The theoretical and experimental analysis of an elastic hyperlens for far-field subwavelength imaging in a plate

Abstract

The hyperlens is a novel imaging device that is capable to overcome the diffraction limit, a fundamental limit due to exponentially-decaying wave components containing subwavelength information. Because a hyperlens converts evanescent waves to propagating waves and magnify them, it can transfer a subwavelength image to the far field beyond the hyperlens. These interesting capabilities can be achieved through an extreme anisotropy in an effective permittivity tensor in optics while in a density tensor in acoustics. The extreme anisotropy in an elastic regime, however, is determined by elastic stiffness rather than density unlike in acoustics. We show, by using the homogenization method, how to evaluate the effective elasticity tensor of an elastic plate hyperlens consisting of alternating layers of metal and air. To experimentally demonstrate far-field subwavelength imaging by the hyperlens, a specially-configured experimental setup is suggested. The ratio of the input power to the output power is investigated both theoretically and experimentally.