New approach to all-angle-negative-refraction in two-dimensional photonic crystals

We show that with appropriate surface grating, all-angle-negative-refraction is possible in other frequency windows that were not realized before in two-dimensional photonic crystals. Previous flat lens using photonic crystals requires u+v $<<$ d. Our approach can be used to design flat lens with u+v$>>$d, thus being able to image large and/or far away objects. Our results are confirmed by FDTD simulations.