Proof of the feasibility of a nanocell-based wide-range optical magnetometer.

We present an experimental scheme performing scalar magnetometry based on the fitting of Rb $ {{\rm D}_2} $D2 line spectra recorded by derivative selective reflection spectroscopy from an optical nanometric-thick cell. To demonstrate its efficiency, the magnetometer is used to measure the inhomogeneous magnetic field produced by a permanent neodymium--iron-boron alloy ring magnet at different distances. The computational tasks are realized by relatively cheap electronic components: an Arduino Due board for external control of the laser and acquisition of spectra, and a Raspberry Pi computer for the fitting. The coefficient of variation of the measurements remains under 5% in the magnetic field range of 40-200 mT, limited only by the size of the oven and translation stage used in our experiment. The proposed scheme is expected to operate with high measurement precision also for stronger magnetic fields ($ {\gt} {500}\;{\rm mT}$>500mT) in the hyperfine Paschen-Back regime, where the evolution of atomic transitions can be calculated with high accuracy.

Dark resonance formation with magnetically induced transitions: extension of spectral range and giant circular dichroism.

Dark resonances were formed via electromagnetically induced transparency for the first time, to the best of our knowledge, involving magnetically induced ΔF=±2 atomic transitions of alkali metal atoms, which are forbidden at zero magnetic field. The probability of these transitions undergoes rapid growth when 300-3000 G magnetic field is applied, allowing formation of dark resonances, widely tunable in the GHz range. It is established that for ΔF=+2 (ΔF=-2) transition, the coupling laser tuned to ΔF=+1 (ΔF=-1) transition of the hyperfine Λ-system must be σ+ (σ-) polarized, manifesting anomalous circular dichroism.

Selective reflection from an Rb layer with a thickness below λ/12 and applications.

We have studied the peculiarities of selective reflection from an Rb vapor cell with a thickness L<70 nm, which is smaller than the length scale of evanescent fields λ/2π and more than an order of magnitude smaller than the optical wavelength. A 240 MHz redshift due to the atom-surface interaction is observed for a cell thickness of L=40 nm. In addition, complete frequency-resolved hyperfine Paschen-Back splitting of atomic transitions to four components for Rb87 and six components for Rb87 is recorded in a strong magnetic field (B>2 kG).

Magnetic-field-compensation optical vector magnetometer.

A concept for an optical magnetometer used for the measurement of magnitude and direction of a magnetic field (B-field) in two orthogonal directions is developed based on double scanning of a B-field to compensate the measured field to zero value, which is monitored by a resonant magneto-optical process in an unshielded atomic vapor cell. Implementation of the technique using the nonlinear Hanle effect on the D2 line of rubidium demonstrates viability and efficiency of the proposed concept. The ways to enhance characteristics of the suggested technique and optimize its performance, as well as the possible extension to three-axis magnetometry, are discussed.

N-type resonances in a buffered micrometric Rb cell: splitting in a strong magnetic field.

N-type resonances excited in rubidium atoms confined in micrometric-thin cells with variable thickness from 1 µm to 2 mm are studied experimentally for the cases of a pure Rb atomic vapor and of a vapor with neon buffer gas. Good contrast and narrow linewidth were obtained for thicknesses as low as 30 µm. The higher amplitude and sharper profile of N-type resonances in the case of a buffered cell was exploited to study the splitting of the 85Rb D1 N-resonance in a magnetic field of up to 2200 G. The results are fully consistent with the theory. The mechanism responsible for forming N-resonances is discussed. Possible applications are addressed.

Hyperfine Paschen-Back regime realized in Rb nanocell.

A simple and efficient scheme based on a one-dimensional nanometric-thin cell filled with Rb and strong permanent ring magnets allows direct observation of the hyperfine Paschen-Back regime on the D(1) line in the 0.5-0.7 T magnetic field. Experimental results are perfectly consistent with the theory. In particular, with σ(+) laser excitation, the slopes of the B-field dependence of frequency shifts for all 10 individual transitions of (85,87)Rb 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.

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 pressure > 0.5 Torr. A spectacular difference is that for L = lambda , VSOP resonances are still observable even when neon pressure is > or = 6 Torr. Narrow fluorescence spectra at L = lambda /2 allow one to realize online buffer gas pressure monitoring. A good agreement with theoretical model is observed.