Focus |

PT symmetry

The exploration of photonic systems embracing the concepts of PT symmetry, topology and non-reciprocity has become highly active in recent years. Studies on these topics are not only providing rich scientific insight in terms of new physics but also potentially have important long-term technological implications, including the development of on-chip optical systems that support states of light that are immune to back scatter, are robust against perturbation and feature guaranteed unidirectional transmission.


The exploitation of non-Hermitian quantum physics concepts in classical photonics has spawned much research activity during 2017. We conclude the year with a focus issue on parity–time symmetry and concepts with overlapping goals, in particular topological and non-reciprocal photonics.

Editorial | | Nature Photonics

Nature Photonics spoke to Demetrios Christodoulides, of CREOL, The College of Optics & Photonics, University of Central Florida, about the birth of the parity–time-symmetry concepts in optics and the challenges and prospects on the path ahead.

Q&A | | Nature Photonics

Topological photonic structures offer unique features such as reflection-free and non-reciprocal devices. This Review highlights the experimental progress in the relatively new field of photonic topology.

Review Article | | Nature Photonics