On wave-breaking free fiber lasers mode-locked with two saturable absorber mechanisms

We propose a hybrid mode-locking scheme for wave-breaking free fiber lasers based on a saturable Bragg reflector and the nonlinear polarization evolution in the fiber section. With this scheme, the self-starting operation is ensured by the saturable Bragg reflector while the nonlinear polarization evolution acts as an additional pulse shaper in the steady state. Owing to the sensitivity of the pulse dynamics to filtering effects, a tuning range of more than 10nm as well as the suppression of undesired modes of operation became possible. The impact of the modulation depth and the non-saturated losses is discussed via comparative measurements with different saturable Bragg reflectors.