The Experts below are selected from a list of 1260 Experts worldwide ranked by ideXlab platform
P. Lambropoulos - One of the best experts on this subject based on the ideXlab platform.
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Theory of laser-induced dielectronic recombination: a case study in Helium
Zeitschrift für Physik D Atoms Molecules and Clusters, 1997Co-Authors: P. Schlagheck, P. LambropoulosAbstract:We present the theoretical description of laserinduced dielectronic recombination in the density matrix formalism and show how the continuum components can be eliminated. The resulting equations are applied to the calculation of specific recombination processes in Helium from the point of view of resolving the involved Autoionizing States in the recombination spectrum. We examine how the shape of the spectrum depends on the laser pulse duration in processes in which the Autoionizing State to which the system recombines is coupled to a bound State. In addition, we consider processes in which the Autoionizing State is coupled to another Autoionizing State and discuss the possibility of resolving the resonance in the recombination spectrum
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A theoretical description of laser induced dielectronic recombination
Hyperfine Interactions, 1997Co-Authors: P. Schlagheck, P. LambropoulosAbstract:We present the theoretical description of a dielectronic recombination process in which the Autoionizing State is coupled to a bound State by a laser field. The system is described by density matrix equations in which the continuum components of the density matrix have been eliminated. Model calculations with these density matrix equations have been performed in order to compare the spectra of laser induced dielectronic recombination with the corresponding autoionization spectra.
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Third harmonic generation through double resonances: a model in He
Journal of Physics B: Atomic Molecular and Optical Physics, 1996Co-Authors: S. J. Van Enk, Jian Zhang, P. LambropoulosAbstract:We present a theory of third harmonic generation with XUV radiation through a double resonance, and examine the possibilities of enhancing the conversion efficiency by an additional laser field. We apply the theory to He where a photon of 21.22 eV leads to a one-photon resonance with the bound State , and a three-photon resonance with the Autoionizing State .
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Population transfer through an Autoionizing State by pulse delay
Zeitschrift für Physik D Atoms Molecules and Clusters, 1996Co-Authors: Takashi Nakajima, P. LambropoulosAbstract:We obtain the conditions for complete population transfer through an Autoionizing State in terms of asymmetry parameters q , which characterize the coupling strength between a discrete State and a continuum. In some limits, thus obtained conditions correspond to those for population transfer through a smooth continuum as well as a bound State.
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Pump-induced transparency and enhanced third-harmonic generation near an Autoionizing State.
Physical review. A Atomic molecular and optical physics, 1994Co-Authors: S. J. Van Enk, Jian Zhang, P. LambropoulosAbstract:We analyze an electromagnetically induced transparency near an Autoionizing State, which is at the same time stabilized against ionization. We show that the effect is fairly general as long as only one continuum is involved. We compare the efficiency for third-harmonic generation in this system with that in an intermediate two-photon resonance system, and discuss the advantages of the former. Explicit calculations are presented for a specific Autoionizing resonance in Ca.
S. J. Van Enk - One of the best experts on this subject based on the ideXlab platform.
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Third harmonic generation through double resonances: a model in He
Journal of Physics B: Atomic Molecular and Optical Physics, 1996Co-Authors: S. J. Van Enk, Jian Zhang, P. LambropoulosAbstract:We present a theory of third harmonic generation with XUV radiation through a double resonance, and examine the possibilities of enhancing the conversion efficiency by an additional laser field. We apply the theory to He where a photon of 21.22 eV leads to a one-photon resonance with the bound State , and a three-photon resonance with the Autoionizing State .
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Pump-induced transparency and enhanced third-harmonic generation near an Autoionizing State.
Physical review. A Atomic molecular and optical physics, 1994Co-Authors: S. J. Van Enk, Jian Zhang, P. LambropoulosAbstract:We analyze an electromagnetically induced transparency near an Autoionizing State, which is at the same time stabilized against ionization. We show that the effect is fairly general as long as only one continuum is involved. We compare the efficiency for third-harmonic generation in this system with that in an intermediate two-photon resonance system, and discuss the advantages of the former. Explicit calculations are presented for a specific Autoionizing resonance in Ca.
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Radiation amplification near an Autoionizing State
Acta Physica Polonica A, 1994Co-Authors: P. Lambropoulos, Jian Zhang, S. J. Van EnkAbstract:We present an internally consistent theory of amplification near the minimum of Autoionizing States with quantitative application to calcium. We have included a completely specified three-photon pumping and we find certain unusual aspects of the system. We find conditions under which the system remains in a steady State, although being coupled to the continuum. For incoherent pumping we obtain quantitative results for the gain. Our results and their extensions are also discussed in the context of present-day experimental possibifities.
Jian Zhang - One of the best experts on this subject based on the ideXlab platform.
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Third harmonic generation through double resonances: a model in He
Journal of Physics B: Atomic Molecular and Optical Physics, 1996Co-Authors: S. J. Van Enk, Jian Zhang, P. LambropoulosAbstract:We present a theory of third harmonic generation with XUV radiation through a double resonance, and examine the possibilities of enhancing the conversion efficiency by an additional laser field. We apply the theory to He where a photon of 21.22 eV leads to a one-photon resonance with the bound State , and a three-photon resonance with the Autoionizing State .
