Spectral filtering for high-energy mode-locking in normal dispersion fiber lasers

We present a theoretical description of the generation of ultrashort, high-energy pulses in an all-normal dispersion laser cavity with spectral filtering. A reduced variational model based upon the Haus master mode-locking equations with quintic saturation is shown to characterize the experimentally observed dynamics. Critical in driving the intracavity dynamics is the nontrivial phase profiles generated and their periodic modification from the spectral filter. The theory gives a simple geometrical description of the intracavity dynamics and possible operation modes of the laser cavity. Further, it provides a simple and efficient method for optimizing the laser cavity performance. (C) 2008 Optical Society of America