Researches On The Rear Earth Doped Fiber Laser

Due to the potential applications of rear-earth doped fiber lasers in many fields and the tendency they have shown to gradually replace the traditional high power lasers, researches on the theory and new technology of rear-earth doped fiber lasers, such as 3 jam and 2 m cascaded Ho3+:ZBLAN fiber laser, Tm3+:Ho3+ co-doped silica fiber laser, and Er3+:Yb3+ co-doped double cladding fiber laser, not only have important scientific values, but also be helpful for the development of medicine, communication, military, and industry machining fields.The main research works and innovations of this dissertation are summarized as follows:Firstly, based on the operation principles of the 3 m and 2 m cascaded Ho3+:ZBLAN fiber laser, the dynamic and steady state rate equations, as well as the power propagation equations along with the corresponding boundary conditions of this 3 m and 2 m cascaded Ho3+:ZBLAN fiber laser pumped by at 1.1 /urn band are given for the first time in domestic, which result in a relatively complete theoretical model. Then numerical analysis of both the dynamic and steady state characteristics of the 3 m and 2 m cascaded Ho3+:ZBLAN fiber laser is performed. The analysis shows that cascade oscillation of the Ho3+:ZBLAN fiber laser can produce 3 m and 2 m laser beams with high conversion efficiency, and it is easy to achieve cascaded oscillation.Secondly, the first domestic experimental research on the 3 m and 2 m cascaded Ho3+:ZBLAN fiber laser is carried through. Very week cascaded radiations at about 2920 nm and 2040 nm have been generated.Thirdly, the mechanism of the Tm3+:Ho3+ co-doped silica fiber laser to produce 2m region radiation is investigated for the first time in domestic, and steady state numerical analysis is performed for each situation after the theoretical models of Tm3+:Ho3+ co-doped silica fiber laser pumped at 796 ran or 1180 ran laser is built. Then, experimental research on the Tm3+:Ho3+ co-doped silica fiber laser is carried through for the first time in domestic, pumped by a 796 ran Ti:S laser or a 1180 ran Raman fiber laser, respectively. A maximum output power of 930 mW at central wavelength of 1880 ran was achieved with an optical to optical conversion efficiency of 30% when the fiber length is 1 m, which was due to the transition of Tm ions. By contrast, the maximum output power decreased to 650 mW but central wavelength shifted to 1960 ran, due to contribution of the Ho ions transition when the cavity length increased to 3 meters.Fourthly, by using Ti:S laser as the pump source and using Ti:S laser cavity combined with a piece of Tm:Ho co-doped single-mode silica fiber to form a compound cavity, high beam quality 820 ran band single transverse mode laser is produced for the first time by frequency-selecting with Tm:Ho co-doped fiber as the external cavity. The maximum output power of 1 W is achieved with an optical to optical conversion efficiency of 15.7%, which could make the Ti:S laser have the convenience of optical fiber laser to some extent.Lastly, steady state numerical analysis is performed for the Er3+:Yb3+ co-doped double cladding fiber laser after the theoretical model is built. By using two kind of Er3+:Yb3+ co-doped double cladding fiber, two Er3+:Yb3+ co-doped double cladding fiber lasers are developed with maximum output power of multimode 3.5 W and single mode 2.2 W at about 1565 ran, respectively, which are the highest output power obtained from the Er3+:Yb3+ co-doped double cladding fiber in domestic.