Berlin 2001 – wissenschaftliches Programm

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MO: Molekülphysik

MO 14: Spektroscopy II

MO 14.3: Vortrag

Freitag, 6. April 2001, 16:15–16:30, H1058

Photoacoustic detection of water vapour absorption in multi-mode thulium-doped fibre laser — •Arnold Stark, Luis Correia, Valery Baev, and Peter Toschek — Institut für Laser-Physik, Universität Hamburg, Jungiusstr.9, 20355 Hamburg

External photoacoustic detection of intra-cavity absorption implemented with a multi-mode dye laser allows the detection of molecular gases absorbing in the visible [1]. Versatility and increased sensitivity require a small-size laser operating in the infra-red. For highly sensitive detection of water vapour we use a diode-pumped, thulium-doped fibre laser that includes an absorption cell and is tuneable from 1.7 to 2 µm. The laser emission spectrum is several nanometers wide and is structured by many absorption lines of water vapour [2]. The stabilised mean laser wavelength, 1.85 µm, is modulated at 4 kHz by electromagnetically moving the intra-cavity lens back and forth. The modulated absorption signal is detected by an external photoacoustic cell. With this compact and stable set-up sub-ppb detection of water vapour is feasible.

[1] T.J.Latz, G.Weirauch, V.M.Baev, P.E.Toschek, Appl.Opt. 38, 2625 (1999).

[2] M.Teichmann, A.Stark, C.Larsen, V.M.Baev, P.E.Toschek, Verhandl. DPG (VI) 34, 405, Q21.6 (1999).