Topological Materials

Photonic crystals with a touch of topology

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Science  12 Mar 2021:
Vol. 371, Issue 6534, pp. 1118
DOI: 10.1126/science.371.6534.1118-b

Manmade photonic crystals offer a flexible platform for controlling the propagation and flow of light. Such control can be extended across the electromagnetic spectrum by correctly engineering the bandgap. Limitations in the fabrication process, however, can result in structural imperfections that allow the light or energy to leak out. Wang et al. add magnetism to the mix to form heterostructures of magnetic photonic crystals. They demonstrate that, for microwaves, this magnetic addition provides a topological aspect to the band structure, resulting in the propagation of the microwaves in one direction that is robust to defects. The ability to controllably route and collimate electromagnetic waves also could be applied to electronic and phononic waveguide systems.

Phys. Rev. Lett. 126, 067401 (2021).

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