Abstract

In this work we present a unified treatment of pulse train generation and the onset of spatio temporal chaos in nonlinear dispersive fiber cavities. We consider here both synchronously pumped passive and active fiber ring cavities. We show that modulational instabilities constitute a general mechanism for pulse generation from the break up of continuous wave (cw) laser oscillation. By averaging the lumped gain, loss, dispersion and nonlinearity over each transit in the cavity, we obtain a single partial differential equation of the Ginzburg-Landau type with a forcing term which describes the external pumping. We carry out the linear stability analysis of the cw solutions of this equation which permits to determine the optimal conditions for the onset of nonlinear mode locking in the cavity. These results are relevant in the design of ultrashort pulse active and passive (i.e., with purely parametric gain) fiber lasers, and may lead to important physical insight into the origin of chaotic pulsing behavior.

© 1992 IQEC