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Stable, tunable and single-mode operation of an erbium-doped fibre laser system using a saturable absorber for gas spectroscopy applications

Arsad, N. and Stewart, G. (2009) Stable, tunable and single-mode operation of an erbium-doped fibre laser system using a saturable absorber for gas spectroscopy applications. Proceedings of SPIE: The International Society for Optical Engineering, 7195. p. 719525. ISSN 0277-786X

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Abstract

We present an erbium doped fibre ring laser system to realize single frequency lasing by incorporating a reflector with ~2m of un-pumped polarization-maintaining erbium-doped fibre to act as a saturable absorber. Depending on the particular requirements, the fibre reflector may be a fibre Bragg grating (FBG), loop mirror (LM) or a reflective coating on the fibre end. In this way, a transient grating is formed in the saturable absorber which acts as a narrow-band optical filter, reducing the number of modes over which the laser can operate and hence suppressing mode hopping in the cavity. Polarization-maintaining (PM) components are used throughout the system, except for the EDFA, and a polarization controller is used for enhancing stability and to ensure that the state of polarization is properly aligned. With this system we have observed a long period of stable, narrow line-width and single mode operation, tuneable over 30nm. The intended application is for gas spectroscopy using wavelength scanning and pump modulation. A Sagnac loop filter (SLF) can be used to scan the centre wavelength over a gas absorption line while the pump modulation produces an amplitude modulated signal on the output, suitable for detection by a lock-in (phase-sensitive) amplifier. The method is useful for the recovery of absorption line-shapes in the near-IR where the overtone absorption lines are weak. Compared with the use of a traditional DFB laser source, the fibre laser offers the advantages of a much broader tuning range and recovery of distortion-free line-shapes since wavelength and amplitude modulation may be performed independently

Item type: Article
ID code: 14444
Keywords: spectroscopy, lasers, Electrical engineering. Electronics Nuclear engineering, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Electrical and Electronic Engineering, Applied Mathematics, Computer Science Applications
Subjects: Technology > Electrical engineering. Electronics Nuclear engineering
Department: Faculty of Engineering > Electronic and Electrical Engineering
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Depositing user: Strathprints Administrator
Date Deposited: 05 Oct 2010 10:45
Last modified: 08 Jul 2014 05:01
URI: http://strathprints.strath.ac.uk/id/eprint/14444

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