Research On Thulium-doped Fiber Lasers

Thulium-doped fiber laser can launch laser at the wavelength of 2μm. 2μm is in the range of eye-safe wavelength, water molecules have a strong mid-infrared absorption peak at that wavelength, and 2μm is in the low-loss optical transmission atmospheric window, so thulium-doped fiber laser has important applications in the field of laser surgery, sapce optical communications, laser radar and photoelectric countermeasures. Besides, thulium-doped fiber laser can be used as a pump source to pump other work materials and finally produces laser which wavelength is from 4μm to 5μm.In this paper, we study the thulium-doped fiber laser from theoretical and experimental. The main research work in this paper as follows:(1) The basic theory and the structure of the thulium-doped fiber laser is researched. We discuss the structure and absorption efficiency of double-clad fiber, the cavity and the coupling technology.(2) Study on the characteristic of the energy level structure of thulium, and analysis the pumping process of three kinds of pump scheme of thulium-doped fiber laser(3H6â†'3F4,3H6â†'3H5,3H6â†'3H4). Study on the 3H6â†'3H4 pump scheme of the thulium-doped fiber laser by theoretically analyzing it with the rate equation, then build the mathematical model of this pump scheme. Simulate the characterstics of the thulium-doped fiber laser under 3H6â†'3H4 pump scheme using Matlab, Analysis the pump power distribution along the fiber, the relationship between coupler coupling ration as well as the doping concentration and the output power.(3) Build the system of thulium-doped fiber laser that using 793nm pump source under the current condition of laboratory. Complete the output power test of the pump source, the test of laser spectrum, and analysis the experiment phenomenon.