High-resolution spectroscopy of a cesium-vapor layer with micrometric thickness for the development of frequency reference

Experimental results are presented related to high-resolution atomic spectroscopy of a cesium-vapor layer confined in extremely thin cells (ETCs) with thicknesses equal to the wavelength ? (852?nm) of the irradiating light and 6?. It is shown that increasing the ETC thickness by a few micrometers results in a strong enhancement of the sub-Doppler resonance contrast observed in the center of the fluorescence profile of the hyperfine transition.