Laser demonstration of Yb3Al5O12 (YbAG) and materials properties of highlydoped Yb : YAG

We have demonstrated the first stoichiometric Yb3+ laser based on Yb3Al5O12 (YbAG), The laser operated in pulsed mode with a highest possible duty cyc le of 85%. A slope efficiency of 27%, with respect to absorbed energy, was measured and the free-running lasing wavelength was 1048 nm for a 10% duty cycle. In a systematic analysis, measurements of spectroscopic and material s properties of (YbxY1-x)(3)Al5O12 for nominal x values of 0.05, 0.1, 0.15, 0.18, 0.25, 0.5, and 1 are reported. We also present a formalism to calcul ate the intrinsic fluorescence quantum efficiency (free of radiation trappi ng) and the fraction of reabsorbed light, based on measurements of the bulk and intrinsic emission lifetimes and the fractional thermal loading. Our b est YbAG sample has an intrinsic lifetime of 0.664 ms at 94% quantum effici ency and a thermal conductivity at room temperature of 0.072 W/(cm-K).