Advances and Prospects in Topological Nanoparticle Photonics

Abstract

Topological nanophotonics is a new avenue for exploring nanoscale systems from visible to THz frequencies, with unprecedented control. By embracing their complexity and fully utilizing the properties that make them distinct from electronic systems, we aim to study new topological phenomena. In this Perspective, we summarize the current state of the field and highlight the use of nanoparticle systems for exploring topological phases beyond electronic analogues. We provide an overview of the tools needed to capture the radiative, retardative, and long-range properties of these systems. We discuss the application of dielectric and metallic nanoparticles in nonlinear systems and also provide an overview of the newly developed topic of topological insulator nanoparticles. We hope that a comprehensive understanding of topological nanoparticle photonic systems will allow us to exploit them to their full potential and explore new topological phenomena at very reduced dimensions.

Optical Control over Thermal Distributions in Topologically Trivial and Non-Trivial Plasmon Lattices

“…However, despite the infinite system having γ ⊥ = π, none of the finite system eigenvectors associated with the red bullets in Figure a are found to be localized to the array edges (Supporting Information), indicating this system is in the regime where the bulk-boundary correspondence breaks down . This is, perhaps, not surprising, because strong intra-sublattice (i.e., A–A and B–B) coupling drives the breakdown of the bulk-boundary correspondence, ,,− while SLRs generally involve transverse modes associated with strong intra-sublattice coupling characterized by boldS⃡ ( k ∥ , ω ) . Nevertheless, Figure c illustrates the existence of edge-localized induced dipole moments in the optically excited system.…”

“…Furthermore, non-Bravais lattices with >1 NP per unit cell − open the possibility for modes exhibiting hierarchical excitation and thermal spatial profiles on both the unit cell and array length scales. Careful tuning of intra- and inter-unit-cell interactions in non-Bravais NP arrays can also, under suitable conditions, lead to the existence of topologically protected hybrid modes that are strongly localized to the array edges, , which could potentially be exploited to achieve thermal profiles that are similarly biased toward the array edges.…”

Exploiting oriented field projectors to open topological gaps in plasmonic nanoparticle arrays

“…With these goals and restriction in mind, metal nanoparticles using plasmonic resonances are probably the best candidates. This has made it possible for many researchers to look at what we can call topological nanoparticle photonics [9,10].…”

“…In addition, particular care needs to be taken due to the long-range nature of these interactions and the radiative corrections [10,18,19], which can spoil the topological protection of the system. Here, instead of focusing on such loss of protection, we explore degrees of freedom of the nanoparticles which could be exploited for topology beyond condensed matter systems.…”

Loss-driven topological transitions in lasing

“…From the fundamental perspective, photonics BICs can be viewed as vortex centers of light polarization. This description has naturally connected the BICs to the realm of more general topological phenomena, including topological robustness and topological transitions [9][10][11][12]. The polarization vortex is associated with the existence of a protected and quantized topological charge [13,14], which is conserved and cannot be removed with small perturbations.…”