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Proceedings Paper

Semiconductor lasers used as the metrology source in Fourier-transform spectrometers: effect of their noise
Author(s): Caroline S. Turcotte; Pierre Tremblay; Jerome E Genest
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Paper Abstract

Spaceborne Fourier-transform spectrometers must use a reliable metrology source to replace the conventional HeNe laser acting as the spatial sampling reference in ground instruments. Because of their lifetime and ruggedness, semiconductor lasers appear to be ideal candidates. However the fringe signal resulting from a semiconductor laser exhibits a noisier behavior than the one from an HeNe laser. This results in more important sampling errors. We present the effect of the phase and intensity noises of semiconductor lasers upon the quality of the reference fringe signal. The semiconductor laser is modelized using a standard rate equations approach, which gives rise to coupled intensity and phase fluctuations. The laser field is sent in a scanning Michelson interferometer modelized as a variable time delay applied to the field in one arm. The recombined field is sent to a fast photodetector, resulting in a noisy fringe signal. We evaluate the signal-to-noise ratio which is used as a measure of the error made when using the zero crossings of the metrology source as a sampling reference. It relies on the noise characteristics of the laser, the optical path differences of the interferometer and the bandwidth of the photodetector. Both theoretical predictions and simulation results are shown.

Paper Details

Date Published: 8 October 1998
PDF: 13 pages
Proc. SPIE 3415, Laser Diodes and Applications III, (8 October 1998); doi: 10.1117/12.326627
Show Author Affiliations
Caroline S. Turcotte, COPL/Univ. Laval (Canada)
Pierre Tremblay, COPL/Univ. Laval (Canada)
Jerome E Genest, COPL/Univ. Laval (Canada)

Published in SPIE Proceedings Vol. 3415:
Laser Diodes and Applications III
Pierre Galarneau, Editor(s)

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