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

Physical Review A

Temporal character of pulsed-laser cone emission

Wojciech Gawlik, R. Shuker, A. Gallagher

Published Jul 2, 2001• 10 citations
Publisher

Abstract

Temporal character of cone emission from Sr vapor excited with \ensuremath{\sim}3-ns, near-resonant laser pulses is studied with \ensuremath{\sim}0.5-ns resolution. The cone pulses appear significantly narrower than the laser pulse. Their properties (amplitude, width, energy, delay, and angular distribution) systematically depend on the laser energy and detuning in a way that contradicts present, steady-state models of cone emission.

DOI
10.1103/physreva.64.021801

Related papers

Conical emission by 2-ps excitation of potassium vapor

David G. Sarkisyan, B. D. Paul, Steven T. Cundiff +2 more

Conical emission, redshifted from the atomic resonance, is observed when a ∼2-ps laser beam, blueshifted from resonance, propagates through potassium vapor. In contrast, no cone is visible when a 150-fs pulse is used. The 2-ps-pulse-induced cone has a unique, small, angular spread of Δθ/θ≈0.1, compared with Δθ/θ≈0.3 from other pulsed experiments, which used 25-ps–5-ns-excitation pulses. In addition, the fraction of the 2-ps-pulse power emitted in the cone reached 7.5%, far exceeding this fraction from the longer-pulse experiments. An additional, unexpected result is that the spectral width of the laser pulse is narrower, without significant intensity loss, after propagation through the vapor. The vapor densities and laser detunings that yield cones in the present experiment are similar to those from the longer-pulse experiments. Although the 2-ps-pulse spectrum partially overlaps the resonance, the cone spectrum and cone angles versus density and laser detuning are similar to those previously reported for nanosecond pulses. The fourth (blue-detuned) wave required for satisfying four-wave mixing is absent, again equivalent to what is observed in the nanosecond experiments. The physical origin of cone emission by pulsed excitation of atomic vapors is still largely unknown, and this high efficiency and narrow angular spread of a spectrally broad cone further contradicts existing models, perhaps ultimately providing a clue to a correct explanation.

Journal of the Optical Society of America B•Feb 1, 2001•11 citations

Time resolved cone emission

R. Shuker, Wojciech Gawlik, Alan C. Gallagher

The time characteristics of the conical emission that results in the propagation of blue detuned, single mode laser through Sr vapor is presented. This red detuned emission exhibits unexpectedly shorter pulses than the drive laser.

Nonlinear Optics•Jan 1, 2002•0 citations

Observation of conical emission from a single self-trapped beam

B. D. Paul, Marla L. Dowell, Alan C. Gallagher +1 more

We report observations of conical emission from a pulsed laser beam with incident laser power, detuning, and beam diameter matched to a range of single, steady-state filaments. The beam thus propagates with nearly constant diameter through 5 cm of strontium (Sr) vapor. Emission angles $(\ensuremath{\theta})$ are imaged as the height on the input slit of a 1.5 m spectrometer; a charge-coupled device camera in the spectrometer exit plane measures energy as a function of $\ensuremath{\theta}$ and frequency. Data are reported versus laser-pulse energy, diameter and detuning, and the collisional dephasing rate. Spectrally broad, red-detuned cones are observed, but only when the laser beam is predominately self-trapped. As previously observed in experiments where the beam breaks up into multiple filaments, forward emission at the blue-detuned Rabi sideband is much weaker than at the red (cone) sideband. The cone angle is largely independent of the phase velocity of the self-trapped laser beam, which varies from the vapor to the vacuum speed. The efficiency of the cone emission shows incomplete saturation, as well as strong dependence on self-trapped filament parameters.

