The development of interband cascade lasers (ICLs) has made the strong C-H transitions in the 3 μm spectral region increasingly accessible. We present the demonstration of a single mode distributed feedback ICL coupled to a V-shaped optical cavity in an optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) experiment. We achieved a minimum detectable absorption coefficient, αmin, of cm−1 for a spectrum of CH4 at 3.24 μm with a two second acquisition time (100 scans averaged). This corresponds to a detection limit of 3 ppb CH4 at atmospheric pressure, which is comparable to previously reported OF-CEAS instruments with diode lasers or quantum cascade lasers. The ability to frequency lock an ICL source in the important 3 μm region to an optical cavity holds great promise for future spectroscopic applications.
Optical feedback cavity-enhanced absorption spectroscopy with a 3.24 μm interband cascade laser
K. M. Manfred, G. A. D. Ritchie, N. Lang, J. Röpcke, J. H. van Helden; Optical feedback cavity-enhanced absorption spectroscopy with a 3.24 μm interband cascade laser. Appl. Phys. Lett. 1 June 2015; 106 (22): 221106. https://doi.org/10.1063/1.4922149
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