共查询到20条相似文献,搜索用时 15 毫秒
1.
Maciej Lewenstein 《Zeitschrift für Physik B Condensed Matter》1984,56(1):69-75
We investigate the distribution of Stokes pulse energies in the transient nonlinear regime of stimulated Raman scattering. Nonlinear effects lead to a stabilization of Stokes pulse energies. The character of the transition from the chaotic linear regime to the nonlinear regime is studied in detail. The results compare nicely with recent experiments of Walmsey and Raymer. 相似文献
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We present the results of experimental and theoretical studies of fs-pulse Raman-frequency conversion in gases in the regime of medium pumping with pulses shorter than the molecular vibrational period Tv. The spectral transformation of both intense excitation pulses and variably delayed injection pulses is analyzed as a function of laser parameters and gas pressure. For intense 40 fs pump pulses propagating in a SF6-filled hollow waveguide, we observed a continuous (pressure-dependent) redshift of the carrier frequency, amounting to several thousand cmу. By transmitting a weak injection pulse with a narrow spectrum through impulsively excited SF6, we observed multiple Stokes and anti-Stokes lines of the injection radiation corresponding to scattering on the symmetric vibrational mode of SF6. Since the pumping and scattering processes are decoupled in this delayed-pulse scheme, the effect of Kerr self-action on the injection field scattering was completely eliminated. Our physical model of the fs-pulse stimulated Raman scattering is in good quantitative agreement with the observed effects. 相似文献
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Chapman T Hüller S Masson-Laborde PE Heron A Pesme D Rozmus W 《Physical review letters》2012,108(14):145003
The autoresonant behavior of Langmuir waves excited by stimulated Raman scattering (SRS) is clearly identified in particle-in-cell (PIC) simulations in an inhomogeneous plasma. As previously shown via a 3-wave coupling model [T. Chapman et al., Phys. Plasmas 17, 122317 (2010)], weakly kinetic effects such as trapping can be described via an amplitude-dependent frequency shift that compensates the dephasing of the resonance of SRS due to the inhomogeneity. The autoresonance (AR) leads to phase locking and to growth of the Langmuir wave beyond the spatial amplification expected from Rosenbluth's model in an inhomogeneous profile [M. N. Rosenbluth, Phys. Rev. Lett. 29, 565 (1972)]. Results from PIC simulations and from a 3-wave coupling code show very good agreement, leading to the conclusion that AR arises even beyond the so-called weakly kinetic regime. 相似文献
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The switching dynamics of short pulses propagating in a two-core optical fiber under the effects of intrapulse stimulated
Raman scattering (ISRS) and intermodal dispersion is investigated theoretically. We find that, when the input pulses are short
and intense enough, ISRS in general reduces the width of the pulses propagating in the launching core of the fiber and, at
the same time, slows down the pulses. However, if the two-core fiber contains sufficient intermodal dispersion, the pulse-narrowing
effect of ISRS can be weakened. Using typical fiber parameters, we demonstrate with numerical examples how the interaction
of ISRS and intermodal dispersion affects the pulse shape.
PACS 40.42.65.-k; 40.42.65.Dr; 40.42.65.Tg; 42.81.-i; 42.81.Dp 相似文献
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N. I. Shamrov 《Optics and Spectroscopy》2002,93(1):95-101
An analytical solution is obtained for equations of transient stimulated Raman scattering for short samples and a weak seed Stokes wave in the approximation of a given pump field, and a numerical solution for more extended media or more intense input Stokes pulses with allowance for pump depletion. The dependence of the anti-Stokes wave energy on its spatial mismatch with the Stokes and laser waves is studied. The optimum angle of the anti-Stokes generation is found as a function of the length of the system, transverse relaxation rate, laser pulse energy, and intensity ratio of the Stokes and pump pulses at the entrance of the sample. 相似文献
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We demonstrate a technique for multiplicatively increasing the pulse spacing of subfemtosecond pulse trains generated by high-order stimulated Raman scattering, which uses pairs of off-resonant two-photon excitation of a molecular Raman mode to establish strong molecular modulation in the medium. Every laser pair has two single-mode laser beams tuned slightly off two-photon resonance, and the laser pairs have their corresponding carrier frequencies shifted from each other by one half, one third, or one fourth of the selected molecular Raman mode frequency. Theoretical analyses and calculations based on the fundamental vibrational transition of solid hydrogen show that the pulse spacing of the subfemtosecond pulse trains thus generated can readily be doubled, tripled, or even quadrupled. 相似文献
10.
