Creating all-angle negative refraction by using insertion

The all-angle negative refraction (AANR) is generally very important to design a microsuperlens. However, it is usually absent from some two-dimensional (2D) photonic crystals (PCs). In this letter, we present a method to create and enlarge the AANR region by using insertion. For some 2D dielectric PC systems without the AANR, the AANR region can be created by adding a fraction of a metallic component to the center of each dielectric cylinder. At the same time, the AANR region can be enlarged by adjusting the size of the metal cylinder. To illustrate this phenomenon, the microsuperlens is designed and numerically demonstrated.