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The structure of thulium-doped fiber laser is very simple. It not only has high conversion efficiency, wide range of transmission, tunable wavelength and low prices, but also has a very important value in optical communications, medical treatment, close-sensing technology, spectroscopy, ultra-fast optics and other aspects of environmental protection. So it attracts more and more attention, thulium-doped double-clad fiber laser is studied in detail in this thesis.The energy level structure of Tm3+ is first introduced, then the basic working principle of fiber lasers, resonant cavity types, double-claded fiber structure and practical pump technology. At the same time, the paper uses the commercial rate equations of the three-level system to build the thulium-doped fiber laser model and talks about the impact of the main parameters in its theoretical simulation.For the coupled system of the fiber laser , we conduct a numerical simulation and has got the important parameters to affect it. This thesis also introduces a variety of techniques using in the thulium-doped fiber laser, such as, the set up of coupling laser, pump laser coupling, fiber end processing, FBG carving.For the experimental part, this thesis uses two types of fiber to build fiber lasers and analysises the effect of the pump power and fiber length on the experiment. When we use the 15/210μm fiber to do experiment, we find that the best length of the fiber is 2.9m, the output wavelength of the laser is 1910nm, the threshold power is 2.5W, the maximum output power of the laser is 7.4W. Finally, we carve fiber grating in the the core of 15/210μm fiber and get well selected frequency of the laser, which also makes the 1910nm spectral FWHM become smaller.
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