Nonlinear pulse combining and compression using twisted hexagonal multi-core fibers

We demonstrate numerically and analytically that the twisting of the 7-core hexagonal fiber leads to an increase in the efficiency of pulse combining and to a reduction of the distance along the fiber to the combining point

Nonlinear Fourier transform for analysis of optical spectral combs

The nonlinear Fourier transform (NFT) is used to characterize the optical combs in the Lugiato-Lefever equation with both anomalous and normal dispersion. We demonstrate that the NFT signal processing technique can simplify analysis of the formation of dissipative dark solitons and regimes exploiting modulation instability for a generation of coherent structures, by approximating the comb with several discrete eigenvalues, providing a platform for the analytical description of dissipative coherent structures

Nonlinear Fourier Transform for Analysis of Coherent Structures in Dissipative Systems

Using the cubic Ginzburg-Landau equation as an example, we demonstrate how the inverse scattering transform can be applied to characterize coherent structures in dissipative nonlinear systems. Using this approach one can reduce the number of the effective degrees of freedom in the system when the dynamic is dominated by the coherent structures, even if they are embedded in the dispersive waves and demonstrate unstable behavior

Nonlinear combining and compression in multicore fibers

We demonstrate numerically light-pulse combining and pulse compression using wave-collapse (self-focusing) energy-localization dynamics in a continuous-discrete nonlinear system, as implemented in a multicore fiber (MCF) using one-dimensional (1D) and 2D core distribution designs. Large-scale numerical simulations were performed to determine the conditions of the most efficient coherent combining and compression of pulses injected into the considered MCFs. We demonstrate the possibility of combining in a single core 90% of the total energy of pulses initially injected into all cores of a 7-core MCF with a hexagonal lattice. A pulse compression factor of about 720 can be obtained with a 19-core ring MCF

Characterization of coherent structures in dissipative systems using nonlinear Fourier transform

We demonstrated how the nonlinear Fourier transform based on the Zakharov-Shabat spectral problem can be used to characterise coherent structures in dissipative systems. We consider as a particular, albeit important practical example model equation that is widely used to analyse laser radiation and demonstrate that dissipative solitons can be described by a limited number of degrees of freedom - discrete eigenvalues. Our approach can be applied for signal processing in a number of optical systems, from lasers to micro-resonators

Finding spatiotemporal light bullets in multicore and multimode fibers

A two-level iterative algorithm for finding stationary solutions of coupled nonlinear Schrödinger equations describing the propagation dynamics of an electromagnetic pulse in multimode and multicore optical fibers of various structures was developed and tested. Using as an example the proposed analytical soliton solution which is localized in space and time, test calculations were performed, and the convergence of the algorithm was demonstrated

Nonlinear dynamics in twisted multicore fibers with PT-symmetry

Linear and nonlinear modes of PT-symmetric multicore fibers twisted around the central axis are studied. We determine the spectral properties of such systems and show that the presence of a central core and twist can significantly change the mode structure, as well as the PT-symmetry breaking threshold. We also construct stationary nonlinear modes and investigate their stability

Nonlinear twisted multicore fibers with PT-symmetry

We investigate linear and nonlinear modes of parity-time (PT)-symmetric multicore fibers with a twist of peripheral cores with gain and loss around the lossless central core. We determine the spectral properties of such a light guiding system and demonstrate that the presence of the lossless central core combined with the fiber twist may significantly change the supermode structure, as well as the PT-symmetry breaking threshold of the multicore fiber with gain and loss. We also construct stationary nonlinear modes of the fiber and verify their stabilit

Discrete phase front focusing in multi-core fibers with simultaneous pulse compression

We demonstrate numerically by a genetic algorithm the possibility of effective discrete phase front focusing implemented in the 7-core hexagonal multi-core fiber. Moreover, the compression of a focused pulse in an arbitrary core is demonstrated

Spatiotemporal multiplexing based on hexagonal multicore optical fibres

Based on a genetic algorithm, we have solved the problem of finding the parameters of optical Gaussian pulses which make their efficient nonlinear combining possible in one of the peripheral cores of a 7-core hexagonal fibre. Two approaches based on individual selection of peak powers and field phases of the pulses launched into the fibre are considered. The found regimes of Gaussian pulse combining open up new possibilities for the development of devices for controlling optical radiation