Investigation of the Beam Quality of a Compact Non-Chain Pulsed DF Laser with a Confocal Positive Branch Unstable Resonator

The results of detailed studies on the beam quality of a non-chain pulsed electric discharged DF laser based on a compact inner cavity confocal positive branch unstable resonator were presented herein. The theoretical and experimental divergence angles for magnification M = 1.65, 1.85, 2.05, and 2.25 were calculated according to Fraunhofer diffraction and measured by the method of calibrated apertures. The smallest divergence of theta = 0.66 mrad was obtained with M = 2.25 in our experiment, which is 1.95 times the theoretical value. The corresponding far-field energy density at 10 km distance from the laser exit was 82.8 mJ/m(2). The beam quality and energy density were increased by 11 and 91 times, respectively, compared with a similar stable resonator in our lab.