Passive harmonic mode-locking in a fiber laser by using a microfiber-based graphene saturable absorber

Passive harmonic mode-locking (HML) in a fiber laser with a microfiber-based graphene saturable absorber (SA) is presented. The microfiber-based graphene SA is employed to enhance the nonlinear effect of the laser cavity, which is beneficial to achieving high-order HML operation. Depending on the pump power level, up to 101st HML (555 MHz) was obtained. The results demonstrate that the microfiber-based graphene SA could be used as highly nonlinear photonic devices in fiber lasers for effectively realizing high-order passive HML operation.