Observation of surface solitons in chirped waveguide arrays
  We report the observation of surface solitons in chirped semi-infinite waveguide arrays whose waveguides exhibit exponentially decreasing refractive indices. We show that the power threshold for surface wave formation decreases with an increase of the array chirp and that for sufficiently large chirp values linear surface modes are supported. 
A. Szameit, Yaroslav V. Kartashov, F. Dreisow, M. Heinrich, T.   Pertsch, S. Nolte, A. Tunnermann, V. A. Vysloukh, L. Torner