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Journal of Experimental and Theoretical Physics

Time Dependence of Resonant Photoprocesses Induced by Electromagnetic Pulses with Various Durations

Valery Alexandrovich Astapenko

Published Jul 1, 2022• 5 citations
Publisher

Abstract

Abstract The time dependence (on the pulse duration and on current time) of resonant photoprocesses induced by electromagnetic pulses of various durations (including ultrashort and quasi-monochromatic pulses) is analyzed using perturbation theory. Pulses with the Gaussian and exponential envelopes, as well as the Lorentzian and Gaussian spectral profiles of a photoprocess cross section are considered. Simple analytic expressions are obtained for the probability in the long-time limit. The time dependence for a given pulse duration is investigated analytically in the monochromatic and ultrashort limits and numerically for intermediate values of parameters. Specific features of the temporal dynamics, which are common for resonant photoprocesses and depend on the pulse shape and the spectral cross section profile are established.

DOI
10.1134/s106377612206005x

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Abstract In the framework of the consistent microscopic theory, universal analytic expressions describing absorption of laser pulses of an arbitrary duration in an optically dense medium have been derived, and their limiting cases have been considered. For the Gaussian and Lorentzian spectral profiles, simple expressions have been obtained for the absorption coefficient as a function of dimensionless parameters (optical thickness of the medium, the pulse duration and carrier frequency). Based on the performed calculations, the effect of the optical thickness of the medium on the dependences of the absorption coefficient on the pulse parameters has been revealed.
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Abstract The dynamics of photoexcitation of the hydrogen atom in the discrete and continuous spectra under the action of laser pulses in the attosecond range of time and pulse durations has been analyzed using perturbation theory. It is shown that over time interval shorter than or on the order of pulse duration, the time dependence of the photoexcitation probability is generally oscillating by nature. It has been established that for certain values of parameters, the envelope of this dependence has a peak, the position of which is determined by the pulse duration and carrier frequency.