Soliton states and bifurcation phenomena in three-core nonlinear fiber couplers

We determine, analytically and numerically, the coupled soliton states in three-core equilateral-triangle nonlinear fiber couplers. It is shown that in the coupler there are many types of composite soliton state that consist of three strongly interacting pulses of complicated shapes. The bifurcation diagram for the new types of soliton state is constructed.