DEVELOPMENT OF THULIUM DOPED FIBER LASER EMITTING >34W WATTS OF CW POWER AT 1940 NM

A Thulium doped fiber laser, with an all-fiber architecture based on standard 125 µm cladding diameter fibers has been designed, developed and characterized, the results of which are presented here. The amplified spontaneous emission of spectrum of the fiber has been measured and used to determine laser wavelength in such a way that the laser wavelength falls near gain peak of the spectrum. Different pumping configurations are assessed before choosing contra directional pumping with normal cleaved fiber facet as output coupler for scaling up of output power. The laser has a continuous-wave (cw) output power of more than 34 W at 1940 nm with a conversion efficiency of ~54% and with a temporal stability of about 2% (peak-to-peak value) and ~0.3% (root mean square value).