Techniques for measuring small changes in the intensity of a pulsed laser

Several techniques are described that compensate for the pulse-to-pulse laser fluctuations that occur when small absorption or gain measurements are taken with pulsed lasers. The best approach tested used two matched diodes that were mounted in a bridge circuit with their bias batteries. One diode w...

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Bibliographic Details
Published in:Applied optics (2004) 1992-05, Vol.31 (15), p.2814-2819
Main Authors: Borysow, J, Golnabi, H, Taylor, R H, Keto, J W
Format: Article
Language:English
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Summary:Several techniques are described that compensate for the pulse-to-pulse laser fluctuations that occur when small absorption or gain measurements are taken with pulsed lasers. The best approach tested used two matched diodes that were mounted in a bridge circuit with their bias batteries. One diode was illuminated by a single beam, and a second was illuminated by a reference beam. The bridge circuit output forms the difference in the two laser intensities. Using pulsed lasers with 8-ns widths, we observed that the error in subtraction was 0.01% of the pulse area. This was only 1.5 times the shot noise of the pulses. The technique is examined for application to Raman-induced Kerr-effect spectroscopy, in which difficulties arise because of the use of polarization-sensitive detection.
ISSN:1559-128X
DOI:10.1364/AO.31.002814