Abstract
We propose an alignment-free and polarization-selective bidirectional absorber composed of a one-dimensional bilayer Au grating array buried in a silicon nitride spacer. The absorptivity of the designed structure is more than 95% (77%) under normal forward (backward) TM-polarized light incidence, and is more than 80% (70%) within a forward (backward) incident angle up to 30°. The great bidirectional absorption performance is illustrated by the resonance coupling of the surface plasmon polaritons (SPPs) resonance, the propagating surface plasmon (PSP) resonance and the localized surface plasmon (LSP) resonance under TM-polarized wave illumination. Moreover, the excitation of the Fano-like resonance mode of the proposed metasurface can produce two significantly different peaks in the absorption spectrum under the oblique TM-polarized incidence, which is beneficial for the plasmon-sensing application. Therefore, the proposed bidirectional metasurface absorber can be a candidate in the application of optical camouflage, thermal radiation, solar cells and optical sensing.
Highlights
Metasufaces, as extraordinary artificial structures, have attracted wide attention due to their outstanding nature in the context of many applications, such as electromagnetic wave stealth [1,2,3], imaging [4,5,6], flat metalens [7,8], optical filters [9], detectors and sensors [10,11]
We have proposed a polarization-selective bidirectional absorber based on a bilayer metal grating array buried in a silicon nitride spacer
The surface plasmon polaritons (SPPs) resonance combines with propagating surface plasmon (PSP) resonance and localized surface plasmon (LSP) resonance between bilayer metal gratings, causing this great absorption effect
Summary
Metasufaces, as extraordinary artificial structures, have attracted wide attention due to their outstanding nature in the context of many applications, such as electromagnetic wave stealth [1,2,3], imaging [4,5,6], flat metalens [7,8], optical filters [9], detectors and sensors [10,11]. Compared to the inherent bulk and loss of conventional optical materials, metasurfaces have unparalleled advantages in the integration and miniaturization of optical systems. Metasurfaces still inevitably undergo some energy losses in their application. Optical absorbers can take the advantage of light loss to create a perfect absorption effect [12,13,14,15,16,17,18]. Perfect optical absorbers without the ability to reflect and transmit light have been the focus interested study for many years, due to their excellent absorption performance. Researchers concentrate their work on theoretical and experimental studies of optical absorbers with various structures, including gratings, nanoparticles, antenna arrays and multilayer composite structures. Many narrow-band, multiband and broadband metasurface-based absorbers have been investigated, and their operating bands covers from the visible region to the microwave band
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