Berlin 2001 – scientific programme

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Q: Quantenoptik

Q 32: Poster: Laser Spectroscopy

Q 32.8: Poster

Friday, April 6, 2001, 12:30–15:00, AT2

The measurement of broadband absorption by intracavity laser spectroscopy — •Evgeny Ovchinnikov and Valery Baev — Institut für Laser-Physik, Universität Hamburg, Jungiusstr.9, 20355 Hamburg

The emission spectrum of a multimode laser is very sensitive to intracavity absorption, if the absorptive linewidth does not exceed the homogeneous linewidth of the gain [1]. This condition is fulfilled with gaseous absorbers of small molecules placed in most broadband lasers. When, however, liquid or solid-state absorbers are placed in the laser cavity, the sensitivity may significantly drop. This feature is experimentally studied, simulating the weak intracavity absorption inside of Nd- and Yb- doped fibre lasers with extended cavity by a low-loss glass etalon with variable base. The sensitivity of a Nd-doped fibre laser drops by several orders of magnitude, if the etalon base is less than 50 µm, i.e. with the spectral loss more than 5 nm wide. In contrast, an Yb-doped fibre laser shows sensitivity reduction only when the etalon base is ten times smaller, providing that the Yb-doped fibre laser has larger homogeneous broadening and is better suited for sensitive measurements of broadband intracavity absorption.

[1] V.M.Baev, T.Latz, P.E.Toschek, Applied Physics B 69, 171 (1999).