Physical Review Letters

Long-Range Interactions between cw Self-Focused Laser Beams in an Atomic Vapor

A. C. Tam, W. Happer

Published Feb 7, 1977• 69 citations

Abstract

We have observed that circularly polarized laser beams of opposite (equal) polarizations in an alkali vapor repel (attract) each other for laser frequencies on the high-frequency wing of the ${D}_{1}$ line. Our experiments indicate that these long-range noncontact interactions are mediated by the exchange of polarized atoms between the beams. The repulsion between ${\ensuremath{\sigma}}_{+}$ and ${\ensuremath{\sigma}}_{\ensuremath{-}}$ beams leads to the breakup of a linearly polarized laser beam into two coherent beams of opposite circular polarization.

DOI: 10.1103/physrevlett.38.278

Related papers

Strong amplification of sidebands in self-focused laser beams in an atomic vapor

A. C. Tam

Physical Review AMay 1, 197962 citations

Transverse ‘‘bouncing’’ of polarized laser beams in sodium vapor

R. Holzner, Patrik Eschle, A. W. McCord +1 more

Physical Review LettersOct 12, 199221 citations

Repulsive light beams

G.H.C. New, W.T. Welford

Laser beams of opposite circular polarization which travel along adjacent (but not overlapping) paths in sodium vapour, appear to 'repel' each other when the frequency of the light is just above that of the D 1 transition. This effect, which has recently been demonstrated by A C Tam and W Happer (see Phys. Rev. Lett. 1977 38 278–82), can be understood in terms of the optical pumping of the sodium atoms by the respective radiation fields.

Physics BulletinMay 1, 19770 citations

Self-induced planar and cylindrical splitting of a laser beam in sodium vapor

A. Gahl, J. P. Seipenbusch, Andreas Aumann +2 more

Physical Review AAug 1, 199423 citations

Dynamics of laser beam switching in sodium vapor

S. Dangel, Patrik Eschle, B. Röhricht +3 more

Journal of the Optical Society of America BApr 1, 19958 citations

Resonant self-induced separation of polarization components: comparison between theory and experiment

David E. McClelland, A. W. McCord, R. J. Ballagh +2 more

Journal of the Optical Society of America BJan 1, 19938 citations

Physical Review Letters

Long-Range Interactions between cw Self-Focused Laser Beams in an Atomic Vapor

A. C. Tam, W. Happer

Published Feb 7, 1977• 69 citations

Publisher

Abstract

We have observed that circularly polarized laser beams of opposite (equal) polarizations in an alkali vapor repel (attract) each other for laser frequencies on the high-frequency wing of the

{D}_{1}

line. Our experiments indicate that these long-range noncontact interactions are mediated by the exchange of polarized atoms between the beams. The repulsion between

{\ensuremath{\sigma}}_{+}

and

{\ensuremath{\sigma}}_{\ensuremath{-}}

beams leads to the breakup of a linearly polarized laser beam into two coherent beams of opposite circular polarization.

DOI: 10.1103/physrevlett.38.278

Related papers

Strong amplification of sidebands in self-focused laser beams in an atomic vapor

A. C. Tam

A cw dye-laser beam tuned to the high-frequency wing of the Na ${D}_{2}$ line (at 2-6 GHz from the center of the ${D}_{2}$ line) is focused into a Na vapor, forming a self-focused laser filament. The incident laser beam, which is mainly single frequency, contains very weak sidebands at about \ifmmode\pm\else\textpm\fi{} 1 GHz from the main frequency and of intensity \ensuremath{\sim} ${10}^{\ensuremath{-}3}$ of the main frequency. Such sidebands are found to be strongly amplified by the vapor. Amplification factors in excess of 100 have been observed at suitable Na density, laser power, and detuning. Such strong sideband amplification, previously unknown, is explained as an off-resonant stimulated Raman scattering process.A cw dye-laser beam tuned to the high-frequency wing of the Na ${D}_{2}$ line (at 2-6 GHz from the center of the ${D}_{2}$ line) is focused into a Na vapor, forming a self-focused laser filament. The incident laser beam, which is mainly single frequency, contains very weak sidebands at about \ifmmode\pm\else\textpm\fi{} 1 GHz from the main frequency and of intensity \ensuremath{\sim} ${10}^{\ensuremath{-}3}$ of the main frequency. Such sidebands are found to be strongly amplified by the vapor. Amplification factors in excess of 100 have been observed at suitable Na density, laser power, and detuning. Such strong sideband amplification, previously unknown, is explained as an off-resonant stimulated Raman scattering process.

Physical Review AMay 1, 197962 citations

Transverse ‘‘bouncing’’ of polarized laser beams in sodium vapor

R. Holzner, Patrik Eschle, A. W. McCord +1 more

Two intersecting laser beams of orthogonal circular polarization near resonant to the homogeneously broadened D1 transition of Na vapor were observed to deflect each other upon contact. The experimental results are in good agreement with calculations based on a model which includes diffraction and a local nonlinear atomic susceptibility wihch fully takes into account saturation and optical pumping effects. The contact deflection (or ``bouncing'') was also observed when both beams were tuned to the atomic resonance frequency.Two intersecting laser beams of orthogonal circular polarization near resonant to the homogeneously broadened D1 transition of Na vapor were observed to deflect each other upon contact. The experimental results are in good agreement with calculations based on a model which includes diffraction and a local nonlinear atomic susceptibility wihch fully takes into account saturation and optical pumping effects. The contact deflection (or ``bouncing'') was also observed when both beams were tuned to the atomic resonance frequency.

