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Proceedings Paper

Stable operation of uncoated laser diodes in an extended cavity configuration
Author(s): Peter Kohns
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Paper Abstract

The analysis of process gases is an important task in process control. Optical methods like spectroscopy using laser diodes are very sensitive and work without disturbance of the process. A strong drawback of laser diodes is the appearance of mode hops which limit the tunability and often prevent the emission of the absorption line of a gas component under study. This problem can be solved by stabilizing the laser diode by the optical feedback of a grating, where laser diode and grating form an extended cavity. Usually either expensive antireflex coated laser diodes or additional optics are required to guarantee a stable operation of the extended cavity laser. This paper describes the use of uncoated laser diodes in extended cavity configurations. In order to prevent multimode oscillation the laser diode was used as both the gain medium and a single mode providing etalon. The linewidth of the laser system was in the order of 1 MHz. The laser frequency could be tuned continuously by several GHz by varying the length of the extended cavity without effecting the spectral purity. The laser system is capable to analyze gases of technical interest. As an application we present absorption signals obtained by sending its light beam through water vapor.

Paper Details

Date Published: 17 September 1997
PDF: 7 pages
Proc. SPIE 3098, Optical Inspection and Micromeasurements II, (17 September 1997); doi: 10.1117/12.281203
Show Author Affiliations
Peter Kohns, Optikzentrum NRW (Germany)

Published in SPIE Proceedings Vol. 3098:
Optical Inspection and Micromeasurements II
Christophe Gorecki, Editor(s)

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