Eur. Phys. J. D (2012) 66: 266
https://doi.org/10.1140/epjd/e2012-30408-6

Regular Article

Defect solitons in optical lattices with parity-time symmetric defect

¹ Department of Physics, Guangdong University of Petrochemical Technology, Maoming 525000, P.R. China
² Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510631, P.R. China

^a e-mail: huwei@scnu.edu.cn

Received: 3 July 2012
Received in final form: 28 August 2012
Published online: 18 October 2012

Abstract

The existence and stability of defect solitons in optical lattices with parity-time (PT) symmetric defect are reported. For positive or zero defects, in-phase solitons and out of phase solitons can exist stably in the semi-infinite gap and the first gap, respectively. For negative defects, in-phase solitons can be stable in both the semi-infinite gap and the first gap, whereas out of phase solitons are unstable in the first gap. For in-phase solitons with positive defect in the semi-infinite gap and negative defect in the first gap, there exists a cutoff point of the propagation constant below which the defect solitons vanish. The imaginary parts of the PT-symmetric defect potentials deeply affect the stability of solitons.