Elimination of residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy using an optical fiber delay line

Arup Lal Chakraborty, Keith C. Ruxton, W. Johnstone, Michael Lengden, K. Duffin

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

A new fiber-optic technique to eliminate residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy is presented. The modulated laser output is split to pass in parallel through the gas measurement cell and an optical fiber delay line, with the modulation frequency / delay chosen to introduce a relative phase shift of pi between them. The two signals are balanced using a variable attenuator and recombined through a fiber coupler. In the absence of gas, the direct laser intensity modulation cancels, thereby eliminating the high background. The presence of gas induces a concentration-dependent imbalance at the coupler's output from which the absolute absorption profile is directly recovered with high accuracy using 1f detection.
LanguageEnglish
Pages9602-9607
Number of pages6
JournalOptics Express
Volume17
Issue number12
DOIs
Publication statusPublished - Jun 2009

Fingerprint

delay lines
elimination
optical fibers
semiconductor lasers
modulation
couplers
gases
wavelengths
spectroscopy
attenuators
laser outputs
frequency modulation
fiber optics
phase shift
fibers
output
profiles
cells
lasers

Keywords

  • pressure
  • temperature
  • frequency
  • gases

Cite this

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title = "Elimination of residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy using an optical fiber delay line",
abstract = "A new fiber-optic technique to eliminate residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy is presented. The modulated laser output is split to pass in parallel through the gas measurement cell and an optical fiber delay line, with the modulation frequency / delay chosen to introduce a relative phase shift of pi between them. The two signals are balanced using a variable attenuator and recombined through a fiber coupler. In the absence of gas, the direct laser intensity modulation cancels, thereby eliminating the high background. The presence of gas induces a concentration-dependent imbalance at the coupler's output from which the absolute absorption profile is directly recovered with high accuracy using 1f detection.",
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Elimination of residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy using an optical fiber delay line. / Chakraborty, Arup Lal; Ruxton, Keith C.; Johnstone, W.; Lengden, Michael; Duffin, K.

In: Optics Express, Vol. 17, No. 12, 06.2009, p. 9602-9607.

Research output: Contribution to journalArticle

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AU - Duffin, K.

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KW - temperature

KW - frequency

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