Use of rotational sideband absorption for high sensitivity methane detection with a 1.64 μm DFB laser

Abstract

High sensitivity methane detection using a 1.64 μm DFB laser in the rotational sideband of the 2v3 overtone region is demonstrated. A sensitivity of 2 ppm.m was achieved which is comparable with recent measurements in the purely vibrational Q branch and therefore relaxes the wavelength constraints of DFB lasers for methane sensing.