Abstract

Gas detection based on direct optical absorption spectroscopy using single frequency distributed feedback (DFB) laser diodes is a well established sensing technique. Only recently, vertical cavity surface emitting lasers (VCSELs) which also provide narrow single frequency emission and arc considered suitable for these sensing applications have become available. We compare such laser structures for use in high sensitivity gas sensing applications and report on some key device characteristics which influence the relative performance of the two laser types for low gas detection limits by targeting the R and P rotational branches of the A band of Oxygen in the b¹Σ⁺g<− X³Σ⁻g electronic transition which is centred at 762 nm.

© 1996 IEEE