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 Modern Optics

Line-shape Distortion due to Self-focusing Effects When Using Frequency Modulation Techniques in Saturation Spectroscopy

L. Robertsson

Published Jul 1, 1994• 3 citations
Publisher

Abstract

A spatial dependence of the demodulated signal over the cross-section of a laser beam used for saturation spectroscopy has been observed. If the detector is not exposed to the full beam this spatial dependence causes a distortion of the line-shape. In extreme cases this distortion can lead to frequency shifts as large as 15% of the full width of the resonance. A model is presented in which the self-focusing effect acts to separate spatially the different frequency components of the modulated laser beam and thus allows for a spatial inhomogeneity of the demodulated signal. Numerical evaluation of the model agrees well with the experimental data provided a strong enhancement of the beam convergence in the absorption medium is applied.

DOI
10.1080/09500349414551281

Related papers

Phase and amplitude near-resonance self-action in periodically modulated laser beams

Vladimir Leonardovich Derbov, Vladislav Viktorovich Serov, Inna L. Plastun +1 more

Full space-time numerical modeling of near-resonance self-action of a beam, whose frequency is harmonically modulated in time, is presented. Maxwell-Bloch equations describing the propagation of the beam through a two-level medium with saturable absorption and refraction are solved using an original stable numerical scheme for multidimensional nonlinear Schrodinger equations. Delayed redistribution of intensity over the beam cross-section due to nonlinear self-focusing and self-phase-modulation effects is shown to affect the phase and the amplitude dynamics of the output signal in a rather nontrivial way, depending on the carrier laser frequency.

International Conference on Transparent Optical Networks•Feb 3, 2004•2 citations

Intensity dependent phase shifts in frequency modulation spectroscopy

H.-R. Xia, J. I. Cirac, Stephen D. Swartz +4 more

We discuss experimental observations of an induced phase shift of the rf signal produced in FM saturated absorption measurements under the conditions of large probe beam intensities. This phase shift can be understood in terms of the phase difference between the phase modulation of the optical driving field and the steady state macroscopic polarization of the medium. This phase difference is relatively insensitive to detuning of the laser from the atomic resonance, such that essentially the same spectrum can be observed by changing the rf detection phase. We also present theoretically calculated spectra which are based on the optical Bloch equations, and which are in excellent agreement with the experimental results.

AIP conference proceedings•Jan 1, 1993•1 citation

Resonant Self-Focusing and Non-Stationary Coherent Transients Manifestations in Frequency-Modulated Laser Beams Propagation

Vladimir Leonardovich Derbov, Inna L. Plastun, Vladislav Viktorovich Serov +1 more

Periodical modulation of frequency, typical for spectroscopic purposes, is numerically modelled in transversely limited, propagating through a saturable two-level absorber. At modulation periods comparable with the atomic relaxation times the time and frequency dependence of the output intensity exhibits the manifestations of delayed medium response, including time-dependent lens and aperture effects that may be of importance in spectroscopy

International Conference on Actual Problems of Electron Devices Engineering•Sep 1, 2006•0 citations

Phase shifts and intensity dependence in frequency-modulation spectroscopy

H.-R. Xia, J. I. Cirac, Stephen D. Swartz +4 more

We discuss experimental observations of an induced phase shift of the rf signal produced in frequency-modulated saturated-absorption measurements under the conditions of large probe-beam intensities. This phase shift can be understood in terms of the phase difference between the phase modulation of the optical driving field and the steady-state macroscopic polarization of the medium. We also present theoretically calculated spectra that are based on the optical Bloch equations and that are in excellent agreement with the experimental results.

Journal of the Optical Society of America B•May 1, 1994•6 citations

Spatial-asymmetry distribution of a saturated-absorption peak

A. Le Floch, Roger Le Naour, J. Lenormand +1 more

The amount of asymmetry of saturated-absorption peaks observed outside a cavity with two collinearly counter-propagating Gaussian beams is analyzed at different points in the cross section of the probe beam. Although the total beam exhibits a quasi-symmetric line shape, a spatial distribution of asymmetries with different amounts and signs is obtained versus the distance to the beam axis. A simple model taking account of pure focusing and defocusing effects induced by a saturated Gaussian beam leads to agreement between experiment and theory for the 5944-A neon line in the case of saturated-absorption spectroscopy.

