Characteristics of fundamental and superregular modes in a multiple self-induced transparency system

We study fundamental and superregular (SR) nonlinear modes on a plane-wave background in a multiple self-induced transparency system, which is governed by the multicomponent coupled Maxwell-Bloch equations. Important characteristics of fundamental mode transitions and SR waves induced by the interaction between different components are revealed in detail. In particular, we demonstrate that the SR waves can exhibit some novel states, including the half-transition, full-transition, and full-suppression modes, which are absent in the standard SR wave theory reported previously. It is shown that these different nonlinear states can be evolved from an identical initial perturbation. Our results illuminate the difference between nonlinear modes in the multiple and single self-induced transparency systems. Since SR waves describe a complete scenario of modulation instability (MI) that develops from localized small perturbations, our results will enrich the MI understanding of the nonlinear stage in a coupled multicomponent wave system.