Widely tunable, high slope efficiency waveguide lasers in a Yb-doped glass chip operating at 1  μm.

Ultrafast laser inscribed waveguide lasers can lead to highly efficient and compact optical devices. This Letter reports an average lasing efficiency of 65%±2.5% from a multi-waveguide 2.5 mol. % ytterbium-doped ZrF ₄ - BaF ₂ - LaF ₃ - AlF ₃ - NaF (Yb:ZBLAN) chip in an extended-cavity configuration. A maximum output power of 750 mW with a lasing efficiency of 68% is also achieved. A monolithic end-coupled configuration reached a maximum output power of 784 mW with a lasing efficiency of 70%. The lasing wavelength is tuned from 1001 to 1045 nm in a Littrow configured cavity. A beam propagation factor of the lowest-order transverse-mode output was routinely achieved with an M ² of 1.15.