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Pulse duration
About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.
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TL;DR: Numerical simulation of the laser excitation dynamics of OH in an atmospheric pressure H(2)/O(2/N(2) flame indicates that the balanced cross-rate model will give accurate results provided that the rotational relaxation rates in the upper and lower sets of rotational levels are approximately equal.
Abstract: The balanced cross-rate model is proposed to analyze laser-induced molecular fluorescence signals when the laser pulse length is of the order of nanoseconds. Nanosecond pulse length lasers, specifically Q-switched Nd:YAG-pumped dye lasers, are attractive for saturated molecular fluorescence spectroscopy because of their high peak power and because their short pulse length minimizes the risk of laser-induced chemistry. In the balanced cross-rate model, single upper and lower rotational levels are assumed to be directly coupled by the laser radiation. Because the laser-induced processes which couple these levels are so fast at saturation intensities, a steady state is established between the two levels within picoseconds. Provided that the total population of the two laser-coupled rotational levels is constant during the laser pulse, the total molecular population can be calculated from the observed upper rotational level population using a two-level saturation model and Boltzmann statistics. Numerical simulation of the laser excitation dynamics of OH in an atmospheric pressure H2/O2/N2 flame indicates that the balanced cross-rate model will give accurate results provided that the rotational relaxation rates in the upper and lower sets of rotational levels are approximately equal.
81 citations
TL;DR: It is shown that stable passive Q-switching with Cr(2+):ZnS saturable absorbers resulted in minimum pulse duration and maximum pulse energy and peak power of 1.26 mJ and 166 kW, respectively.
Abstract: We demonstrate efficient continuous-wave (CW) and passively Q-switched Tm:LiLuF4 laser operation near 1.9 μm. The CW slope efficiency reached 54.8% with respect to absorbed power. Stable passive Q-switching with Cr2+:ZnS saturable absorbers resulted in minimum pulse duration of 7.6 ns and maximum pulse energy and peak power of 1.26 mJ and 166 kW, respectively.
81 citations
TL;DR: In this paper, the acceleration of light and heavy ions in an expanding plasma slab with hot electrons produced by an intense and short laser pulse is studied by using the hybrid Boltzmann-Vlasov-Poisson model.
Abstract: The acceleration of light and heavy ions in an expanding plasma slab with hot electrons produced by an intense and short laser pulse is studied by using the hybrid Boltzmann–Vlasov–Poisson model. Spatial profiles, energy distributions, and maximum energies of accelerated ions are analyzed in function of the plasma and hot electron parameters. The crucial parameter for ion acceleration is found to be the ratio of the foil thickness to the hot electron Debye length. Special attention is paid to characterization of protons accelerated from a thin hydrogenated layer at the target surface. The evolution of the proton spectrum is studied for the cases of isothermal and cooling hot electron distributions. The obtained dependencies of the ion energy on the pulse duration and the target characteristics allow one to define the optimal conditions for the ion acceleration with lasers.
81 citations
TL;DR: The results are discussed with regard to the general problem of femtosecond pulse distortion in an optical system and a simple procedure for optimal pulse restoration is described.
Abstract: The construction of a two-photon/confocal microscope system is described in detail. For two-photon illumination, a Ti:sapphire modelocked laser generating 62-fs pulses at 715 nm was used. The effect of the optical train on illumination pulse width was examined and the observed increase in pulse duration was almost completely removed by the addition/adjustment of a prism compressor system. The imaging capabilities of the two-photon microscope are demonstrated and it is shown that the imaging performance of the two-photon microscope is similar to that of a conventional confocal microscope. With two-photon illumination, the resolution (full width at half-maximum intensity) was 0.42 microM (x-y) and 0.81 microM axially, while with single-photon illumination (at 488 nm in the same instrument with a confocal pinhole detector) the resolution was 0.3 microM (x-y) and 0.75 microM axially. The results are discussed with regard to the general problem of femtosecond pulse distortion in an optical system and a simple procedure for optimal pulse restoration is described.
81 citations
TL;DR: In this article, a 8.2 W UV laser with the compact extra-cavity sum-frequency mixing was reported with a high power and high beam quality Q-switched Nd:YVO4 oscillator.
Abstract: A 8.2 W UV laser was reported with the compact extra-cavity sum-frequency mixing. The IR fundamental frequency source was a high power and high beam quality Q-switched Nd:YVO4 oscillator. 38 W fundamental frequency laser at 1064 nm was obtained at the pulse repetition rate of 450 kHz with the beam quality factors of M2x = 1.27, M2y = 1.21. The type I and type II phase-matched LBO crystals were used as the extra-cavity frequency doubling and mixing crystals respectively. At 38 kHz, 8.2 W UV laser at 355 nm was achieved with the pulse duration of 8 ns corresponding to the pulse peak power as high as 27 kW, and the optical-optical conversion efficiency from IR to UV was 25.6%. The output characteristics of the IR and the harmonic generations varying with the pulse repetition rate were also investigated detailedly.
81 citations