Unified Model for Breathing Solitons in Fiber Lasers: Mechanisms across Below- and Above-Threshold RegimesRemoveYing Zhang, Bo Yuan, Junsong Peng, Xiuqi Wu, Yulin Sheng, Yuxuan Ren, Christophe Finot, Sonia Boscolo, and Heping ZengPhys. Rev. Lett. 136, 123801 (2026)