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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.

We theoretically and experimentally demonstrate that magnetic plasmonic gradient metasurfaces (GMSs) can convert a spatially propagating wave to a one-way edge state or vice versa with high efficiency. Consisting of an array of ferrite rods with a rotation gradient introduced to the rod dimers in the unit cell, GMSs can covert an incident wave beam to a one-way edge state with efficiency over 77%, and almost fully radiate into free space from the one-way edge state. The phenomenon arises from the unidirectional coupling of the spatial electromagnetic wave with magnetic plasmonic GMSs, which is evidenced from the photonic band diagrams of the edge state. The one-way edge state can radiate to or be excited from air with different angles by either engineering the gradient of the GMSs or tuning the bias magnetic field. By designing magnetic plasmonic GMSs with more exquisite configurations, we can expect many more nonreciprocal properties, adding additional freedom in manipulating electromagnetic waves.

Phase gradient metagrating (PGM) refers to introduction of a local abrupt phase change covering 2π at an interface, which generates a phase gradient to control the direction and propagation of electromagnetic waves. PGM has provided unprecedented opportunities for wavefront manipulation. In this work, we combine PGMs and zero-index metamaterials to achieve high-efficiency asymmetric angular selected transmission. Our research shows that the wave can pass through the system only at a specific incident angle. Furthermore, the incident angle corresponding to the angular selected transmission can be adjusted by modifying the period length of the PGM. This design philosophy is applicable to both electromagnetic wave and acoustic wave systems. Our results open innovative avenues to extend the potential applications of PGM.