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Proceedings Paper

Laser frequency stability: a simple approach for a quantitative analysis
Author(s): Alexandre Cabral; Manuel Abreu; José M. Rebordão
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Paper Abstract

The characterization of the laser linewidth and laser frequency stability is critically important for the evaluation of a metrology system performance when the working principle is based in interferometric processes. In particular, the midterm stability range, corresponding to noise in the hundreds of hertz to kilohertz bandwidth, affects strongly the measurement final accuracy when working at measurement rates at the ksample/s level. In this case, it is of crucial importance to know the uncertainty associated to the measurement of the laser instantaneous frequency and what is the variance of this value within the measurement period. In this paper we present a simple method to measure the frequency noise and obtain the Allan variance statistics for an External Cavity Diode Laser (ECDL) used in a Frequency Sweeping Interferometry (FSI) scheme for long distance high accuracy measurements. For this type of lasers, the main contributors affecting the midterm stability are the current and technical noise, including thermal and mechanical fluctuations, optical feedback, as well as the feedback stabilization techniques employed to reduce acoustic disturbances. The proposed method is based in the principle of delayed interferometry, where the variation of the laser center frequency is characterized for measurement conditions in the kilohertz range. The final accuracy of the metrology system is evaluated in accordance with the laser stability characteristics obtained by this method.

Paper Details

Date Published: 26 July 2011
PDF: 8 pages
Proc. SPIE 8001, International Conference on Applications of Optics and Photonics, 80010V (26 July 2011); doi: 10.1117/12.890751
Show Author Affiliations
Alexandre Cabral, Univ. of Lisbon (Portugal)
Manuel Abreu, Univ. of Lisbon (Portugal)
José M. Rebordão, Univ. of Lisbon (Portugal)

Published in SPIE Proceedings Vol. 8001:
International Conference on Applications of Optics and Photonics
Manuel Filipe Costa, Editor(s)

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