Pulsating dynamics of dissipative pure-quartic soliton in a fiber laser.

Recently, dissipative pure-quartic soliton (DPQS) has been proposed in the mode-locked fiber lasers driven by positive fourth-order dispersion (FOD). However, few efforts have been devoted to investigating the nonlinear dynamics of DPQS. Herein, we numerically investigate the pulsating dynamics of the DPQS in a passively mode-locked fiber laser. The pulsating behavior similar to those dominated by negative FOD can be observed firstly, exhibiting the symmetrical energy exchange between the main lobe of DPQS and pedestals at two edges. By further increasing the saturation energy, it is found that the energy of the main lobe of DPQS can be transferred into the pedestals completely, leading to the formation of an M-shape pulse. The gain competition between the two temporal peaks of the M-shape pulse results in a generation and collapse of the leading and trailing peaks alternatively. As the leading and trailing peaks of DPQS are constituted by the longitudinal modes with lower and higher frequencies, respectively, the DPQS pulsation shows a creeping behavior owing to the variation of the center wavelength in this scenario. These findings will provide new insights into the pulsating dynamics of mode-locked soliton in fiber lasers, which is also beneficial to further understanding of the nonlinear behavior of DPQS.