  We report the relative frequency stabilization of a distributed feedback
erbium-doped fiber laser on an optical cavity by serrodyne frequency shifting.
A correction bandwidth of 2.3 MHz and a dynamic range of 220 MHz are achieved,
which leads to a strong robustness against large disturbances up to high
frequencies. We demonstrate that serrodyne frequency shifting reaches a higher
correction bandwidth and lower relative frequency noise level compared to a
standard acousto-optical modulator based scheme. Our results allow to consider
promising applications in the absolute frequency stabilization of lasers on
optical cavities.
