Abstract-Dual-regulated broadband terahertz absorber based on vanadium dioxide and graphene

 

Chunyu Zhang, Heng Zhang, Fang Ling, and Bin Zhang

https://www.osapublishing.org/ao/abstract.cfm?uri=ao-60-16-4835

A tunable broadband terahertz (THz) absorber based on vanadium dioxide (VO2${\mathrm{V}\mathrm{O}}_2$) and graphene is proposed. The absorber, consisting of the VO2${\mathrm{V}\mathrm{O}}_2$ square loop, polymethacrylimide (PMI) dielectric layer, and a layer of unpatterned graphene, can achieve absorption over 90% from 1.04 THz to 5.51 THz and relative bandwidth of up to 136.5% under normal incidence. Its absorption bandwidth and absorption peak can be adjusted by changing the conductivity of VO2${\mathrm{V}\mathrm{O}}_2$ or the chemical potential of graphene. The physical mechanism of the absorber is analyzed in detail by the use of the impedance matching theory and the electric field distributions of the VO2${\mathrm{V}\mathrm{O}}_2$ layer and graphene layer. The proposed absorber, with polarization insensitivity and incidence angle of 30° for both TE and TM polarizations, may have potential applications in tunable sensors, modulators, and imaging.

© 2021 Optical Society of America

Abstract-Tunable broadband terahertz absorber based on multilayer graphene-sandwiched plasmonic structure

Yijun Cai and Kai-Da Xu

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-24-31693

We numerically demonstrate a tunable broadband terahertz absorber with near-unity absorption by using multilayer graphene ribbons sandwiched in a plasmonic integrated structure. By stacking slightly different widths of graphene ribbons in a sandwiched configuration, the absorption bandwidth can be increased because of the different resonant modes closely positioned together. The absorption spectrum’s center frequency can be manipulated by varying the graphene’s chemical potential, which provides a flexible way to design and optimize absorption property after fabrication. Furthermore, the structure can tolerate a wide range of incident angles, while the improved structure with graphene nanoparticles also shows polarization-independent feature. In this routine, stacking more graphene ribbons or particles with well-designed dimensions can further increase the bandwidth, as long as the metamaterial dimension satisfies the sub-wavelength condition. Therefore, our research provides an important theoretical guide for designing various graphene-based tunable broadband absorbers at terahertz, infrared, and microwave frequencies. This may have promising applications in imaging, sensing, and novel optoelectronic devices.

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