CW and passively Q-switched 1064-nm laser emission of concentrated Nd:YAG components under 885-nm diode laser pumping

Summary form only given. Reports the results on 1064 nm emission in concentrated Nd:YAG components under pumping with a diode laser into the thermally activated band at 885 nm. The pump was made with a fiber array packaged diode bar FAP-81-16C-800B laser, whose output is a 19-fiber bundle contained within an 800 /spl mu/m diameter aperture and NA = 0.16. The 1064-nm CW laser emission results for a 3.0 mm long 2.4 at.% Nd:YAG single crystal are shown The maximum slope efficiency of 0.64 was obtained for the 90% reflectivity output mirror with a corresponding emission threshold of /spl sim/1.5 W. With a 95% reflectivity output mirror the slope efficiency decreases to 0.62, however with a reduced threshold of /spl sim/0.9 W. Employing the 95% reflectivity output mirror, the slope efficiency for the 3.5 at.% Nd:YAG crystal was 0.49 with 0.7 W absorbed power at threshold; slope efficiencies of 0.43 and 0.42 were obtained for the 3.8 at.% Nd:YAG ceramics of 1.5 and 2.5 mm thickness, respectively, with threshold powers of 1.2 and 1.6 W. The Q-switch regime was investigated with Cr/sup 4+/:YAG saturable absorber as passive Q-switch. Employing a Cr/sup 4+/:YAG crystal of 90% initial transmission, which was placed close to the 90% reflectivity output mirror of a 90 mm length plane-plane resonator, an average output power of 0.9 W resulted at 5.2 W absorbed power for the 2.4 at.% Nd:YAG crystal; the transverse mode distribution was Gaussian.