Abstract
We present a design of an ultra-broadband metamaterial absorber in the visible and near- infrared regions. The unit cell structure consists of a single layer of metallic truncated-pyramid resonator-dielectric-metal configuration, which results in a high absorption over a broad wavelength range. The absorber exhibits 98% absorption at normal incidence spanning a wideband range of 417–1091 nm, with >99% absorption within 822–1054 nm. The broadband absorption stability maintains 95% at large incident angles up to 40° for the transverse electric (TE)-mode and 20° for the transverse magnetic (TM)-mode. Furthermore, the polarization-insensitive broadband absorption is presented in this paper by analyzing absorption performance with various polarization angles. The proposed absorber can be applied for applications such as solar cells, infrared detection, and communication systems thanks to the convenient and compatible bandwidth for electronic THz sources.
Highlights
Nowadays, the metamaterial absorber (MA) has drawn substantial attention for both fundamental studies and practical applications due to its high applicability in the microwave MA with near-unity absorption intensity [1], the surface-enhanced sensing, and ultra-sensitive sensing [2,3]
Many technologies have been proposed to enhance the light absorption of the plasmonic metamaterial structures in both the intensity and broadband
Crystals 2020, 10, 784 multi-shaped metallic configurations stacking of dielectric-meta layers [18,19], hole-arrays working as resonators [20], the shaped rectangular grating [21], shaped L grating [22,23], cylinder array [24], epsilon-near-zero (ENZ) materials [25,26], nanoporous materials that exhibit high efficiency in terms of broadband absorption, as well as their high applicability in sensors and fabricable devices [27,28,29,30]
Summary
The metamaterial absorber (MA) has drawn substantial attention for both fundamental studies and practical applications due to its high applicability in the microwave MA with near-unity absorption intensity [1], the surface-enhanced sensing, and ultra-sensitive sensing [2,3]. Crystals 2020, 10, 784 multi-shaped metallic configurations stacking of dielectric-meta layers [18,19], hole-arrays working as resonators [20], the shaped rectangular grating [21], shaped L grating [22,23], cylinder array [24], epsilon-near-zero (ENZ) materials [25,26], nanoporous materials that exhibit high efficiency in terms of broadband absorption, as well as their high applicability in sensors and fabricable devices [27,28,29,30] These MA structures still have many disadvantages such as narrow absorption bandwidth, and polarization sensitivity due to the asymmetry structures having a low order of rotational symmetry, whereas many practical applications require the polarization-insensitive feature. The physical mechanism of the MA structure is explained through the effective impedance parameter of a homogeneous structure by using the retrieval method [33]
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