Research On Yb Fiber Laser With Sub-Nanosecond Short Pulse Output

With high efficiency,good beam quality and compactness,short pulse fiber lasers draw a lot of attentions in many research groups.With high peak power,high repetition rate and short pulse fiber lasers are widely used in ultra-fast optics,ultra-fast biology,ultra-fast spectroscopy,which become one of the international research hotspots.This thesis focused on research of sub-nanosecond mode-locked fiber laser and ns-level self-seeded fiber laser.First,we did research on short pulse fiber laser which based on new saturable absorber.Based on the diamond saturable absorber and by a linear cavity structure,we obtained self-mode-locked laser output with a repetition rate of 4.616MHz and a center wavelength of 1063.6nm.When the maximum pump power was 368mW,the output power of the laser was 60mW with the optical-to-optical conversion efficiency of 16.3%.We also reported a continuously mode-locked and Q-switched mode-locked fiber laser based on MoO3 saturable absorber.With the laser diode centering at wavelength of 974nm,MoO3 saturable absorber based on polyvinyl alcohol and Yb-Doped fiber as a ring cavity configuration,ps-level mode-locked pulse laser output was realized under 95mW pump power.As the pump power increased to 280mW,Q-switched mode-locked pulse was obtained.The center wavelength,pulse width and repetition rate were 1067nm,130ps and 17MHz respectively.Then,we did research on self-seeded pulse fiber laser based on gain-switched technique.With laser diode centering at wavelength of 1067.2nm and fiber bragg grating centering at wavelength of 1064.2nm,the self-seeded fiber laser was obtained by self-seed injection.The repetition rate and pulse width were 10MHz and 5ns respectively.The output power was 4.75mW after passing the isolator.Finally,we amplified the seed by using master oscillator power amplifier technique.The output power reached 698mW.