Microchip Yb:CaLnAlO4lasers with up to 91% slope efficiency

Identifier:  imarina:3823722

Handle: https://hdl.handle.net/20.500.11797/imarina3823722

Authors:  Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Xu, Xiaodong; Xu, Jun; Jambunathan, Venkatesan; Navratil, Petr; Lucianetti, Antonio; Mocek, Tomas; Zhang, Xuzhao; Griebner, Uwe; Petrov, Valentin; Aguilo, Magdalena; Diaz, Francesc; Major, Arkady

Abstract:
© 2017 Optical Society of America. Multi-watt continuous-wave (CW) operation of tetragonal rare-earth calcium aluminate Yb:CaLnAlO 4 Ln Gd;Y) crystals in plano–plano microchip lasers was demonstrated with an almost quantum-defect-limited slope efficiency. Pumped at 978 nm by an InGaAs laser diode, a 3.4 mm long 8 at. % Yb:CaGdAlO 4 laser generated 7.79 W at 1057–1065 nm with a slope efficiency of ? 84% (with respect to the absorbed pump power). An even higher ? 91% was achieved with a 2.5 mm long 3 at. % Yb:CaYAlO 4 laser, from which 5.06 W were extracted at 1048–1056 nm. Both lasers produced linearly polarized output (?-polarization) with an almost circular diffraction-limited beam (M 2 x,y < 1.1). The output performance of the developed lasers was modeled, yielding an internal loss coefficient as low as 0.004?0.007 cm ?1 . In addition, their spectroscopic properties were revisited.