High efficiency ~2 μm laser in a single mode Tm doped lead germanate composite f

A highly Tm-doped lead germanate glass fiber is developed using the rod-in-tube method. The ~2 μm laser beam quality of the fiber is ~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 las