Nonlinear surface waves in curved waveguide arrays

The features and applications of linear and nonlinear surface waves in periodic photonic structures are attracting increasing attention. It was found that, while strong surface localization is impossible for an array of identical waveguides, Tamm surface waves can exist when the edge waveguide is modified and the introduced detuning exceeds a certain threshold [1]. On the other hand, it was recently predicted theoretically and demonstrated experimentally that arrays of periodically curved waveguide arrays can support a novel type of linear surface modes without any surface defects [2]. In this work, we study, for the first time to our knowledge, the interplay between both types of localized surface modes at the edge of a semi-infinite periodically curved waveguide array with a surface defect. We demonstrate experimentally the signature of such modes, and show that nonlinear beam self-action can provide effective control and switching between different surface states.