Giant optical nonlocality near the Dirac point in metal-dielectric multilayer metamaterials

TL;DR

This paper reveals and analyzes giant optical nonlocality near the Dirac point in metal-dielectric multilayer metamaterials, showing unique phenomena like epsilon-near-zero shift and beam splitting due to nonlocal effects.

Contribution

It analytically locates the Dirac point and demonstrates the giant optical nonlocality and associated phenomena in multilayer metamaterials, advancing understanding of nonlocal effects in plasmonic structures.

Findings

Giant optical nonlocality occurs near the Dirac point.

The Dirac point results from degeneracy of surface plasmon polariton modes.

Beam splitting at the Dirac point is caused by optical nonlocal effects.

Abstract

The giant optical nonlocality near the Dirac point in lossless metal-dielectric multilayer metamaterials is revealed and investigated through the analysis of the band structure of the multilayer stack in the three-dimensional omega-k space, according to the transfer-matrix method with the optical nonlocal effect. The position of the Dirac point is analytically located in the omega-k space. It is revealed that the emergence of the Dirac point is due to the degeneracy of the symmetric and the asymmetric eigenmodes of the coupled surface plasmon polaritons. The optical nonlocality induced epsilon-near-zero frequency shift for the multilayer stack compared to the effective medium is studied. Furthermore, the giant optical nonlocality around the Dirac point is explored with the iso-frequency contour analysis, while the beam splitting phenomenon at the Dirac point due to the optical nonlocal effect is also demonstrated.