title: Focusing ultrasound with an acoustic metamaterial network.
abstract: We present the first experimental demonstration of focusing ultrasound waves through a flat acoustic metamaterial lens composed of a planar network of subwavelength Helmholtz resonators. We observed a tight focus of half-wavelength in width at 60.5 kHz by imaging a point source. This result is in excellent agreement with the numerical simulation by transmission line model in which we derived the effective mass density and compressibility. This metamaterial lens also displays variable focal length at different frequencies. Our experiment shows the promise of designing compact and lightweight ultrasound imaging elements.
authors.affiliation: Department of Mechanical Science and Engineering and Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: Leilei
authors.initials: L
authors.lastname: Yin
authors.forename: Nicholas
authors.initials: N
authors.lastname: Fang