Doppler-free spectroscopy of the Cs $6\text{S}_{1/2}-7\text{P}_{3/2}$ atomic transition at 456 nm in a nanometric-thick vapor layer

TL;DR

This paper investigates Doppler-free spectroscopy of the Cs 6S1/2-7P3/2 transition at 456 nm in a nanometric vapor layer, revealing narrow resonances suitable for high-resolution applications and frequency references.

Contribution

It demonstrates Doppler-free resonances in a nanometric vapor layer for a weak transition, with observed Dicke narrowing and surface interaction effects, advancing high-resolution spectroscopy techniques.

Findings

Dicke narrowing observed at layer thickness ~λ/2

Linewidths below 20 MHz achieved in single-pass configuration

Resonances suitable for high-resolution spectroscopy and frequency references

Abstract

The features of Doppler-free resonances detected by probing the $^{133}$Cs atom $6S_{1/2}-7P_{3/2}$ transition at 456 nm in a nanometric-thick vapor layer are investigated. The matrix element of this transition is about 11 times smaller than that of the Cs D$_2$ line (852 nm). When the vapor layer thickness is $\ell = \lambda/2 \simeq 230$ nm, we observe Dicke narrowing of the lines, accompanied by a red frequency shift of the atomic transitions, which is attributed to atom-surface interactions. Realizing optical pumping with $\ell\simeq 460$ nm in a single-pass configuration, we observe Doppler-free resonances with a linewidth $<20$ MHz, located at the atomic transitions frequencies with a correspondence of the amplitudes to the transition intensities. These narrow resonances are of interest for high-resolution spectroscopy and instrumentation, and could serve as a frequency reference.