Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of the Optical Society of America B

Saturation-spectroscopy transients from Raman coherence between metastable levels

Ch. Lerminiaux, M. Dumont

Published Apr 1, 1986• 2 citations
Publisher

Abstract

We present a theoretical and experimental study of the time evolution of the saturation-spectroscopy line shape when the saturating beam is suddenly switched on. We consider two metastable levels coupled by two Doppler-broadened transitions with a common excited level. In this special case, the fast transients from the upper level are rapidly damped, and the slow transients from populations and from Raman coherence in the metastable levels are easy to observe and are used for studying the collisional relaxation. For the sake of clarity, the theoretical analysis is developed according to a perturbation calculation. Nevertheless, saturation of the metastable levels must be taken into account in a more realistic theory (velocity-selective optical pumping): We give only a few results that are in excellent agreement with the experiments performed on neon metastable levels 3P0 and 3P2.

DOI
10.1364/josab.3.000477

Related papers

Laser saturation spectroscopy in the time-delayed mode. Theory of optical free induction decay in coupled Doppler-broadened systems

M. Ducloy, J. R. Rios Leite, Michael S. Feld

This paper describes a new class of techniques, called time-delayed laser saturation spectroscopy, which combine frequency- and time-domain methods of laser spectroscopy to provide a way of studying a molecular system as it evolves from an initially prepared stationary state to a second, final state. The specific example analyzed here is three-level free induction decay, in which the time-dependent gain of a Doppler-broadened molecular transition is probed after the sudden termination of an intense field resonating with a coupled transition. The theoretical calculation is based on the coupled density-matrix equations of motion in the slowly-varying envelope approximation. The time-delayed line shapes, which may be studied in either transmission or side fluorescence, exhibit linewidth asymmetries, line-shape deformations, Ramsey-type fringes, power broadening and dephasing, and dynamic Stark splittings and oscillatory decays. The technique provides a unique way of distinguishing the influence of Raman-type processes from that of population saturation and a means to separately measure the associated decay rates. The relationship of the present work to other studies is also discussed.

Physical Review A•Feb 1, 1978•36 citations

Collisional Narrowing of a Fine-Structure Raman Transition

S. Saoudi, Ch. Lerminiaux, M. Dumont

The line shape of the Raman transition between metastable levels of neon ($^{3}p_{0}\mathrm{and}^{3}p_{2}$) is studied as a function of the pressure of a helium buffer gas. Dicke narrowing of the Doppler-broadened nonresonant Raman signal (for large optical detunings) gives the first evidence of conservation of a fine-structure coherence by velocity-changing collisions. Pressure broadening of the resonant Raman signal gives a measurement of the velocity-changing-collision rate.

Physical Review Letters•May 19, 1986•6 citations

Laser-induced transients in coupled doppler-broadened systems

M. Ducloy, Michael S. Feld

A new type of experiment is proposed to study optical nutation and free induction decay in a Doppler-broadened transition, by observing the transmission of a weak probe field resonating at a coupled transition. These techniques open new possibilities for direct detailed observations of relaxation phenomena and effects of velocity dephasing in gases, and provide an experimental method for separately studying the effects of population saturation and Raman-type processes in three level systems.

Journal de Physique Lettres•Jan 1, 1976•7 citations

Selectivity in coherent transient Raman measurements of vibrational dephasing in liquids

Roger F. Loring, Shaul Mukamel

The microscopic information content of coherent transient Raman measurements is analyzed. It is shown that for short pulses and optically thin samples the Kaiser–Laubereau pulse sequence is the Raman analog of the optical free induction decay, and that the experimental observable contains the same dynamical information as the isotropic, spontaneous Raman line shape. Under these conditions, the experiment therefore cannot be used to selectively measure the homogeneous dephasing time of a system with an inhomogeneously broadened line. The results of our analysis are at variance with the earlier results of Kaiser and Laubereau and the more recent predictions of Oxtoby. However, these experiments, under certain circumstances, may be used to obtain a nonselective line narrowing, as found by Zinth, Polland, Laubereau, and Kaiser. We also consider the situation in which the sample is optically dense, in which case laser depletion must be taken into account. The distinction between saturation of the vibrational transition and depletion of the pump pulse is discussed, and selectivity is shown to arise from the former phenomenon, rather than from the latter. This result is at variance with the predictions of George and Harris. An alternative pulse sequence, the Raman echo, is suggested as a tool to achieve selectivity. A unified theory of the Raman echo is developed, which is valid for a bath with arbitrary time scale and which interpolates between the limits of homogeneous and inhomogeneous line broadening.

