Mode Competition in High-Power Homogeneously Broadened Lasers

Abstract

Study of mode competition of transverse modes in a high-power homogeneously broadened gas laser with confocal geometry reveals that all transverse modes will be excited by a corresponding longitudinal mode. This applies from very low operating levels all the way to the highly saturated region of operation. Physically the reason is due to the presence of excited atoms along the transverse dimensions of the laser where modes overlap spatially. When apertures are inserted to increase the losses in the higher-order modes, these atoms are not available to supply energy to the desired single mode so that the total output power will be decreased when one goes from multimode to single-mode operation.