%0 Journal Article %T Saturation effects in the sub-Doppler spectroscopy of Cesium vapor confined in an Extremely Thin Cell %A C. Andreeva %A S. Cartaleva %A L. Petrov %A S. M. Saltiel %A D. Sarkisyan %A T. Varzhapetyan %A D. Bloch %A M. Ducloy %J Physics %D 2007 %I arXiv %R 10.1103/PhysRevA.76.013837 %X Saturation effects affecting absorption and fluorescence spectra of an atomic vapor confined in an Extremely Thin Cell (cell thickness $L < 1 \mu m$) are investigated experimentally and theoretically. The study is performed on the $D_{2}$ line ($\lambda ~= ~852 nm)$ of $Cs$ and concentrates on the two situations $L = \lambda /2$ and $L =\lambda$, the most contrasted ones with respect to the length dependence of the coherent Dicke narrowing. For $L = \lambda /2$, the Dicke-narrowed absorption profile simply broadens and saturates in amplitude when increasing the light intensity, while for $L =\lambda$, sub-Doppler dips of reduced absorption at line-center appear on the broad absorption profile. For a fluorescence detection at $L =\lambda$, saturation induces narrow dips, but only for hyperfine components undergoing a population loss through optical pumping. These experimental results are interpreted with the help of the various existing models, and are compared with numerical calculations based upon a two-level modelling that considers both a closed and an open system. %U http://arxiv.org/abs/0706.0837v1