Bifurcation to multisoliton complexes in the ac-driven, damped nonlinear Schrodinger equation

We study bifurcations of localized stationary solutions of the externally driven, damped nonlinear Schrodinger equation i Psi(t) + Psi(xx) +2\Psi\(2) Psi = -i gamma Psi - he(i Omega t) in the region of large gamma (gamma>1/2). For each pair of h and gamma, there are two coexisting solitons Psi(+) and Psi(-). As the driver's strength h increases for the fixed gamma, the Psi(+) soliton merges with the flat background while the Psi(-) forms a stationary collective state with two "Psi pluses": Psi(-) --> Psi((+-+)). We obtain other stationary solutions and identify them as multisoliton complexes Psi((++)), Psi((--)), Psi((-+)), Psi((---)), Psi((-+-)), etc.