Studies on Q-switching and Mode-locking

This work presents theoretical and experimental studies on Q-switched and mode-locked pulse generation in fiber cavity with saturable absorber (SA). The fundamental principles of fiber laser systems are outlined, which include fiber modes, losses in fiber, and fiber dispersion and nonlinearity. The various nonlinear refractive index effects in addition to the other two important nonlinear scattering effects; stimulated Raman scattering and stimulated Brillouin scattering are discussed. Moreover, the characteristics of the laser gain medium and the basis of SA are outlined. The basics of laser Q-switching, optical pulse propagation in fiber, and the general concepts of mode-locking operation are presented. Numerical simulations of Q-switching and mode-locking operations in fiber cavity with SA have been developed taking into account the SA dynamics. The effects of each component in the laser cavity have been investigated as well as the pulse energy for different cavity arrangements. Furthermore, novel SA materials are introduced experimentally as efficient Q-switchers and mode-lockers for fiber laser pulse generation.