Gyrating solitons in a necklace of optical waveguides

TL;DR

This paper studies light pulses in a circular array of coupled nonlinear optical waveguides, revealing stable and unstable gyrating solitons, and demonstrates control over their motion through gain-loss tuning.

Contribution

It introduces the concept of gyrating solitons in a necklace of optical waveguides, including their stability properties and control via gain-loss parameters.

Findings

Gyrating solitons can be stable or weakly unstable.

Gain-loss tuning can reverse soliton gyration.

The array supports patterns like traveling pulses and breathers.

Abstract

We consider light pulses in a circular array of $2N$ coupled nonlinear optical waveguides. The waveguides are either hermitian or alternate gain and loss in a $\mathcal{PT}$-symmetric fashion. Simple patterns in the array include a ring of $2N$ pulses travelling abreast, and a breather -- a string of pulses where all even and all odd waveguides flash in turn. In addition, the structure displays solitons gyrating around the necklace by switching from one waveguide to the next. Some of the gyrating solitons are stable while other ones are weakly unstable and evolve into gyrating multiflash strings. By tuning the gain-loss coefficient, the gyration of solitons in a nonhermitian array may be reversed without changing the direction of their translational motion.