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Optical Engineering

Applications of spectral analysis and filter design in laser frequency locking for Na Doppler lidars
Author(s): John Anthony Smith; Xinzhao Chu; Wentao Huang; Bo Tan
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Paper Abstract

A dye ring laser is stabilized to a D2a Doppler-free feature of sodium vapor using a LabVIEW®-based, phase-sensitive servo. Locking precision and stability, at better than ±1 MHz, are suitable for Na lidar applications. This performance was achieved with improved digital filtering and new approaches to the problem. The inverse (type II) Chebyshev discrete filter employed demonstrates superior filtering and computational efficiency plus improved flexibility. New approaches include the determination of optimum modulation frequency, laser-tuning sensitivity, and bandwidth requirements via spectral analyses of the noise spectrum, derivative scan, and modulated spectrum. This practice guides a user in selecting the system operation parameters and negotiating the trade-offs involved when expanding the filter's passband. Allan deviation plots provide a quantitative description of the short- and long-term frequency excursions. A comparison of Allan deviation plots before and after locking shows a substantial improvement in stability throughout time scales from 0.10 to 10 s.

Paper Details

Date Published: 1 October 2009
PDF: 7 pages
Opt. Eng. 48(10) 104301 doi: 10.1117/1.3251080
Published in: Optical Engineering Volume 48, Issue 10
Show Author Affiliations
John Anthony Smith, Cooperative Institute for Research in Environment Sciences (United States)
Xinzhao Chu, Univ. of Colorado at Boulder (United States)
Wentao Huang, Cooperative Institute for Research in Environment Sciences (United States)
Bo Tan, Cooperative Institute for Research in Environment Sciences (United States)

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