Research Of Thulium Doped Fiber Laser

Tm-doped fiber laser has very great application value in medicine, super speed optics, eye safe, short-distance remote sensing and long-distance detective systems, now is being the research focus of fiber lasers at eye safe wavelength. Presently, most of the research method of Tm-doped fiber laser is experiment, which is hard to analysis the influence of the structure and parameters to the fiber laser, also the Tm-doped fiber is expensive. Consequently, for obtaining high capability of the Tm-doped fiber laser, build mathematical model and simulating the Tm-doped fiber laser to analysis the parameters' influence is very useful.In this paper, we use velocity equation to analysis the capability of the Tm-doped fiber laser, and build the mathematical model, do a lot of simulations with MATLAB. The major and innovational work is as follows:1. For the energy level structure of thulium, we have Researched the characteristic of it and analyzed the absorption spectrum, present three kinds of pump scheme of the Tm-doped fiber laser: ³F₄â†'³H₆,³H₅â†'³H₆,³H₄â†'³H₆, and analysis the pumping process. The absorption cross section of ³H₄ at the pump wavelength is larger than the others, the pumping scheme of ³F₄â†'³H₆ is hard to reverse the particle for it is two energy system, the energy ³H₅ has ESA, than, conclude that the pumping scheme ³H₄â†'³H₆ is more excellent.2. For the pumping mode of the fiber laser, we have researched and analyzed the factor that influence the capability of the Tm-doped fiber laser. The pumping mode of single end , as forward and backward, could damage the fiber for the over large power density at the pumping end, bidirectional pumping mode could absorb the pump light more sufficient.3. For the three pumping scheme of Tm-doped fiber laser, we have theoretically analyzed it with the velocity equation, have built the mathematical model of the every pumping scheme of Tm-doped fiber laser, than, discussed the parameters of the model.4. For the Tm-doped fiber laser, we have simulated it, and researched the relationship between the output power, threshold pump power and slope efficiency of the laser and the Tm³⁺-doped concentration, fiber length and the reflectivity of the output coupler. For optimizing the high capability of the Tm³⁺-doped fiber laser, we have got the optimum value of the doped concentration of Tm³⁺, fiber length, reflectivity of the output coupler. Besides, we also find out that for sufficiently shortening the fiber length, we can improve the doped concentration of Tm³⁺ and reduce the reflectivity of the output coupler.