Collapse and revival of a Dicke-type coherent narrowing in potassium vapor confined in a nanometric-thin cell

Abstract

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 $\lambda /2$ ($λ=\unit[770]{nm}$ 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 observed for $L=\lambda /2$ ($\sim \unit[120]{ MHz}$ at FWHM) and $L=3/2\lambda$, whereas for $L=\lambda$ and $L=2\lambda$ the spectrum broadens. At moderate laser intensities narrowband velocity selective optical pumping (VSOP) resonances appear at $L=\lambda$ and $L=2\lambda$ with the linewidth close to the natural one. A comparison with saturated absorption spectra obtained in a 1-cm-sized K cell is presented. The developed theoretical model well describes the experiment.

12 pages

References in corpus (7)

• ElecSus: A program to calculate the electric susceptibility of an atomic ensemble
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• Saturation effects in the sub-Doppler spectroscopy of Cesium vapor confined in an Extremely Thin Cell
• Optical response of gas-phase atoms at less than $\lambda /80$ from a dielectric surface
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Cited by in corpus (7)

• A practical guide to electromagnetically induced transparency in atomic vapor
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• Circular dichroism in atomic vapors: magnetically induced transitions responsible for two distinct behaviors
• Hyperfine Paschen-Back regime of Potassium D${}_2$ line observed by Doppler-free spectroscopy
• Selective reflection from a Potassium atomic layer with a thickness as small as $\lambda /13$
• Features of Magnetically-induced atomic transitions of Rb D${}_1$ line studied by Doppler-free method based on the second derivative of the absorption spectra