title: Novel Helmholtz-based photoacoustic sensor for trace gas detection at ppm level using GaInAsSb/GaAlAsSb DFB lasers.
abstract: A new and compact photoacoustic sensor for trace gas detection in the 2-2.5 microm atmospheric window is reported. Both the development of antimonide-based DFB lasers with singlemode emission in this spectral range and a novel design of photoacoustic cell adapted to the characteristics of these lasers are discussed. The laser fabrication was made in two steps. The structure was firstly grown by molecular beam epitaxy then a metallic DFB grating was processed. The photoacoustic cell is based on a Helmholtz resonator that was designed in order to fully benefit from the highly divergent emission of the antimonide laser. An optimized modulation scheme based on wavelength modulation of the laser source combined with second harmonic detection has been implemented for efficient suppression of wall noise. Using a 2211 nm laser, sub-ppm detection limit has been demonstrated for ammonia.
authors.affiliation: Omnisens SA, Science Park, CH-1015 Lausanne, Switzerland. Mario.Mattiello@epfl.ch
authors.forename: Mario
authors.initials: M
authors.lastname: Mattiello
authors.forename: Marc
authors.initials: M
authors.lastname: Niklès
authors.forename: Stéphane
authors.initials: S
authors.lastname: Schilt
authors.forename: Luc
authors.initials: L
authors.lastname: Thévenaz
authors.forename: Abdelmajid
authors.initials: A
authors.lastname: Salhi
authors.forename: David
authors.initials: D
authors.lastname: Barat
authors.forename: Aurore
authors.initials: A
authors.lastname: Vicet
authors.forename: Yves
authors.initials: Y
authors.lastname: Rouillard
authors.forename: Ralph
authors.initials: R
authors.lastname: Werner
authors.forename: Johannes
authors.initials: J
authors.lastname: Koeth
mesh_terms: D000162:Acoustics; D000641:Ammonia; D005740:Gases / Q000032:analysis*; D007834:Lasers; D008027:Light; D010783:Photometry; D011789:Quantum Theory; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods; D014159:Transducers
chemical_list: D005740:Gases; D000641:Ammonia