Tetragonal rare-earth calcium aluminates, CaLnAlO4 where Ln = Gd or Y (CALGO and CALYO, respectively), are attractive laser crystal hosts due to their locally disordered structure and high thermal conductivity. In the present work, we report on highly-efficient power-scalable microchip lasers based on 8 at.% Yb:CALGO and 3 at.% Yb:CALYO crystals grown by the Czochralski method. Pumped by an InGaAs laser diode at 978 nm, the 6 mm-long Yb:CALGO microchip laser generated 7.79 W at 1057–1065 nm with a slope efficiency of η = 84% (with respect to the absorbed pump power) and an optical-to-optical efficiency of ηopt = 49%. The 3 mm-long Yb:CALYO microchip laser generated 5.06 W at 1048–1056 nm corresponding to η = 91% and ηopt = 32%. Both lasers produced linearly polarized output (σ- polarization) with an almost circular beam profile and beam quality factors M2x,y <1.1. The output performance of the developed lasers was modeled yielding a loss coefficient as low as 0.004-0.007 cm-1. The results indicate that the Yb3+- doped calcium aluminates are very promising candidates for high-peak-power passively Q-switched microchip lasers.
Pavel Loiko, Josep Maria Serres, Xavier Mateos, Xiaodong Xu, Jun Xu, Konstantin Yumashev, Uwe Griebner, Valentin Petrov, Magdalena Aguiló, Francesc Díaz, and Arkady Major, "Highly-efficient multi-watt Yb:CaLnAlO4 microchip lasers," Proc. SPIE 10082, Solid State Lasers XXVI: Technology and Devices, 1008215 (Presented at SPIE LASE: February 01, 2017; Published: 17 February 2017); https://doi.org/10.1117/12.2254056.
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