Evidence of local effects in anomalous refraction and focusing properties of dodecagonal photonic quasicrystals

TL;DR

This study investigates the refraction and focusing behaviors of dodecagonal photonic quasicrystals, revealing local effects and challenging the effective negative refractive index explanation through combined simulations and experiments.

Contribution

The paper provides new insights into the local effects influencing anomalous refraction and focusing in photonic quasicrystals, emphasizing the importance of short-range interactions over effective negative index models.

Findings

Observed anomalous refraction and focusing in multiple frequency regions.

Challenged the effective negative refractive index interpretation.

Highlighted the significance of local order and symmetry effects.

Abstract

We present the key results from a comprehensive study of the refraction and focusing properties of a two-dimensional dodecagonal photonic ``quasicrystal'' (PQC), carried out via both full-wave numerical simulations and microwave measurements on a slab made of alumina rods inserted in a parallel-plate waveguide. We observe anomalous refraction and focusing in several frequency regions, confirming some recently published results. However, our interpretation, based on numerical and experimental evidence, differs substantially from the one in terms of ``effective negative refractive-index'' that was originally proposed. Instead, our study highlights the critical role played by short-range interactions associated with local order and symmetry.