Etude des effets cohérents dans la vapeur de rubidium atomique sous irradiation laser bi-chromatique

L effet de la transparence induite électromagnétiquement est observée à l aidede cellules nanométriques et de cellules micrométriques. La résonance EIT avec de bons paramètres (fort contraste et faible largeur du signal à mi-hauteur) est obtenue dans des cellules étroites. L' éclatement de la résonance EIT dans un champ magnétique est observé pour les raies D1 du 85Rb et 87Rb. Nous présentons un modèle théorique qui explique la dépendance du déplacement en fréquence des composantes de la résonance EIT en fonction de l intensité du champ magnétique. Les résultats théoriques et expérimentaux sont comparés et démontrent un bon accord.Pour la première fois une résonance de type N est obtenue dans une micro-cellule. Nous obtenons de bons paramètres (fort contraste et faible largeur du signal à mi-hauteur) dela résonance N à l aide d une micro-cellule. Cela nous permet d observer le comportement d une résonance N dans un champ magnétique. L éclatement de la résonance N dans unchamp magnétique est observé pour les raies D1 du 85Rb et 87Rb. Nous présentons les calculs théoriques qui expliquent la dépendance du déplacement en fréquence des composantes dela résonance N en fonction de l intensité du champ magnétique. Les résultats théoriques et expérimentaux sont comparés et démontrent un bon accord. Le comportement de la résonance N en régime hyperfin Paschen-Back est présenté et expliqué. Enfin une comparaison des résonances EIT et N est faiteThe effect of electromagnetically induced transparency is observed, using nanocelland microcell. The EIT-resonance with good parameters (high contrast and small FWHM) is obtained in thick cells. The EIT-resonance splitting in magnetic field is observed for the cases of D1-line of 85Rb and 85Rb. The theoretical model, explaining the EIT-resonance components frequency shift dependence on magnetic field strength is presented. The theoretical and experimental results are compared and good agreement is shown. Also the EIT-resonance behavior in hyperfine Paschen-Back regime is presented and explained. For the first time the N-type resonance in microcell is observed. Good parameters of theN-type resonance in microcell are obtained. It allows us to observe the N-type resonance behavior in magnetic field. The N-resonance splitting in magnetic field is observed for the cases of 85Rb and 85Rb. The theoretical calculations of the N-resonance components frequency shift dependence on magnetic field is presented. The theoretical and experimental results are compared and good agreement is shown. Also the N-resonance behavior in hyperfine Paschen-Back regime is presented and explained. Simultaneous observation of N- and EIT-resonance is shown. Comparison of EIT- and N-resonance is madeDIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

Hyperfine Paschen-Back regime realized in Rb nanocell

A simple and efficient scheme based on one-dimensional nanometric thin cell filled with Rb and strong permanent ring magnets allowed direct observation of hyperfine Paschen-Back regime on D1 line in 0.5 - 0.7 T magnetic field. Experimental results are perfectly consistent with the theory. In particular, with sigma+ laser excitation, the slopes of B-field dependence of frequency shift for all the 10 individual transitions of 85,87Rb are the same and equal to 18.6 MHz/mT. Possible applications for magnetometry with submicron spatial resolution and tunable atomic frequency references are discussed.Comment: 3 page

Formation of narrow optical resonances using submillimeter and sibmicron-thin atomic vapor layer.

International audienceElectromagnetically induced transparency (EIT) resonance, along with peculiarities of the accompanying velocity selective optical pumping/saturation (VSOP) resonances, have been studied using a thin cell with the thickness of Rb vapor column varying in L = 10-700 &mgr;m range, as well as using an extremely thin cell (ETC) with the thickness varying in the range of radiation wavelength &lgr; = 780 nm (L = 0.5&lgr; - 2.5&lgr;). The &Lgr;-systems on D2 line of 85Rb and 87Rb have been studied experimentally with the use of bichromatic radiation of two separate diode lasers. It is demonstrated that size-conditioned strongly anisotropic contribution of atoms with different velocities in ETC results in several dramatic distinctions in formation of EIT and VSOP resonances in ETC, as compared with ordinary cm-size cell. The boundary between these two regimes falls on L ~ 10 &mgr;m. Theoretical model taking into account the peculiarities of the transmission spectra as a function of the ratio L/&lgr; is developed. The experimental transmission spectra are well described by the theoretical model

PECULIARITIES OF RESONANT ABSORPTION AND FLUORESCENCE IN EXTREMELY THIN CELL FILLED WITH Rb AND BUFFER GAS.

