Optical control of high-density alkali atom vapor in antirelaxation coated cells

S Tsvetkov,E Mariotti,S Gateva

doi:10.1088/1742-6596/1859/1/012055

Abstract

In this work, we report on our investigations on LIAD (Light Induced Atomic Desorption) aimed at achieving high density of alkali atoms vapor in a coated cell at room temperature. The experimental results show the possibility to reach a density up to the limit when the medium becomes optically thick by applying highly efficient homogeneous illumination. The photon reabsorption mechanism prevents the precise evaluation of the density by measuring the absorption of a probe laser beam, but there is clear evidence that densities can be achieved higher by two orders of magnitude than the thermodynamic equilibrium value.

Highlights

Antirelaxation (AR) coatings are organic films used in optical absorption cells to maintain the laser-induced polarization of the atoms after collisions with the cell’s walls
We report on our investigations on light-induced atomic desorption (LIAD) (Light Induced Atomic Desorption) aimed at achieving high density of alkali atoms vapor in a coated cell at room temperature
The photon reabsorption mechanism prevents the precise evaluation of the density by measuring the absorption of a probe laser beam, but there is clear evidence that densities can be achieved higher by two orders of magnitude than the thermodynamic equilibrium value

Summary

Introduction

Antirelaxation (AR) coatings are organic films (as, for example, paraffin, PDMS, OTS, SC-77 among others) used in optical absorption cells to maintain the laser-induced polarization of the atoms after collisions with the cell’s walls. The atomic density in а cell containing an alkali metal vapor is defined by the coldest point of the cell. This is the reservoir (the stem), which is kept some degrees colder to avoid a thin film deposition on the cell’s walls, which contributes to making the relaxation properties very poor [3]. The main disadvantage of the thermal control for application in AR coated cells is the deterioration of the AR properties of the coating at high temperatures [4] Another way to control the alkali metal vapor density in AR coated cells is the light-induced atomic desorption (LIAD) [2]. Longterm LIAD density stabilization has been reported in a few papers, but due to the influence of the stem, it requires increasing light intensities to sustain the atomic density [6]

Methods

Results

Conclusion