Er: YLF Laser Development. Part 2

Growth and laser performance of the laser material ErYLF was investigated. This is a 4 level emitting at 0.85 microns and operated in the flash pumped mode at room temperature. Large, uniform diameter boules of ErYLF have been grown under automatic diameter control in an argon atmosphere. 0.25 x 3 inch rods with scattering loss less than 0.5 1cm and optical path distortion of less than 1 fringe per inch have been routinely grown on this program. The rod yield is limited only by external geometry there are no cores in this material. Boule uniformity and boule-boule reproducibility was excellent. Two feed purification procedures were employed in this program. Comparative laser testing showed a linear increase in laser efficiency with Er concentration from 2 - 5 Er. At 10 Hz, long pulse, 1.1 watts output were measured from a 0.25 x 3 inch rod with a slope efficiency of 0.5 overall efficiency 0.3 at room temperature. Higher output powers were constrained by flashlamp peak current limitations. Q-switched outputs at 12 the long pulse efficiency were obtained.