Theoretical study of an actively mode-locked fiber laser stabilized by an intracavity Fabry-Perot etalon: linear regime

We study theoretically the effect of an intracavity etalon on actively mode-locked fiber lasers by solving the master equation for the laser when nonlinearity in the laser is negligible. The first-order dispersion of the material inside the etalon can increase the pulse duration by a factor of 10. The minimum pulse duration is obtained when the relative frequency offset between the free spectral range of the etalon and the modulation frequency of the active mode locking is of the order of 10(-2). The group-velocity dispersion of the material inside the etalon as well as the finesse of the etalon affect the total cavity dispersion. The etalon helps to suppress both a simultaneous lasing in several supermodes and lasing in higher-order pulse modes of the master equation. The etalon also helps lock the central wavelength of the laser to the etalon comb. (c) 2007 Optical Society of America.