Gap solitons supported by parity-time-symmetric optical lattices with defocusing saturable nonlinearity

We show that the parity-time (PT)-symmetric optical lattices can support stable fundamental, in-phase multipeak gap solitons in defocusing saturable media. These stable solitons exist in the first finite gap and the saturation parameter can affect the existence of the solitons. The out-of-phase multipeak solitons can also exist in the first gap, but they are unstable. We also investigate the transverse energy flow of these solitons in saturable media. The imaginary part of the PT-symmetric periodic potentials will affect the stability of these solitons. (C) 2013 Elsevier B.V. All rights reserved.