Wannier-type photonic higher-order topological corner states induced solely by gain and loss

Abstract

Photonic crystals have provided a controllable platform to examine excitingly new topological states in open systems. In this work, we reveal photonic topological corner states in a photonic graphene with mirror-symmetrically patterned gain and loss. Such a nontrivial Wannier-type higher-order topological phase is achieved through solely tuning on-site gain/loss strengths, which leads to annihilation of the two valley Dirac cones at a time-reversal-symmetric point, as the gain and loss change the effective tunneling between adjacent sites. We find that the symmetry-protected photonic corner modes exhibit purely imaginary energies and the role of the Wannier center as the topological invariant is illustrated. For experimental considerations, we also examine the topological interface states near a domain wall. Our work introduces an interesting platform for non-Hermiticity-induced photonic higher-order topological insulators, which, with current experimental technologies, can be readily accessed.

7 pages, 5 figures

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Cited by in corpus (10)

• Classical higher-order topological insulators
• Topology of anti-parity-time-symmetric non-Hermitian Su-Schrieffer-Heeger model
• Non-Bloch bands in two-dimensional non-Hermitian systems
• Non-Hermitian higher-order topological superconductors in two-dimension: statics and dynamics
• Competition of non-Hermitian skin effect and topological localization of corner states observed in circuits
• Two-dimensional anisotropic non-Hermitian Lieb lattice
• Higher-order topological corner states induced solely by onsite potentials with mirror symmetry
• Berry curvature inside parity-time-symmetry protected exceptional surface
• Floquet topological phases with time-reversal and space inversion symmetries and dynamical detection of topological charges
• Scattering Dynamics and Boundary States of a Non-Hermitian Dirac Equation