Effects of shapes and symmetries of scatterers on acoustic dual-negative refraction

Abstract

The potential operating conditions of acoustic dual-negative refraction (ADNR) are investigated by band structure theory for scatterers with different shapes and symmetries. Specifically, two types of lattices (triangular and honeycomb) and four different shapes of scatterers (circle, hexagon, square and triangle) are considered. Based on the generation mechanism of the ADNR effect, which is dependent on the frequency of the incident wave at the overlapping second and third Bloch bands, the optimum operating frequencies of ADNR with different crystal structures are given. The calculations demonstrate that the ADNR effect can be generated at the normalized frequency from 0.8 to 1.05.

Experimental demonstration in X-band of dual-negative refraction in photonic crystals

“…Experimental setup and demonstrations. -To further verify the theoretical results of the anomalous refraction phenomena experimentally, a near-field scanning system (microwave planar waveguide) is applied to measure the spatial mapping of the EMW in X-band (8)(9)(10)(11)(12) propagating through the PhC slab samples. As fig.…”

“…-Recently, great effort has been made to realize anomalous propagation behaviors of light, such as negative refraction [1][2][3][4] by means of deliberately designed artificial nanostructures, which can be applied to fabricate flat superlens [5] and plano-concave lens [6,7] and beam splitting [8] to break the diffraction limit and reach subwavelength resolutions. Based on the overlapping of two bands satisfying the condition of negative refraction at the same frequency, DNR has been investigated in various artificial materials, such as sonic crystal [9,10], dielectric PhCs [11], metallic PhCs [12] and ferrite-based metamaterial [13] (including split-ring resonators (SRR), Omega-like resonators, and short-wire pairs).…”