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

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 $\ell =\hat{I}»/2\simeq 230$ 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.