High-Power Laser Performance of ${\hbox {Yb:}}{\hbox {YAl}}_{3}({\hbox {BO}}_{3})_{4}$ Crystals Cut Along the Crystallographic Axes

High-power continuous-wave laser operation near 1 mum was demonstrated at room temperature with c-cut and a-cut Yb:YAl
₃
(BO
₃
)
₄
crystals end-pumped by a fiber-coupled diode laser. Using a 2-mm-thick c-cut crystal, 10.6 W of output power was generated with an optical-to-optical efficiency of 65% and a slope efficiency of 72%. The complex polarization state of the generated laser radiation was also studied. With a 2-mm-thick a-cut crystal, sigma-polarized laser oscillation was obtained, producing a maximum output power of 8.1 W; the optical-to-optical and slope efficiencies were 56% and 61%, respectively. Complete absorption and emission cross section spectra of the Yb:YAl
₃
(BO
₃
)
₄
crystal were also derived, revealing very strong anisotropy of the spectroscopic properties