Reconfigurable Elastic Metamaterials: Engineering Dispersion with Beyond Nearest Neighbors

Extreme Spatial Dispersion in Nonlocally Resonant Elastic Metamaterials

“…While metamaterials were initially electromagnetic [11,12], they have since flourished in acoustics [13][14][15], thermal physics [16], and mechanics [17][18][19][20][21], merging with auxetic materials [22,23]. Long-range interactions have recently been shown to extend the capabilities of metamaterials, either through radiative coupling [24] or with explicit beyond-next-neighbor connectors [25][26][27]. Such couplings induce local minima in the dispersion branches, called rotons [28,29].…”

“…Nonlocally resonant metamaterials, which unify the present elastic metamaterials and interlaced wire media, also shed new light on another type of metamaterial: roton metamaterials [24][25][26][27][28][29]41]. Although based on a different physical mechanism, namely, long-range interactions, roton metamaterials also achieve wide domains of negative group velocity by leveraging a type of nonlocality.…”

Acoustic metasurfaces with Frieze symmetries

“…3,4 The effects of symmetry, and its strategic breaking, have been utilized across wave physics, from the passive beam-steering applications to topological surfaces and insulators. [5][6][7][8][9][10] There has been a recent interest in the design of reconfigurable one-dimensional (1D) waveguiding structures, [11][12][13][14] whereby the symmetries of the unit cell are used, or broken, to tailor the dispersion of supported modes. Glide-symmetry has been extensively investigated in the electromagnetic regime, [15][16][17][18] with notable studies done by Hessel et al in 1973 19 with periodically loaded waveguides.…”

Dispersion Engineering by Hybridizing the Back‐Folded Soft Mode of Monomode Elastic Metamaterials with Stiff Acoustic Modes

“…[4][5][6] Numerous further types of avoided crossing have been discussed in the literature. [7,8] Recently, the hybridization of different photon modes [9] or phonon [11][12][13][14][15][16][17][18] modes has been exploited to realize dispersion relations resembling the roton dispersion relation of sound in liquid helium-4. [19] This dispersion relation contains a broad region of backward waves, for which group velocity and phase velocity have opposite signs, indicating a negative refractive index.…”