Transient dynamics in mode-locked all-PM Er-doped fiber laser with NALM

In this study, we utilized the Time-Stretch Dispersive Fourier Transform (TS-DFT) method to explore rapid transient states in both time and frequency domains of an all-polarization-maintaining dispersion-managed figure-eight mode-locked laser with Nonlinear Amplifying Loop Mirror (NALM). We detail the different stages of build-up dynamics at varying pump powers, encompassing the Q-switching (QS) stage, transient single pulse formation, pulsation beating patterns, bound states, and the final transition to a single pulse state. Our findings reveal that the mode-locked bound state regime emerges from a single pulse stage following QS, different from previously reported directly resulting from QS pulses or relaxation oscillations. In a novel contribution to the field, we have experimentally demonstrated the transient single pulse stage of build-up dynamics and compared it with the fundamental mode-locked single pulse. •Transient soliton bound-states of PM mode-locked laser with NALM were analyzed in time and frequency domains.•Different stages of build-up dynamics at various pump power levels were investigated.•The ML state doesn't originate directly from QS pulse or relaxation oscillations but from a single pulse stage after the QS.•Experimental comparison of ML fundamental pulse with build-up transient stage single pulses was performed for the first time.•One of the fastest transitions from a multipulse to a single pulse is observed in fewer than ten roundtrips.