Paper
17 May 2011 Fibre lasers for photo-acoustic gas spectroscopy
Norhana Arsad, George Stewart
Author Affiliations +
Proceedings Volume 7753, 21st International Conference on Optical Fiber Sensors; 77533L (2011) https://doi.org/10.1117/12.884944
Event: 21st International Conference on Optical Fibre Sensors (OFS21), 2011, Ottawa, Canada
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.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Norhana Arsad and George Stewart "Fibre lasers for photo-acoustic gas spectroscopy", Proc. SPIE 7753, 21st International Conference on Optical Fiber Sensors, 77533L (17 May 2011); https://doi.org/10.1117/12.884944
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KEYWORDS
Modulation

Fiber lasers

Absorption

Spectroscopy

Acoustics

Fiber Bragg gratings

Optical amplifiers

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