Vector solitons in PT-symmetric lattices

TL;DR

This paper investigates vector solitons in PT-symmetric optical lattices, revealing how lattice symmetry restricts soliton configurations and identifying conditions for their stability in focusing and defocusing media.

Contribution

It introduces the existence and stability conditions of multi-hump vector solitons with specific phase relations in PT-symmetric lattices, highlighting the impact of lattice symmetry.

Findings

Asymmetric intensity distributions are prohibited by lattice symmetry.

Stable out-of-phase solitons exist in focusing media.

Stable in-phase solitons exist in defocusing media.

Abstract

I study vector solitons involving two incoherently-coupled field components in periodic PT-symmetric optical lattices. The specific symmetry of the lattice imposes the restrictions on the symmetry of available vector soliton states. While all configurations with asymmetric intensity distributions are prohibited, such lattices support multi-hump solitons with equal number of "in-phase" or "out-of-phase" spots in two components, residing on neighboring lattice channels. In the focusing medium only the solitons containing out-of-phase spots in at least one component can be stable, while in the defocusing medium stability is achieved for structures consisting of in-phase spots. Mixed-gap vector solitons with components emerging from different gaps in the lattice spectrum also exist and can be stable in the PT-symmetric lattice.