Experimental demonstration of an Er-doped fiber ring laser mode-locked with a Tm–Ho co-doped fiber saturable absorber

Mode-locking operation of an Er-doped fiber laser with a Tm?Ho co-doped fiber saturable absorber is demonstrated for the first time. Q-switching, Q-switched mode-locking and CW mode-locking operation modes are observed sequentially with increase of the pump power. In the mode-locking operation mode, a repetition rate at the fundamental cavity frequency of 9.05?MHz is obtained with a pulse duration of 46.3 ns. By rotating the polarization controller, a repetition rate up to 887?MHz is achieved, and the pulse duration is shortened to 0.548?ns.