Cs vapour cells: absorption and fluorescence may vary by several orders of magnitude

Summary form only given. We have studied the absorption and fluorescence of the D/sub 2/ line [6S/sub 1/2/(F=3,4)-6P/sub 3/2/(F=2,3,4.5)] in dilute Cs atomic vapour for 3 vapour cells: an extremely thin cell with a column length of 8 /spl mu/m, a 16.5 mm-long cell with pure Cs vapour, and a 10.4 mm-long Cs cell containing 40 Torr of Ne. A laser diode with a 20 MHz-linewidth and the maximum intensity of 40 mW/cm/sup 2/ was used. In order to have a comparable peak absorption (for the case of low laser intensity), the extremely thin cell was heated to /spl sim/100/spl deg/C. The effective absorption cross-sections of these cells versus laser intensity are shown. It is important to note that the same behaviour was observed for the resonance fluorescence. The effect of optical pumping of Zeeman sublevels, leads to a dramatically different behaviour of absorption for the /spl nu//sub 3/ and the /spl nu//sub 4/ transitions at a laser intensity /spl ges/0.1 mW/cm/sup 3/ and the absorption of /spl nu//sub 3/ is very sensitive to the presence of a weak external magnetic field. Meanwhile, there is no hint for this effect both for the extremely thin and the buffer gas-filled cells.