Polarization-Orthogonal Nondegenerate Plasmonic Higher-Order Topological States

Yuanzhen Li; Su Xu; Zijian Zhang; Yumeng Yang; Xinrong Xie; Wenzheng Ye; Haoran Xue; Zuojia Wang; Qi-Dai Chen; Hong-Bo Sun; Erping Li; Hongsheng Chen; Fei Gao

arXiv · 2110.05703

Polarization-Orthogonal Nondegenerate Plasmonic Higher-Order Topological States

Yuanzhen Li·Su Xu·Zijian Zhang·Yumeng Yang·Xinrong Xie·Wenzheng Ye·Haoran Xue·Zuojia Wang·Qi-Dai Chen·Hong-Bo Sun·Erping Li·Hongsheng Chen·Fei Gao

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Abstract

Photonic topological states, providing light-manipulation approaches in robust manners, have attracted intense attention. Connecting photonic topological states with far-field degrees of freedom(DoFs) has given rise to fruitful phenomena. Recently emerged higher-order topological insulators (HOTIs), hosting boundary states two or more dimensions lower than those of bulk, offer new paradigms to localize/transport light topologically in extended dimensionalities. However, photonic HOTIs have not been related to DoFs of radiation fields yet. Here, we report the observation of polarization-orthogonal second-order topological corner states at different frequencies on a designer-plasmonic Kagome metasurface in the far field.Such phenomenon stands on two mechanisms, i.e., projecting the far-field polarizations to the intrinsic parity DoFs of lattice modes and the parity splitting of the plasmonic corner states in spectra. We theoretically and numerically show that the parity splitting originates from the underlying inter-orbital coupling. Both near-field and far-field experiments verify the polarization-orthogonal nondegeneratesecond-order topological corner states. These results promise applications in robust optical single photon emitters and multiplexed photonic devices.

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Yuanzhen Li, Su Xu, Zijian Zhang, Yumeng Yang, Xinrong Xie, Wenzheng Ye, Haoran Xue, Zuojia Wang, Qi-Dai Chen, Hong-Bo Sun, Erping Li, Hongsheng Chen, Fei Gao. 2021-10-12. Polarization-Orthogonal Nondegenerate Plasmonic Higher-Order Topological States. https://arxiv.org/abs/2110.05703

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