Fractal interwoven resonator based penta-band metamaterial absorbers for THz sensing and imaging

Abstract

This paper presents a unique penta-band metamaterial absorber platform for terahertz imaging systems.The proposed fractal metamaterial absorber (FMMA) consists of fractal triangle section metasurfaces. By combining fractal resonators posing different operation skills in the same unit cell, the absorber shows multiband spectral response. The proposed unit cell structure operates at five near perfect absorption modes corresponding to the frequency bands of 1.1 THz, 3.4 THz, 4.9 THz, 5.9 THz, and 7.8 THz, respectively. Based on the fractal metamaterial absorber array, we also propose a sensing pixel design for bimaterial cantilever array sensing systems. The single pixel assembles 4x6 fractal resonator array and $$SiO_2$$ S i O 2 -Al bimaterial microcantilevers. The sensing region of the FMMA pixel can bend the bimaterial cantilevers effectively at multiple modes, enhancing the imaging capacity. The effective medium theory is executed to visualize the constitute parameters during the absorption and reveal the origin of the rising modes. The absorption mechanism is also discussed based on the surface current distributions and electric field profiles. The numerical outcomes prove that the proposed fractal metamaterial unit cell is a promising candidate as an absorbing platform for THz band sensing and imaging applications. The derived iterative formula used in the fractal design procedure is explained for further investigations of microelectromechanical systems (MEMS) compatible compact absorber arrays.

Metasurface-Assisted Terahertz Sensing

“…Then in 2022, to overcome the single and narrowband response of the sensors, Ozpinar designed a novel structure in ref. [110], which was a fractal metasurface absorber actuated by MEMS thermomechanical bi-material microcantilevers. The unit cell consisted of triangular sectional fractal metasurfaces, shown in Figure 6e, resulting in penta-band absorption at 1.1 THz, 3.4 THz, 4.9 THz, 5.9 THz, and 7.8 THz, respectively.…”

Design and analysis of K and Ku-band wide-angle polarization-insensitive dual-band perfect metamaterial absorber

“…It has characteristics such as negative dielectric constant and negative magnetic permeability that materials in nature do not have [1]. These properties enable metamaterials to be applied in various aspects, including sensing [2][3][4], imaging [5,6], lensing [6,7], antennas [8][9][10], absorbers [11,12], etc. Applying this material, an emerging absorption device, the metamaterial absorber, has been proposed and achieves almost perfect electromagnetic waves (EM) wave absorption [13].…”

“…Further effective refractive index can be determined by equation(4).where k is the wave number and d is the equivalent thickness of the metamaterial.…”

Fractal Metamaterial Surfaces for UHF Sensing Applications

“…These properties enable the creation of compact MAs that utilize the available space effectively, making them suitable for integration into small devices and systems. To the best of our knowledge, only a few studies [26]- [28] have employed fractal MAs to develop sensors with high absorption capacity while minimizing their physical footprint. Research should continue to explore new designs in the field of fractal MAs in order to exploit their full potential.…”