Atomic Sodium Vapor Research Articles

Electromagnetically induced diffraction in sodium vapor

By using a sodium atomic vapor we have observed a honeycomb-type multiple-diffraction pattern that was due to a grating induced optically by three noncollinear bichromatic excitation beams. In particular, when the two incident frequencies satisfy the two-photon resonance condition and the atomic density is high, the diffraction is enhanced by electromagnetically induced transparency, and strong Stokes and anti-Stokes components are generated in well-defined directions.

Coherent Raman beats from dark states

We have observed coherent Raman beat signals from a Lambda-type three-level system in a sodium atomic vapor. The sample is first prepared in a coherent superposition state of the ground-state hyperfine levels, or a dark state, by resonant bichromatic radiation. A following sudden frequency shift of one of the excitation beams causes the beat signals. Detailed analytical calculations based on the three-level Liouville equations are presented and are compared with experimental results. This simple technique is particularly suited for the obtaining of information on the generated sublevel coherence, including magnitude, phase, and decay time.

Observation of correlated anti-Stokes emissions by multiwave mixing in sodium vapor

We study experimentally nonlinear optical processes in which Stokes and anti-Stokes fields build up under strong, resonant, counterpropagating pump laser excitation in atomic sodium vapor. We find that, at some pump frequency, two off-axis anti-Stokes emissions propagating along reflection-symmetric directions are strongly temporally correlated, with a correlation time of 0.5 {mu}s and a correlation range of 1 mrad. It is shown by the numerical analysis based on six-wave mixing process involving pump, Stokes, and anti-Stokes waves in the forward and the backward directions that such correlated anti-Stokes emissions are possible when the medium is opaque for the Stokes field and transparent for the anti-Stokes field. Possibilities of quantum correlation for entangled photon generation using this system are discussed.

Clifford V. Heer

Clifford V. Heer

Role of quadratic and cubic spectral phases in ladder climbing with ultrashort pulses

Two-photon excitation of a quantum ladder system by an ultrashort chirped pulse leads to interferences in the excited-state population, between direct and sequential paths. Experimental results have been obtained in atomic sodium vapor. The presence of several intermediate and final states leads to new phenomena. The interplay between the two sequential paths leads to strongly contrasted oscillations and a large enhancement of the transition probability for precise values of the chirp. A cubic spectral phase modifies significantly the behavior of the quantum interferences and can be used to enhance the two-photon absorption rate.

Influence of coherent Raman scattering on coherent population trapping in atomic sodium vapor

We study how coherent Stokes and anti-Stokes Raman scattering influence coherent population trapping. In an experiment using an atomic sodium vapor cell we observe induced transparency, induced absorption, and gain features, all of subnatural linewidth. The electromagnetically induced resonance is a peak or a dip depending on which side of the optical transition the fields are tuned to, and thus whether coherent anti-Stokes Raman scattering or coherent Stokes Raman scattering is the dominant process.

Competition between sequential and direct paths in a two-photon transition

Two-photon excitation of a quantum ladder system by a chirped pulse leads to interferences in the excited-state population, due to the phase differences between direct and sequential paths. First, based on an analytical approach, we separate and discuss the features of the contributions arising from these two paths. Then interferences with two intermediate levels are observed experimentally in atomic sodium vapor. Interplay between the two sequential paths leads to strongly contrasted oscillations and a great enhancement of the transition probability for some values of the chirp.

Nonlinear Optics: Honeycomb Pattern Formation by Laser-Beam Filamentation in Atomic Sodium Vapor

Nonlinear Optics: Honeycomb Pattern Formation by Laser-Beam Filamentation in Atomic Sodium Vapor

High-resolution spectroscopy of hyperfine Zeeman components of the sodium D_1 line by coherent population trapping

High-resolution spectroscopy of hyperfine Zeeman components in a sodium atomic vapor has been performed by a coherent population trapping (CPT) technique. The measurement features the simple configuration of a single laser source with a frequency-swept double-pass acousto-optic modulator. Well-resolved CPT dip signals in the presence of longitudinal or transverse static magnetic fields can be nicely explained by a theory based on two-photon resonance.

Honeycomb pattern formation by laser-beam filamentation in atomic sodium vapor.

We have observed transverse pattern formation leading to highly regular structures in both the near and far fields when a near-resonant laser beam propagates without feedback through an atomic sodium vapor. One example is a regular far-field honeycomb pattern, which results from the transformation of the laser beam within the vapor into a stable three-lobed structure with a uniform phase distribution and highly correlated power fluctuations. The predictions of a theoretical model of the filamentation process are in good agreement with these observations.

