Comparison of Mode Locking Regimes Based on Nonlinear Rotation of the Polarization Plane in Erbium Fiber-Optic Lasers with Dumbbell-Type and Annular Cavity Designs

The stable generation regimes of both single ultrashort pulses and pulse packages in the spectral range of 1540–1600 nm are demonstrated for two cavity designs of fiber-optic lasers: dumbbell-type and annular. In both designs the mode locking regime is provided by the nonlinear rotation of the polarization plane. It is demonstrated that using the dumbbell-type cavity design with circulator is more advantageous in erbium fiber-optic laser for obtaining the single-pulse generation compared against the classical annular design constructed on analogous elements.