Ho3+/Pr3+ Co-Doped AlF3 Based Glass Fibers for Efficient ~2.9 μm Lasers

In this letter, we demonstrated efficient
$\sim 2.9~\mu \text{m}$
lasing in Ho
³⁺
/Pr
³⁺
co-doped AlF
₃
based glass fibers. The Ho
³⁺
/Pr
³⁺
co-doped fibers were fabricated by using a rod-in-tube method based on the AlF
₃
- BaF
₂
- YF
₃
- MgF
₂
- PbF
₂
glass. By using a 50 cm long Ho
³⁺
/Pr
³⁺
co-doped AlF
₃
based glass fiber as the gain medium and an 1120 nm fiber laser as the pump source, lasing at 2868 nm was obtained, the obtained maximum unsaturated power was about 189 mW for a launched pump power of ~1.28 W, and the corresponding slope efficiency was ~15.3%, which was three times as high as that derived from singly Ho
³⁺
-doped AlF
₃
based glass fibers. Our results indicated that Ho
³⁺
/Pr
³⁺
co-doped AlF
₃
based glass fibers were promising gain media for constructing efficient
$\sim 2.9~\mu \text{m}$
fiber lasers.