Foreword for the Special Issue ——International Workshop on Metamaterials and Negative Refraction

Electromagnetic properties of materials are often described using the concept of refraction index. The re- fraction index of a natural material is always positive. However, some artificially designed materials–so-called metamaterials–can act as negative-index media (NIM). Such media open new avenues for achieving extraor- dinary physical properties functionality unattainable with naturally-existing materials. On entering another medium from one medium, light usually refracts at a positive …