Broadband optical absorption using graphene-wrapped cross-hair/nano-rod combination

Abstract

In this paper, an assembly of substrate mediated graphene-coated cylindrical nano-rods is proposed as an efficient broadband absorber. Initially, a square lattice of isolated graphene-based particles is considered and a single-band perfect optical absorber is obtained. Then, the possibility of absorption spectrum modulation using the lattice periodicity is illustrated. Moreover, it is exhibited that the performance is stable concerning any polarization state and incident angle up to around 60°. The absorption mechanism relies on the excitation of localized surface plasmon resonances (LSPRs) of various orders on the different sections of the unit cell. Later, the particles are connected through optimized bridges to enhance the operating bandwidth. The bridges also offer the opportunity for the real-time tunability of the absorption spectrum by the electrostatic scheme. The attained absorption band regarding the efficiency of 90% is extended to a 15.43 THz span (18.57–34 THz) using a geometrically simple structure.

KEYWORDS:

• Graphene
• cylinder
• absorber
• wideband

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Shiva Hayati Raad

Shiva Hayati Raad received the B.S. and M. S. degrees in electrical engineering from Tabriz University, Tabriz, Iran, respectively in 2011, 2014. She received her Ph.D. degree in electrical engineering from the department of electrical and computer engineering, Tarbiat Modares University in 2019. Her research interests include 2D materials, plasmonics, Green's function derivation, and metamaterials.

Zahra Atlasbaf

Zahra Atlasbaf (M'08-SM'17) received the B.S. degree in electrical engineering from the University of Tehran, Tehran, Iran, in 1993, and the M.S. and Ph.D. degrees in electrical engineering from the University of Tarbiat Modares, Tehran, in 1996 and 2002, respectively. She is currently an Associate Professor with the Department of Electrical and Computer Engineering, Tarbiat Modares University. Her current research interests include numerical methods in electromagnetics, theory and applications of metamaterials, and microwave and antenna design.