Abstract-Switchable and Dual-Tunable Multilayered Terahertz Absorber Based on Patterned Graphene and Vanadium Dioxide

 

Hongyao Liu,  Panpan Wang, Jiali Wu, Xin Yan,  Xueguang Yuan, Yangan Zhang, Xia Zhang

https://www.mdpi.com/2072-666X/12/6/619/htm

In this paper, a switchable and dual-tunable terahertz absorber based on patterned graphene and vanadium dioxide is proposed and analyzed. By controlling the Fermi level of graphene and the temperature of vanadium dioxide, the device’s function can be switched and its absorbing properties can be tuned. When the vanadium dioxide is in an insulator state, the device can be switched from near-total reflection (>97%) to ultra-broadband absorption (4.5–10.61 THz) as the Fermi level of graphene changes from 0 to 0.8 eV. When the vanadium dioxide is changed to a metal state, the device can act as a single-band absorber (when the Fermi level of graphene is 0 eV) and a dual-band absorber with peaks of 4.16 THz and 7.3 THz (when the Fermi level of graphene is 0.8 eV). Additionally, the absorber is polarization-insensitive and can maintain a stable high-absorption performance within a 55° incidence angle. The multilayered structure shows great potential for switchable and tunable high-performance terahertz devices.

Abstract-A graphene‐based tunable miniaturized‐element frequency selective surface in terahertz band and its application in high‐isolation multiple‐input multiple‐output system

Yanbin Luo, Qingsheng Zeng,  Xin Yan, Nan Hu, Wenqing Xie, Yong Wu, Qichao Lu, Xia Zhang

https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.31975

Graphene is a promising material for terahertz (THz) reconfigurable devices due to the tunability of the surface conductivity. Here, a graphene‐based THz miniaturized‐element tunable band‐stop frequency selective surface (FSS) is demonstrated. The proposed FSS unit cell consists of convoluted metallic strips with graphene embedded between adjacent metallic strips. The center resonance frequency of the stop band shows an obvious blue shift from 1.76 to 2.56 THz when increasing the chemical potential of the graphene from 0 to 0.5 eV. Particularly, the convoluted design leads to an ultra‐small cell dimension of 11.73% of the free space wavelength at resonance frequency (1.76 THz). In addition, the positive role of the proposed FSS in enhancing the isolation of the multiple‐input multiple‐output (MIMO) system has been verified through two simple models. This work provides an effective method to design miniaturized‐element graphene‐based tunable FSSs, and gives a simple way to realize high‐isolation MIMO systems.

Abstract-Sensitive detection of cancer cell apoptosis based on the non-bianisotropic metamaterials biosensors in terahertz frequency

Zhang Zhang, Hongwei Ding, Xin Yan, Lanju Liang, Dequan Wei, Meng Wang, Qili Yang, and Jianquan Yao

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-8-3-659&origin=search

The apoptosis of cancer cells was experimentally measured by terahertz (THz) biosensors based on the metamaterials (MMs). The non-bianisotropic resonance with an electric field of up to 106 V/m was exhibited at 0.85 THz, where the magnetic dipoles were cancelled in the unit cell. The simulate results show the dependence of the frequency shift on the occupying ratio and refractive index of analytes. The theoretical sensitivity was calculated to 182 GHz/RIU. The experimental results imply that the resonant frequency would red shift with the increase of the concentration of cancer cells. Furthermore, the apoptosis of cancer cells HSC3 under the effect of drug concentration from 1 to 15 μM and drug action time from 24 to 72 hours were also studied by the biosensors, respectively. It shows that the trend agrees with the results measured by the biological CCK-8 kits method. Our proposed MMs-based biosensors may supply a novel viewpoint on cell apoptosis from a physical perspective and be a valuable complementary reference for biological study.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Broadband and wide-angle RCS reduction using a 2-bit coding ultrathin metasurface at terahertz frequencies

• Lanju Liang
• , Minggui Wei
• , Xin Yan
• , Dequan Wei
• , Dachuan Liang
• , Jiaguang Han
• , Xin Ding
• , GaoYa Zhang
•  & Jianquan Yao

http://www.nature.com/articles/srep39252

A novel broadband and wide-angle 2-bit coding metasurface for radar cross section (RCS) reduction is proposed and characterized at terahertz (THz) frequencies. The ultrathin metasurface is composed of four digital elements based on a metallic double cross line structure. The reflection phase difference of neighboring elements is approximately 90° over a broadband THz frequency. The mechanism of RCS reduction is achieved by optimizing the coding element sequences, which redirects the electromagnetic energies to all directions in broad frequencies. An RCS reduction of less than −10 dB bandwidth from 0.7 THz to 1.3 THz is achieved in the experimental and numerical simulations. The simulation results also show that broadband RCS reduction can be achieved at an incident angle below 60° for TE and TM polarizations under flat and curve coding metasurfaces. These results open a new approach to flexibly control THz waves and may offer widespread applications for novel THz devices.

Abstract-Broadband, wide-angle, low-scattering terahertz wave by a flexible 2-bit coding metasurface

Xin Yan, Lanju Liang, Jing Yang, Weiwei Liu, Xin Ding, Degang Xu, Yating Zhang, Tiejun Cui, and Jianquan Yao
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-22-29128

Abstract: Expanding bandwidths and arbitrary control of technology remain key issues in the field of electromagnetic waves, especially in terahertz (THz) wave. In this paper, we propose a novel method to achieve broadband low-scattering THz characteristics with wide-angle and polarization independence by a 2-bit flexible and nonabsorptive coding metasurface. The coding metasurface is composed of four digital elements based on double cross metallic line for “00”, “01”, “10”, and “11.” The reflection phase difference of neighboring elements is about 90° over a broad THz frequency band and wide incident angles. The low scattering coefficients below –10 dB were achieved over a wide frequency band from 0.8 THz to 1.5 THz when the incident angle is less than 50° by coding the four elements sequences. This superior property is maintained when the flexible coding metasurface is wrapped around a metallic cylinder with different dimensions. These results present a novel method to control THz waves freely and demonstrate significant scientific value in practical applications.

© 2015 Optical Society of America

Full Article  |  PDF Article