Abstract-Broadband one-way propagation and rainbow trapping of terahertz radiations

Jie Xu, Sanshui Xiao, Chiaho Wu, Hang Zhang, Xiaohua Deng, and Linfang Shen

Fig. 1 Schematics of the metal-semiconductor-dielectric-metal (a) and related semiconductordielectric-metal (b) structures for sustaining one-way SMPs. An external dc magnetic field is applied along the −y direction in the two structures.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-8-10659

Surface magnetoplasmon (SMP) supported at an interface between magnetized plasmonic and dielectric materials has been widely explored; however, it suffers with narrow bandwidth for one-way propagation. Here we propose a novel metal-semiconductor-dielectricmetal (MSDM) structure showing the large bandwidth for the complete one-way propagation (COWP). Because of the compression of the zone for two-way propagating modes in the semiconductor layer by reducing semiconductor thickness, the bandwidth is significantly increased by several times. More importantly, in such MSDM structure, the SMP dispersion can be engineered by controlling the semiconductor thickness, and based on this, slowing wave and trapping rainbow can be realized in a tapered system at terahertz frequencies.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Tunable terahertz broadband absorber based on a composite structure of graphene multilayer and silicon strip array

Zhaocheng Zhai,  Le Zhang,  Xiangjun Li,  Sanshui Xiao,




https://www.sciencedirect.com/science/article/abs/pii/S0030401818307983

We propose a terahertz broadband absorber composed by silicon strips with continuous graphene on top of a metal mirror. The simulation results show that under the combined effect of the Fabry–Perot resonance and the dipole mode oscillation excited in the silicon strip array interacting with graphene, this structure can achieve an ultra-wide absorption band from 0.73 to 1.95 THz with absorbance of 90%. By changing the size of the silicon strips or the Fermi level of graphene, the working band of the absorber can be tuned.

Abstract-Broadband, wide-angle and tunable terahertz absorber based on cross-shaped graphene arrays

Binggang Xiao, Mingyue Gu, and Sanshui Xiao

https://www.osapublishing.org/ao/abstract.cfm?uri=ao-56-19-5458

Tunable terahertz absorbers composed of periodically cross-shaped graphene arrays with the ability to achieve near-unity absorbance are proposed and studied. Our results demonstrate that the bandwidth of absorption rate above 90% can reach up to 1.13 terahertz by use of a single layer of cross-shaped graphene arrays. By simply stacking the double layer cross-shaped graphene with careful design, the working bandwidth can be broadened compared with the single-layer graphene-based absorber. The proposed absorbers have the properties of being polarization insensitive and having large angle tolerance, and the tunability of the Fermi level in graphene allows us to realize tunable terahertz absorbers with potential interest in integrated terahertz optoelectronic devices.

© 2017 Optical Society of America