Electromagnetically induced inhibition of two-photon absorption in sodium vapor

We report the observation of the electromagnetically induced inhibition of two-photon absorption with atomic sodium vapor as a test medium. A 60% reduction of two-photon resonant absorption was recorded at the $3S\ensuremath{-}4D$ transition when a cw coupling laser was applied at the $3P\ensuremath{-}5S$ transition.

Phase-preserving wavefront amplification at 590 nm by stimulated Raman scattering

This paper presents an experimental demonstration of high-gain optical-wavefront amplification by stimulated Raman scattering near the D 1 resonance in atomic sodium vapor. Single-pass weak-field gain of nearly 400 is achieved with only 800 mW of pump power. Through judicious focusing, the weak wavefront is confined to the central region of the focused pump wave where saturation of the dispersion profile minimizes phase distortions due to self-focusing effects. Phase-preserving amplification is demonstrated by interferometric measurements of an amplified TEM 00 wavefront.

Study of the formation and growth of light-induced sodium clusters

The temporal dependence of the spatial distributions of sizes and of the concentration of sodium clusters induced by laser light was investigated. Time-dependent measurements of the scattered light intensity were made as a function of the separation between probing and inducing laser beams for various thermodynamic conditions and various intensities of the inducing laser light. Diffusion of atomic sodium vapour and of clusters is discussed. The rate of cluster growth and the cluster size distribution are estimated.

Coherent population trapping on the sodium D_1 line in high magnetic fields

We consider the coherent-population-trapping (CPT) phenomenon in a sodium atomic vapor. The experiment leading to the first observation of CPT is revisited with an improved experimental setup and a larger range of magnetic-field strengths. From the analysis of the ground-state hyperfine splitting as a function of the applied magnetic field, we conclude that we have observed the whole spectrum of dark resonances within the D1 line corresponding to the nonabsorbing coherent superposition of two Zeeman sublevels of two different components of the 32S1/2 level. This was not obvious a priori because the transition probabilities at high magnetic-field strengths, as applied in the experiment, have to be taken into account. The differences in the contrast of the various black lines are explained in terms of pumpings outside the interaction scheme preparing the nonabsorbing state. Possible applications of CPT in high magnetic fields are discussed.

Hole burning in a sodium atomic vapor in presence of high pressure of heavy buffer gas

The hole burning in a sodium atomic vapor in presence of argon at the pressure of 50 Torr is experimentally studied. The experimental conditions correspond to a strong collisional regime, the atomic velocity change in a single collision not being small. It is found that the hole is not destroyed by the velocity-changing collisions, but is very broad, nearly as broad as the hyperfine splitting of the 3 2 S 1 2 ground state. This suggests a low efficiency of heavy buffer gas in redistributing the atomic velocities. This hypothesis is supported by a comparison of the absorptions of the Na + Ar to the absorption of Na + He.

Nonlinear optical patterns: classical and quantum effects, perspectives for applications

