  High-power ultra-low noise single-mode single-frequency lasers are in great
demand for interferometric metrology. Robust, compact all-fiber lasers
represent one of the most promising technologies to replace the current laser
sources in use based on injection-locked ring resonators or multi-stage
solid-state amplifiers. Here, a linearly-polarized high-power ultra-low noise
all-fiber laser is demonstrated at a power level of 100 W. Special care has
been taken in the study of relative intensity noise (RIN) and its reduction.
Using an optimized servo actuator to directly control the driving current of
the pump laser diode (LD), we obtain a large feedback bandwidth of up to 1.3
MHz. The RIN reaches-160 dBc/Hz between 3 kHz and 20 kHz.
