Open AccessDoppler-broadened fiber-laser-based NICE-OHMS – Improved detectability
Author(s) -
Florian M. Schmidt,
Aleksandra Foltynowicz,
Weiguang Ma,
Tomas Lock,
Ove Axner
Publication year - 2007
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.15.010822
Subject(s) - optics , finesse , heterodyne detection , materials science , laser , fiber laser , doppler effect , detection limit , heterodyne (poetry) , dispersion (optics) , absorption (acoustics) , wavelength , fabry–pérot interferometer , physics , chemistry , chromatography , astronomy , acoustics
The performance of fiber-laser-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) has been improved by elimination of the technical constraints that limited its first demonstration. Doppler-broadened detection of C(2)H(2) and CO(2) at ~1531 nm is demonstrated using a cavity with a finesse of 4800. Frequency and wavelength modulated detection at absorption and dispersion phase are compared and the optimum mode of detection is discussed. A minimum detectable absorption of 8 x 10-(11) cm(-1), which corresponds to a detection limit of 4.5 ppt (2 ppt.m) for C(2)H(2), was obtained for an acquisition time of 0.7 s by lineshape fitting. The linearity of the pressure dependence of the signal strengths is investigated for both C(2)H(2) and CO(2).