Active metamaterials
Freqeuncy dispersion and matrix form of response of metamaterials can be virtualized by a digital convolution, now with arbitrary specification using a computer program.
Nature Commun. 11, 251 (2020) (Intro at PHYS.ORG)
Willis coupling beyong passivity bound:
Communications Physics 4, 82 (2021)
Unidirectional amplification with acoustic non-Hermitian space−time varying metamaterial:
Communications Physics 5, 18 (2022)
Willis metamaterial on a structured beam
Willis coupling is the analogy of electromagnetic bianisotropy in elastic waves. Here, we provide a realization on flexural waves.
Phys. Rev. X 9, 011040 (2019)
Elastic metasurfaces
Metasurface based on space-coiling unit cells for elastic waves. Source illusion with target phase profile = original excitation + phase discontinuity by metasurface
Phys. Rew. Lett. 119, 034301 (2017)
Negative refractive index
Coiling up space for airborne acoustic waves.
Negative index, cone-like dispersion and large index without local resonances,
Phys. Rev. Lett. 108, 114301 (2012)
Sci. Rep. 3, 1614 (2013) (arxiv)
Highlight: APS
Exper. from Cummer: Phys. Rev. Lett. 110, 175501 (2013)
Coherent perfect absorption
Perfect absorption with coherent input waves when we have either resonating dynamic density or modulus.
Appl. Phys. Lett. 104, 121902 (2014)
Expriment from Yang: Sci. Rep. 7 43574 (2017)
Subwavelength imaging to the far-field
Capturing subwavelength imaging resolution and project to far-field using highly anisotropic dispersion surface.
Nature Materials 8, 931 (2009)
Highlight: PopSci, nature.com
Elastic wave expr. from Kim: Appl. Phys. Lett. 98, 241912 (2011)
Meaning of an acoustic negative index
Resonating breathing mode to negative modulus and resonating oscillating mode to negative density.
This double negativity gives a negative index
Phys. Rev. E 70, 055602(R) (2004)