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Proceedings Paper

Fibre lasers for photo-acoustic gas spectroscopy
Author(s): Norhana Arsad; George Stewart
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Paper Abstract

We report here on the use of fiber lasers for recovery of gas absorption line shapes by photo-acoustic spectroscopy. We demonstrate the principle of operation using an erbium-doped fiber, stabilized using a length of un-pumped doped fibre as a saturable absorber. Intensity modulation of the laser output for phase sensitive detection is performed by modulation of the pump current while the wavelength is scanned through the absorption line by a PZT on a fibre Bragg grating. This avoids the distortions that arise in recovered signals due to simultaneous wavelength and intensity modulation, as is the case with conventional DFB diode lasers. Furthermore, the near zero off-line signals with photo-acoustic spectroscopy means that high modulation indices can be used with simple intensity modulation of the fiber laser output. The modulation frequency is set to the acoustic resonance frequency of the gas cell and measurements are made on the P17 absorption line of acetylene at 1535.39nm showing good agreement with the theoretical line-shape profile.

Paper Details

Date Published: 17 May 2011
PDF: 4 pages
Proc. SPIE 7753, 21st International Conference on Optical Fiber Sensors, 77533L (17 May 2011); doi: 10.1117/12.884944
Show Author Affiliations
Norhana Arsad, Univ. of Strathclyde (United Kingdom)
Univ. Kebangsaan Malaysia (Malaysia)
George Stewart, Univ. of Strathclyde (United Kingdom)


Published in SPIE Proceedings Vol. 7753:
21st International Conference on Optical Fiber Sensors
Jacques Albert; Wojtek J. Bock, Editor(s)

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