Generation and categories of solitons in various mode-locked fiber lasers

Optical solitons generated from fiber lasers have been extensively investigated for their good stability, narrow pulse width and high peak power, which play an indispensable role in many fields such as mechanical micromachining, optical microscope, imaging technology, optical soliton communication and so on. In this review, we summarize the development of soliton fiber laser, and the current application of soliton pulses. There are many different kinds of mode-locking technologies to generate solitons, such as actively mode-locked fiber lasers, passively mode-locked fiber lasers and hybrid mode-locked fiber lasers. During the long-term research of solitons, various types of solitons have been gradually realized under different group velocity dispersion (GVD) conditions in passively mode-locked fiber lasers, such as conventional solitons (CSs) (GVD < 0), dispersion-managed solitons (DMSs) (GVD≈0), self-similar solitons (GVD ≥ 0), dissipative solitons (DSs) (GVD > 0). And in order to apply solitons to more fields, soliton amplification and compression technologies are widely used to improve the performance of solitons, such as chirped pulse amplification (CPA) technology, self-similar soliton amplification technology, large-mode area (LMA) fiber, etc. Finally, the development prospect of soliton in the future is prospected.