Amplitude-modulated fiber-ring laser

Soliton pulses generated by a fiber-ring laser are investigated by numerica l simulation and perturbation methods. The mathematical modeling is based o n the nonlinear Schrodinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self-starting of stable solitonic pulses from small random noise, provided the modulation d epth is small. The perturbative analysis leads to a nonlinear coupled retur n map for the amplitude, phase, and position of the soliton pulses circulat ing in the fiber-ring laser. We established the validity of this approach b y comparison with the full numerical simulations. Finally, we discuss possi ble sources of instability that are due to resonances in the device. (C) 20 00 Optical Society of America [S0740-3224(00)00805-5]. OCIS codes: 060.5530 , 140.3430, 140.3510, 140.3560, 250.5530, 320.5540.