title: Experimental study on acoustic subwavelength imaging of holey-structured metamaterials by resonant tunneling.
abstract: A holey-structured metamaterial is proposed for near-field acoustic imaging beyond the diffraction limit. The structured lens consists of a rigid slab perforated with an array of cylindrical holes with periodically modulated diameters. Based on the effective medium approach, the structured lens is characterized by multilayered metamaterials with anisotropic dynamic mass, and an analytic model is proposed to evaluate the transmission properties of incident evanescent waves. The condition is derived for the resonant tunneling, by which evanescent waves can completely transmit through the structured lens without decaying. As an advantage of the proposed lens, the imaging frequency can be modified by the diameter modulation of internal holes without the change of the lens thickness in contrast to the lens due to the Fabry-Pérot resonant mechanism. In this experiment, the lens is assembled by aluminum plates drilled with cylindrical holes. The imaging experiment demonstrates that the designed lens can clearly distinguish two sources separated in the distance below the diffraction limit at the tunneling frequency.
authors.affiliation: Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education, and School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
authors.forename: Haijing
authors.initials: H
authors.lastname: Su
authors.affiliation: Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education, and School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education, and School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
authors.forename: Xianchen
authors.initials: X
authors.lastname: Xu
authors.affiliation: Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education, and School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
authors.forename: Gengkai
authors.initials: G
authors.lastname: Hu