Abstract: The disclosed method and apparatus for stabilizing a mode-locked regime of a fiber ring oscillator based on a NPR include tapping a portion of light, which has a broad spectral bandwidth, from a fiber ring resonator into at least first and second control channels. The control channels are configured to guide respective first and second fractions of the tapped portion. One of the control channels is provided with a bandpass filter operative to extract a region from the broad spectral bandwidth. The fractions with respective full spectral bandwidth and region thereof are then evaluated in a central processing unit which is operable to generate a control signal if a predetermined criterion is not met. The control signal is received by one or more polarization controller units operative to dynamically modulate a state of polarization of light in the fiber ring resonator until the evaluation meets the predetermined criterion.