Doppler-free Selective Reflection spectroscopy of the $6s$ $^2S_{1/2} \to 7p$ $^2P_{3/2}$ transition of Cesium using a nanofabricated vapor cell

TL;DR

This paper demonstrates Doppler-free Selective Reflection spectroscopy of Cesium's $6s$ to $7p$ transition using a nanofabricated vapor cell, achieving high spectral resolution and observing atom-surface interactions.

Contribution

First implementation of SR spectroscopy on Cesium's $6s$ to $7p$ transition with a nanometric-thin cell, revealing hyperfine resolution and surface effects.

Findings

Achieved 30-fold Doppler width narrowing.

Resolved hyperfine transitions clearly.

Observed red shifts due to atom-surface interactions.

Abstract

Selective Reflection (SR) spectroscopy of the $6s$ $^2S_{1/2} \rightarrow$ $7p$ $^2P_{3/2}$ electric dipole transition of Cesium ($\lambda~=~456$ nm) is performed for the first time using a nanometric-thin cell ($L=50 - 1500$~nm). We succesfully form narrow resonances corresponding to the $F_g = 3,4 \rightarrow F_e =2,3,4,5$ hyperfine transitions. All transitions are well spectrally resolved and the geometry of the cell allows us to obtain a strong 30 times narrowing of the Doppler width with a single beam pass. For lower thicknesses ($L < 400$~nm), we observe a red shift of the \ac{SR} lines which we attribute to atom-surface interactions, and provide estimates of the $C_3$ interaction coefficient. The SR signal reaches several percent of the incident radiation up to a saturation intensity of 100 mW/cm$^2$. SR is a convenient tool for laser spectroscopy of the hyperfine structure of atoms as well as for the study of Zeeman transitions in magnetic fields. Experimental measurements are in good agreement with theoretical calculations.