Microwave Applications of Photonic Topological Insulators

Abstract

This Perspective examines the emerging applications of photonic topological insulators (PTIs) in the microwave domain. The introduction of topological protection of light has revolutionized the traditional perspective of wave propagation through the demonstration of backscatter-free waveguides in the presence of sharp bending and strong structural defects. The pseudospin degree of freedom of light enables the invention of novel topological photonic devices with useful functionalities. Here we aim to summarize the recent development and potential application directions of the PTI demonstrations mainly in the microwave regime, and explain the key features giving rise to topological protection, along with a comparison of different designs and realizations.