排序方式: 共有34条查询结果,搜索用时 15 毫秒
1.
Q. Luo H.L. Xu S.A. Hosseini J.-F. Daigle F. Théberge M. Sharifi S.L. Chin 《Applied physics. B, Lasers and optics》2006,82(1):105-109
The fluorescence spectrum of ethanol molecules induced by femtosecond laser pulses has been recorded as the fingerprint of
the molecules. It was demonstrated that, if this is combined with a LIDAR technique, the fluorescence from pollutants in the
atmosphere could be detected over a long distance.
PACS 42.68.Wt; 42.62.Fi; 42.65.Re 相似文献
2.
Ultraviolet and infrared conical emissions were observed during the filamentation in air of powerful femtosecond laser pulses produced by a portable terawatt laser system. The broadband spectrum was measured from 200 nm up to 14 microm and covered the complete optical transmission window of the atmosphere. The angularly resolved spectrum showed some X-wave structure across the frequency range analyzed. However, we demonstrated that the strong conical emission observed in the mid- and far-infrared is mainly owing to the four-wave mixing between the pump pulse and its blueshifted conical emission. 相似文献
3.
S. L. Chin H. L. Xu Q. Luo F. Théberge W. Liu J. F. Daigle Y. Kamali P. T. Simard J. Bernhardt S. A. Hosseini M. Sharifi G. Méjean A. Azarm C. Marceau O. Kosareva V. P. Kandidov N. Ak?zbek A. Becker G. Roy P. Mathieu J. R. Simard M. Chateauneuf J. Dubois 《Applied physics. B, Lasers and optics》2009,95(1):1-12
All matters in the path of filaments induced by an intense femtosecond laser pulse propagating in air could be fragmented
and result in the emission of characteristic fluorescence spectra from the excited fragments. The fluorescence spectra exhibit
specific signatures (fingerprints) that can be used for the identification of various substances including chemical and biological
species. In this paper, we present an overview of the recent progress in our laboratory concerning the “remote” sensing of
chemical and biological agents/pollutants in air using filamentation-induced nonlinear fluorescence techniques. 相似文献
4.
The synthesis of a new molecule specifically designed to exhibit both ferroelectric and nonlinear optical properties is presented. This molecule possesses an optically active phenyl sulphinic group, which introduces a dipole moment directly linked to the chromophore group, with a nitro group in the meta -position. The rest of the molecule comprises a tolane and a benzoate group. Such a structure results in an enantiotropic smectic C*-smectic A phase sequence in its polymorphism. A first measurement of the spontaneous polarization shows a high value. The polymorphism of the racemic homologous molecule possessing the nitro group in the ortho-position is also presented, and also shows the smectic C-smectic A phase sequence. 相似文献
5.
By using intensity clamping as a guideline for the definition of a filament, we propose that a filament is the propagation core where plasma is generated. 相似文献
6.
Filamentation nonlinear optics 总被引:1,自引:0,他引:1
A filamenting femtosecond laser pulse self-stabilizes the intensity fluctuation inside the filament core due to intensity
clamping and generates an excellent spatial beam quality inside the core due to self-spatial filtering. The high quality of
the core can be sampled by nonlinear processes. A few experimental examples are shown: self-phase modulation, four-wave mixing,
third-harmonic generation and waveguide writing in glass.
PACS 42.65.Jx; 52.35.Mw 相似文献
7.
V.?KoubassovEmail author J.F.?Laprise F.?Théberge E.?F?rster R.?Sauerbrey B.?Müller U.?Glatzel S.L.?Chin 《Applied Physics A: Materials Science & Processing》2004,79(3):499-505
The interaction of intense femtosecond laser pulses with wide band-gap fused silica and quartz is investigated. It is shown that during target irradiation, melting of SiO2 occurs. Laser pulses with fluences above the damage threshold induce partial phase transition of fused silicia into quartz and vice-versa. PACS 42.62.-b; 61.46.+w; 81.30.Hd 相似文献
8.
W. Liu J.-F. Gravel F. Théberge A. Becker S. L. Chin 《Applied physics. B, Lasers and optics》2005,80(7):857-860
We report an experiment to demonstrate the crucial effect of the so-called background reservoir during the propagation of femtosecond laser pulses in air. The background reservoir was blocked by allowing only the filament to pass through a pinhole generated by the filament itself in an aluminum foil. We observed that the filamentation process is terminated immediately after the pinhole. Consequently, to achieve long-range filamentation, it is necessary to maintain the dynamic energy exchange between the reservoir and the self-foci. 相似文献
9.
Pion-nucleus scattering in the (3,3) resonance region is described using a version of the Brown-Rho bag model. Terms involving iterations of the crossed Born graphs, as well as excitation of the three-quark delta, both give significant contributions to the scattering amplitude. 相似文献
10.