Negative index materials

The possibility of negative refraction has brought about a reconsideration of many fundamental optical and electromagnetic phenomena. This new degree of freedom has provided a tremendous stimulus for the physics, optics and engineering communities to investigate how these new ideas can be utilized. Many interesting and potentially important effects not possible in positive refracting materials, such as near-fieId refocusing and sub-diffraction limited imaging, have been predicted to occur when the refractive index changes sign. In this talk, I will give a historical appraisal of the field and also review our own work on negative refraction in metamaterials, and describe the possible impact of them as new types of optical elements. In particular, I will present theoretical and experimental results on engineered microstructures designed to have both e and mu negative. Results for different polarizations and propagation directions will be presented. Recent results on microstructures operating at 100-200 THz will be also discussed, and the role of losses will be also examined.