Near‐Field Characterization of Higher‐Order Topological Photonic States at Optical Frequencies
Abstract
Higher‐order topological insulators (HOTIs) represent a new type of topological system, supporting boundary states localized over boundaries, two or more dimensions lower than the dimensionality of the system itself. Interestingly, photonic HOTIs can possess a richer physics than their original condensed matter counterpart, supporting conventional HOTI states based on tight‐binding coupling, and a new type of topological HOTI states enabled by long‐range interactions. Here, a new mechanism to establish all‐dielectric infrared HOTI metasurfaces exhibiting both types of HOTI states is proposed, supported by a topological transition accompanied by the emergence of topological Wannier‐type polarization. Two kinds of near‐field experimental studies are performed: i) the solid immersion spectroscopy and ii) near‐field imaging using scattering scanning near‐field optical microscopy to directly observe the topological transition and the emergence of HOTI states of two types. It is shown that the near‐field profiles indicate the displacement of the Wannier center across the topological transition leading to the topological dipole polarization and emergence of the topological boundary states. The proposed all‐dielectric HOTI metasurface offers a new approach to confine the optical field in micro‐ and nano‐scale topological cavities and thus paves the way to achieve a novel nanophotonic technology.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 18, 2021
- Source ID
- 10.1002/adma.202004376
Entities
People
- Alexander B Khanikaev
- Andrea Alù
- Anton Vakulenko
- Dmitry Korobkin
- Dmitry Zhirihin
- Mengyao Li
- Mingsong Wang
- Sriram Guddala
- Svetlana Kiriushechkina
- Xiang Ni
Organizations
- CUNY Graduate School and University Center
- City College of New York
- City University of New York
- Defense Advanced Research Projects Agency
- National Science Foundation
- Office of Naval Research
- Russian Science Foundation
- Simons Foundation
- United States Department of Energy