Sensitive detection of methane via absorption spectroscopy using a mid-infrared DFB interband cascade laser

We have demonstrated sensitive detection of methane using an absorption spectrometer based on a mid-infmred DFB Intehand Cascade laser at 3.47 microns. Using balanced ratiometric detection, we demonstrated a minimum measurable peak absorption of 4 x for the line at 2878.362 cm-'. 02002 Optical Society of America OCIS codes: (300.6340) Spectroscopy, infrared; (300.1030) Absorption; (140.3490) Lasers, distributed-feedback