Multicore-fiber solitons and laser-pulse self-compression at light-bullet excitation in the central core of multicore fibers

Abstract

The propagation of laser pulses in multi-core fibers (MCF) made of a central core and an even number of cores located in a ring around it is studied. Approximate quasi-soliton homogeneous solutions of the wave field in the considered MCF are found. The stability of the in-phase soliton distribution is shown analytically and numerically. At low energies, its wave field is distributed over all MCF cores and has a duration, which exceeds the duration of the NSE soliton with the same energy by many (five-six) times. On the contrary, almost all of the radiation at high energies is concentrated in the central core with a duration similar to the NSE soliton. The transition between the two types of distributions is very sharp and occurs at a critical energy, which is weakly dependent on the number of cores and on the coupling coefficient with the central core. The self-compression mechanism of laser pulses was proposed. It consists in injecting such MCF with a wave packet being similar to the found soliton and having an energy larger than the critical value. It is shown that the compression ratio weakly depends on the energy and the number of cores and is approximately equal to 6 times with an energy efficiency of almost 100%. The use of longer laser pulses allows one to increase the compression ratio up to 30-40 times with an energy efficiency of more than 50%. The obtained analytical estimates of the compression ratio and its efficiency are in good agreement with the results of numerical simulation.

Angular momentum supercontinuum from fibre rings

“…Note that the former is obtained in each fibre when the coupling Δ vanishes , while the latter results from neglecting the time dependence Bt sech ( ). The m=0 variant, and its stability against azimuthal perturbations, is also discussed in [36]. The modification to the propagation constant…”

“…Hence we use a coupled mode approach, in which we consider only the complex amplitude of the fundamental guided mode within each core. The timeindependent nonlinear properties of such multicore arrays have been widely studied before [29][30][31][32][33] and understanding of the dynamics of solitons therein is developing rapidly [34][35][36][37], with and without an extra central core which is not considered here. In addition the fibre cores may be twisted around the cladding rod's central axis at a uniform rate, which can greatly change the supercontinuum spectra even for very moderate twist rates.…”