PHASE-LOCKING AND PERIODIC EVOLUTION OF SOLITONS IN PASSIVELY MODE-LOCKED FIBER LASERS WITH A SEMICONDUCTOR SATURABLE ABSORBER

Passively mode-locked lasers with intracavity weakly birefringent fibe r are theoretically analyzed based on two coupled complex one-dimensio nal Ginzburg-Landau equations. The model includes fiber birefringence, spectral filtering, saturable gain, and saturable loss. Phase-locked soliton solutions are found for small amounts of birefringence and sev eral types of soliton with periodic polarization evolution for higher amounts of birefringence. Numerical simulations show qualitative agree ment with experimental results. (C) 1998 Optical Society of America.