~2 μm single frequency/ultrafast fiber lasers have attracted a great deal of interests due to their applications in medicine, eye safe lidar, atmospheric monitoring, and laser precision process. However, core technology of high quality ~2 μm single mode active fibers is now controlled by a few developed countries.

The high power laser components R&D center at Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences(SIOM,CAS), led by Prof. Hu Lili, has recently made a staged progress on ~2 μm highly doped single mode tellurite glass double-clad fiber. Researchers in this laboratory developed a novel tungsten tellurite double-clad single mode fiber with a ~8 μm core diameter and an NA of 0.14. A 490 mW fiber laser operating at ~1.9 μm was achieved in a Tm3+ doped 20 cm long fiber, the laser beam quality factor M2 was 1.09. A 100 mW ~2.1 μm laser was also demonstrated in a piece of 14 cm long Tm3+-Ho3+ co-doped tellurite fiber, the M2 was 1.31. Both of the fibers were one end pumped by a commercial 793 nm laser diode.

The laboratory will develop ~2 μm single frequency/ultrafast fiber lasers based on this novel ~2 μm active fiber in the future.

Fig1.  The spectra of ~2.1 μm and ~1.9 μm single mode tellurite glass double-clad fiber laser (pumped by a 793 nm LD）(Image by SIOM)