Nonlinear localized modes at phase-slip defects in waveguide arrays
  We study light localization at a phase-slip defect created by two semi-infinite mismatched identical arrays of coupled optical waveguides. We demonstrate that the nonlinear defect modes possess the specific properties of both nonlinear surface modes and discrete solitons. We analyze stability of the localized modes and their generation in both linear and nonlinear regimes. 
Mario I. Molina and Yuri S. Kivshar