The Journal of Chemical Physics•Sep 1, 1985•174 citations

Theory of optical heterodyne three-level saturation spectroscopy via collinear non-degenerate four-wave mixing in coupled Doppler-broadened transitions

S. Le Boiteux, Daniel Bloch, M. Ducloy

We present a theoretical analysis of high-frequency optical heterodyne saturation spectroscopy in Doppler-broadened coupled three-level systems. The saturating beam, which is assumed to be amplitude modulated at frequency δ (double-sideband suppressed carrier amplitude modulation) is resonant for one of the transitions. Through non-degenerate four-wave mixing processes, this modulation is transferred to a probe beam, resonant for the coupled transition. Saturating and probe fields may be either co-propagating or counter-propagating. The lineshape of the probe modulation is analysed via a third-order perturbation expansion of the atomic density matrix with respect to the incident field amplitudes. The resulting signal is integrated over velocities, in the Doppler limit approximation. Both population saturation effects and coherent (Raman-type, or two-photon) processes contribute to the signal. The various contributions appear as Lorentzian-type resonance doublets. We show that, in the absence of relaxation processes (collisional dephasing, or radiative cascades), destructive interferences between population saturation and coherent two-photon processes are responsible for the disappearance of one resonance doublet. Phase-interrupting collisions are thus predicted to lead to the existence of a « pressure-induced extra-resonance » (PIER) doublet, which could yield information on collisional processes in the impact regime. The properties of the predicted PIER doublets are analysed in relation with other types of PIER signals studied in four-wave mixing, and in time-resolved saturation spectroscopy.

Journal de physique•Jan 1, 1986•10 citations

Optical pumping effects in high resolution laser spectroscopy

Shigeru Nakayama

A theoretical analysis of the relative intensities of the Doppler-free signals in saturation spectroscopy, velocity selective optical pumping (VSOP) spectroscopy, polarization spectroscopy and a mixing of saturation and polarization spectroscopies is presented using the approximation of a single cycle of optical pumping in a four-level system. An optical pumping process in the Zeeman sublevels is taken into account owing to the important role of spontaneous emission even if the sublevels are degenerate. Arbitrary polarization combinations are considered for pump and probe beams. The similarities and differences between three kinds of spectroscopy are made clear. Both circular and linear optical anisotropies induced by the pump beam are considered in this theoretical calculation. The magnitude and sign of Doppler-free resonances in each spectroscopy are quite different owing to the polarizations of the pump and probe beams. The four-level system is important as a three-level approximation. The results obtained from the four-level optical pumping theory are in good agreement with experimental reports.