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Laser avoided crossing in the ionization continuum
Journal of Physics B: Atomic Molecular and Optical Physics, 1995Co-Authors: Y L Shao, Jian Zhang, Olivier Faucher, Dimitris CharalambidisAbstract:We present experimental results in AC-Stark splitting of an Autoionizing State probed by a multiphoton process. In the experiment performed in calcium, the 3d4f1P1 Autoionizing State is single-photon coupled with the 4s6s1S0 excited State. The splitting caused by this coupling is probed by three-photon excitation from the ground State. Detuning and laser intensity dependent measurements have been carried out in a collision-free environment. The experimental results can be interpreted and modelled in terms of a few levels system.
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Pump-induced transparency and enhanced third-harmonic generation near an Autoionizing State.
Physical review. A Atomic molecular and optical physics, 1994Co-Authors: S. J. Van Enk, Jian Zhang, P. LambropoulosAbstract:We analyze an electromagnetically induced transparency near an Autoionizing State, which is at the same time stabilized against ionization. We show that the effect is fairly general as long as only one continuum is involved. We compare the efficiency for third-harmonic generation in this system with that in an intermediate two-photon resonance system, and discuss the advantages of the former. Explicit calculations are presented for a specific Autoionizing resonance in Ca.
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Radiation amplification near an Autoionizing State
Acta Physica Polonica A, 1994Co-Authors: P. Lambropoulos, Jian Zhang, S. J. Van EnkAbstract:We present an internally consistent theory of amplification near the minimum of Autoionizing States with quantitative application to calcium. We have included a completely specified three-photon pumping and we find certain unusual aspects of the system. We find conditions under which the system remains in a steady State, although being coupled to the continuum. For incoherent pumping we obtain quantitative results for the gain. Our results and their extensions are also discussed in the context of present-day experimental possibifities.
T Usmanov - One of the best experts on this subject based on the ideXlab platform.
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efficient selection of single high order harmonic caused by atomic Autoionizing State influence
Optics Letters, 2009Co-Authors: I A Kulagin, T UsmanovAbstract:It is shown that the influence of atomic Autoionizing States on the phase matching of high harmonic generation results in efficient selection of the single harmonic generated in the plateau region. The change of relative concentration of the atomic medium components and variation of the fundamental laser frequency can be used for tuning of the selected harmonic frequency. The possibility of achievement of contrast for the selected single harmonic of more than 104 at intensity conversion efficiency of ~10−3 has been shown.
Tsuneyuki Ozaki - One of the best experts on this subject based on the ideXlab platform.
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Intense vortex high-order harmonics generated from laser-ablated plume
Applied Physics Letters, 2019Co-Authors: Mangaljit Singh, M. A. Fareed, A. Laramée, E. Isgandarov, Tsuneyuki OzakiAbstract:In this study, we demonstrate intense extreme-ultraviolet optical vortices generated using laser-ablation plume as the nonlinear medium. We used two types of plumes that are known to generate intense high-order harmonics for driving lasers with Gaussian beam profiles, but through different mechanisms, namely, carbon (diatomic carbon molecules) and tin (resonance with the Autoionizing State). We find that the harmonic fluxes for diatomic carbon molecules are similar for Gaussian and vortex driving fields. However, for harmonics from the Autoionizing State of tin (∼26.3 eV), the enhancement factor of the resonant harmonic intensity decreases by ∼50% when using the vortex driving field. The intense extreme-ultraviolet optical vortices demonstrated in this study will be useful for many applications including a material characterization technique known as optical angular momentum dichroism as well as the spectroscopy of spin-forbidden electronic transitions.In this study, we demonstrate intense extreme-ultraviolet optical vortices generated using laser-ablation plume as the nonlinear medium. We used two types of plumes that are known to generate intense high-order harmonics for driving lasers with Gaussian beam profiles, but through different mechanisms, namely, carbon (diatomic carbon molecules) and tin (resonance with the Autoionizing State). We find that the harmonic fluxes for diatomic carbon molecules are similar for Gaussian and vortex driving fields. However, for harmonics from the Autoionizing State of tin (∼26.3 eV), the enhancement factor of the resonant harmonic intensity decreases by ∼50% when using the vortex driving field. The intense extreme-ultraviolet optical vortices demonstrated in this study will be useful for many applications including a material characterization technique known as optical angular momentum dichroism as well as the spectroscopy of spin-forbidden electronic transitions.
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High-order harmonic generation below the ionization potential using laser-ablated Indium plume
2018 3rd International Conference on Microwave and Photonics (ICMAP), 2018Co-Authors: Mangaljit Singh, M. A. Fareed, Nicolas Thiré, S. Mondal, Bruno E. Schmidt, François Légaré, Tsuneyuki OzakiAbstract:We study high-order harmonic generation from laser ablated Indium plumes below the ionization potential at various driving laser wavelengths. Apart from intense harmonic from the Autoionizing State, we also observe enhanced harmonic generation below the ionization potential.
