Efficient, tunable, zero-line diode-pumped, continuous-wave Yb 3+ :Ca 4 LnO(BO 3 ) 3 (Ln = Gd, Y) lasers at room temperature and application to miniature lasers

We demonstrate an efficient cw 976-nm-diode-pumped Yb3+:Ca4GdO(BO3)3 laser. At room temperature we obtained 814 mW of power with a slope efficiency of 77% and a small-signal gain per round trip of 1.67. We also demonstrate that the Yb3+:Ca4LnO(BO3)3(Ln=Gd, Y) crystals are suitable for a plano–plano microchip-type cavity. With this microlaser we have obtained an average power of 300 mW, which corresponds to an optical–optical conversion efficiency of 27%.