Time-varying beam quality factor and mode evolution in TEA CO_2 laser pulses

Abstract

The time evolution of the transversal modes in a TEA CO_2 laser cavity has been investigated from the analysis of the time-varying beam quality factor M^2 of the emitted pulses. The experiments reveal a significant change in this parameter during the pulse evolution, which can be translated into an evolution of the modes of the laser cavity to reach a nearly stationary behavior. Attention is focused on both the appearance of a particular mode and the duration of its growing process.