Physical Review A•Jun 1, 1999•18 citations

Theory of optical near-resonant cone emission in atomic vapor

B. D. Paul, J. Cooper, Alan Gallagher +1 more

A time-dependent theory for conical emission during near-resonant propagation of laser light in an atomic vapor, which includes full propagation for the laser and frequency sidebands in a nonlinear two-level medium is presented. The density-matrix equations for the dipole moment and population are solved in the dressed atomic frame. The polarization source terms are accurate to order \ensuremath{\gamma}/R, where \ensuremath{\gamma} is a damping constant and R is the generalized Rabi frequency. Analytical plane-wave solutions and numerical, cylindrically symmetric propagation simulations including diffraction are presented. It is shown that the calculations with cylindrically symmetric fields and atomic excitation profiles are incapable of accounting for the high levels of optical gain that are responsible for the intense conical emission observed in experiments. This result is at first surprising, since the model accounts rigorously for all of the physical phenomena that have been previously proposed as being responsible for generating large gains, and the calculation matches the symmetry of the observations. The lack of large calculated gain seems to imply the existence of higher-order $(m>0)$ radial modes in the field for the experimental conditions that give rise to cone emission. In the simulations, however, the cylindrically symmetric fields do produce weak red-detuned cones with angular-frequency distributions similar to those seen in experiments.

Physical Review A•Dec 31, 2002•8 citations

Conical emission and coherent sideband generation in laser propagation

Michael E. Crenshaw, Cyrus D. Cantrell

Computational results show that the conical emission and Rabi sidebands observed when a nearly resonant laser pulse propagates through an atomic vapor are the result of the breakup of the pulse into solitary waves. For an incident pulse with a transverse as well as a temporal profile, the crests and troughs of the 2-D solitary waves are curved in a time-radius plane. The temporal modulation associated with pulse breakup appears as Rabi sidebands in the spectrum, while the curvature of the solitary waves in the time-radius plane results in a transverse spatial modulation, resulting in conical emission in the far field. These results were obtained by performing detailed numerical calculations of the time-dependent paraxial propagation of a cylindrically symmetric laser pulse through a vapor of two-level atoms. Our results can be interpreted readily in terms of optical nutation on the Bloch sphere and in terms of noncollinear phase matching through the curvature of the solitary waves rather than through additional parametrically generated waves. The cone opening angle depends on the initial transverse profile of the pulse and the process of beam breakup as well as self-focusing.

Annual Meeting Optical Society of America•Jan 1, 1988•0 citations

Near-resonant femtosecond laser induced cone emission from rubidium vapor

Silvije Vdović, Hrvoje Skenderović, Gordana Školnik +4 more

In this work we report the CE from the dense rubidium vapor excited by the output from the mode-locked, 100 fs laser oscillator. The cone emission was observed only when the laser beam propagated through the high-density vapor (N>5x1016 cm− 3) and for the smaller densities no CE was observed. The laser central wavelength was changed in the wide interval, from the far blue wing of the D2 line to the far red wing of the D1 line. The observed CE in the far blue wing of the D2 line is interpreted as a consequence of the self-focusing and self-phase modulation according to the adiabatic following limit. The emission in the red wing of the D2 line shows defocusing of the propagating beam. In contrast to the CE reported so far, the bright central spot was not observed in the far blue wing. In the near blue wing the central spot appears due to the two- photon resonance at 778 nm. The temporal shape of the CE, measured by cross-correlation in the SHG crystal shows pulse breaking and extreme lengthening.

