Nonlinear topological photonics

TL;DR

This paper introduces the emerging field of nonlinear topological photonics, exploring how topological phases of light combined with nonlinear effects can lead to robust, advanced optical devices with new functionalities.

Contribution

It reviews recent developments in designing topological photonic structures with nonlinear responses and discusses potential applications and future research directions.

Findings

Design of novel topological photonic platforms with nonlinear responses

Observation of edge solitons in topological lattices due to nonlinear effects

Demonstration of harmonic generation and lasing in topological structures

Abstract

Rapidly growing demands for fast information processing have launched a race for creating compact and highly efficient optical devices that can reliably transmit signals without losses. Recently discovered topological phases of light provide a novel ground for photonic devices robust against scattering losses and disorder. Combining these topological photonic structures with nonlinear effects will unlock advanced functionalities such as nonreciprocity and active tunability. Here we introduce the emerging field of nonlinear topological photonics and highlight recent developments in bridging the physics of topological phases with nonlinear optics. This includes a design of novel photonic platforms which combine topological phases of light with appreciable nonlinear response, self-interaction effects leading to edge solitons in topological photonic lattices, nonlinear topological circuits, active photonic structures exhibiting lasing from topologically-protected modes, and harmonic generation from edge states in topological arrays and metasurfaces. We also chart future research directions discussing device applications such as mode stabilization in lasers, parametric amplifiers protected against feedback, and ultrafast optical switches employing topological waveguides.