Laser pulse compression up to few-cycle durations in multicore fiber

A mechanism for self-compression of laser pulses in a multicore fiber on the basis of nonlinear combining of radiation from many cores, surrounding the central core in a ring and its trapping into the central core in a chirp-free and pedestal-free soliton-like pulse, is proposed. It is shown that the compression ratio is weakly dependent on the energy and the number of cores in the fiber and approximately equal to 6 with an almost 100% energy efficiency. The compression ratio can be increased to 40 with an efficiency of more than 50% by using additional compression of longer pulses with approximately the same energy. The possibility of a 38-fold compression of a laser pulse to a duration of 15 fs with a pulse energy of 4 nJ in the fiber with realistic parameters was demonstrated numerically.