Abstract-Characteristic analysis of a photoexcited tunable metamaterial absorber for terahertz waves

• 
  • Pibin Bing, 
   
  • Xinyue Guo, Hua
   
  •  Wang, 
   
  • Zhongyang Li, J
   
  • ianquan Yao,
   https://link.springer.com/article/10.1007%2Fs12596-019-00533-1

The absorption characteristics of a photoexcited tunable perfect metamaterial absorber (PMA) at terahertz (THz) frequencies are analyzed based on the split-ring resonators (SRRs)-dielectrics-metallic structure, which are caused by different thicknesses and dielectric constants of polyimide, cell sizes and widths of SRRs, and lengths and conductivities of the photosensitive silicon. The results manifest that the resonance frequency and absorption strength of the designed PMA can be tuned by adjusting the shape, size, thickness, and properties of the metallic structure and dielectric spacer. The simple design and wide frequency tuning range of the PMA can find potential applications in terahertz detectors, filters, switchers, and absorbers.

Abstract-A flexible metamaterial absorber with four bands and two resonators

• Yong Zhang^a, b, 
• Junping Duan^a, b, 
• Binzhen Zhang^a, b,, 
• Wendong Zhang^a, b, 
• Wanjun Wang^c

• ^a Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China
• ^b School of Instrument and Electronics, North University of China, Taiyuan, Shanxi, 030051, China
• ^c Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA
• 
  

http://www.sciencedirect.com/science/article/pii/S0925838817305030

An efficient approach for achieving more resonance bands with fewer resonators is proposed in this paper. We investigate the theory, design, simulation, fabrication, and performance of a flexible metamaterial perfect absorber (MPA) with two resonators and four resonances located in GHz and THz ranges. The sandwich microstructure of the MPA consists of periodic “回” shaped metal patches on a metasurface, a dielectric of FR4 board on the interlayer, and a continuous copper film on the substrate. The four peaks of absorptivity owing to the coupling effect of the strong LC and surface resonance of the outer ring resonator as well as the strong LC and surface resonance of the inner ring resonator are 93.887%, 99.479%, 98.296%, and 93.035% at 38.165 GHz, 155.48 GHz, 231.71 GHz, and 275.27 GHz, respectively. The influences on absorptivity produced by angles, dimensions, and materials are also studied. The proposed MPA, equipped with strong flexibility, ultrathin thickness, light weight, strong absorption, sparks inspirations in designing the MPA with more resonances and fewer resonators.

Abstract-Ground-plane-less bidirectional terahertz absorber based on omega resonators

Alexei Balmakou, Maxim Podalov, Sergei Khakhomov, Doekele Stavenga, and Igor Semchenko
https://www.osapublishing.org/ol/abstract.cfm?uri=ol-40-9-2084

We present a new ultrathin metamaterial that acts as a frequency-selective absorber of terahertz radiation. The absorber is a square array of pairs of omega-shaped micro-resonators made of high-ohmic-loss metal. The metamaterial provides significant suppression of transmitted and reflected radiation in a bidirectional regime (that is, for both forward and backward propagating radiation). The absorber is efficient in a wide range of angles of incidence. The absence of a ground plane makes the absorber unique in comparison with numerous analogs with a ground plane that operate in a unidirectional regime. The novel metamaterial potentially enables controllable transmission of terahertz radiation in imaging systems. Analytical calculations as well as finite-element electromagnetic modeling are presented for an exemplary case with peak absorption at ∼3  THz.

© 2015 Optical Society of America

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