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Effect of noise-induced wavelength fluctuation in tunable diode lasers on narrow-linewidth absorption measurements

Krishna, Yedhu and O'Byrne, Sean and Munuswamy, Kannan and Jagadeesh, Gopalan (2018) Effect of noise-induced wavelength fluctuation in tunable diode lasers on narrow-linewidth absorption measurements. In: APPLIED OPTICS, 57 (17). pp. 4943-4949.

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Official URL: https://dx.doi.org/ 10.1364/AO.57.004943


Tunable diode laser absorption spectroscopy is being widely used to make sensors for diagnostic purposes in various engineering applications. Since the wavelength of many diode lasers used in such sensors is sensitive to the driving current, even noise as small as a few mu A(rms) in the driving current can cause a wavelength fluctuation of similar to +/- 0.5 pm, which is large enough to interfere with sensitive absorption measurements. Although these fluctuations are small, they can cause significant systematic error in measured absorption spectra in applications where the absorption line probed is narrow, as is the case for low-density hypersonic flows. As an example, at a pressure of 300 Pa and 297 K, the error in the full width at half-maximum was +/- 6.5% in an absorption spectrum obtained using a system based on a vertical-cavity surface-emitting laser scanned at 10 kHz. This paper analyzes the effect of such systematic errors on measured temperature and velocity and suggests some remedial measures. (C) 2018 Optical Society of America

Item Type: Journal Article
Additional Information: Copyright of this article belong to OPTICAL SOC AMER, 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Depositing User: Id for Latest eprints
Date Deposited: 03 Jul 2018 14:49
Last Modified: 03 Jul 2018 14:49
URI: http://eprints.iisc.ac.in/id/eprint/60127

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