Low side bands wide spectrum width femtosecond passively mode-locked fiber laser

Abstract

Femtosecond (fs) fiber laser is very useful in fiber sensor and OTDM optical soliton communication systems. To study the suppression of side bands and the broadening of spectrum width in fs fiber laser, passively mode-locked fiber ring laser were experimentally studied. This study was based on side bands generation principle and nonlinear polarization rotation (NPR) mode lock principle. 3m deeply doped fiber was used in the ring of NPR fiber laser in the experiments, so that there were enough group velocity dispersion (GVD), chirp and high-level nonlinear effects in the ring. And these effects would help suppressing side bands and broadening spectrum width. The fiber laser with low side bands, spectrum width of 25.4nm, spectrum width tuning range of 12.4nm and repetition rates of 15.8MHz was gotten in the experiments. The theoretical limiting pulse width was about 300fs and the pulse amplitude had gotten 4% fluctuation.