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Observation of bulk Fermi arc and polarization half charge from paired exceptional points
Science ( IF 56.9 ) Pub Date : 2018-01-11 , DOI: 10.1126/science.aap9859
Hengyun Zhou 1 , Chao Peng 1, 2 , Yoseob Yoon 3 , Chia Wei Hsu 4 , Keith A. Nelson 3 , Liang Fu 1 , John D. Joannopoulos 1 , Marin Soljačić 1 , Bo Zhen 5
Affiliation  

Exploring photonic topology Scattering topological effects are being explored in a variety of electronic and optical materials systems owing to their robustness against defects (see the Perspective by Özdemir). Yang et al. designed and fabricated an ideal optical analog of a three-dimensional Weyl system. Angular transmission measurements revealed four Weyl points at the same energy, as well as the signature helicoidal arcs associated with such an exotic topological system. Zhou et al. theoretically proposed and experimentally demonstrated the formation of a topologically protected bulk Fermi arc. They attributed the formation of the arc to the topological nature of paired exceptional points (points at which gain and loss in the system are matched). Photonic crystals may provide a powerful platform for studying exotic properties of topological electronic systems and may also be used to develop optical devices that exploit topological properties of light-matter interactions. Science, this issue p. 1013, p. 1009; see also p. 995 Photonic crystals provide a powerful platform to study topological effects in non-Hermitian systems. The ideas of topology have found tremendous success in closed physical systems, but even richer properties exist in the more general open or dissipative framework. We theoretically propose and experimentally demonstrate a bulk Fermi arc that develops from non-Hermitian radiative losses in an open system of photonic crystal slabs. Moreover, we discover half-integer topological charges in the polarization of far-field radiation around the bulk Fermi arc. Both phenomena are shown to be direct consequences of the non-Hermitian topological properties of exceptional points, where resonances coincide in their frequencies and linewidths. Our work connects the fields of topological photonics, non-Hermitian physics, and singular optics, providing a framework to explore more complex non-Hermitian topological systems.
更新日期:2018-01-11
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