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

Cone emission induced by femtosecond excitation in rubidium vapor

Hrvoje Skenderović, Ticijana Ban, Nataša Vujičić, Damir Aumiler, Silvije Vdović, Goran Pichler

Published Jun 11, 2008• 11 citations
Publisher

Abstract

We studied the emission from dense rubidium vapor under 100-fs pulsed laser excitation in the 730--820 nm range. Self-focusing along with a conical emission (CE) was observed for the excitation in the blue wing of $D2$ atomic resonance. Self-defocusing occurred for the red-wing excitation. This is in accordance with the theory of the intensity dependent nonlinear refraction index. In the case of the CE observation, our experimental results are attributed to the self-phase modulation of the laser beam interacting with the near-resonant atomic medium.

DOI
10.1103/physreva.77.063816

Related papers

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

Femtosecond laser-induced cone emission in dense cesium vapor

Damir Aumiler, Ticijana Ban, Goran Pichler

We report the observation of cone emission generated when $\ensuremath{\sim}10\text{\ensuremath{-}}\mathrm{nJ}$, 100-fs laser pulses in the 730--770 nm wavelength range are transmitted through a dense cesium vapor. The spatial and spectral characteristics of the observed cone emission were studied experimentally. Cone angle dependence on the laser wavelength, laser average power, and Cs atomic and molecular concentrations were investigated. The cone emission (CE) was only observed when the laser beam self-focused after passing through the medium. We identify the self-phase modulation as a dominant mechanism for CE generation in our experiment.

Physical Review A•Jun 13, 2005•21 citations

Conical emission as a result of self-phase-modulation in near-resonant Sm vapor: spectroscopic application

Won‐Kyu Lee, Young-Chul Noh, Jin-Ho Jeon +4 more

In our experiment conical emission (CE) has no wavelength shift and the same polarization as the original beam. Varying laser power, detuning, and atomic density, the images of CE were captured and analyzed. Typical far-field images are presented. Under the blue detuning condition, manifest CE patterns were observed, and under red detuning, original beam blurs due to not only to self-defocusing but also the conical pattern were observed. By comparing laser power and atomic density dependence of cone angle and theoretical curve, we could estimate spectroscopic data such as nonlinear refractive index. From the density dependence data, we get the fact that cone angle is proportional to atomic density which supports the self-phase-modulation (SPM) model. In conclusion, we observed and analyzed CE from near-resonant Sm vapor. With this simple setup, we could measure spectroscopic data.

Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR)•Jan 20, 2003•0 citations

Conical emission as a result of self-phase modulation in samarium vapor under the near-resonant condition

Won-Kyu Lee, Young-Chul Noh, Jin-Ho Jeon +4 more

We studied the conical emission in samarium (Sm) vapor under the near-resonant condition. The incident dye laser was tuned to the transition line, 4f66s2 7F→4f6(7F)6s6p(1P0)(λ=562.601 nm), of the Sm atom. Using a high-temperature oven, we could obtain the atomic density of 8×1014 atoms/cm3, large enough to observe the conical emission. We observed one to three rings around the original laser beam, and the number of the rings depended on the laser intensity, the laser wavelength, and the atomic density. These results are attributed to the self-phase modulation of the laser beam interacting with the near-resonant atomic medium. We give a simple expression that describes the dependence of the locations of the rings on the laser intensity. We compare the experimental results with this expression quantitatively and then estimate the nonlinear susceptibility of Sm vapor.

Journal of the Optical Society of America B•Jan 1, 2001•7 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 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
We studied the emission from dense rubidium vapor under 100-fs pulsed laser excitation in the 730--820 nm range. Self-focusing along with a conical emission (CE) was observed for the excitation in the blue wing of D2D2D2 atomic resonance. Self-defocusing occurred for the red-wing excitation. This is in accordance with the theory of the intensity dependent nonlinear refraction index. In the case of the CE observation, our experimental results are attributed to the self-phase modulation of the laser beam interacting with the near-resonant atomic medium.
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.
We report the observation of cone emission generated when $\ensuremath{\sim}10\text{\ensuremath{-}}\mathrm{nJ}$, 100-fs laser pulses in the 730--770 nm wavelength range are transmitted through a dense cesium vapor. The spatial and spectral characteristics of the observed cone emission were studied experimentally. Cone angle dependence on the laser wavelength, laser average power, and Cs atomic and molecular concentrations were investigated. The cone emission (CE) was only observed when the laser beam self-focused after passing through the medium. We identify the self-phase modulation as a dominant mechanism for CE generation in our experiment.
In our experiment conical emission (CE) has no wavelength shift and the same polarization as the original beam. Varying laser power, detuning, and atomic density, the images of CE were captured and analyzed. Typical far-field images are presented. Under the blue detuning condition, manifest CE patterns were observed, and under red detuning, original beam blurs due to not only to self-defocusing but also the conical pattern were observed. By comparing laser power and atomic density dependence of cone angle and theoretical curve, we could estimate spectroscopic data such as nonlinear refractive index. From the density dependence data, we get the fact that cone angle is proportional to atomic density which supports the self-phase-modulation (SPM) model. In conclusion, we observed and analyzed CE from near-resonant Sm vapor. With this simple setup, we could measure spectroscopic data.
We studied the conical emission in samarium (Sm) vapor under the near-resonant condition. The incident dye laser was tuned to the transition line, 4f66s2 7F→4f6(7F)6s6p(1P0)(λ=562.601 nm), of the Sm atom. Using a high-temperature oven, we could obtain the atomic density of 8×1014 atoms/cm3, large enough to observe the conical emission. We observed one to three rings around the original laser beam, and the number of the rings depended on the laser intensity, the laser wavelength, and the atomic density. These results are attributed to the self-phase modulation of the laser beam interacting with the near-resonant atomic medium. We give a simple expression that describes the dependence of the locations of the rings on the laser intensity. We compare the experimental results with this expression quantitatively and then estimate the nonlinear susceptibility of Sm vapor.
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.
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.