Abstract-Terahertz topological photonics for on-chip communication

Xiongbin Yu, Prakash Pitchappa, Julian Webber, Baile Zhang, Masayuki Fujita, Tadao Nagatsuma, Ranjan Singh



https://www.nature.com/articles/s41566-020-0618-9

The realization of integrated, low-cost and efficient solutions for high-speed, on-chip communication requires terahertz-frequency waveguides and has great potential for information and communication technologies, including sixth-generation (6G) wireless communication, terahertz integrated circuits, and interconnects for intrachip and interchip communication. However, conventional approaches to terahertz waveguiding suffer from sensitivity to defects and sharp bends. Here, building on the topological phase of light, we experimentally demonstrate robust terahertz topological valley transport through several sharp bends on the all-silicon chip. The valley kink states are excellent information carriers owing to their robustness, single-mode propagation and linear dispersion. By leveraging such states, we demonstrate error-free communication through a highly twisted domain wall at an unprecedented data transfer rate (exceeding ten gigabits per second) that enables real-time transmission of uncompressed 4K high-definition video (that is, with a horizontal display resolution of approximately 4,000 pixels). Terahertz communication with topological devices opens a route towards terabit-per-second datalinks that could enable artificial intelligence and cloud-based technologies, including autonomous driving, healthcare, precision manufacturing and holographic communication.

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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