title: Purely wavelength- and amplitude-modulated quartz-enhanced photoacoustic spectroscopy.
abstract: We report here on a quartz-enhanced photoacoustic (QEPAS) sensor employing a quantum cascade laser (QCL) structure capable of operating in a pure amplitude or wavelength modulation configuration. The QCL structure is composed of three electrically independent sections: Gain, Phase (PS) and Master Oscillator (MO). Selective current pumping of these three sections allows obtaining laser wavelength tuning without changes in the optical power, and power modulation without emission wavelength shifts. A pure QEPAS amplitude modulation condition is obtained by modulating the PS current, while pure wavelength modulation is achieved by modulating simultaneously the MO and PS QCL sections and slowly scanning the DC current level injected in the PS section.
authors.forename: Pietro
authors.initials: P
authors.lastname: Patimisco
authors.forename: Angelo
authors.initials: A
authors.lastname: Sampaolo
authors.forename: Yves
authors.initials: Y
authors.lastname: Bidaux
authors.forename: Alfredo
authors.initials: A
authors.lastname: Bismuto
authors.forename: Marshall
authors.initials: M
authors.lastname: Scott
authors.forename: James
authors.initials: J
authors.lastname: Jiang
authors.forename: Antoine
authors.initials: A
authors.lastname: Muller
authors.forename: Jerome
authors.initials: J
authors.lastname: Faist
authors.forename: Frank K
authors.initials: FK
authors.lastname: Tittel
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Spagnolo