Antichiral Gyromagnetic Photonic Crystal Used to Split Configurable Topological Beam.

An anti-chiral gyromagnetic photonic crystal used to split a configurable topological beam

Recent publication from Optoelectronic science illustrates the adaptable division of a topological beam by an anti-chiral gyromagnetic photonic crystal.

Construction of antichiral gyromagnetic photonic crystal. (a) Schematic representation of an antichiral gyromagnetic photonic crystal. (b) The first Brillouin zone of the honeycomb lattice. (c) Non-magnetized gyromagnetic photonic crystal. (d) Uniformly magnetized gyromagnetic photonic crystal. (e) Composite magnetized gyromagnetic photonic crystal. Image credit: OEA

Topological insulators whose bulky states are prohibited, while surface / edge states are topologically protected and conductive. Recent advances in topologically protected boundary states have received a great deal of attention in the photonics and optics community.

In 2008, Haldane and Raghu first theoretically speculated that a topologically protected chiral one-way boundary state could be created analogously to the integer quantum Hall effect in a two-dimensional (2D) electron gas system, where one-way boundary states propagate. along opposite directions at two parallel edges of the gyromagnetic photonic crystal [Phys. Rev. Lett. 100, 013904 (2008)].

In 2020, Professor Zhi-Yuan Li’s research team at the University of South China hypothetically proposed another fascinating case in which one-way edge states on two opposite parallel zigzag edges may propagate in the same direction and are referred to as antichiral one-way edge states. [Phys. Rev. B 101, 214102 (2020)].

Until now, antichiral one-way boundary states have been studied on various bosonic and fermionic platforms, but many studies have focused only on illustrating antichiral one-way transport properties and only a few have explored new properties of antichiral topological platforms and unique applications.

This paper deals with the creation and observation of topological beam splitting with an easily modifiable ratio from right to left in an antichiral gyromagnetic photonic crystal. The hub is configurable and compact, has high transmission efficiency, is resistant to crosstalk, allows multi-channel use and is resistant to errors and obstacles.

This performance is attributed to a special feature in that antichiral unidirectional edge states can exist only on the zigzag edge and not on the chair edge of the antichiral gyromagnetic photonic crystal.

When two rectangular antichiral gyromagnetic photonic crystals are integrated that hold the left and right propagating antichiral unidirectional edge states, respectively, bi-directionally radiating unidirectional edge states can be achieved at two parallel zigzag edges.

Finally, they designed a topological beam split with a configurable split ratio that can only be easily changed by adjusting the source excitation conditions. These observations can improve the current understanding of basic physics and advance topological photonic applications.

Magazine link:

Chen, JF, et al. (2022) Configurable topological beam splitting by an anti-chiral gyromagnetic photonic crystal. Optoelectronic science.


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