Shi Jun-Kai, Wang Guo-Ming, Li Yao, Gao Shu-Yuan, Liu Li-Tuo, Zhou Wei-Hu. Influence of spectral filtering on mode-locking operation of figure-eight Er-doped fiber laserJ. Acta Physica Sinica, 2019, 68(6): 064206. DOI: 10.7498/aps.68.20182144