Extension of wavelength-modulation spectroscopy to large modulation depth for diode laser absorption measurements in high-pressure gases

Applied Optics
Hejie LiR K Hanson

Abstract

Tunable diode laser absorption measurements at high pressures by use of wavelength-modulation spectroscopy (WMS) require large modulation depths for optimum detection of molecular absorption spectra blended by collisional broadening or dense spacing of the rovibrational transitions. Diode lasers have a large and nonlinear intensity modulation when the wavelength is modulated over a large range by injection-current tuning. In addition to this intensity modulation, other laser performance parameters are measured, including the phase shift between the frequency modulation and the intensity modulation. Following published theory, these parameters are incorporated into an improved model of the WMS signal. The influence of these nonideal laser effects is investigated by means of wavelength-scanned WMS measurements as a function of bath gas pressure on rovibrational transitions of water vapor near 1388 nm. Lock-in detection of the magnitude of the 2f signal is performed to remove the dependence on detection phase. We find good agreement between measurements and the improved model developed for the 2f component of the WMS signal. The effects of the nonideal performance parameters of commercial diode lasers are especially important away...Continue Reading

References

Sep 7, 2001·Measurement Science & Technology·M G Allen
Sep 7, 2001·Applied Optics·D RichterF K Tittel
Dec 9, 2003·Applied Optics·Stéphane SchiltPhilippe Robert

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Citations

Jun 1, 2015·The Review of Scientific Instruments·Madison A KelleyJason M Porter
Dec 3, 2016·Optics Express·Torrey R S Hayden, Gregory B Rieker
Jan 22, 2015·Applied Optics·Avishek Guha, Ingmar Schoegl
Nov 25, 2018·Optics Express·Yanjun DuYanjun Ding
Jun 16, 2018·Optics Letters·Pedro Martín-MateosCristina Gutiérrez-Escobero
Nov 22, 2018·Applied Optics·Joshua M WeisbergerPaul E DesJardin
Nov 24, 2011·Optics Express·Peng ZhiminZheng Kangjie
May 6, 2019·Optics Express·S M ButlerS P Hegarty

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