Research Of Thulium Doped Fiber Laser

The thulium-doped fiber lasers have been paide more attention because of good characteristics,including low threshold,high efficiency,beam quality,spatial compactness,high reliability and good heat dissipation.Thulium-doped fiber laser whos output tuning range of 1780～2050nm has very great application value in medicine, biology,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. And thulium-doped fiber laser can work in the S-band.The research of thulium-doped fiber laser is significant for the development of potential resources in the frequency of communications spacethe and broadening optical communication bandwidth.In this paper,through the establishment of mathematical model to analysis Tapered coupling and the capability of the Tm-doped fiber laser,and study the relationship between Tm-doped fiber laser and various parameters.The major and innovational work is as follows:1.Analysis the transmission properties of tapered fiber and the power losses by the scalar wave equation and catch-up method.From the analyses,it could come to the conclusion that the less gradient-index is,the lower the power losses;the shorter the taper is,the higher the transmission efficiency becomes.2.Study the energy level structure of thulium and analyse the pump scheme of the Tm-doped fiber laser:³H₄â†'³H₆.Discuss the parameters of the model by theoretically analyzing it with the velocity equation and building the mathematical model of Tm-doped fiber laser.3.Simulate the characteristics of the Tm³⁺-doped linear cavity fiber laser and analyse the relationship between some parameters and the laser output power,such as the Tm³⁺ doping concentration,fiber length,coupler coupling ratio,pump power. Through the analysis,the doping concentration,fiber length and the reflectivity of the resonant cavity have a best value to obtain the maximum output power of thulium-doped fiber laser under the same conditions.Deviation from the optimal value will result in the reduction of output power.So appropriately increasing the doping concentration of the gain medium or the reflectivity of the resonant cavity can effectively reduce the thulium-doped fiber length.4.Simulate the characteristics of the Tm³⁺-doped ring fiber laser and analyse the relationship between some parameters and the laser output power,such as the Tm³⁺ doping concentration,fiber length,coupler coupling ratio,pump power.We can get the same conclusion that the doping concentration,fiber length and coupling ratio exists a best value to obtain the maximum output power of thulium-doped fiber laser under the same conditions.So appropriately increasing the doping concentration of the gain medium or coupling ratio can effectively reduce the thulium-doped fiber length.