Restricted accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Lugiato L. A. , Barnett Stephen Mark , Brambilla M , Gatti A. , Marzoli I. , Oppo G. - L. , Prati F. , Stefani M. , Travagnin M. and Wiedemann H. 1996Nonlinear optical patterns: classical and quantum effects, perspectives for applicationsPhil. Trans. R. Soc. A.354767–778http://doi.org/10.1098/rsta.1996.0030SectionRestricted accessArticleNonlinear optical patterns: classical and quantum effects, perspectives for applications L. A. Lugiato Google Scholar Find this author on PubMed Search for more papers by this author , Stephen Mark Barnett Google Scholar Find this author on PubMed Search for more papers by this author , M Brambilla Google Scholar Find this author on PubMed Search for more papers by this author , A. Gatti Google Scholar Find this author on PubMed Search for more papers by this author , I. Marzoli Google Scholar Find this author on PubMed Search for more papers by this author , G. - L. Oppo Google Scholar Find this author on PubMed Search for more papers by this author , F. Prati Google Scholar Find this author on PubMed Search for more papers by this author , M. Stefani Google Scholar Find this author on PubMed Search for more papers by this author , M. Travagnin Google Scholar Find this author on PubMed Search for more papers by this author and H. Wiedemann Google Scholar Find this author on PubMed Search for more papers by this author L. A. Lugiato Google Scholar Find this author on PubMed Search for more papers by this author , Stephen Mark Barnett Google Scholar Find this author on PubMed Search for more papers by this author , M Brambilla Google Scholar Find this author on PubMed Search for more papers by this author , A. Gatti Google Scholar Find this author on PubMed Search for more papers by this author , I. Marzoli Google Scholar Find this author on PubMed Search for more papers by this author , G. - L. Oppo Google Scholar Find this author on PubMed Search for more papers by this author , F. Prati Google Scholar Find this author on PubMed Search for more papers by this author , M. Stefani Google Scholar Find this author on PubMed Search for more papers by this author , M. Travagnin Google Scholar Find this author on PubMed Search for more papers by this author and H. Wiedemann Google Scholar Find this author on PubMed Search for more papers by this author Published:15 March 1996https://doi.org/10.1098/rsta.1996.0030AbstractWe introduce the field of transverse nonlinear optics, and discuss some perspectives for applications, namely the use of spatial solitons for parallel information processing, femtojoule switching and logic gates in vertical cavity surface emitting lasers. We illustrate the quantum aspects of nonlinear optical patterns, focusing on quantum images and critical fluctuations in the degenerate optical parametric oscillator below threshold.FootnotesThis text was harvested from a scanned image of the original document using optical character recognition (OCR) software. As such, it may contain errors. Please contact the Royal Society if you find an error you would like to see corrected. Mathematical notations produced through Infty OCR. Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsCited by NAGASAKO E, BENTLEY S, ROBERT W and AGARWAL G (2010) Parametric downconversion vs optical parametric amplification: a comparison of their quantum statistics, Journal of Modern Optics, 10.1080/09500340110090819, 49:3-4, (529-537), Online publication date: 1-Mar-2002. Bennink R, Wong V, Marino A, Aronstein D, Boyd R, Stroud C, Lukishova S and Gauthier D (2002) Honeycomb Pattern Formation by Laser-Beam Filamentation in Atomic Sodium Vapor, Physical Review Letters, 10.1103/PhysRevLett.88.113901, 88:11 Torruellas W, Jian P, Trillo S, Haelterman M, Peschel U and Lederer F (1999) Solitons in Cavities with Quadratic Nonlinearities Optical Solitons: Theoretical Challenges and Industrial Perspectives, 10.1007/978-3-662-03807-9_21, (367-384), . Longhi S (1998) Spatial solitary waves in nondegenerate optical parametric oscillators near an inverted bifurcation, Optics Communications, 10.1016/S0030-4018(97)00729-3, 149:4-6, (335-340), Online publication date: 1-Apr-1998. Lugiato L, Gatti A, Ritsch H, Marzoli I and Oppo G (1997) Quantum images in nonlinear optics, Journal of Modern Optics, 10.1080/09500349708231854, 44:10, (1899-1915), Online publication date: 1-Oct-1997. Brambilla M, Lugiato L, Penco R, Pregnolato A and Spinelli L (1996) Spatial Soliton Addressing in Semiconductor Devices EQEC'96. 1996 European Quantum Electronic Conference, 10.1109/EQEC.1996.561923, 0-7803-3171-0, (231-231) This Issue15 March 1996Volume 354Issue 1708 Article InformationDOI:https://doi.org/10.1098/rsta.1996.0030Published by:Royal SocietyPrint ISSN:1364-503XOnline ISSN:1471-2962History: Published online01/01/1997Published in print15/03/1996 License:Scanned images copyright © 2017, Royal Society Citations and impact

Observation of magnetically controllable spatial pattern formation and symmetry breaking

Near-field spatial patterns have been observed which form when a circularly polarised laser beam propagates near-resonant to the D 1 transition through atomic sodium vapour buffered by argon gas in the presence of a small transverse magnetic field. An off-axis ring pattern in the near-field develops smoothly into filaments, with a breaking of the input cylindrical symmetry, as the strength of the magnetic field is increased. The effects have been observed over a relatively wide range of parameter values, but only for positive (self-focusing) detunings. The detailed structure of the patterns is very sensitive to small departures of the input beam from a Gaussian spatial intensity distribution.

Torsion and interaction of polarized photons

The contribution of the interacting vector and pseudovector torsion components to the interaction of polarized photons in an atomic sodium vapor is investigated. Estimates are obtained for the parameters of the gauge-theoretical model of gravitation.

Continuous-wave self-pumped optical phase conjugation in atomic sodium vapor

Self-pumped optical phase conjugation has been demonstrated for the first time to our knowledge in a resonant atomic system. This process was implemented by using a single cw pump beam to excite a sodium-vapor oscillator. The counterpropagating optical fields inside this oscillator then combine with the pump beam in an internal fourwave-mixing interaction to yield the phase conjugate of the incident (pump) beam.

Polarization instabilities of counterpropagating laser beams in sodium vapor.

We have observed temporal instabilities in the polarizations of counterpropagating laser beams in atomic sodium vapor. For intensities slightly above the instability threshold, the polarizations fluctuate periodically. For higher intensities, the fluctuations are chaotic and the system evolves on a strange attractor whose fractal dimension increases with increasing laser intensity.