Low-threshold and broadly tunable lasers of Yb³⁺ -doped yttrium lanthanum oxide ceramic

We experimentally demonstrated diode-pumped continuous wave and tunable laser operation of Yb³⁺ -doped yttrium lanthanum oxide transparent ceramic [Yb: (Y_1-x La_x)₂O₃,x=0.1], which was fabricated with nanopowders and sintered in H2 atmosphere. As low as 400 mW pumping threshold and a slope efficiency of 52% were realized at 1080 nm under a high-brightness 976 nm diode pump with a fiber core of 50 μm and a numerical aperture of 0.22. A maximum output power of 2.1 W was obtained when the non-lasing absorbed pump power was 19.5 W at 976 nm with diode laser of 400 μm fiber core. A smooth tunable curve from 1018 to 1086 nm was achieved at 940 nm diode pump. Broadband lasing spectra up to 30 nm were observed in the tunable laser experiment.