•Apr 6, 2009•0 citations
Temporal character of cone emission from Sr vapor excited with \ensuremath{\sim}3-ns, near-resonant laser pulses is studied with \ensuremath{\sim}0.5-ns resolution. The cone pulses appear significantly narrower than the laser pulse. Their properties (amplitude, width, energy, delay, and angular distribution) systematically depend on the laser energy and detuning in a way that contradicts present, steady-state models of cone emission.
Conical emission, redshifted from the atomic resonance, is observed when a ∼2-ps laser beam, blueshifted from resonance, propagates through potassium vapor. In contrast, no cone is visible when a 150-fs pulse is used. The 2-ps-pulse-induced cone has a unique, small, angular spread of Δθ/θ≈0.1, compared with Δθ/θ≈0.3 from other pulsed experiments, which used 25-ps–5-ns-excitation pulses. In addition, the fraction of the 2-ps-pulse power emitted in the cone reached 7.5%, far exceeding this fraction from the longer-pulse experiments. An additional, unexpected result is that the spectral width of the laser pulse is narrower, without significant intensity loss, after propagation through the vapor. The vapor densities and laser detunings that yield cones in the present experiment are similar to those from the longer-pulse experiments. Although the 2-ps-pulse spectrum partially overlaps the resonance, the cone spectrum and cone angles versus density and laser detuning are similar to those previously reported for nanosecond pulses. The fourth (blue-detuned) wave required for satisfying four-wave mixing is absent, again equivalent to what is observed in the nanosecond experiments. The physical origin of cone emission by pulsed excitation of atomic vapors is still largely unknown, and this high efficiency and narrow angular spread of a spectrally broad cone further contradicts existing models, perhaps ultimately providing a clue to a correct explanation.
We report observations of conical emission from a pulsed laser beam with incident laser power, detuning, and beam diameter matched to a range of single, steady-state filaments. The beam thus propagates with nearly constant diameter through 5 cm of strontium (Sr) vapor. Emission angles $(\ensuremath{\theta})$ are imaged as the height on the input slit of a 1.5 m spectrometer; a charge-coupled device camera in the spectrometer exit plane measures energy as a function of $\ensuremath{\theta}$ and frequency. Data are reported versus laser-pulse energy, diameter and detuning, and the collisional dephasing rate. Spectrally broad, red-detuned cones are observed, but only when the laser beam is predominately self-trapped. As previously observed in experiments where the beam breaks up into multiple filaments, forward emission at the blue-detuned Rabi sideband is much weaker than at the red (cone) sideband. The cone angle is largely independent of the phase velocity of the self-trapped laser beam, which varies from the vapor to the vacuum speed. The efficiency of the cone emission shows incomplete saturation, as well as strong dependence on self-trapped filament parameters.
A time-dependent theory for conical emission during near-resonant propagation of laser light in an atomic vapor, which includes full propagation for the laser and frequency sidebands in a nonlinear two-level medium is presented. The density-matrix equations for the dipole moment and population are solved in the dressed atomic frame. The polarization source terms are accurate to order \ensuremath{\gamma}/R, where \ensuremath{\gamma} is a damping constant and R is the generalized Rabi frequency. Analytical plane-wave solutions and numerical, cylindrically symmetric propagation simulations including diffraction are presented. It is shown that the calculations with cylindrically symmetric fields and atomic excitation profiles are incapable of accounting for the high levels of optical gain that are responsible for the intense conical emission observed in experiments. This result is at first surprising, since the model accounts rigorously for all of the physical phenomena that have been previously proposed as being responsible for generating large gains, and the calculation matches the symmetry of the observations. The lack of large calculated gain seems to imply the existence of higher-order (m>0)(m>0)(m>0) radial modes in the field for the experimental conditions that give rise to cone emission. In the simulations, however, the cylindrically symmetric fields do produce weak red-detuned cones with angular-frequency distributions similar to those seen in experiments.
Computational results show that the conical emission and Rabi sidebands observed when a nearly resonant laser pulse propagates through an atomic vapor are the result of the breakup of the pulse into solitary waves. For an incident pulse with a transverse as well as a temporal profile, the crests and troughs of the 2-D solitary waves are curved in a time-radius plane. The temporal modulation associated with pulse breakup appears as Rabi sidebands in the spectrum, while the curvature of the solitary waves in the time-radius plane results in a transverse spatial modulation, resulting in conical emission in the far field. These results were obtained by performing detailed numerical calculations of the time-dependent paraxial propagation of a cylindrically symmetric laser pulse through a vapor of two-level atoms. Our results can be interpreted readily in terms of optical nutation on the Bloch sphere and in terms of noncollinear phase matching through the curvature of the solitary waves rather than through additional parametrically generated waves. The cone opening angle depends on the initial transverse profile of the pulse and the process of beam breakup as well as self-focusing.
In this work we report the CE from the dense rubidium vapor excited by the output from the mode-locked, 100 fs laser oscillator. The cone emission was observed only when the laser beam propagated through the high-density vapor (N>5x1016 cm− 3) and for the smaller densities no CE was observed. The laser central wavelength was changed in the wide interval, from the far blue wing of the D2 line to the far red wing of the D1 line. The observed CE in the far blue wing of the D2 line is interpreted as a consequence of the self-focusing and self-phase modulation according to the adiabatic following limit. The emission in the red wing of the D2 line shows defocusing of the propagating beam. In contrast to the CE reported so far, the bright central spot was not observed in the far blue wing. In the near blue wing the central spot appears due to the two- photon resonance at 778 nm. The temporal shape of the CE, measured by cross-correlation in the SHG crystal shows pulse breaking and extreme lengthening.