Fundamental Soliton Propagation Research Articles

Numerical study of the fundamental fiber soliton propagation

This work presents a numerical approach to understand the self-regeneration mechanism of the fundamental soliton propagation driven by the nonlinear Schr\"odinger equation in the nonlinear fiber formalism. This approach shows that the interplay between dispersion and nonlinearity results in a compensation effect in the phase and the instantaneous frequency representation of the pulse envelope. For a better understanding of this compensation process, 3D mapping propagation graphs are presented.

Partition of the instantaneous and delayed nonlinear responses for the propagation of ultrashort solitons in optical fibers

We address the long-standing issue of accurately partitioning the nonlinear response of silica glass into electronic (Kerr) and nuclear (Raman) contributions to correctly describe the propagation of ultrashort solitons in a unified way independently of their duration. This is done with a semianalytical approach leading to a modified nonlinear coefficient and thus to a modified condition for fundamental soliton propagation valid for durations much less, in the same order, or much greater than the characteristic time scale of the Raman response function. The results provided by this model are in good agreement with numerical integration of the nonlinear Schr\"odinger equation taking the Raman response into account.

Soliton switching and propagation in two-core nonlinear fiber coupler with high order coupling coefficient

We use the variational approach (VA) and the split-step Fourier transforms (SSFT) to study the transmission and switching characteristics inside the fiber nonlinear directional coupler (NDLC). The results, based on the VA, indicate that the second-order coupling coefficient dispersion and initiative chirp all reduce the coupling length, and the second-order coupling coefficient dispersion makes the switching characteristics become sharper and threshold power become bigger under the case of not having initiative chirp. The outcomes, based on the SSFT, indicate that the first order intermodal dispersion coefficient make optical pulses splitting in the propagation of fundamental solitons, and the second-order coupling coefficient dispersion reduces the coupling length, sharpens the switching characteristics and increases the switching threshold power, the results agrees well with those from the VA.

Effect of two photon absorption on nonlinear pulse propagation in gain medium

The effects of two photon absorption (TPA) and gain dispersion on soliton propagation in amplified medium are investigated. For finite gain bandwidth, the effect of gain dispersion becomes significant along with TPA and is treated as perturbation in fundamental soliton propagation. Including these perturbing effects an analytical expression of integrated intensity is formulated applying a completely new methodology by adopting Rayleigh’s dissipation function in the framework of variational approach. With classical analogy, the Euler–Lagrange equation in non-conservative system is used to solve the problem analytically. In order to justify the analytical prediction a numerical verification is made by split-step beam propagation method following Ginzburg–Landau equation.

Optical soliton near zero-dispersion regime in a raman pumped fiber

Near zero-dispersion regime, the fundamental soliton propagation and the collision of two copropagating solitons with different frequencies in a Raman pumped fiber are studied. It is found that pulse shape distortion and velocity change are reduced near zero-dispersion regime.