Designing topological interface states in phononic crystals based on the full phase diagrams

TL;DR

This paper introduces a scheme using full phase diagrams to design topological interface states in phononic crystals, enabling precise control over their existence within specified bandgaps, verified through simulations and experiments.

Contribution

It presents a novel method based on full phase diagrams for designing topological interface states in phononic crystals, adaptable to various periodic systems.

Findings

Interface states can be engineered within specific bandgaps.

Verification of interface states through simulations and experiments.

The scheme is extendable to other periodic systems like photonic and plasmonic crystals.

Abstract

The topological invariants of a periodic system can be used to define the topological phase of each band and determine the existence of topological interface states within a certain bandgap. Here, we propose a scheme based on the full phase diagrams, and design the topological interface states within any specified bandgaps. As an example, here we propose a kind of one-dimensional phononic crystals. By connecting two semi-infinite structures with different topological phases, the interface states within any specific bandgap or their combinations can be achieved in a rational manner. The existence of interface states in a single bandgap, in all odd bandgaps, in all even bandgaps, or in all bandgaps, are verified in simulations and experiments. The scheme of full phase diagrams we introduce here can be extended to other kinds of periodic systems, such as photonic crystals and designer plasmonic crystals.