Dual-polarization topological phases and phase transition in magnetic photonic crystalline insulator

Abstract

Two-dimensional topological photonic crystals have rapidly emerged as a recent and fascinating branch of photonic research. However, most of them were limited to a specific type of polarization, TE or TM polarization. Here, we explored the dual-polarization topological phases in two-dimensional magnetic photonic crystal (PC) which are composed of ferrite rod clusters in the plasma background. Under the perturbations of the bias magnetic field and/or the cluster distortion in the unit cell, the PC exhibited dual-polarization topological phases, including the quantum Hall (QH) phase, the higher-order quantum spin Hall (HO-QSH) phase and the conventional insulator (CI) phase. We studied the topological nature of these phases by the Wilson loop, Chern number, and unidirectional edge states. Intriguingly, we showed that the HO-QSH phases could present in PC of C 3v symmetry instead of being restricted to C 6v symmetry. The lower symmetry enlarges the gap in the edge states, which helps for the emergence of corner states. By continuously deforming the unit cell configuration, we demonstrated the phase transition in the system was dual-polarization. Our results extend the topological phases in the PCs and pave the way for the dual-polarization topological devices and their applications.

All-optical logic gates based on topological edge and corner states in two-dimensional photonic crystals with square dielectric columns

“…two-dimensional (2D) topological PC systems can be characterized by Z 2 invariants or Chern numbers [8,9]. The generation of topological edge states (TESs) and topological corner states (TCSs) has been achieved through topological phase transitions [10,11]. The structures composed of two PCs with different Chern numbers exhibit edge states in the band gap, protected by their topology [11,12].…”

“…The generation of topological edge states (TESs) and topological corner states (TCSs) has been achieved through topological phase transitions [10,11]. The structures composed of two PCs with different Chern numbers exhibit edge states in the band gap, protected by their topology [11,12]. As a result, these edge states remain robust even existing defects, disorders, and impurities, which is called TES [13][14][15].…”

Valley-dependent topological edge states in plasma photonic crystals

“…However, topological edge states in all-dielectric photonic crystals can only be observed in a specific frequency range with fixed lattice structures and electromagnetic parameters, and the electromagnetic modes are not switchable. Several materials such as liquid crystals and barium titanate have been used to explore the reconfigurable topological states [21,22]. Qiu et al used plasmonic to form honeycomb lattices.…”