Narrowband and flexible perfect absorber based on a thin-film nano-resonator incorporating a dielectric overlay

Abstract

We developed a flexible perfect absorber based on a thin-film nano-resonator, which consists of metal–dielectric–metal integrated with a dielectric overlay. The proposed perfect absorber exhibits a high quality (Q-)factor of ~ 33 with a narrow bandwidth of ~ 20 nm in the visible band. The resonance condition hinging on the adoption of a dielectric overlay was comprehensively explored by referring to the absorption spectra as a function of the wavelength and thicknesses of the overlay and metal. The results verified that utilizing a thicker metal layer improved the Q-factor and surface smoothness, while the presence of the overlay allowed for a relaxed tolerance during practical fabrication, in favor of high fidelity with the design. The origin of the perfect absorption pertaining to zero reflection was elucidated by referring to the optical admittance. We also explored a suite of perfect absorbers with varying thicknesses. An angle insensitive performance, which is integral to such a flexible optical device, was experimentally identified. Consequently, the proposed thin-film absorber featured an enhanced Q-factor in conjunction with a wide angle of acceptance. It is anticipated that our absorber can facilitate seminal applications encompassing advanced sensors and absorption filtering devices geared for smart camouflage and stealth.

Broadband Perfect Absorber in the Visible Range Based on Metasurface Composite Structures

“…The bandwidth of an absorber is important for many scientific and technical applications. The narrowband absorbers are quite important for sensing applications, such as temperature or refractive index sensing, absorption filtering, and optical signal processing [ 19 , 20 , 21 ]. On the other hand, broadband absorbers facilitate seminal applications encompassing photovoltaic cells and optoelectronic detectors.…”

Ta/NiO subwavelength bilayer for wide gamut, strong interference structural color

“…Despite the rapid development of structural color filters, most nanostructures are rigid once fabricated. In recent years, flexible devices have gained attention due to their potential applications for flexible electronics [9,[19][20][21][22][23][24][25].…”

Experimental Mid-Infrared Absorption (84%) of Single-Layer Graphene in a Reflective Asymmetric Fabry–Perot Filter: Implications for Photodetectors

“…Perfect absorption or large absorption values in graphene and 2D materials are, however, quite challenging. − In general, narrowband absorbers are desirable for sensors and absorption filters, wideband absorbers are desirable for energy harvesting applications, , while either wide and narrow wideband absorbers can be suitable for specific imaging applications. Both broadband and narrowband graphene-based photodetectors have been proposed. , …”

“…Both broadband and narrowband graphenebased photodetectors have been proposed. 6,23 As far as graphene is concerned, researchers' efforts have been devoted mainly to pattern exfoliated graphene by e-beam or ion-beam lithography 24,25 or to couple graphene with photonic crystals or metamaterials, 26,27 mostly demonstrating high absorption on small area graphene or on thick, prismbased, broadband optical devices. 28 Another approach to enhance the absorption of graphene is to exploit the constructive interference of the electromagnetic radiation inside an optical multilayer structure.…”