<title>Absorption and fluorescence in atomic submicron cell: high laser intensity case</title>

Abstract

Absorption and fluorescence in Rb sub-micron cell on D₂ line have been studied when the thickness L varies in the range of 0.5 &#955; - 3.5 &#955;, and the laser intensity is 0.1 - 1 W/cm² (&#955; = 780 nm, &#955;_L ~ 5 MHz). When <i>L</i> = (2n +1) &#955;/2 (n-integer) and <i>I</i> ~ 0.1 W/cm², revival of peaks of Dicke-type coherent narrowing effect with some modification of the spectra (as compared with low intensity regime) are still observable. The experimental results obtained at <i>I</i> ~ 1 W/cm² for <i>L</i> = &#955;/2 show that there are no "dips" of a reduced absorption in the spectra, though there is a strong spectral broadening of the absorption (and fluorescence), as well as a reduction of the absorption (in contrast, <i>I</i> ~ 1 mW/cm² is sufficient to create the dips when <i>L</i> = &#955;). Probably, this is caused by a strong Dicke narrowing regime when <i>L</i> = &#955;/2. Several additional differences of fluorescence and absorption spectra behaviour at high intensities are revealed.