Preparation and characterizations of Yb:YAG-derived silica fibers drawn by on-line feeding molten core approach

Three Yb:YAG transparent ceramics with Yb2O3 doping concentrations of 1, 10, and 15 at%, respectively were made into silica-clad hybrid fibers using an on-line feeding molten core approach. The diffusion of silica was mitigated such that the lowest SiO2 concentration was 36.4 wt%, and consequently, the Yb2O3 content could reach 8.93 wt% in the fiber core. The fiber core transformed from a YAG ceramic to an yttrium aluminosilicate glass, and the formation of abundant Q2 silicate species implied that the structure of the core glass maintained some environments similar to that of YAG with Q2-AlO4 tetrahedra. The absorption and emission spectra of the obtained fibers were compared to those of Yb:YAG ceramics, and the self-absorption effect was analyzed in detail. All three fibers could output lasers under 940 or 970 nm pumping. The maximum output power of the Yb:YAG-derived fibers was higher than that of ceramic wafers owing to the cladding pump technology, which offered a new method to improve the application of ceramics.