Abstract-Switchable dual-band and ultra-wideband terahertz wave absorber

 

Yi Chen and Jiu-Sheng Li

Configuration of the proposed absorber, (a) Three-dimensional view, (b) Top view; (c) Middle layer patterns and geometric parameters.

https://www.osapublishing.org/ome/fulltext.cfm?uri=ome-11-7-2197&id=452105

In this paper, we introduced a switchable dual-band and ultra-wideband terahertz wave absorber based on photoconductive silicon combining with vanadium dioxide (VO2). In the terahertz absorber, photoconductive silicon cross array, silicon dioxide layer, vanadium dioxide windmill type array, silicon dioxide dielectric layer, and gold ground plane are placed from the top layer to bottom layer in sequence. When VO2 is in a metallic state and the conductivity of photoconductive silicon is 2.5×10−4 S/m, the designed structure represents an ultra-wideband absorber with an absorption larger than 90% in the range of 3.14∼7.80 THz. As VO2 is in an insulation state and the conductivity of photoconductive silicon becomes 8.0×104 S/m, the designed device acts as two absorption bands, with a terahertz wave absorber with absorption more than 98% at 1.78∼2.90 THz and 7.35∼8.45 THz. The results show that the absorption band (dual-band or ultra-wideband) and absorption intensity (from 2% to 99%) can be switched by changing the phase transition of the VO2 and the conductivity of photoconductive silicon. Furthermore, the proposed device exhibits polarization insensitive and wide incident angles (lager than 70°) for TE- and TM- polarizations incidence.

© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Broadband Adjustable Terahertz Absorption in Series Asymmetric Oval-Shaped Graphene Pattern

Jian-Zhong Sun, Jiu-Sheng Li

https://www.frontiersin.org/articles/10.3389/fphy.2020.00245/full


We propose a broadband adjustable graphene absorber in terahertz regime. A prototype is designed to verify the terahertz absorption characteristics by a periodic array layer of series asymmetric oval-shaped graphene patterns on polyimide and bottom layer of metal plate. The absorber with 92% absorption and the bandwidth ranging from 3.39 to 5.96 THz is achieved. By changing the Fermi level of graphene, the bandwidth and absorption can be flexibly adjusted. The absorption is more than 92% in the range of 0~40° incident angle. Using these characteristics, the simple absorber has broad application prospects in the fields of filter and switch in terahertz region.

Abstract-Graphene-embedded coding metasurface for dynamic terahertz manipulation

Chen Zhou, Xiao-qing Peng, Jiu-sheng Li

https://www.sciencedirect.com/science/article/abs/pii/S0030402620307737

With the rapid development of terahertz wave technology and application systems, the dynamic manipulation of terahertz radiation is highly needed. We have investigated the performances of a graphene-embedded coding metasurface that can dynamically control the terahertz wave transmission. The coding element consists of gold substrate, silicon-polyimide interlayer and the top graphene-embedded metallic pattern that can realize abrupt reflection phase shift by adjusting the graphene Fermi level. Especially, by changing the Fermi energy of the graphene through bias voltage and pre-designed coding sequence, the new coding metasurface structure can control the reflected terahertz wave beams to various directions. The method brings us much freedom in design of terahertz wave manipulation device.

Abstract-Frequency coding metasurface for multiple directions manipulation of terahertz energy radiation

AIP Advances

Shao-He Li, Jiu-Sheng Li,

Four basic frequency coding unit cells and their simulation results. (a-d) Basic unit cells. (e) and (f) Simulated reflection spectra and phase, respectively.

https://aip.scitation.org/doi/10.1063/1.5089617

A multifunctional frequency coding metasurface is proposed in terahertz frequency band. Different from the previous coding metasurface with a fixed phase difference of the neighbor coding unit cells in the whole working frequency band, the proposed frequency coding metasurface has the linear change phase difference in the operating frequency band with different phase sensitivity. It can flexibly control the reflected terahertz waves to the numerous directions by changing the working frequency without redesign the coding metasurface structure. Additionally, we demonstrate the polarization insensitive properties of our frequency coding metasurface by using 1-bit frequency coding metasurface with the periodic sequences of “0-0, 0-1” along the x-direction, 2-bit random frequency coding metasurface and non-periodic frequency coding metasurface. Our frequency coding metasurface provides a novel and flexible way to manipulate the energy radiation of terahertz wave and has tremendous values in terahertz systems.

Abstract- Terahertz Bandpass Filter Based on Frequency Selective Surface

Jiu-Sheng Li,  Yang Li,   Le Zhang,

http://ieeexplore.ieee.org/document/8194866/


We designed a terahertz bandpass filter based on double-layer frequency selective surface. Details of the proposed terahertz wave filter design and of the related parametric analysis are presented and discussed. The proposed terahertz filter was fabricated by laser technology. The transmission spectrum was characterized by terahertz time-domain spectroscopy. The results show that the center frequency of the terahertz filter is about 1 THz with 3-dB bandwidth of 400 GHz.

Abstract-Photonic crystal-based waveguide terahertz wave Set-Reset latch

• Jian-Zhong Sun, 
• Jiu-Sheng Li

• ^, 

• Centre for THz Research, China Jiliang University, Hangzhou, 310018, Chin
• 
  
• http://www.sciencedirect.com/science/article/pii/S0030402617308495
• 
  

In terahertz system, controlling terahertz wave propagation is a very important issue. In this letter, we have proposed and demonstrated a terahertz wave Set-Reset latch based on two-dimensional photonic crystal. The present device consists of two photonic crystal NOR gates and two photonic crystal multimode-interfere structures. Finite-difference time-domain method is used to analyze and confirm the propagation properties of the device. The total size of our proposed Set-Reset latch is equal to 85a × 40a. The response time of the Set-Reset latch is 3.25 ps. Our study suggests that the Set-Reset latch has great potential in future terahertz wave information processing integrated circuit.

Abstract-Compact terahertz wave polarization beam splitter using photonic crystal

Guo-qiang Mo and Jiu-sheng Li
https://www.osapublishing.org/ao/abstract.cfm?uri=ao-55-25-7093

Electromagnetic polarization conveys valuable information for signal processing. Manipulation of a terahertz wave polarization state exhibits tremendous potential in developing applications of terahertz science and technology. We propose an approach to efficiently split transverse-electric and transverse-magnetic polarized terahertz waves into different propagation directions over the frequency range from 0.9998 to 1.0007 THz. Both the plane wave expansion method and the finite-difference time-domain method are used to calculate and analyze the transmission characteristics of the proposed device. The present device is very compact and the total size is 1.02  mm×0.99  mm. This polarization beam splitter performance indicates that the structure has a potential application for forthcoming terahertz-wave integrated circuit fields.

© 2016 Optical Society of America

Full Article  |  PDF Article