Two-dimensionally confined topological edge states in photonic crystals

Abstract

We present an all-dielectric photonic crystal structure that supports two-dimensionally confined helical topological edge states. The topological properties of the system are controlled by the crystal parameters. An interface between two regions of differing band topologies gives rise to topological edge states confined in a dielectric slab that propagate around sharp corners without backscattering. Three-dimensional finite-difference time-domain calculations show these edges to be confined in the out-of-plane direction by total internal reflection. Such nanoscale photonic crystal architectures could enable strong interactions between photonic edge states and quantum emitters.

Snowflake phononic topological insulator at the nanoscale

“…[30] for the corresponding experimental implementation and Refs. [17,18,23,31] for related theoretical work), we are able to create a topological insulator for mechanical waves based on a proven nanoscale platform.…”

“…A similar behavior has been observed also in Refs. [29,31] for related C 6 -based photonic topological insulators. Second, inspired by this unexpected behavior, we have investigated a related scenario where the suppression of backscattering would seem at a first sight even less probable: randomly shaped domain walls.…”

Electromagnetic‐Dual Metasurfaces for Topological States along a 1D Interface

“…The discovery of topological insulators in condensed‐matter systems has promoted extensive research on analogous systems of classical waves including acoustics and photonics . Uniquely, these systems have insulating bulk but conducting interfaces that host chiral one‐way or helical spin‐polarized edge states. As a result, wave propagation is immune to backscattering unlike in ordinary photonic circuitry, where realistic fabrication imperfections, disorder, or arbitrary bends could severely reduce signal transmission, hence device performance.…”

“…However, the conservation of pseudospins, which relies on the directional coupling between the rings, necessitates a large ring diameter, hence an extensive footprint of the system. Alternatively, crystalline symmetry could be exploited in photonic crystal structures to give rise to modal degeneracies that play the role of pseudospin states . Commonly, the lattice valleys are folded onto the center of the Brillouin zone of a new lattice, thus creating photonic “molecules” supporting hybridized dipolar and quadrupolar circularly polarized eigenmodes.…”

Robust Edge States in Amorphous Gyromagnetic Photonic Lattices

“…In recent years, several photonic Chern insulators, featuring topologically-protected electromagnetic edge states, have been demonstrated [9][10][11][12][13][14][15] . The field of "topological photonics" 16 has been fruitfully extended into many other areas, including anomalous Floquet insulators [17][18][19][20][21] , crystalline and valley-Hall insulators [22][23][24][25] , and Weyl points [26][27][28][29] . Various groups have also explored the realization of topological band insulators using mechanical oscillators 30,31 , acoustics [32][33][34][35] , and electronics 36 .…”