The availability of manufacturing tools to shape materials at a scale of ten nanometers has opened the way to the development of artificial materials consisting of random or periodic arrangements of nano-elements in a host matrix. Such materials may provide optical properties that are entirely new, such as negative or near zero refractive index.
Despite some successful results and remarkable demonstrations, most of them before 2010, 3D metamaterials today suffer from some intrinsic drawbacks (high losses, small sample size, uncontrolled dispersion) which seem difficult to overcome and which prevent their practical use in components dedicated to visible or near infrared parts of the spectrum. In addition, negative refraction is not always evidence of a negative refractive index, which introduces additional questioning to this already complex landscape.
On the other hand, the recent application of manufacturing tools to 2D components has enabled the realization of highly integrated planar optical functions, called metasurfaces. The development of these metasurfaces is characterized by a rapid and continuous growth with achievements that are already impressive.
Our presentation will provide a synthetic overview of these nanostructured components, and will try to express main challenges and possible opportunities, especially in connection with the field of thin-film coatings.