摘要： This work demonstrates an actively mode-locked all-normal dispersion Yb-fiber ring laser, delivering pulses of few nano-seconds (ns) to sub-ns duration at a 4 MHz repetition rate. Employing a filterless cavity architecture and different, long-length intra-cavity nonlinear fibers; a broadband output spectrum in the 1060–1140 nm wavelength region was obtained. With an increasing pump power, the pulse width reduced along with the appearence of new pulses, resulting into a muti-pulsing output. For a fixed pump power, the number of pulses and the amount of spectral broadening varied for different non-linear fibers. In the multi-pulsing state, the pulses were found to be located seperately in both time and wavelength, where Raman stokes corresponding to individual pulses could also be observed. The maximum output pulse energy achieved in a single pulse state was around 8.7 nJ, which increased to 14.5 nJ in a multi-pulse state. To the best of the authors’ knowledge, this is the first demonstration of a filterless active mode-locked fiber ring laser producing high-repetition rate broadband nano-second pulses in single and multi-pulse states at 1 μm.