# Topological phase transition and interface states in hybrid plasmonic-photonic systems

## TL;DR

This paper explores the topological phase transition and interface states in hybrid plasmonic-photonic systems made of graphene, revealing how degeneracy points lead to topological changes and localized states with potential photonic applications.

## Contribution

It systematically investigates topological properties and interface states in graphene-based hybrid plasmonic-photonic crystals, identifying diabolic points and associated topological phase transitions.

## Key findings

- Identification of diabolic degeneracy points in the system
- Berry phase of Pi around the degeneracy point
- Existence of topological interface states linked to degeneracy points

## Abstract

The geometric phase and topological property for one-dimensional hybrid plasmonic-photonic crystals consisting of a simple lattice of graphene sheets are investigated systematically. For transverse magnetic waves, both plasmonic and photonic modes exist in the momentum space. The accidental degeneracy point of these two kinds of modes is identified to be a diabolic point accompanied with a topological phase transition. For a closed loop around this degeneracy point, the Berry phase is Pi as a consequence of the discontinuous jump of the geometric Zak phase. The wave impedance is calculated analytically for the semi-infinite system, and the corresponding topological interface states either start from or terminate at the degeneracy point. This type of localized interface states may find potential applications in photonics and plasmonics.

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Source: https://tomesphere.com/paper/1703.00346