Heidelberg 1999 – scientific programme
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Q: Quantenoptik
Q 26: Poster: Laserspektroskopie
Q 26.11: Poster
Tuesday, March 16, 1999, 16:30–18:30, PH
Effects of Finite Laser Beam Diameter in Absorption in an Alkali Metal Vapour Cell — •Arno Huss1, Igor E. Mazets2, Leonid B. Shifrin3, Eugeny A. Korsunsky1, and Laurentius Windholz1 — 1Inst. f. Experimentalphysik, TU Graz, Graz, Austria — 2Ioffe Phys. Tech. Inst., St.Petersburg, Russia — 3St.Petersburg State TU, St.Petersburg, Russia
We present a theory describing propagation of laser light in an alkali-metal vapour cell accounting for effects of optical pumping of atoms to the ground state hyperfine sublevel which is out of resonance with the narrow-band laser radiation. In such a situation atoms which cross the light beam contribute to absorption mainly in the peripherial (outermost) region of the beam. The light intensity near the beam symmetry axis is not attempted significantly. Hence, the intensity-decrease law cannot be described by the exponential Beer’s law unless the optical density exceeds by orders of magnitude the product of two values: (i) the optical pumping rate into the ground state, (ii) mean time of flight of an atom across the light beam at the cell entrance. The theory presented here is also compared with measurements made in a sodium vapour cell.