Surface-wave photonic quasicrystal

TL;DR

This paper demonstrates that surface-wave photonic quasicrystals, despite lacking periodicity, can exhibit forbidden band gaps and support waveguiding, expanding the design possibilities for surface electromagnetic devices.

Contribution

It extends the concept of surface-wave photonic crystals to non-periodic quasicrystals, showing they can also have forbidden band gaps and function as waveguides.

Findings

Quasicrystals exhibit forbidden band gaps for surface waves.

Point defects in quasicrystals show unique properties.

Line-defect waveguides can be created in quasicrystals to guide surface waves.

Abstract

In developing strategies of manipulating surface electromagnetic waves, it has been recently recognized that a complete forbidden band gap can exist in a periodic surface-wave photonic crystal, which has subsequently produced various surface-wave photonic devices. However, it is not obvious whether such a concept can be extended to a non-periodic surface-wave system that lacks translational symmetry. Here we experimentally demonstrate that a surface-wave photonic quasicrystal that lacks periodicity can also exhibit a forbidden band gap for surface electromagnetic waves. The lower cutoff of this forbidden band gap is mainly determined by the maximum separation between nearest neighboring pillars. Point defects within this band gap show distinct properties compared to a periodic photonic crystal for the absence of translational symmetry. A line-defect waveguide, which is crafted out of this surface-wave photonic quasicrystal by shortening a random row of metallic rods, is also demonstrated to guide and bend surface waves around sharp corners along an irregular waveguiding path.