Physical Review LettersOct 12, 199221 citations

Repulsive light beams

G.H.C. New, W.T. Welford

Physics BulletinMay 1, 19770 citations

Self-induced planar and cylindrical splitting of a laser beam in sodium vapor

A. Gahl, J. P. Seipenbusch, Andreas Aumann +2 more

An almost linearly polarized laser beam focused into a sodium vapor cell may split into different patterns ranging from two spots to a spot and a ring of opposite circular polarization. The patterns are controlled by static magnetic fields of the order of the earth's field. The behavior is explained, allowing for a longitudinal component of the dielectric polarization in the paraxial wave equation. Numerical results reveal the delicate balance between light shift, influence of the magnetic field, and the creation of ground-state orientation by the competing polarization components.An almost linearly polarized laser beam focused into a sodium vapor cell may split into different patterns ranging from two spots to a spot and a ring of opposite circular polarization. The patterns are controlled by static magnetic fields of the order of the earth's field. The behavior is explained, allowing for a longitudinal component of the dielectric polarization in the paraxial wave equation. Numerical results reveal the delicate balance between light shift, influence of the magnetic field, and the creation of ground-state orientation by the competing polarization components.

Physical Review AAug 1, 199423 citations

Dynamics of laser beam switching in sodium vapor

S. Dangel, Patrik Eschle, B. Röhricht +3 more

The interaction of left- and right-hand circularly polarized narrow-band cw laser beams that copropagate through sodium vapor and are tuned to the homogeneously broadened D1 transition can lead to the mutual extinction of both beams. Such beam switching is caused by an intensity- and polarization-dependent refractive index due to optical pumping even at low intensities. The dynamics of beam switching is investigated experimentally and explained qualitatively by the conventional J = 1/2 to J = 1/2 transition model. The accurate quantitative description, however, is only achieved by an extended model comprising hyperfine ground states in spite of homogeneous line broadening by argon buffer gas, which is larger than the hyperfine splitting.The interaction of left- and right-hand circularly polarized narrow-band cw laser beams that copropagate through sodium vapor and are tuned to the homogeneously broadened D1 transition can lead to the mutual extinction of both beams. Such beam switching is caused by an intensity- and polarization-dependent refractive index due to optical pumping even at low intensities. The dynamics of beam switching is investigated experimentally and explained qualitatively by the conventional J = 1/2 to J = 1/2 transition model. The accurate quantitative description, however, is only achieved by an extended model comprising hyperfine ground states in spite of homogeneous line broadening by argon buffer gas, which is larger than the hyperfine splitting.

Journal of the Optical Society of America BApr 1, 19958 citations

Resonant self-induced separation of polarization components: comparison between theory and experiment

David E. McClelland, A. W. McCord, R. J. Ballagh +2 more

An elliptically polarized laser beam tuned to the D1 transition of atomic sodium is sent through a vapor of sodium atoms that has been collisionally broadened by a buffer gas. The beam, initially Gaussian, is observed to break up into a narrower, pure circularly polarized spot surrounding an annulus of the opposite circular polarization. The sense of circular polarization of the central output spot corresponds to the weaker polarization component of the input field, and the polarization of the annular output beam corresponds to the stronger polarization component of the input field. A detailed comparison is made between the behavior observed and a recently developed theory of self-induced spatial separation of circularly polarized components.An elliptically polarized laser beam tuned to the D1 transition of atomic sodium is sent through a vapor of sodium atoms that has been collisionally broadened by a buffer gas. The beam, initially Gaussian, is observed to break up into a narrower, pure circularly polarized spot surrounding an annulus of the opposite circular polarization. The sense of circular polarization of the central output spot corresponds to the weaker polarization component of the input field, and the polarization of the annular output beam corresponds to the stronger polarization component of the input field. A detailed comparison is made between the behavior observed and a recently developed theory of self-induced spatial separation of circularly polarized components.

Journal of the Optical Society of America BJan 1, 19938 citations

We have observed that circularly polarized laser beams of opposite (equal) polarizations in an alkali vapor repel (attract) each other for laser frequencies on the high-frequency wing of the

{D}_{1}

line. Our experiments indicate that these long-range noncontact interactions are mediated by the exchange of polarized atoms between the beams. The repulsion between

{\ensuremath{\sigma}}_{+}

and

{\ensuremath{\sigma}}_{\ensuremath{-}}

beams leads to the breakup of a linearly polarized laser beam into two coherent beams of opposite circular polarization.

A cw dye-laser beam tuned to the high-frequency wing of the Na

{D}_{2}

line (at 2-6 GHz from the center of the

{D}_{2}

line) is focused into a Na vapor, forming a self-focused laser filament. The incident laser beam, which is mainly single frequency, contains very weak sidebands at about \ifmmode\pm\else\textpm\fi{} 1 GHz from the main frequency and of intensity \ensuremath{\sim} ${10}^{\ensuremath{-}3}$ of the main frequency. Such sidebands are found to be strongly amplified by the vapor. Amplification factors in excess of 100 have been observed at suitable Na density, laser power, and detuning. Such strong sideband amplification, previously unknown, is explained as an off-resonant stimulated Raman scattering process.