Study On Yb³⁺-doped Ultrashort Pulse Fiber Amplifier

As the constant development and extensive application of fiber communication, the technique of fiber amplification has improved a lot. Lanthanon doped fiber amplifier, i.e. Yb³⁺ doped fiber amplifier, which is paid more and more attention to in many areas such as ultrashort pulse amplification because of its unique characteristics, is the hot and cutting-edge researching topic in the field of ultrashort pulse laser amplification. This paper research ultrashort pulse Yb³⁺ doped fiber amplifier theoretically and practically, and mainly includes:1. The research for the basic theory of ring cavity Yb³⁺ doped ultrashort pulse fiber lasera. Introduce basic mode-locked principle of mode-locked fiber laser.b. Simulate with PC and particularly discuss slope efficiency, threshold power and output power of ring cavity Yb³⁺ doped fiber laser. Particular analyze of the relationship among the important parameters such as the output coupling ratio of ring cavity Yb³⁺ doped fiber laser, slope efficiency and fiber length and pumped power; solve the time-domain mode-locked equations meanwhile. The result of the simulation data demonstrates that the impact of the output coupling ratio to the performance of the ring cavity Yb³⁺ doped fiber laser is great, and the optimum coupling ratio should be taken into consideration when designing structure of the cavity.2.The research for the basic theory of ultrashort pulse Yb³⁺ doped fiber amplifiera. Summarize the technique of laser amplification theoretically, introduce the characteristics of Yb³⁺ particularly; starting from Maxwell Equations, deduce nonlinear Schrodinger equation particularly, introduce the definition of pulse width and spectrum.b. Analyze the impact of group velocity dispersion (GVD) and self phase modulation (SPM) to pulse transmission without chirped, and conduct the data simulation on PC. Discover that in positive dispersion medium, dispersion widens the pulse, however, doesn't affect the spectrum of pulse. GVD widens the spectrum of the pulse, however, doesn't affect the wave form of the pulse.3. Research for experiment of ultrashort pulse fiber amplifiera. Expatiate the implementation of mode-locked principle of ring cavity Yb³⁺ doped fiber laser. By the technique of non-linear polarization rotation, through carefully adjust the angle of fiber polarization controller and the pump power, get stable pulse output of Q switched, Q switched mode-locked and mode-locked constantly.b. Through carefully adjust the angle of fiber polarization controller and the pump power of laser and amplifier, amplify and analyze the outcome of the stable pulse output of ring cavity Yb³⁺ doped ultrashort pulse laser respectively in three ways: Q switched, Q switched and mode-locked constantly.