Broadband passive harmonic mode locking in a dispersion-managed Er-doped fiber laser

We report on an Erbium-doped fiber laser operated at harmonic mode locking (HML) state with broadband spectrum. Stable pulse train emitted from the light source can continuously vary from 2
^nd
to 17
^th
order with spectrum bandwidth beyond 50 nm. The bandwidth can be up to 57 nm at 10
^th
order HML. The pulse duration is measured to be 966 fs by an autocorrelator, and the corresponding time band product is 6.7, indicating high chirped pulse profile. In addition, stable states of noise-like pulse, domain wall, bound solitons could be also observed.