In this paper, we present an ytterbium-fiber laser system with a cladding-pumped single-mode active fiber achieving mode-locking by nonlinear polarisation rotation. It consists of the following principal modules: A double-clad ytterbium fiber, quarter-(QWP) and half-wave-plates (HWP) for polarization control, an optical isolator for unidirectional laser operation and a dispersive delay line with two parallel mounted diffraction gratings for compensation of the normal fiber dispersion. The pump light is delivered by a 980 nm laser diode through a dichroic mirror and the polarization beam splitter at the isolator rejected one polarization and acted as the output port.