Impact of third-order dispersion on the dynamics of dissipative solitons in an ultrafast fiber laser.

Dissipative solitons (DSs), due to the complex interplay among dispersion, nonlinear, gain and loss, illustrate abundant nonlinear dynamics behaviors. Especially, dispersion plays an important role in the research of DS dynamics in ultrafast fiber lasers. Previous studies have mainly focused on the effect of even-order dispersion, i.e., group velocity dispersion (GVD) and fourth-order dispersion. In fact, odd-order dispersions, such as third-order dispersion (TOD), also significantly influences the dynamics of DSs. However, due to the lack of dispersion engineering tools, few experimental researches in this domain have been reported. In this work, by employing a pulse shaper in ultrafast fiber laser, an in-depth exploration of the DS dynamics influenced by TOD was conducted. With the increase of TOD value, the stable single DS undergoes a splitting into two solitons and then enters explosion state, and ultimately evolves into a chaotic state. The laser operation state is correlated to dispersion profile, which could be controlled by TOD. Here, the positive dispersion at long-wavelength side will be gradually shifted to negative dispersion by increasing the TOD, where soliton effect will drive the transitions. These findings offer valuable insights into the nonlinear dynamics of ultrafast lasers and may also foster applications involving higher-order dispersion.

Anti-phase pulsation of counter-propagating dissipative solitons in a bidirectional fiber laser.

Due to its unique geometric structure, the bidirectional ultrafast fiber laser is an excellent light source for dual-comb applications. However, sharing the same gain between the counter-propagating solitons also gives rise to complex dynamics. Herein, we report the anti-phase pulsation of counter-propagating dissipative solitons in a bidirectional fiber laser. The in-phase and anti-phase soliton pulsation can be manipulated by adjusting the intracavity birefringence. The periodic modulation of polarization-dependent gain (PDG) caused by polarization hole burning (PHB) in the gain fiber can be responsible for anti-phase pulsation of bidirectional dissipative solitons. These findings offer new, to the best of our knowledge, insights into the complex dynamics of solitons in dissipative optical systems and performance improvement of bidirectional ultrafast fiber lasers.