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Title: Multiplexed gas spectroscopy using tunable VCSELs

Abstract

Detection and identification of gas species using tunable laser diode laser absorption spectroscopy has been performed using vertical cavity surface emitting lasers (VCSEL). Two detection methods are compared: direct absorbance and wavelength modulation spectroscopy (WMS). In the first, the output of a DC-based laser is directly monitored to detect for any quench at the targeted specie wavelength. In the latter, the emission wavelength of the laser is modulated by applying a sinusoidal component on the drive current of frequency {omega}, and measuring the harmonics component (2{omega}) of the photo-detected current. This method shows a better sensitivity measured as signal to noise ratio, and is less susceptible to interference effects such as scattering or fouling. Gas detection was initially performed at room temperature and atmospheric conditions using VCSELs of emission wavelength 763 nm for oxygen and 1392 nm for water, scanning over a range of approximately 10 nm, sufficient to cover 5-10 gas specific absorption lines that enable identification and quantization of gas composition. The amplitude and frequency modulation parameters were optimized for each detected gas species, by performing two dimensional sweeps for both tuning current and either amplitude or frequency, respectively. We found that the highest detected signal is observedmore » for a wavelength modulation amplitude equal to the width of the gas absorbance lines, in good agreement with theoretical calculations, and for modulation frequencies below the time response of the lasers (<50KHz). In conclusion, we will discuss limit of detection studies and further implementation and packaging of VCSELs in diode arrays for continuous and simultaneous monitoring of multiple species in gaseous mixtures.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1046102
Report Number(s):
LLNL-JRNL-548132
Journal ID: ISSN 0277-786X; PSISDG; TRN: US201216%%81
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Journal Name:
Proceedings of SPIE - The International Society for Optical Engineering
Additional Journal Information:
Journal Volume: 8366; Journal ID: ISSN 0277-786X
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ABSORPTION SPECTROSCOPY; DETECTION; FREQUENCY MODULATION; GAS ANALYSIS; MODULATION; SIGNAL-TO-NOISE RATIO; SPECTROSCOPY; WAVELENGTHS

Citation Formats

Bond, T, Bond, S, McCarrick, J, Zumstein, J, Chang, A, Moran, B, and Benett, W J. Multiplexed gas spectroscopy using tunable VCSELs. United States: N. p., 2012. Web.
Bond, T, Bond, S, McCarrick, J, Zumstein, J, Chang, A, Moran, B, & Benett, W J. Multiplexed gas spectroscopy using tunable VCSELs. United States.
Bond, T, Bond, S, McCarrick, J, Zumstein, J, Chang, A, Moran, B, and Benett, W J. Tue . "Multiplexed gas spectroscopy using tunable VCSELs". United States. https://www.osti.gov/servlets/purl/1046102.
@article{osti_1046102,
title = {Multiplexed gas spectroscopy using tunable VCSELs},
author = {Bond, T and Bond, S and McCarrick, J and Zumstein, J and Chang, A and Moran, B and Benett, W J},
abstractNote = {Detection and identification of gas species using tunable laser diode laser absorption spectroscopy has been performed using vertical cavity surface emitting lasers (VCSEL). Two detection methods are compared: direct absorbance and wavelength modulation spectroscopy (WMS). In the first, the output of a DC-based laser is directly monitored to detect for any quench at the targeted specie wavelength. In the latter, the emission wavelength of the laser is modulated by applying a sinusoidal component on the drive current of frequency {omega}, and measuring the harmonics component (2{omega}) of the photo-detected current. This method shows a better sensitivity measured as signal to noise ratio, and is less susceptible to interference effects such as scattering or fouling. Gas detection was initially performed at room temperature and atmospheric conditions using VCSELs of emission wavelength 763 nm for oxygen and 1392 nm for water, scanning over a range of approximately 10 nm, sufficient to cover 5-10 gas specific absorption lines that enable identification and quantization of gas composition. The amplitude and frequency modulation parameters were optimized for each detected gas species, by performing two dimensional sweeps for both tuning current and either amplitude or frequency, respectively. We found that the highest detected signal is observed for a wavelength modulation amplitude equal to the width of the gas absorbance lines, in good agreement with theoretical calculations, and for modulation frequencies below the time response of the lasers (<50KHz). In conclusion, we will discuss limit of detection studies and further implementation and packaging of VCSELs in diode arrays for continuous and simultaneous monitoring of multiple species in gaseous mixtures.},
doi = {},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
issn = {0277-786X},
number = ,
volume = 8366,
place = {United States},
year = {2012},
month = {4}
}