Nonlinear Effects in Atomic Vapors; - and Two - Transitions.

We present experiments of a laser with variable pulse energy and beam width saturating sodium vapor near the ${D}_{1}$ -line transition. At high optical depth and in a buffer gas atmosphere of argon, the effect of nonlinear radiation trapping is shown to drastically change the spatial distribution and temporal evolution of the excited-state population and of the fluorescence light trapped by the nonlinear medium. Besides observing the transient behavior of the fluorescence light, a pump-probe beam experiment enables us to gain a tomographic view inside the atomic vapor. Nitrogen as a buffer gas is used to compare with the situation where radiation trapping effects are negligible. Finally, numerical simulations based upon equations of radiative transfer for a two-level atomic system elucidate the role of nonlinear radiation trapping and support given interpretations of the experiments.We present experiments of a laser with variable pulse energy and beam width saturating sodium vapor near the ${D}_{1}$-line transition. At high optical depth and in a buffer gas atmosphere of argon, the effect of nonlinear radiation trapping is shown to drastically change the spatial distribution and temporal evolution of the excited-state population and of the fluorescence light trapped by the nonlinear medium. Besides observing the transient behavior of the fluorescence light, a pump-probe beam experiment enables us to gain a tomographic view inside the atomic vapor. Nitrogen as a buffer gas is used to compare with the situation where radiation trapping effects are negligible. Finally, numerical simulations based upon equations of radiative transfer for a two-level atomic system elucidate the role of nonlinear radiation trapping and support given interpretations of the experiments.

Physical Review ASep 1, 20014 citations

Non-linear effects in atomic vapors

Lambros G. Johnson

Jan 1, 19810 citations

Double-quantum spectroscopy of dense atomic vapors: Interplay between Doppler and self-broadenings

Cyril Falvo, Hebin Li

In this article, we present a simulation study of the linear and nonlinear spectroscopy of dense atomic vapors. Motivated by recent experiments, we focus on double quantum spectroscopy, which directly probes dipole-dipole interactions. By explicitly including thermal velocity, we show that temperature has an important impact on the self-broadening mechanisms of the linear and nonlinear spectra. We also provide analytical expressions for the response functions in the short time limit using the two-body approximation, which shows that double quantum spectroscopy for atomic vapors directly probes the transition amplitude of the electronic excitation between two atoms. We also propose an expression for the double quantum spectrum that includes the effect of Doppler broadening, and we discuss the effect of density on the spectrum. We show that when Doppler broadening is negligible compared to self-broadening, the double quantum spectrum scales with the atomic density, while when Doppler broadening dominates, it scales as the square of the density.In this article, we present a simulation study of the linear and nonlinear spectroscopy of dense atomic vapors. Motivated by recent experiments, we focus on double quantum spectroscopy, which directly probes dipole-dipole interactions. By explicitly including thermal velocity, we show that temperature has an important impact on the self-broadening mechanisms of the linear and nonlinear spectra. We also provide analytical expressions for the response functions in the short time limit using the two-body approximation, which shows that double quantum spectroscopy for atomic vapors directly probes the transition amplitude of the electronic excitation between two atoms. We also propose an expression for the double quantum spectrum that includes the effect of Doppler broadening, and we discuss the effect of density on the spectrum. We show that when Doppler broadening is negligible compared to self-broadening, the double quantum spectrum scales with the atomic density, while when Doppler broadening dominates, it scales as the square of the density.

arXiv:2305.09494The Journal of Chemical PhysicsAug 14, 20232 citations

Investigation of odd-order nonlinear susceptibilities in atomic vapors

Yaqi Yan, Zhenkun Wu, Jinhai Si +5 more

Annals of PhysicsFeb 28, 20134 citations

Nonlinear reflection of laser beam from high density atomic vapor

Vladimir A. Sautenkov, Sergey A. Saakyan, E V Vilshanskaya +3 more

We have investigated the nonlinear selective reflection of a laser beam (λ = 780 nm) from a high density rubidium vapor. The laser frequency was tuned over atomic transitions and coherent optical excitation of the atomic vapor was realized. The observed narrowing of reflection spectral profile is associated with a competition of two nonlinear processes: optical field induced coherent broadening (Rabi broadening) and optical saturation induced decreasing of dipole–dipole broadening of atomic transitions. For more complete understanding the spectral narrowing we suggest to perform a set of new experiments.We have investigated the nonlinear selective reflection of a laser beam (λ = 780 nm) from a high density rubidium vapor. The laser frequency was tuned over atomic transitions and coherent optical excitation of the atomic vapor was realized. The observed narrowing of reflection spectral profile is associated with a competition of two nonlinear processes: optical field induced coherent broadening (Rabi broadening) and optical saturation induced decreasing of dipole–dipole broadening of atomic transitions. For more complete understanding the spectral narrowing we suggest to perform a set of new experiments.

Journal of Physics Conference SeriesJan 1, 20192 citations

INTRODUCTION TO THE THEORY OF FIELD-INDUCED ATOMIC TRANSITIONS

WORLD SCIENTIFIC eBooksJan 1, 19980 citations

We present experiments of a laser with variable pulse energy and beam width saturating sodium vapor near the

{D}_{1}

-line transition. At high optical depth and in a buffer gas atmosphere of argon, the effect of nonlinear radiation trapping is shown to drastically change the spatial distribution and temporal evolution of the excited-state population and of the fluorescence light trapped by the nonlinear medium. Besides observing the transient behavior of the fluorescence light, a pump-probe beam experiment enables us to gain a tomographic view inside the atomic vapor. Nitrogen as a buffer gas is used to compare with the situation where radiation trapping effects are negligible. Finally, numerical simulations based upon equations of radiative transfer for a two-level atomic system elucidate the role of nonlinear radiation trapping and support given interpretations of the experiments.