Pure-three-level Yb:GdCOB CW laser at 976 nm.

We present what is, to the best of our knowledge, the first pure-three-level Yb:Ca4 GdO(BO3 )3 (Yb:GdCOB) laser emitting at 976 nm based on the F5/2 2-F27/2 transition, generally used for a quasi-three-level emission at 1032 nm. A maximum power of 782 mW at 976 nm has been achieved in continuous-wave (CW) operation pumped by a quasi-three-level Nd:SrLaAlO4 laser emitting at 902 nm. Moreover, a self-frequency-doubling CW blue laser has also been demonstrated with a maximum power of 133 mW at 488 nm.