A Designed Broadband Absorber Based on ENZ Mode Incorporating Plasmonic Metasurfaces

• Main Authors: Phuc Toan Dang, Khai Q. Le, Ji-Hoon Lee, Truong Khang Nguyen
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Micromachines
• Subjects: epsilon-near-zero; wideband absorber; plasmon mode; brewster mode
• Online Access: https://www.mdpi.com/2072-666X/10/10/673

In this paper, we present a numerical study of a metamaterial absorber that provides polarization-insensitive absorption over a broad bandwidth of operation over the mid-infrared region. The absorber consists of a periodically patterned metal-dielectric-metal structure integrated with an epsilon-near-zero (ENZ) nanolayer into the insulating dielectric gap region. Such an anomalous broadband absorber is achieved thanks to a couple of resonant modes including plasmon and ENZ modes that are excited under mid-IR light illumination. By adding a 0.06-μm-thick ENZ layer between the patterned gold rectangular grating and the SiO₂ dielectric layer, the absorber captures >95% light over a 1.5 µm bandwidth centered at a near-8-μm wavelength over a wide range of oblique incidence under transverse-magnetic and -electric polarizations. The designed ENZ-based wideband absorber has potential for many practical applications, including sensing, imaging and solar energy harvesting over a wide frequency regime.