Ytterbium-doped fiber lasers are attractive in many fields due to their high output power and good beam quality. Meanwhile, fiber fusion splicing—a necessary and inevitable process in building a fiber laser—could affect not only the output power but also the output beam quality of a fiber laser. The influences of fusion splicing on laser beam quality are studied and discussed in this paper. A model based on the beam propagation method and computation of the M2 factor is employed to research the effects of fiber splicing. Different cases of spatial deviation during fusion splicing, including shifting and tilting, are simulated. Fiber splicing with drift in one and two dimensions is investigated as well, the results of which show good agreement with the simulated ones. Furthermore, the effects of splice shifting and tilting on laser beam quality are compared to select the most critical one. Beam quality variations under different circumstances, such as deviation direction, fiber type, and input beam quality, are also discussed.

In this demonstration, we proposed a novel wavelength-tunable thulium-doped fiber laser (TDFL) with a self-made Fabry-Perot (F-P) filter. When the F-P filter was not inserted, the maximum output power of 11.1 W was achieved when the pump power was 70.2 W. The corresponding optical-to-optical conversion efficiency was 15.8% and the slope efficiency was 22.1%. When the F-P filter was inserted, the output wavelength could be tuned from 1952.9 to 1934.9 nm with the change of cavity length of F-P filter which was fixed on a piezoelectric ceramic transducer (PZT) controlled by the voltage applied to it. The full width at half maximum (FWHM) was no more than 0.19 nm. Furthermore, the wavelength fluctuations of the tunable fiber laser were kept within ±0.2 nm.