Research On 980nm All Fiber YB-Doped Fiber Oscillator And Amplifier

980 nm all-fiber-format ytterbium doped fiber oscillators possess numerous advantages such as compact configuration, high integration, high stability and so forth. 980 nm fiber lasers can produce green and blue radiation by frequency doubling. Moreover, they are desirable pump sources for erbium-doped or Yb-doped fiber lasers and Er-doped fiber amplifiers. With the development of fiber communication techniques, the increasing requirements for Er-doped fiber amplifiers are proposed. So, high power Yb-doped fiber oscillators and amplifiers become crucial solutions for these problems. This thesis is dovoted to the experimental and theoretical research of high power all fiber fiber oscillators and amplifiers.The main points are presented as follows:The first part demonstrates the theoretical research of 980 nm mode-locked Ybdoped fiber oscillator and amplifier. According to the emission and absorption crosssection of Yb-ion, it is vital for 980 nm radiation to suppress the four-level oscillation and reduce serious re-absorption effect at 980 nm. Then, the mechanism of NPR and SESAM mode locking are introduced respectively. On the basis of nonlinear Schrodinger equation(NLSE), the theoretical analysis on passive mode-locked equations with NPR or SESAM are carried out. Finally, the expressions of pump power and amplified pulses power for single-pass plused amplifier are introduced with the basis of the expressions of rare equations. And the influence factors of dispersion and SPM for output properties of fiber amplifier are also analyzed.The second section demonstrates the experimental investigation of 980 nm all fiber NPR mode-locked fiber oscillator and its amplifier. Oscillator is built in all fiber configuration based on the NPR mode-locked mechanism. We experimentally obtain the appropriate length of Yb-doped fiber for 980 nm mode-locked laser. And then we discuss the experiment study of 980 nm NPR mode-locked fiber oscillator. The oscillator generates the average output power of 26.1 mW with the repetition rate of 20.38 MHz. The pulse width is about 159.48 ps. The output spectrum is centered at 977 nm with a fullwidth half maximum 10 nm and its profile exhibits typical spectral characteristics of dissipative solitons mode-locking. Moreover, 205 mW output power at 980 nm and 178.10 ps amplified pluse duration are achieved based on two stage allfiber-integrated amplifier with our homemade pulsed fiber oscillator as the seed source.The third part investigates 980 nm all fiber SESAM mode-locked Yb-doped fiber oscillator and its amplifier. The oscillator is constructed in an all fiber linear configuration and the cavity mirror consists of a pig-tailed SESAM and a narrow bandwidth FBG. Two different kinds of cavity length are applied to obtain stable modelocking fiber oscillators. One of oscillator generates the average output power of 3.5 mW with the repetition rate of 16.67 MHz, corresponding to pulse width of 76.27 ps and the other produces a 20.96 MHz repetition rate, 4.4 mW maximum output power with 61.15 ps pluse width. Then 20.96 MHz mode-locked oscillator works as a seed source injecting into all fiber amplifier system and the ultimate output laser exhibits an average power of 740 mW, a pluse width of 200 ps.The forth section demonstrates the combination of SESAM and NPR effect modelocked all fiber oscillator and its amplifier around 980 nm. The theoretical simulation verifies the experimental feasibility. The experimental study of 980 nm mode-locked fiber oscillator obtain 23.84 MHz repetition rate, 1.8 mW average output power and 6.6 ps pulse width. The spectrum is centered at 978 nm with a 3dB bandwidth of 4.5 nm and its profile exhibits the typical spectrum characteristics of dissipative solitons. With two-stage all fiber amplifier system, we attain 684 mW output power and the pulse duration of 165.6 ps.