1,720,969 research outputs found
Maximal coherence in a three-level autoionising atom for the generation of subpicosecond pulses in the extreme ultraviolet
No full textWe discuss the possibility of using a three-level ladder atomic system, with a final autoionizing state, for the efficient generation of short radiation pulses in the extreme ultraviolet through a process of sum-frequency mixing in the presence of maximal coherence. The results of numerical calculations are presented, investigating the effects of photoionization, dynamic Stark shift and electron impact dephasing on the conversion efficiency in a single atom model.
The results of this investigation can be useful in identifying a real candidate for a possible experiment
Temporal compression of short-wavelength laser pulses by coherent control in rare gases
No full textWe present a theoretical study of temporal compression of a short-wavelength laser pulse predicted in a real, Doppler-broadened, atomic system. The compression is the result of the coherent control peculiarities of electromagnetically induced transparency-propagation dynamics. Numerical results are reported and discussed, showing a temporal compression of 2 orders of magnitude (from 10 ns to 100 ps) of a 106.7-nm laser pulse in argon atoms at room temperature
Comment on Large enhancement of four-wave mixing by suppression of photon absorption from electromagnetically induced transparency
No full textIn this Comment we deal with a recent study of Ying Wu et al. Phys. Rev. A 67, 013811 2003 on a four-wave mixing process. We show that the authors’ claim, that a large enhancement of the generation
efficiency can be obtained by suppression of photon absorption from electromagnetically induced transparency, is not correct
Coherent control of temporal pulse shaping by electromagnetically induced transparency
No full textWe present the coherent control of the temporal shape of laser pulses obtained by exploiting the propagation dynamics of electromagnetically induced transparency. Temporal compression, as a special case of pulse tailoring, is discussed. We envisage applications in nonlinear optics processes and control of pulse shapes in the vacuum ultraviolet spectral region
Comment [on Opening optical four-wave mixing channels with giant enhancement using ultraslow pump waves]
No full textIn their recent study [Phys. Rev. Lett. 88, 143902 (2002)] on a four-wave mixing (FWM) process, Deng et al. state that ‘‘many orders of magnitude enhancement in the amplitude of the generated wave’’ is obtained when electromagnetically induced transparency (EIT) is present. Here we will show that their claim is deeply misleading
Laser pulse compression by coherent control in a Doppler broadened medium: Analytical and numerical studies
No full textWe have studied the temporal compression of laser pulses occurring in a scheme based on the coherent control peculiarities of electromagnetically induced transparency. This work extends earlier model studies, including the effect of Doppler broadening in a real hot medium. For definiteness and consistency of the atomic parameters employed, we have treated a scheme in argon. In this way, we establish a realistic model that enables us to predict quantitatively the performance of laser pulse compression experiments
Temporal pulse compression and retardation by incoherent all-optical control
No full textWe present a theoretical analysis of a new scheme for temporal retardation combined with temporal compression of weak laser pulses, optically controlled by the presence of one additional light pulse. A realistic realization of this scheme in hot Rb is discussed, showing that a large range of values of the optically controllable delay-bandwidth product can be obtained with a limited pulse distortion
Frequency shift by optical coherent control
No full textWe report the experimental observation of an optically controllable shift of the central frequency of a laser pulse, using a scheme based on dynamical electromagnetically induced transparency. This is evidence of frequency shift controllable by a coherent process. Original theoretical results are in agreement with the experimental data
Coherent control of laser pulse temporal duration: An experimental proposal
No full textWe present a study of temporal compression resulting from the coherent control peculiarities of electromagnetically induced transparency propagation dynamics. We discuss the crucial conditions required to accomplish temporal compression in an experiment with
a sample of hot atoms
Propagation dynamics of maximal coherence and nonlinear mixing in an ionizing three-level medium
No full textWe show through modeling the effect of pulse propagation upon the evolution of coherence and nonlinear frequency mixing in an ionizing three-level medium. This work extends earlier studies, in which the coherence dephasing due to photoelectrons was considered, by including the effects of pulse reshaping as the coupled fields propagate through the medium. In this way we establish a realistic model that enables us to predict qualitatively the performance of experimental coherence enhanced frequency mixing schemes
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