High-efficiency similar to 2 mu m laser in a single-mode Tm-doped lead germanate composite fiber

A highly Tm-doped lead germanate glass fiber is developed using the rod-in-tube method. The similar to 2 mu m laser beam quality of the fiber is similar to 1.5. The lead germanate composite fiber jumpers are homemade for all the fiber laser investigations. When core is pumped by a 1590 nm Yb/Er fiber laser, a maximum laser output of 313 mW is achieved at a 670 mW pump power, and the corresponding slope efficiency is similar to 52.8%. Moreover, by using a 2 cm-long lead germanate fiber as the gain medium, a 33 mW 1942 nm Tm laser is also demonstrated.