Abstract

Mid-infrared laser diodes are highly attractive sources for gas spectroscopy applications due to the presence of strong absorption lines of many gaseous species in this spectral range. Particularly, the 2.3 - 3.3 μm wavelength range contains strong absorption lines of some pollutants as CH₄, NH₃ or HF while CO₂ and H₂O interference absorption lines are very low which renders possible the highly selective and sensitive detection of these pollutants. Vertical-cavity surface-emitting lasers (VCSELs) appear especially well adapted to be used as laser sources for absorption spectroscopy due to several intrinsic characteristics that they offer. The low threshold, single-mode operation, the circular output beam with low divergence are only some of their well-known advantages.

© 2009 IEEE