A truly hyperbolic elastic metamaterial lens

Abstract

Sub-wavelength imaging is possible if metamaterial lenses realizing hyperbolic or elliptic Equi-Frequency Contours (EFCs) are used. Theoretically, lenses exhibiting hyperbolic EFCs allow imaging with unlimited resolution, but only metamaterials of elliptic EFCs producing limited resolution have been so far realized in elastic field. Thus, an elastic metamaterial lens realizing truly hyperbolic EFCs can lead to superior-resolution ultrasonic imaging. This Letter presents the realization of an elastic lens exhibiting truly hyperbolic EFCs and its experimental verification.