Hyperbolic metamaterials enable nanoscale `fingerprinting`
(PHYSorg.com Physics)

Hyperbolic metamaterials are artificially made structures that can be formed by depositing alternating thin layers of a conductor such as silver or graphene onto a substrate. One of their special abilities is supporting the propagation of a very narrow light beam, which can be generated by placing a nanoparticle on its top surface and illuminating it with a laser beam.