Abstract
A successful continuous-wave (CW) ultraviolet (UV) laser in a Tm
+3
-doped ZBLAN fiber, operated at 284 nm (
1
I
6
→
3
H
6
transition of Tm
+3
) is demonstrated. The excitation uses a four-step upconversion scheme. The pump source is a Nd:YAG laser operated at 1.064 μm. A laser output power of 42 μW continuous wave was obtained for 590 mW of the launched pump power. The slope efficiency with respect to the launched pump power was measured to be 9%. Ultraviolet (at 365 nm) and visible (at 453 and 480 nm) radiation was also observed.