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 tunabl…

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

International audience; 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 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, w…

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.

SELECTIVE AMPLIFICATION OF NARROW RESONANCE FORMED IN TRANSMISSION SPECTRUM OF Rb NANO-CELL IN MAGNETIC FIELD

Recently it was shown that "λ-Zeeman Technique" (λ-ZT) is a convenient tool to study individual transitions between the Zeeman sublevels of hyperfine levels in an external magnetic field. λ-ZT is based on resonant transmission spectrum of nanometric thin cell (NTC) of thickness L = λ, where λ is the resonant wavelength 794 nm for Rb D1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field. Examination of VSOP resonances allows one to identify and investigate an atomic transition in the range of magnetic fields 10 - 5000 G. Here we present a new method for selective addressing of VSOP r…

ATOM-WALL COLLISIONS INFLUENCE ON DARK-LINE ATOMIC RESONANCES IN SUBMICRON THIN VAPOUR CELLS

Symmetry breaking exhibition by magnetic field induced explicit circular dichroism

In this letter we demonstrate universal symmetry breaking by means of magnetically induced circular dichroism. Magnetic field induces forbidden at zero field atomic transitions between $\Delta F = \pm2$ hyperfine levels. In a particular range of magnetic field, intensities of these transitions experience significant enhancement. We have deduced a general rule applicable for the $D_2$ lines of all bosonic alkali atoms, that is transition intensity enhancement is larger for the case of $\sigma^+$ than for $\sigma^-$ excitation for $\Delta F = +2$, whereas it is larger (e.g. up to $10^{11}$ times for $^{85}$Rb atoms) in the case of $\sigma^-$ than for $\sigma^+$ polarization for $\Delta F = -2…

Circular dichroism of magnetically induced transitions for D 2 lines of alkali atoms

In this letter we study magnetic circular dichroism in alkali atoms exhibiting asymmetric behaviour of magnetically induced transitions. The magnetic field induces transitions between hyperfine levels of alkali atoms and in the range of magnetic field, the intensities of these transitions experience significant enhancement. We have inferred a general rule applicable for the D 2 lines of all alkali atoms, that is the transition intensity enhancement is around four times larger for the case of than for excitation for , whereas it is several hundreds of thousand times larger in the case of than that for polarization for . This asymmetric behaviour results in circular dichroism. For experimenta…

Hyperfine Paschen-Back regime in alkali metal atoms: consistency of two theoretical considerations and experiment

Simple and efficient "\lambda-method" and "\lambda/2-method" (\lambda is the resonant wavelength of laser radiation) based on nanometric-thickness cell filled with rubidium are implemented to study the splitting of hyperfine transitions of 85Rb and 87Rb D_1 line in an external magnetic field in the range of B = 0.5 - 0.7 T. It is experimentally demonstrated from 20 (12) Zeeman transitions allowed at low B-field in 85Rb (87Rb) spectra in the case of \sigma+ polarized laser radiation, only 6 (4) remain at B > 0.5 T, caused by decoupling of the total electronic momentum J and the nuclear spin momentum I (hyperfine Paschen-Back regime). The expressions derived in the frame of completely uncoupl…

Complete hyperfine Paschen-Back regime at relatively small magnetic fields realized in potassium nano-cell

A one-dimensional nano-metric-thin cell (NC) filled with potassium metal has been built and used to study optical atomic transitions in external magnetic fields. These studies benefit from the remarkable features of the NC allowing one to use $\lambda/2$- and $\lambda$-methods for effective investigations of individual transitions of the K D_1 line. The methods are based on strong narrowing of the absorption spectrum of the atomic column of thickness L equal to $\lambda/2$ and to $\lambda$(with $\lambda = 770\un{nm}$ being the resonant laser radiation wavelength). In particular, for a $\pi$-polarized radiation excitation the $\lambda$-method allows us to resolve eight atomic transitions (in…

High-Spatial-Resolution Monitoring of Strong Magnetic Field using Rb vapor Nanometric-Thin Cell

We have implemented the so-called $\lambda$-Zeeman technique (LZT) to investigate individual hyperfine transitions between Zeeman sublevels of the Rb atoms in a strong external magnetic field $B$ in the range of $2500 - 5000$ G (recently it was established that LZT is very convenient for the range of $10 - 2500$ G). Atoms are confined in a nanometric thin cell (NTC) with the thickness $L = \lambda$, where $\lambda$ is the resonant wavelength 794 nm for Rb $D_1$ line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field with the frequency positions and transition probabilities depending on th…

Atomic transitions of Rb, D2 line in strong magnetic fields: Hyperfine Paschen–Back regime

An efficient $\lambda/2$-method ($\lambda$ is the resonant wavelength of laser radiation) based on nanometric-thickness cell filled with rubidium is implemented to study the splitting of hyperfine transitions of $^{85}$Rb and $^{87}$Rb $D_2$ lines in an external magnetic field in the range of $B =3$~kG -- 7~kG. It is experimentally demonstrated that at $B > 3$~kG from 38 (22) Zeeman transitions allowed at low $B$-field in $^{85}$Rb ($^{87}$Rb) spectra in the case of $\sigma^+$ polarized laser radiation there remain only 12 (8) which is caused by decoupling of the total electronic momentum $\textbf{J}$ and the nuclear spin momentum $\textbf{I}$ (hyperfine Paschen-Back regime). Note that at $…

QUANTITATIVE SPECTROSCOPY OF Rb ATOMS IN STRONG MAGNETIC FIELD BASED ON SUBMICRON THIN VAPOUR.

The energy levels of atoms placed in an external magnetic field undergo frequency shifts and changes in their transition probabilities. It is demonstrated that using fluorescence spectra from a submicron thin vapour cell (STC) with the thickness L = λ/2, it is possible to efficiently study the above mentioned changes (“half-λ Zeeman technique” (HLZT)). The circularly polarized beam of extended-cavity diode laser (λ = 794 nm, laser bandwidth γL < 1 MHz) resonant with 87Rb D1 transition, after passing through Faraday isolator is directed onto the Rb STC with the thickness L = λ/2. The temperature of the STC is 120 °C, corresponding to N ~ 1013 atom/cm3. STC was provided by a special oven with…

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

A 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 = lambda /2 and L = lambda , where lambda is a resonant laser wavelength 794 nm (D(1) 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 pressure0.5 Torr. A spectacular difference is that for L = lambda , VSOP resonances are still observable even when neon pressure isor = 6 Torr. Narrow fluorescence s…