Laser gain profiling with uniform-field electrodes

Abstract

The small‐signal gain was measured in a uv‐sustained CO₂ laser amplifier employing uniform‐field electrodes of the type used by Chang. Four different profiles were utilized and the spatial distribution of the gain differed for each profile. For a given electrode shape there was an input energy which produced a region of constant gain. A dip or saturation of the gain occurred at the center of the discharge if the input energy exceeded the optimum value, while a monotonic decrease in gain away from the discharge center was produced below this value. The dip in the gain distribution appears to be caused mainly by thermal heating of the gas. The flatter electrode profiles produced wider uniform gain distributions and less saturation because less heating occurred.