Abstract:Broadband perfect absorber based on one ultrathin layer of the refractory metal chromium without structure patterning is proposed and demonstrated. The ideal permittivity of the metal layer for achieving broadband perfect absorption is derived based on the impedance transformation method. Since the permittivity of the refractory metal chromium matches this ideal permittivity well in the visible and near-infrared range, a silica-chromium-silica three-layer absorber is fabricated to demonstrate the broadband per… Show more
“…Gold grating structure with period of 200 nm, filling factor of 0.5 and thickness of 100 nm is deposited on one silica layer. Since the permittivity of Cr 16 matches the ideal permittivity to satisfy the matching impedance condition (6) for broadband waveleng thin the visible and NIR, and the grating structure will reflect the light back to the silica layer for only selected polarization, the proposed structure is expected to work as a broadband polarization sensitive perfect absorber.Figure 3( a ) Schematic of the broadband polarization sensitive perfect absorber. ( b ) Absorption for s-and p-polarization under normal incidence.…”
“…Many polarization-insensitive absorbers at visible and near-infrared regime have been demonstrated such as structures using mesoporous gold surfaces 14 , structures consisting of a metal-insulator-metal stack with trapezoid arrays of nanostructures patterned on the top silver film 15 or structures based on one ultrathin layer of refractory metal 16 . Since the control of light absorbance plays a fundamental role in photonics technology with strong impact for light emitting and sensing components, metamaterial designs that can enable active control of light absorbance are necessary.…”
Section: Introductionmentioning
confidence: 99%
“…Since the control of light absorbance plays a fundamental role in photonics technology with strong impact for light emitting and sensing components, metamaterial designs that can enable active control of light absorbance are necessary. Perfect absorbers that are sensitive to the polarization or incident angle therefore attract much attention, and have been realized recently by introducing anisotropy in the design structure 16–21 . For example, designs of narrowband polarization sensitive perfect absorber with botte-line and cub-like structures are proposed and demonstrated numerically 16 , and the one consisting of arrays of three-dimensional standing U-shaped resonators fabricated by two-photon polymerization followed by blanket coating of the metal is reported 21 .…”
Conventional metamaterial absorbers have multilayer designs, where the dielectric interlayer is sandwiched between a top patterned metallic structure and bottom metallic film. Here, we demonstrate that a highly polarization-sensitive perfect absorber canbe realized by replacing the bottom metallic film with a plasmonic grating. Designs for broadband and narrowband of wavelength are proposed and numerically investigated. The designed absorbers perform high light absorption, which is above 90% over the wavelength range of 0.4–1.4 µm for the broadband absorber and 98% for the absorption peak in case of the narrowband design, with a specific polarization of incident light. We find that the absorption is tunable by changing the polarization. Such absorbers offer new approach for active control of light absorbance with strong impacts for solar energy harvesting, light emitting and sensing.
“…Gold grating structure with period of 200 nm, filling factor of 0.5 and thickness of 100 nm is deposited on one silica layer. Since the permittivity of Cr 16 matches the ideal permittivity to satisfy the matching impedance condition (6) for broadband waveleng thin the visible and NIR, and the grating structure will reflect the light back to the silica layer for only selected polarization, the proposed structure is expected to work as a broadband polarization sensitive perfect absorber.Figure 3( a ) Schematic of the broadband polarization sensitive perfect absorber. ( b ) Absorption for s-and p-polarization under normal incidence.…”
“…Many polarization-insensitive absorbers at visible and near-infrared regime have been demonstrated such as structures using mesoporous gold surfaces 14 , structures consisting of a metal-insulator-metal stack with trapezoid arrays of nanostructures patterned on the top silver film 15 or structures based on one ultrathin layer of refractory metal 16 . Since the control of light absorbance plays a fundamental role in photonics technology with strong impact for light emitting and sensing components, metamaterial designs that can enable active control of light absorbance are necessary.…”
Section: Introductionmentioning
confidence: 99%
“…Since the control of light absorbance plays a fundamental role in photonics technology with strong impact for light emitting and sensing components, metamaterial designs that can enable active control of light absorbance are necessary. Perfect absorbers that are sensitive to the polarization or incident angle therefore attract much attention, and have been realized recently by introducing anisotropy in the design structure 16–21 . For example, designs of narrowband polarization sensitive perfect absorber with botte-line and cub-like structures are proposed and demonstrated numerically 16 , and the one consisting of arrays of three-dimensional standing U-shaped resonators fabricated by two-photon polymerization followed by blanket coating of the metal is reported 21 .…”
Conventional metamaterial absorbers have multilayer designs, where the dielectric interlayer is sandwiched between a top patterned metallic structure and bottom metallic film. Here, we demonstrate that a highly polarization-sensitive perfect absorber canbe realized by replacing the bottom metallic film with a plasmonic grating. Designs for broadband and narrowband of wavelength are proposed and numerically investigated. The designed absorbers perform high light absorption, which is above 90% over the wavelength range of 0.4–1.4 µm for the broadband absorber and 98% for the absorption peak in case of the narrowband design, with a specific polarization of incident light. We find that the absorption is tunable by changing the polarization. Such absorbers offer new approach for active control of light absorbance with strong impacts for solar energy harvesting, light emitting and sensing.
“…To continue the development of layered perfect absorbers, a method based on one ultrathin layer of chromium between two silica layers was devised [3,51]. The thin metal layer is no longer a noble metal and no longer requires any structuring.…”
In the past decade, the realisation of negative index materials has initiated extensive research into metamaterials. Perfect absorbers and reflectors are of particular interest as their usefulness is endless in a range of different fields and devices. Since it was originally shown that a device can achieve unity absorption of electromagnetic waves, it has become a hot area of research to develop perfect absorbers based on polarisation independence and incident angle independence, at a range of frequencies from microwave to optical ones. The amazing performance, flexibility, and tunability of these metamaterials will be discussed here, by presenting the different designs and working mechanisms that have been realised up to now. Their limitations and shortcomings will be addressed and future plans for perfect absorbers and reflectors will be suggested.
“…The thickness and refractive index of each layer are designed to yield a stratiform structure with an equivalent admittance of approximately unity in a designated range of wavelengths3031. However, the absorption is limited by the bandwidth of admittance matching.…”
Metals have been formed into nanostructures to absorb light with high efficiency through surface plasmon resonances. An ultra-thin plasmonic structure that exhibits strong absorption over wide ranges of wavelengths and angles of incidence is sought. In this work, a nearly perfect plasmonic nanostructure is fabricated using glancing angle deposition. The difference between the morphologies of obliquely deposited aluminum and silver nanohelices is exploited to form a novel three-dimensional structure, which is an aluminum-silver nanohelix array on a pattern-free substrate. With a thickness of only 470 nm, densely distributed nanohelices support rod-to-rod localized surface plasmons for broadband and polarization-independent light extinction. The extinctance remains high over wavelengths from 400 nm to 2000 nm and angles of incidence from 0° to 70°.
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