Nonlinear topological photonics

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 novel opportunities for photonic devices robust against scattering losses and disorder. Combining these topological photonic structures with nonlinear effects will unlock advanced functionalities such as magnet-free nonreciprocity and active tunability. Here, we introduce the emerging field of nonlinear topological photonics and highlight the recent developments in bridging the physics of topological phases with nonlinear optics. This includes the 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, frequency conversion, active photonic structures exhibiting lasing from topologically protected modes, and many-body quantum topological phases of light. 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.

Nontrivial coupling of light into a defect: the interplay of nonlinearity and topology

“…Thus far, nonlinear topological effects have been investigated far less than their linear counterparts, although nonlinearity inherently exists in many topological photonic platforms, such as waveguide arrays, coupled resonators, and metamaterials [19][20][21][22][23][24][25][26][27][28][29][30][31] . Seeking unique functionalities and device applications, research in nonlinear topological photonics has been focused mainly on edge solitons in topological structures 21,23,[32][33][34] , nonlinearity-induced topological transitions 24,25 , nonlinear frequency generation [35][36][37] , and topological lasing [38][39][40] .…”

Topological phases in ring resonators: recent progress and future prospects

“…In both cases, the potential advantage of the topological approach is the ability to induce lasing in collective array modes that are localized by the topological band gap. For further information on topological lasing, we recommend the recent reviews by Ota et al [8] and Smirnova et al [11].…”

“…Ring resonators also provide an ideal platform for studying nonlinear topological systems [11] owing to the enhancement of nonlinear effects provided by high quality factor microresonators. Recent experiments have harnessed nonlinearities to generate frequency combs from single resonators [48][49][50][51][52].…”

“…is not yet any disruptive killer application where topological photonic devices have achieved superior performance compared to mature design paradigms, despite growing interest in topological photonics since seminal works published in 2008 [4,5]. To help bridge this gap, several reviews have been published recently, some providing comprehensive surveys of topological photonic systems [1,2,6,7], and others focussing on specific applications such as incorporating topological concepts into active devices such as lasers [8], nanophotonics [9], nonreciprocal devices [10], and nonlinear optical processes [11].…”

Broadband enhancement of second-harmonic generation at the domain walls of magnetic topological insulators

“…Noteworthy, the topologically nontrivial photonic structures have been recently proposed for the enhancement of the higher harmonic generation (see the review by Smirnova et al [18] and the references within). While in most of these studies the nonlinear current is produced by the conventional optically nonlinear media (such as lithium niobate or GaAs), the topologically nontrivial edge and surface states emerging in these structures facilitate the strong field enhancement, extended lifetime, and unidirectional mode propagation which cumulatively increase the conversion efficiency [19].…”