Recently unique extremely thin cells (ETC) containing atomic vapour of alkali metals with the column thickness L of an order and much less than optical light wavelength λ have been developed. It has been demonstrated that these ETC are a very promising tool for a fundamental study of atom-light, atom-atom, atom-surface and atom-external magnetic field interactions. Particularly, a dramatically different behaviour of resonant absorption, fluorescence and resonant magneto-optical processes compared to that obtained with the help of cm-long ordinary cells has been demonstrated. Possible applications based on ETC are described, such as magnetometers with nanometric spatial resolution and tunable atomic frequency references. For the study of buffer gas influence, a multi-region cell (MRC) has been developed. MRC consists of an ETC cell having a wedged thickness of the gap between the windows that allows one to form atomic vapour column thickness in the range of 0.1 ÷ 4 μm. The ETC is connected through a sapphire tube with a 1cm-long sapphire tube having sapphire windows. The 1cm-long cell has a sapphire side-arm containing Rb metal. MRC's are filled with 6 Torr and 20 Torr Neon gas, thus there is Rb vapour and buffer gas inside the MRC. The construction of the MRC allows one to compare absorption and fluorescence processes simultaneously in the case of the ETC use as well as in the case of 1cm-long ordinary cell use. The comparison of the resonant absorption and fluorescence in the extremely thin cell (ETC) filled with pure Rb with another one filled with Rb and Neon gas with the pressures of 6 Torr and 20 Torr is provided. The effect of the collapse and revival of Dicke-type narrowing is still observable for the thicknesses L = λ/2, and L = λ, with λ being the resonant laser wavelength 794 nm (D1 line of Rb), i.e. the spectra of the resonant absorption and fluorescence demonstrate strong sub-Doppler narrowing for the thickness L = λ/2 and broadening for the thickness L = λ. It is important to note that in an ordinary Rb cell with the thickness L in the range of 1mm - 10 cm filled with buffer gas, with the pressure higher than 1 Torr, in the well-known Saturation Absorption scheme, any sub-Doppler features are absent. For L = λ the so called velocity selective optical pumping/saturating resonance (VSOP) located at the atomic transition is still observable when Ne pressure is 6 Torr, while the linewidth is increased by 4 times in comparison with that obtained in a pure Rb ETC. It is also demonstrated that the use of the fluorescence spectra at L = λ/2 allows one to use ETC for the buffer gas pressure measurements. Comparison with the theory will be presented

Sub-doppler features of optical processes in the Rb extremely thin cell filled with an additional buffer gas

International audienceComparison of the resonant absorption and fluorescence in the extremely thin cell (ETC) filled with pure Rb with another one filled with Rb and Neon gas with the pressures 6 Torr and 20 Torr is provided. The effect of the collapse and revival of Dicke-type narrowing is still observable for the thickness L=λ/2, and L=λ, where λ is a resonant laser wavelength 794 nm (D1 line of the Rb), i.e. the spectra of the resonant absorption and fluorescence demonstrate the sub-Doppler narrowing for the thickness L=λ/2 and broadening for the thickness L=λ. It is important to note, that in an ordinary Rb cell with the thickness L in the range of 1mm- 10 cm filled with buffer gas, with a pressure higher than 1 Torr in the Saturation Absorption scheme, any sub-Doppler features are absent. For L= λ the so called velocity selective optical pumping (VSOP) resonance located at the atomic transition is still observable when Ne pressure is 6 Torr , while the linewidth is increased by 4 times in comparison with that obtained in the pure Rb ETC. This VSOP resonance is wash out when Ne pressure is 20 Torr. It is demonstrated that use of the fluorescence spectra at L=λ/2 allows one to use the ETC for the buffer gas pressure measurement. Comparison with the theory is presented

Superluminal pulse propagation in a non-linear Lambda -type atomic medium

International audienceThe propagation of two optical pulses in a non-linear -type atomic medium is considered. The analytical solution to the self-consistent Maxwell-Schrödinger equations in the adiabatic following condition is obtained. Superluminal effects during propagation of pulses in the medium are studied

Essential features of optical processes in neon-buffered submicron-thin Rb vapor cell

International audienceA new submicron thin cell (STC) filled with Rb and neon gas is developed and comparison of resonant absorption with STC containing pure Rb is provided. The effect of collapse and revival of Dicke-type narrowing is still observable for the thickness L = λ /2 and L = λ , where λ is a resonant laser wavelength 794 nm (D1 line). For an ordinary Rb cm-size cell with addition of buffer gas, the velocity selective optical pumping/saturation (VSOP) resonances in saturated absorption spectra are fully suppressed if neon pressure > 0.5 Torr. A spectacular difference is that for L = λ , VSOP resonances are still observable even when neon pressure is ≥ 6 Torr. Narrow fluorescence spectra at L = λ /2 allow one to realize online buffer gas pressure monitoring. A good agreement with theoretical model is observed