Theoretical And Experimental Study On Yb～(3+)-doped Fiber Ultra-Short Pulse Laser

Nowadays, ultrashort pulse laser source is an active research front not only in nonlinear optics and ultrafast optics, but also in, as a key technology, realizing ultra-high speed optical communications. Research on fiber-based ultrashort pulse laser has great significance. In recent years, ytterbium-doped fiber lasers have been attracting great academic and commercial interest because of their advantageous properties. On the basis of our laboratory facilities and a research project, this thesis work was focused, experimentally and theoretically, on a thorough research on an Yb3+-doped fiber laser for generating ultrashort pulses. The main contents of the dissertation are as follows:I. Nonlinear polarization rotation mode-locked Yb3+-doped fiber laser1. Starting from the time-domain mode-locking master equation and NLSE (Nonlinear Schrodinger Equation), we analyzed the mechanism of fast saturable absorber for obtaining ultrashort pulses and fully discussed the influences of cavity parameters, polarization controller states and the angle between the polarizer and the fast-axis of fiber on the realization of mode-locking. 2. Exploiting the nonlinear polarization rotation technique and adjusting the polarization controllers orientations and pump power, we achieved stable operations of Q-switched, Q-switched mode-locked and CW mode-locked regimes in a ring cavity Yb3+-doped fiber laser.II. Line cavity mode-locked Yb3+-doped fiber laser with a saturable absorber1. The self-starting action and stability of a passively mode-locked Yb3+-doped fiber laser have been analyzed and simulated using NLSE.2. For the first time, exploiting a SESAM as a slow saturable absorber and the nonlinear polarization rotation effect as a fast saturable absorber, the Q-switched mode-locked and CW mode-locked pulse trains were obtained in a line cavity mode-locked Yb3+-doped fiber laser.III. Ring cavity mode-locked Yb3+-doped fiber laser with a saturable absorber1. From the time-domain mode-locking master equation, the mechanism of the...