Optics Letters•Jan 1, 1981•5 citations

Influence of the resonant self-action and nonstationary coherent effects on the characteristics of a frequency-modulated laser beam

Vladimir Leonardovich Derbov, Vladislav Viktorovich Serov, Inna L. Plastun +1 more

Self-action of a frequency-modulated laser beam, propagating through a two-level saturable absorber, is modeled numerically basing of the direct solution of Maxwell-Bloch equations. Following the common idea of spectroscopy, we plot the output intensity versus the input laser frequency that periodically changes in time. At modulation frequencies comparable with the relaxation rates the hysteresis loop is observed, i.e. the dependence of the transmitted intensity upon the instantaneous frequency depends on the direction of the frequency change. At large amplitudes of modulation coherent transient oscillations of the output intensity are observed.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jun 21, 2007•2 citations
A spatial dependence of the demodulated signal over the cross-section of a laser beam used for saturation spectroscopy has been observed. If the detector is not exposed to the full beam this spatial dependence causes a distortion of the line-shape. In extreme cases this distortion can lead to frequency shifts as large as 15% of the full width of the resonance. A model is presented in which the self-focusing effect acts to separate spatially the different frequency components of the modulated laser beam and thus allows for a spatial inhomogeneity of the demodulated signal. Numerical evaluation of the model agrees well with the experimental data provided a strong enhancement of the beam convergence in the absorption medium is applied.
Full space-time numerical modeling of near-resonance self-action of a beam, whose frequency is harmonically modulated in time, is presented. Maxwell-Bloch equations describing the propagation of the beam through a two-level medium with saturable absorption and refraction are solved using an original stable numerical scheme for multidimensional nonlinear Schrodinger equations. Delayed redistribution of intensity over the beam cross-section due to nonlinear self-focusing and self-phase-modulation effects is shown to affect the phase and the amplitude dynamics of the output signal in a rather nontrivial way, depending on the carrier laser frequency.
We discuss experimental observations of an induced phase shift of the rf signal produced in FM saturated absorption measurements under the conditions of large probe beam intensities. This phase shift can be understood in terms of the phase difference between the phase modulation of the optical driving field and the steady state macroscopic polarization of the medium. This phase difference is relatively insensitive to detuning of the laser from the atomic resonance, such that essentially the same spectrum can be observed by changing the rf detection phase. We also present theoretically calculated spectra which are based on the optical Bloch equations, and which are in excellent agreement with the experimental results.
We discuss experimental observations of an induced phase shift of the rf signal produced in frequency-modulated saturated-absorption measurements under the conditions of large probe-beam intensities. This phase shift can be understood in terms of the phase difference between the phase modulation of the optical driving field and the steady-state macroscopic polarization of the medium. We also present theoretically calculated spectra that are based on the optical Bloch equations and that are in excellent agreement with the experimental results.
The amount of asymmetry of saturated-absorption peaks observed outside a cavity with two collinearly counter-propagating Gaussian beams is analyzed at different points in the cross section of the probe beam. Although the total beam exhibits a quasi-symmetric line shape, a spatial distribution of asymmetries with different amounts and signs is obtained versus the distance to the beam axis. A simple model taking account of pure focusing and defocusing effects induced by a saturated Gaussian beam leads to agreement between experiment and theory for the 5944-A neon line in the case of saturated-absorption spectroscopy.
Self-action of a frequency-modulated laser beam, propagating through a two-level saturable absorber, is modeled numerically basing of the direct solution of Maxwell-Bloch equations. Following the common idea of spectroscopy, we plot the output intensity versus the input laser frequency that periodically changes in time. At modulation frequencies comparable with the relaxation rates the hysteresis loop is observed, i.e. the dependence of the transmitted intensity upon the instantaneous frequency depends on the direction of the frequency change. At large amplitudes of modulation coherent transient oscillations of the output intensity are observed.