Three-Dimensional All-Dielectric Photonic Topological Insulator

TL;DR

This paper demonstrates the design of a three-dimensional all-dielectric topological insulator that supports robust surface states with Dirac dispersion, enabling new ways to control electromagnetic waves in 3D.

Contribution

It introduces a novel all-dielectric 3D topological photonic system with symmetry-protected states and synthetic gauge fields, advancing topological photonics into three dimensions.

Findings

Robust 3D surface states with Dirac dispersion observed

Complete 3D photonic bandgap achieved through magneto-electric coupling

Surface states propagate along domain walls with numerical confirmation

Abstract

The discovery of two-dimensional topological photonic systems has transformed our views on electromagnetic propagation and scattering of classical waves, and a quest for similar states in three dimensions, known to exist in condensed matter systems, has been put forward. Here we demonstrate that symmetry protected three-dimensional topological states can be engineered in an all-dielectric platform with the electromagnetic duality between electric and magnetic fields ensured by the structure design. Magneto-electric coupling playing the role of a synthetic gauge field leads to a topological transition to an insulating regime with a complete three-dimensional photonic bandgap. An emergence of surface states with conical Dirac dispersion and spin-locking is unimpeded. Robust propagation of surface states along two-dimensional domain walls defined by the reversal of magneto-electric coupling is confirmed numerically by first principle studies. It is shown that the proposed system represents a table-top platform for emulating relativistic physics of massive Dirac fermions and the surface states revealed can be interpreted as Jackiw-Rebbi states confined to the interface between two domains with opposite particle masses.