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.
Circular dichroism in atomic vapors: magnetically induced transitions responsible for two distinct behaviors
Atomic transitions of alkali metals for which the condition $F_e-F_g = \pm2$ is satisfied have null probability in a zero magnetic field, while a giant increase can occur when an external field is applied. Such transitions, often referred to as magnetically-induced (MI) transitions, have received interest because their high probabilities in wide ranges of external magnetic fields which, in some cases, are even higher than that of usual atomic transitions. Previously, the following rule was established: the intensities of MI transitions with $\Delta F=\pm2$ are maximum when using respectively $\sigma^\pm$ radiation. Within the same ground state, the difference in intensity for $\sigma^+$ and…
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…
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…
High-contrast dark resonances on the D1 line in cesium nanocell: the advantages compared with the other alkali D lines
Electromagnetically induced transparency (EIT) effect in a -system formed by Cs atoms line, enclosed in nanometric-thin cells, is studied both experimentally and theoretically for the first time. T...
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…
Electromagnetically Induced Transparency and optical pumping processes formed in Cs sub-micron thin cell
Abstract The Electromagnetically Induced Transparency (EIT) effect in a Λ -system formed by Cs atoms (6 S 1/2 − 6 P 3/2 − 6 S 1/2 ) confined in an extremely thin cell (ETC) (atomic column thickness L varies in the range of 800 nm –3 µm is studied both experimentally and theoretically. It is demonstrated that when the coupling laser frequency is in exact resonance with the corresponding atomic transition, the EIT resonance parameters weakly depend on L , which allows us to detect the effect at L = λ = 852 nm. EIT process reveals a striking peculiarity in case of the coupling laser detuned by Δ from the atomic transition, namely the width of the EIT resonance rapidly increases upon an in…
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…
Approach to quantitative spectroscopy of atomic vapor in optical nanocells
We present a method for recovery of narrow homogeneous spectral features out of a broad inhomogeneous overlapped profile based on second-derivative processing of the absorption spectra of alkali metal atomic vapor nanocells. The method is shown to preserve the frequency positions and amplitudes of spectral transitions, thus being applicable for quantitative spectroscopy. The proposed technique was successfully applied and tested for measurements of hyperfine splitting and atomic transition probabilities, development of an atomic frequency reference, determination of isotopic abundance, study of atom-surface interaction, and determination of magnetic-field-induced modification of atomic tran…
A method for the quantitative study of atomic transitions in a magnetic field based on an atomic vapor cell with L=lambda
We describe the so-called "Lambda-Zeeman method" to investigate individual hyperfine transitions between Zeeman sublevels of atoms in an external magnetic field of 0.1 mT - 0.25 T. Atoms are confined in a nanocell with thickness L = Lambda, where Lambda is the resonant wavelength (794 nm or 780 nm for D1 or D2 line of Rb). Narrow resonances in the transmission spectrum of the nanocell are split into several components in a magnetic field; their frequency positions and probabilities depend on the B-field. Possible applications are described, such as magnetometers with nanometric spatial resolution and tunable atomic frequency references.
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 $…
Dark-Line Atomic Resonances in Micrometric Rb-Vapor Layer
We present measurements of dark-line resonances excited in Rb atomic vapor confined in micrometric cells (MC). In our work, the Lambda-systems on D2 line of 85Rb have been studied with the use of bi-chromatic radiation of two separate narrowband diode lasers.
Extreme increase in atomic transition probability of the Cs D_2 line in strong magnetic fields under selective reflection
Selective reflection of 852-nm laser radiation from the interface between cesium vapor and the sapphire window of a 30-micrometer-thick microcell was used to record an extreme increase in the probability of the Fg=3→Fe=5 transitions associated with the Cs-atom D2 lines in magnetic fields with inductions ranging from 300 to 3200 Gauss. We showed that a group of seven transitions Fg=3, mF=−3, −2, −1, 0, +1, +2, +3→Fe=5, mF=−2, −1, 0, +1, +2, +3, +4 was formed in accordance with the selection rules ΔmF=+1 for σ+-circularly-polarized radiation. These seven transitions have much higher probabilities in 500–1000 Gauss magnetic fields, with three of the transitions having probabilities higher than…
Electromagnetically induced transparency resonances inverted in magnetic field
The electromagnetically induced transparency (EIT) phenomenon has been investigated in a $\Lambda$-system of the $^{87}$Rb D$_1$ line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates $\gamma_{rel}$ are used: a Rb cell with antirelaxation coating ($L\sim$1 cm) and a Rb nanometric-thin cell (nano-cell) with thickness of the atomic vapor column $L$=795nm. For the EIT in the nano-cell, we have the usual EIT resonances characterized by a reduction in the absorption (i.e. dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (i.e. br…
Collapse and revival of a Dicke-type coherent narrowing in potassium vapor confined in a nanometric-thin cell
A nanometer-thin-cell (in the direction of laser beam propagation) has been elaborated with the thickness of the atomic vapor column varying smoothly in the range of $L = \unit[50-1500]{nm}$. The cell allows one to study the behavior of the resonance absorption over the $D_1$ line of potassium atoms by varying the laser intensity and the cell thickness from $L = \lambda / 2$ to $L = 2 \lambda$ with the step $\lambda/2$ ($\lambda =\unit[770]{nm}$ is the resonant wavelength of the laser). It is shown that despite the huge Doppler broadening ($>\unit[0.9]{GHz}$ at the cell temperature $\unit[170]{^{\circ}C}$), at low laser intensities a narrowing of the resonance absorption spectrum is observe…
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…