Abstract-Design of terahertz reconfigurable devices by locally controlling topological phases of square gyro-electric rod arrays

L. Zhang, Sanshui Xiao,

Fig. 4 Normalized electric field distribution of the edge wave propagation. The wave is excited by a point source. Blue areas denote the metal wall and the obstacle. (a) Distribution of edge wave between the array with θ = 0° and a metal wall at 3.5 THz. (b) Transmission spectrum without and with material loss involved when the wave propagates a length of 30a along the edge. (c) Distribution of edge wave between upper sub array with θ = 0° and lower sub array with θ = 45°. (d) Distribution of edge wave along the interface with two right-angled bends.

https://www.osapublishing.org/ome/fulltext.cfm?uri=ome-9-2-544&id=403962

In topological photonics, there is a class of designing approaches that usually tunes topological phase from trivial to non-trivial in a magneto-optical photonic crystal by applying an external magnetic field to break time reversal symmetry. Here we theoretically realize topological phase transition by rotating square gyro-electric rods with broken time reversal symmetry. By calculating band structures and Chern numbers, in a simple square-lattice photonic crystal, we demonstrate the topological phase transition at a specific orientation angle of the rods. Based on the dependence of topological phase on the orientation angle, we propose several terahertz devices including an isolator, circulator and splitter in a 50x50 reconfigurable rod array by locally controlling topological phases of the rods. These results may have potential applications in producing reconfigurable terahertz topological devices.

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