Passive harmonically mode-locked erbium-doped fiber laser

Passive harmonically mode-locked erbium-doped fiber ring laser with scalable repetition rates up to 1.2 gigahertz is experimentally demonstrated, to our best knowledge, which is hitherto maximum repetition rate from only-erbium-doped fiber laser. Owing to the acousto-optic effect, stable passive harmonically mode-locking can only occur at some certain discrete repetition rates corresponding to resonant frequencies of transversal acoustic wave induced by propagating optical pulses in fibers.