An automatic mode-locked fiber laser based on NPR mechanism

Abstract An automatically mode-locked fiber laser based on the nonlinear polarization rotation(NPR) effect was demonstrated and a stable mode-locked pulse train was obtained. A model of parameters such as transmittance, self-phase modulation and self-amplitude modulation of the NPR mode-locked fiber laser was established. The relationship between the equivalent saturable absorption effect and the rotation angles of the waveplates was analyzed. Using that, an automatic mode-locked fiber laser based on NPR method and hill-climbing algorithm was built, and the mode-locked output could be obtained. Output characteristics were discussed also.