Defect Solitons in Parity-Time Symmetric Optical Lattices with Nonlocal Nonlinearity

TL;DR

This paper investigates the existence and stability of defect solitons in PT-symmetric optical lattices with nonlocal nonlinearity, revealing how nonlocality and potential parameters influence soliton stability and existence.

Contribution

It introduces the effects of nonlocal nonlinearity on defect solitons in PT-symmetric lattices, including stability regions and the impact of potential parameters.

Findings

Nonlocality expands the stability region of defect solitons.

Stable fundamental and dipole solitons exist in specific gaps depending on defect type.

A maximum degree of nonlocality limits soliton existence for negative defects.

Abstract

The existence and stability of defect solitons in parity-time (PT) symmetric optical lattices with nonlocal nonlinearity are reported. It is found that nonlocality can expand the stability region of defect solitons. For positive or zero defects, fundamental and dipole solitons can exist stably in the semi-infinite gap and the first gap, respectively. For negative defects, fundamental solitons can be stable in both the semi-infinite gap and the first gap, whereas dipole solitons are unstable in the first gap. There exist a maximum degree of nonlocal nonlinearity, above which the fundamental solitons in the semi-infinite gap and the dipole solitons in the first gap do not exist for negative defects. The influence of the imaginary part of the PT-symmetric potentials on soliton stability is given. When the modulation depth of the PT-symmetric lattices is small, defect solitons can be stable for positive and zero defects, even if the PT-symmetric potential is above the phase transition point.