title: 30% improvement in absorption spectroscopy detectivity achieved by the detuned loading of a quantum cascade laser.
abstract: We perform a direct absorption spectroscopy experiment of carbon monoxide at 2193  cm(-1) by exploring the detectivity improvement potential of an intensity noise (IN)-reduced distributed feedback (DFB) quantum cascade laser. This was achieved by a detuned loading approach via a short, phase-sensitive optical feedback cavity. Under optimum IN reduction conditions, we obtain an improvement in signal-to-noise ratio from 733 to 1048, which transfers into a detection limit improvement from 1.2 ppm to 840 ppb. Therefore, we achieve a 30% lower detection limit, with the IN reduced when compared to the free-running case.
authors.forename: Florian
authors.initials: F
authors.lastname: Michel
authors.forename: Carsten
authors.initials: C
authors.lastname: Juretzka
authors.forename: Mathieu
authors.initials: M
authors.lastname: Carras
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Elsäßer