Multipulse bunches in the Yb-doped mode-locked fiber laser based on NLMMI-NPR hybrid mode locked mechanism

Abstract

In this study, we propose a novel Ytterbium-doped ultrafast fiber laser based on nonlinear multimode interference-nonlinear polarization rotation (NLMMI-NPR) hybrid mode-locked mechanism. Stable single-pulse mode-locked state is achieved in the linear cavity, with a repetition rate of 12.8 MHz. By adjusting the polarization state and pump power inside the cavity, various characteristic modes are obtained, including multipulse bunches, second- and third-harmonic mode-locked states, second- and third-harmonic multipulse bunches states, and a chaotic multipulse state. This is the first exploration of multipulse bunches in Ytterbium-doped ultrafast fiber lasers based on the NLMMI-NPR hybrid mode-locked mechanism. And multipulse mode-locked fiber lasers have unique advantages in numerous fields owing to their higher energy and wider pulse width.