  We present a flexible all-polarization-maintaining (PM) mode-locked ytterbium
(Yb):fiber laser based on a nonlinear amplifying loop mirror (NALM). In
addition to providing detailed design considerations, we discuss the different
operation regimes accessible by this versatile laser architecture and
experimentally analyze five representative mode-locking states. These five
states were obtained in a 78-MHz configuration at different intracavity group
delay dispersion (GDD) values ranging from anomalous (-0.035 ps$^2$) to normal
(+0.015 ps$^2$). We put a particular focus on the characterization of the
intensity noise as well as the free-running linewidth of the
carrier-envelope-offset (CEO) frequency as a function of the different
operation regimes. We observe that operation points far from the spontaneous
emission peak of Yb (~1030 nm) and close to zero intracavity dispersion can be
found, where the influence of pump noise is strongly suppressed. For such an
operation point, we show that a CEO linewidth of less than 10-kHz at 1 s
integration can be obtained without any active stabilization.
