Topological interface modes in photonic superlattices containing negative-index materials

¹ School of Physics and Telecommunication Engineering, South China Normal University Guangzhou 510006, China
² Department of Electronic Information and Physics, Changzhi University - Changzhi, Shanxi 046011, China
³ School of Physics and Astronomy, Shanghai Jiao Tong University - Shanghai 200240, China
⁴ Department of Physics, Zhejiang Normal University - Jinhua 321004, China

^(a) dhy0805@alumni.sjtu.edu.cn
^(b) yhchen@scnu.edu.cn
^(c) fangweiye@sjtu.edu.cn

Received: 22 October 2018
Accepted: 7 December 2018

Abstract

We study the topological properties of one-dimensional photonic superlattices consisting of alternating layers of positive- and negative-index materials. We find that Zak phases of photonic bands of such superlattices are related to the signs of the spatial average of their permittivity and permeability, and the polarization of incident light. Specifically, the Zak phases for transverse electric (TE) waves (transverse magnetic (TM) waves) are determined by only the sign of the spatially averaged permittivity (permeability) of the lattices. Only a single-polarized (TM or TE) topological interface mode occurs at the interface between air and the superlattice with single-negative average permittivity or permeability. The crucial dependence of the topological property of the superlattice on the light polarization suggests a polarization filter application. The topologically protected interface modes for both TM and TE polarizations can coexist at the interface separating air and the superlattices with simultaneously negative signs of averaged permittivity and permeability. The robustness of such topological interface modes for both TM and TE polarizations is also demonstrated.