G.L. Brekhovskikh V.V. Zverev N.Y. Okladnikov A.I. Sokolovskaia 《Optics Communications》1985,53(1):59-63
The energy dependence and the total saturation of the SRS and SBS are investigated in the nanosecond range at different geometries of the illuminated volume. The theoretical explanation of the experimental results for SRS is given, the change of the vibrational level population being taken into account. The solution of the quasi-stationary equations for SRS if shown to have the form of a solitary wave. The results of the work permit to govern the amplitude-phase distribution of the complex light fields at the stimulated scatterings. 相似文献
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We report the generation of high-power picosecond infrared pulses by stimulated electronic Raman scattering in an atomic vapour. Single 30 ps pulses at 532 nm were Raman-shifted in caesium vapour to produce 0.4 mJ pulses at 2.38 μm, with 20% quantum efficiency. This technique can be extended to cover a wide range of infrared wavelenghts by using various Raman transitions. 相似文献
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Yulin Li Jianhua Lu Jialin Jiang Guanchang Cheng 《Applied physics. B, Lasers and optics》1986,39(2):107-110
The time-domain pulse property of quasi-steady stimulated Raman scattering (SRS) in a multimode optical fiber, pumped by an A-O Q-switched Nd: YAG laser, is studied both experimentally and theoretically. Good agreement has been achieved between theory and experiment. Discussion shows that the variation of the Stokes pulse width (FWHM)t
s depends on the shape of input pump pulse. 相似文献
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The switching dynamics of ultrashort pulse under the effects of intrapulse stimulated Raman scattering (ISRS) and intermodal
dispersion in a nonlinear two-core photonic crystal fiber coupler is investigated theoretically. A general model is proposed
that includes all the significant linear and nonlinear effects. In particular, we demonstrate with numerical examples how
the interaction of ISRS and intermodal dispersion affects the pulse shape. 相似文献
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M. Olivík 《Czechoslovak Journal of Physics》1992,42(1):93-102
Coherent state technique and maximal Lyapunov exponent method are used for the study of deterministic chaos in a system governing stimulated Raman scattering. The influence of the external pumping on dynamics of the system is investigated. Phase portraits and FFT spectra are presented.The author would like to express his sincere thanks to prof. J. Peina for his comments and stimulating discussions. 相似文献
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Interaction of coherent light pulses with a three-level medium of the “lambda” configuration is studied analytically and numerically. It is shown that in the course of Raman scattering the Stokes wave can be captured in the region of inversion. Conditions are found for complete energy transfer from the pump 2π-pulse to the Stokes wave. 相似文献
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Dependence of parabolic pulse amplification on stimulated Raman scattering and gain bandwidth 总被引:4,自引:0,他引:4
An analytical model has been developed and verified by numerical simulations to determine limits induced by stimulated Raman scattering (SRS) on parabolic pulse evolution in high-power, high-energy Yb-fiber amplifiers. Our results show that the maximum achievable parabolic pulse energies are limited by SRS at low amplifier gains and by the finite gain bandwidth at high gains. Therefore, an optimum gain value exists that maximizes the achievable output pulse energy. 相似文献
20.
Max Maier 《Applied Physics A: Materials Science & Processing》1976,11(3):209-231
The applications of stimulated Raman scattering reviewed in this paper include: determination of spontaneous Raman parameters
and nonlinear susceptibilities by gain measurements and coherent anti-Stokes Raman spectroscopy, excitation of molecular vibrations
and lattice waves and measurement of their relaxation times, generation of intense tunable light in the infrared region of
the spectrum. The main results of the theory of stimulated Raman scattering relevant to the understanding of these applications
are discussed. 相似文献