Physica Scripta•Jan 1, 1997•29 citations
We present a theoretical and experimental study of the time evolution of the saturation-spectroscopy line shape when the saturating beam is suddenly switched on. We consider two metastable levels coupled by two Doppler-broadened transitions with a common excited level. In this special case, the fast transients from the upper level are rapidly damped, and the slow transients from populations and from Raman coherence in the metastable levels are easy to observe and are used for studying the collisional relaxation. For the sake of clarity, the theoretical analysis is developed according to a perturbation calculation. Nevertheless, saturation of the metastable levels must be taken into account in a more realistic theory (velocity-selective optical pumping): We give only a few results that are in excellent agreement with the experiments performed on neon metastable levels 3P0 and 3P2.
This paper describes a new class of techniques, called time-delayed laser saturation spectroscopy, which combine frequency- and time-domain methods of laser spectroscopy to provide a way of studying a molecular system as it evolves from an initially prepared stationary state to a second, final state. The specific example analyzed here is three-level free induction decay, in which the time-dependent gain of a Doppler-broadened molecular transition is probed after the sudden termination of an intense field resonating with a coupled transition. The theoretical calculation is based on the coupled density-matrix equations of motion in the slowly-varying envelope approximation. The time-delayed line shapes, which may be studied in either transmission or side fluorescence, exhibit linewidth asymmetries, line-shape deformations, Ramsey-type fringes, power broadening and dephasing, and dynamic Stark splittings and oscillatory decays. The technique provides a unique way of distinguishing the influence of Raman-type processes from that of population saturation and a means to separately measure the associated decay rates. The relationship of the present work to other studies is also discussed.
The line shape of the Raman transition between metastable levels of neon (3p0and3p2^{3}p_{0}\mathrm{and}^{3}p_{2}3p0​and3p2​) is studied as a function of the pressure of a helium buffer gas. Dicke narrowing of the Doppler-broadened nonresonant Raman signal (for large optical detunings) gives the first evidence of conservation of a fine-structure coherence by velocity-changing collisions. Pressure broadening of the resonant Raman signal gives a measurement of the velocity-changing-collision rate.
The microscopic information content of coherent transient Raman measurements is analyzed. It is shown that for short pulses and optically thin samples the Kaiser–Laubereau pulse sequence is the Raman analog of the optical free induction decay, and that the experimental observable contains the same dynamical information as the isotropic, spontaneous Raman line shape. Under these conditions, the experiment therefore cannot be used to selectively measure the homogeneous dephasing time of a system with an inhomogeneously broadened line. The results of our analysis are at variance with the earlier results of Kaiser and Laubereau and the more recent predictions of Oxtoby. However, these experiments, under certain circumstances, may be used to obtain a nonselective line narrowing, as found by Zinth, Polland, Laubereau, and Kaiser. We also consider the situation in which the sample is optically dense, in which case laser depletion must be taken into account. The distinction between saturation of the vibrational transition and depletion of the pump pulse is discussed, and selectivity is shown to arise from the former phenomenon, rather than from the latter. This result is at variance with the predictions of George and Harris. An alternative pulse sequence, the Raman echo, is suggested as a tool to achieve selectivity. A unified theory of the Raman echo is developed, which is valid for a bath with arbitrary time scale and which interpolates between the limits of homogeneous and inhomogeneous line broadening.
We present a theoretical analysis of high-frequency optical heterodyne saturation spectroscopy in Doppler-broadened coupled three-level systems. The saturating beam, which is assumed to be amplitude modulated at frequency δ (double-sideband suppressed carrier amplitude modulation) is resonant for one of the transitions. Through non-degenerate four-wave mixing processes, this modulation is transferred to a probe beam, resonant for the coupled transition. Saturating and probe fields may be either co-propagating or counter-propagating. The lineshape of the probe modulation is analysed via a third-order perturbation expansion of the atomic density matrix with respect to the incident field amplitudes. The resulting signal is integrated over velocities, in the Doppler limit approximation. Both population saturation effects and coherent (Raman-type, or two-photon) processes contribute to the signal. The various contributions appear as Lorentzian-type resonance doublets. We show that, in the absence of relaxation processes (collisional dephasing, or radiative cascades), destructive interferences between population saturation and coherent two-photon processes are responsible for the disappearance of one resonance doublet. Phase-interrupting collisions are thus predicted to lead to the existence of a « pressure-induced extra-resonance » (PIER) doublet, which could yield information on collisional processes in the impact regime. The properties of the predicted PIER doublets are analysed in relation with other types of PIER signals studied in four-wave mixing, and in time-resolved saturation spectroscopy.
A theoretical analysis of the relative intensities of the Doppler-free signals in saturation spectroscopy, velocity selective optical pumping (VSOP) spectroscopy, polarization spectroscopy and a mixing of saturation and polarization spectroscopies is presented using the approximation of a single cycle of optical pumping in a four-level system. An optical pumping process in the Zeeman sublevels is taken into account owing to the important role of spontaneous emission even if the sublevels are degenerate. Arbitrary polarization combinations are considered for pump and probe beams. The similarities and differences between three kinds of spectroscopy are made clear. Both circular and linear optical anisotropies induced by the pump beam are considered in this theoretical calculation. The magnitude and sign of Doppler-free resonances in each spectroscopy are quite different owing to the polarizations of the pump and probe beams. The four-level system is important as a three-level approximation. The results obtained from the four-level optical pumping theory are in good agreement with experimental reports.