# Dynamical control of solitons in a parity-time-symmetric coupler by periodic management

## TL;DR

This paper investigates the dynamical control of PT-symmetric solitons in a dual-core nonlinear waveguide with periodic management of gain, loss, and coupling, revealing stability conditions and soliton interactions.

## Contribution

It introduces a novel periodic management scheme for PT-symmetric couplers, enabling exact solutions and stability analysis of solitons with potential optical applications.

## Key findings

- Identified stability regions depending on management parameters.
- Derived analytical predictions for long-period soliton evolution.
- Analyzed collisions between moving solitons in the system.

## Abstract

We consider a dual-core nonlinear waveguide with the parity-time (PT) symmetry, realized in the form of equal gain and loss terms carried by the coupled cores. To expand a previously found stability region for solitons in this system, and explore possibilities for the development of dynamical control of the solitons, we introduce "management" in the form of periodic sinusoidal variation of the loss-gain (LG) coefficients, along with synchronous variation of the inter-core coupling (ICC) constant. This system, which can be realized in optics (in the temporal and spatial domains alike), features strong robustness when amplitudes of the variation of the LG and ICC coefficients keep a ratio equal to that of their constant counterparts, allowing one to find exact solutions for PT-symmetric solitons. A stability region for the solitons is identified in terms of the management amplitude and period, as well as the soliton's amplitude. In the long-period regime, the solitons evolve adiabatically, making it possible to predict their stability boundaries in an analytical form. The system keeping the Galilean invariance, collisions between moving solitons are considered too.