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 the $B$-field. Possible applications are described, such as magnetometers with nanometric local spatial resolution and tunable atomic frequency references.Comment: 12 page

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 two groups of four atomic transitions) and to reveal two remarkable transitions that we call Guiding Transitions (GT). The probabilities of all other transitions inside the group (as well as the frequency slope versus magnetic field) tend to the probability and to the slope of GT. Note that for circular polarization there is one group of four transitions and GT do not exist. Among eight transitions there are also two transitions (forbidden for $B$ = 0) with the probabilities undergoing strong modification under the influence of magnetic fields. Practically the complete hyperfine Paschen-Back regime is observed at relatively low (\sim 1\un{kG}) magnetic fields. Note that for K $D_2$ line GT are absent. Theoretical models describe the experiment very well.Comment: 6 page

Giant modification of atomic transitions probabilities induced by magnetic field: forbidden transitions become predominant

Magnetic field-induced giant modification of probabilities for seven components of 6S1/2 (Fg=3) - 6P3/2 (Fe=5) transition of Cs D2 line forbidden by selection rules is observed experimentally for the first time. For the case of excitation with circularly-polarized laser radiation, the probability of Fg=3,mF=-3 - Fe=5,mF=-2 transition becomes the largest among 25 transitions of Fg=3 - Fe=2,3,4,5 group in a wide range of magnetic field 200 - 3200 G. Moreover, the modification is the largest among D2 lines of alkali metals. A half-wave-thick cell (length along the beam propagation axis L=426 nm) filled with Cs has been used in order to achieve sub-Doppler resolution which allows for separating the large number of atomic transitions that appear in the absorption spectrum when an external magnetic field is applied. For B > 3 kG the group of seven transitions Fg=3 - Fe=5 is completely resolved and is located at the high frequency wing of Fg=3 - Fe=2,3,4 transitions. The applied theoretical model very well describes the experimental curves.Comment: 7 pages, 8 figure

Optical magnetometer with submicron spatial resolution based on Rb vapors

Hakhumyan, G. T.International audienceIt is shown experimentally that use of fluorescence and transmission spectra obtained from nanocells with the thickness of column of rubidium atomic vapor L = lambda/2 and L = lambda, respectively (lambda = 794 nm is the wavelength of laser radiation close to resonance with D (1)-line transition of Rb atoms), by means of a narrowband diode laser allows spectral separation and study of variations of probabilities of atomic transitions between ground and excited states of hfs of D (1) lines of Rb-85 and Rb-87 atoms in the range of magnetic fields from 10 to 5000 G. Small thickness of atomic vapor column (similar to 390 nm and similar to 794 nm) allows applying permanent magnets simplifying essentially creation of strong magnetic fields. Advantages of this technique are discussed as compared with the technique of saturated absorption. The obtained results show that a nanocell with submicrom thickness of vapor column may serve as a basis for designing a magnetometer with submicron local spatial resolution which is important in case of measuring strongly inhomogeneous magnetic fields. Experimental data are in good agreement with the theoretical results

Use of sub-Doppler optical resonances for measurement of weak magnetic fields by means of extremely thin rubidium vapor cell

International audienceWe study experimentally and theoretically D (1) lines of Rb-85 and Rb-87 atoms and show that using atomic-velocity-selective optical resonances which are formed in the transmission spectrum of an atomic rubidium-filled submicron cell at single pass of linearly polarized laser radiation, it is possible to measure weak magnetic fields beginning with 5 G. Having in mind the results obtained earlier with use of also submicron cell with Rb-87 (D (1) line) and circularly polarized laser radiation, the entire range of measurable magnetic fields (both homogeneous and inhomogeneous) becomes 5-5000 G

Study of Rb atomic transitions D 1,2 lines in strong magnetic field based on fluorescence spectra of sub-micron thin cell.

pp : 79980V-1 79980V-8International audienceThe so-called "λ/2-Zeeman technique" (HLZT) for studies of individual optical transition between Zeeman sublevels of atomic hyperfine structure in an external magnetic field of B = 10 - 2500 G is presented. Particularly, implementation of HLZT allows one to realize a direct determination of frequency shift and a strong modification of an optical transition probability between Zeeman components in a B-field. The main advantages of the method compared to "λ-Zeeman technique" (LZT) is that it allows one to study weak transitions. Particularly, with the help of fluorescence on 87Rb, D2 line, Fg = 1 → Fe = 3 transitions, three "forbidden" transitions in magnetic field B are detected and studied. Also, on 87Rb D1 line, Fg = 1, mF = 0 → Fe = 1, mF = 0 "forbidden" transition is detected when B ~ 400 G. A strong modification of the probability for these "forbidden" transitions is revealed. The theoretical model well describes the observed result