Dynamics of the Self-Action of Wave Fields in Multicore Fibers

We review modern studies of the self-action of laser radiation in discrete systems using the example of multicore fibers. The critical power is shown to exist, at which the self-trapping (the discrete analog of collapse) of radiation occurs even in a one-dimensional lattice of weakly coupled cores. The transition of nonlinear dynamics to the stochastic regime in discrete systems is studied, and the threshold amplitude for this transition is determined. It is shown that the use of a special configuration with a dedicated core in the center of a ring of identical cores makes it possible to control the self-trapping process and apply it for nonlinear radiation filtering and self-compression of laser pulses. It is established that arbitrarily powerful coherent radiation can be handled using stable out-of-phase supermodes, which are wave-field distributions over all fiber cores with a maximum propagation constant. Such out-of-phase supermodes are demonstrated for core configurations shaped as a ring, a line, a square matrix, and a hexagonal structure. The first experiments have already shown the feasibility and stability of the found out-of-phase supermodes, in both fibers with a ring configuration and fibers having a square matrix of cores.