Research On The Yb-doped Pulse Fiber Laser

With high efficiency, good beam quality and compactness, high power pulsed fiber lasers draw a lot of attentions of many research groups. With high peak power, ns-level high power fiber lasers are widely used in optical communication, military and medical fields. Ps-level and shorter pulsed fiber lasers can be widely used in ultra-fast optics, ultra-fast biology, ultra-fast spectroscopy, which become one of the international research hotspots. This thesis focuses on research on pulsed fiber lasers, which include an all fiberized Yb-doped pulse fiber laser based on gain-switching technology and a passively mode locked Yb-doped fiber laser based on semiconductor saturable absorber mirror (SESAM).Firstly, a gain-switched Yb-doped pulse fiber laser, which was periodically pumped by a pulsed multi-mode Laser Diode (LD) centering at wavelength of975nm with high power output was demonstrated. The pulsed Yb fiber laser was composed of a piece of Yb-doped double cladding gain fiber and a pair of fiber Bragg gratings. Under pump power of20W and pulse duration of2.4μs at repetition rate of50kHz, stable laser pulse trains were obtained at1060nm with pulse duration of100ns. The shot energy of every pulse was measured up to20μJ. Using this pulsed Yb fiber laser as the seed, a maser-oscillator power amplifier (MOPA) structured high power Yb laser was constructed with pulse energy exceeding200μJ and average power exceeding10W. The slope efficiency of the MOPA was about60%.Then, a self-starting passively mode-locked Yb-doped fiber laser with linear cavity structure was also demonstrated in this thesis. The fiber laser was composed of a reflecting SESAM, a piece of Yb-doped double cladding gain fiber and a piece of high reflection fiber Bragg gratings, which was pumped by a multi-mode LD centering at wavelength of915nm. Under pump power of350mW, stable laser pulse trains were obtained at1060nm with repetition rate of12.5MHz and pulse duration of50ps. When increasing the pump power, the phenomenon of pulse splitting emerged.