The nonlinear optical loop mirror (NOLM) is used as a saturable absorbed to reshape pulses. Experimentally, an actively mode-locked erbium-doped fiber ring laser with figure-eight structure is set up. 2 ? 4 order harmonic pulse train with stable amplitude has been obtained when the RF modulation frequency is about 2.5 GHz.
© 2005 Chinese Optics Letters
Zhaoying Wang, Zhenhong Yu, Peiliang Gao, Tianxin Yang, Ruifeng Zhang, Dongfang Jia, and Shichen Li, "Rational harmonic figure-eight actively-passively mode-locked erbium-doped fiber laser," Chin. Opt. Lett. 1, 283-285 (2003)