Grouping of antiphase oscillations in modulated multimode lasers

Coexistence of periodic states with antiphase periodic states or with grouping states, which consist of qualitatively different motions, is predicted in the model of globally coupled modulated multimode lasers. It is shown that the injection seeding can switch the system from periodic states to antiphase periodic states or to grouping states, which are composed of a large-amplitude periodic (chaotic) antiphase spiking mode group and a small-amplitude periodic (chaotic) mode group. A switching process between different states is investigated and the inverse power-law relation for seeding assignment is demonstrated. A class of synchronized chaos, in which two modes exhibit a small-amplitude synchronized chaotic motion while other modes show a large-amplitude antiphase chaotic motion, is found in the grouping state. Characterization of grouping phenomena is provided by Lyapunov spectrum calculation, phase-space trajectories, return map, and circulation analysis. A grouping is found to occur so as to satisfy the self-organized vanishing-gain-circulation rule, which is the strong constraint which governs globally coupled multimode laser dynamics. Synchronized chaos is shown to take place being accompanied with the cooperative power flow from the antiphase chaotic mode group to the synchronized chaotic mode group. © 1996 The American Physical Society.