Stuttgart 2012 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 42: Laseranwendungen: Spektroskopie und Lebenswiss.

Q 42.3: Vortrag

Donnerstag, 15. März 2012, 11:00–11:15, V38.04

Real Time Monitoring of Exhaled Breath Using Intracavity Absorption Spectroscopy with an Er-Doped Fiber Laser — •Peter Fjodorow, Luis Leal, Benjamin Löhden, Svetlana Kuznetsova, Ortwin Hellmig, Klaus Sengstock, and Valery Baev — Institut für Laserphysik, Universität Hamburg, Germany

Human breath contains more than 1000 molecules, mostly at low concentrations that range from ppm to ppt. Some of these molecules are related to the person’s health condition and allow to identify various diseases. Since most of the relevant molecules in human breath are present in a low concentration, their monitoring requires a very high sensitivity. Broadband laser intracavity absorption spectroscopy (ICAS) [1], is a very effective way to perform multicomponent absorption measurements with a very high sensitivity and time resolution. We present here our first results on sensitive time-resolved measurements of CO₂ absorption spectra in human breath in the cavity of a broadband Er³⁺- doped fiber laser, which emits in the range of 1.52 - 1.62 µm [2]. The concentration of CO₂ is determined by evaluating 12 absorption lines from 1.576 to 1.582 µm. The time evolution of the CO₂ concentration in human breath is measured at normal conditions and after smoking a cigarette. The effective absorption path length of L_eff = 6 km is determined by the laser pulse duration of 20 µs. By choosing a higher sensitivity, monitoring of other important molecules, e.g. CO, C₂H₂, HCN, NH₃, is possible.

[1] V. M. Baev et al., Appl. Phys. B 69, 171 (1999).

[2] B. Löhden et al., Appl. Phys. B, 102, 331 (2011).