Topological phase transition in a stretchable photonic crystal

TL;DR

This paper presents a tunable elastic photonic crystal setup that enables continuous control over topological phases using strain, facilitating experimental testing and cost-effective device fabrication.

Contribution

It introduces a generic design principle for strain-tuning topological phases in photonic crystals, demonstrated through the SSH model, with analytical and numerical validation.

Findings

Topological phase transition can be induced by stretching the photonic crystal.

Bulk modes reveal the phase transition point.

Design allows for continuous tuning of bandstructure and topological invariants.

Abstract

We design a setup to realize tunable topological phases in elastic photonic crystals. Using the Su-Schrieffer-Heeger (SSH) model as a canonical example, we show how a system can be continuously tuned across its topological phase transition by stretching. We examine the setup both analytically and numerically, showing how the phase transition point may be identified from the behavior of bulk modes. Our design principle is generic as it can be applied to a variety of systems, and enables multiple new theoretical predictions to be experimentally tested by continuously strain-tuning system properties, such as the shape of the bandstructure and the topological invariant. In addition, it allows for cost-effective device fabrication, since a wide range of parameter space can be accessed on a single photonic crystal chip.