Stabilization of actively mode-locked Er-doped fiber lasers in the rational-harmonic frequency-doubling mode-locking regime

Stabilization of an actively mode-locked fiber laser in the frequency-doubl ing rational-harmonic mode-locking regime is demonstrated experimentally fo r the first time to the authors' knowledge. The stabilization is achieved b y a method based on minimization of the average optical power at the second output; of a dual-output Mach-Zehnder modulator used as a mode locker. Thi s method produces long-term stable operation of the laser with similar to 3 5-dB suppression of the pulse-to-pulse amplitude fluctuation caused by rati onal-harmonic frequency doubling. (C) 1999 Optical Society of America.