Abstract

The output power tends to transiently decrease with discharge time in a dc electrically pumped fast axial-flow (FAF) CO laser. This output reduction is mainly caused by both the temperature rise of gas mixture and deactivation of the excited CO molecule due to its dissociation into CO₂ and O₂ molecules.¹ Especially, the latter seems to be predominant in the room temperature operated FAF CO laser system. The gas temperature rise due to the discharge can be compensated by fast gas-circulation through a heat exchanger along with either ethanol/dry ice coolants (or liquid nitrogen at subroom temperature operation) , whereas the CO₂ molecules generated through the discharge process cannot be avoided at room temperature operation, though, it is well trapped with a cold trap of liquid nitrogen. Thus, we shall try to recover the output reduction transiently induced above by adsorbing the generated CO₂ molecules by molecular sieve for the room temperature operation together with theoretical explanation. In addition, we shall also examine how the laser parameters such as the small-signal gain γ_0.v saturation intensity I_s and a measure of partial homogeneity m are influenced with insertion of molecular sieve.

© 1998 IEEE