultrabroad bandwidths. The explanation for this is that the group velocities of the signal and the idlers are approximately matched and the GVD is small. However, in order to thoroughly investigate the degeneracy region around 1700 nm we fabricated several periodically poled KTiOPO4 (PPKTP) crystals with different periods, and also one periodically poled RbTiOPO4 (PPRTP). Both collinear and noncollinear configurations were employed for broadband parametric generation in this region. It was found that the optimum pump wavelength is in the region between 800 nm to 850 nm for PPKTP, and we could also conclude that a similar performance was found for PPRTP. This work will allow the design of optical parametric devices for generating few-cycle pulses in the spectral region between 1.1 μm and 3.8 μm. PACS 42.65.Re; 42.65.Ky; 42.65.-k 相似文献