scholarly journals Numerical Study on the Absorption Characteristics of Subwavelength Metallic Gratings Covered with a Lossy Dielectric Layer

2018 ◽  
Vol 8 (9) ◽  
pp. 1445
Author(s):  
Chi-Young Hwang ◽  
Yong-Hae Kim ◽  
Ji Choi ◽  
Gi Kim ◽  
Jong-Heon Yang ◽  
...  
Keyword(s):  
Dielectric Layer ◽  
Numerical Study ◽  
Structural Parameters ◽  
Resonant Cavity ◽  
Visible Range ◽  
Absorption Properties ◽  
Perfect Absorption ◽  
Metallic Gratings ◽  
Band Absorption ◽  
Multi Band

Optical absorbers have been a topic of intense research due to their importance in many applications. In particular, multi-band and perfect absorption features in a desired frequency range are essential in broadband applications. In this work, we numerically studied the absorption properties of subwavelength metallic gratings coated with a dielectric layer. Here, the structure is considered to be an integration between a resonant cavity and a subwavelength metallic grating. Two appropriately designed structures can exhibit multi-band absorption properties. In addition to the numerical simulation results, we elaborate on determining the appropriate structural parameters that yield the desired spectral absorption profile in the visible range. We also numerically identify critical coupling conditions for perfect absorption.

scholarly journals Quad-Band Plasmonic Perfect Absorber for Visible Light with a Patchwork of Silicon Nanorod Resonators

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1954 ◽  
Author(s):  
Can Cao ◽  
Yongzhi Cheng
Keyword(s):  
Visible Light ◽  
Transverse Electric ◽  
Transverse Magnetic ◽  
Localized Surface Plasmon ◽  
Perfect Absorber ◽  
Absorption Properties ◽  
Perfect Absorption ◽  
Potential Applications ◽  
Polarization Insensitive ◽  
Band Absorption

In this paper, a plasmonic perfect absorber (PPA) based on a silicon nanorod resonator (SNRR) for visible light is proposed and investigated numerically. The proposed PPA is only a two-layer nanostructure consisting of a SNRR periodic array and metal substrate. The perfect absorption mainly originates from excitation of the localized surface plasmon resonance (LSPR) mode in the SNRR structure. The absorption properties of this design can be adjusted by varying the radius (r) and height (h) of the SNRR structure. What is more, the stronger quad-band absorption can be achieved by combing four different radius of the SNRR in one period as a super unit-cell. Numerical simulation indicates that the designed quad-band PPA can achieve the absorbance of 99.99%, 99.8%, 99.8%, and 92.2% at 433.5 THz, 456 THz, 482 THz, and 504.5 THz, respectively. Further simulations show that the proposed PPA is polarization-insensitive for both transverse electric (TE) and transverse magnetic (TM) modes. The proposed PPA can be a desirable candidate for some potential applications in detecting, sensing, and visible spectroscopy.

scholarly journals Numerical Study of an Ultra-Broadband All-Silicon Terahertz Absorber

2020 ◽  
Vol 10 (2) ◽  
pp. 436 ◽  
Author(s):  
Jinfeng Wang ◽  
Tingting Lang ◽  
Tingting Shen ◽  
Changyu Shen ◽  
Zhi Hong ◽  
...  
Keyword(s):  
Numerical Study ◽  
Structural Parameters ◽  
Impedance Matching ◽  
Single Layer ◽  
Transverse Magnetic ◽  
Absorption Efficiency ◽  
Absorption Mechanism ◽  
Loss Mechanism ◽  
Perfect Absorption ◽  
Terahertz Absorber

In this article we present and numerically investigate a broadband all-silicon terahertz (THz) absorber which consists of a single-layer periodic array of a diamond metamaterial layer placed on a silicon substrate. We simulated the absorption spectra of the absorber under different structural parameters using the commercial software Lumerical FDTD solutions, and analyzed the absorption mechanism from the distribution of the electromagnetic fields. Finally, the absorption for both transverse electric (TE) and transverse magnetic (TM) polarizations under different incident angles from 0 to 70° were investigated. Herein, electric and magnetic resonances are proposed that result in perfect broadband absorption. When the absorber meets the impedance matching principle in accordance with the loss mechanism, it can achieve a nearly perfect absorption response. The diamond absorber exhibits an absorption of ~100% at 1 THz and achieves an absorption efficiency >90% within a bandwidth of 1.3 THz. In addition, owing to the highly structural symmetry, the absorber has a polarization-independent characteristic. Compared with previous metal–dielectric–metal sandwiched absorbers, the all-silicon metamaterial absorbers can avoid the disadvantages of high ohmic losses, low melting points, and high thermal conductivity of the metal, which ensure a promising future for optical applications, including sensors, modulators, and photoelectric detection devices.

Numerical Study on Controllable Multi-Band Microwave Metamaterial Absorbers

2011 ◽  
Vol 239-242 ◽  
pp. 1260-1264
Author(s):  
Wei Wei Ji ◽  
Tao Wang ◽  
Yan Nie ◽  
Rong Zhou Gong
Keyword(s):  
Numerical Study ◽  
Impedance Matching ◽  
Single Layer ◽  
Surface Current ◽  
Metamaterial Absorber ◽  
Band Absorption ◽  
Different Dimensions ◽  
Resonant Feature ◽  
Difference Time ◽  
Multi Band

Based on the impedance matching and electromagnetic resonant characteristic of composite materials, we present a single-layer metamaterial absorber consisting of arch copper loop and substrate FR-4, of which the resonant frequency depended on the loop’s geometry perimeter. By combining resonant loops with different dimensions together, we can achieve multi-band absorption. The standard finite difference time domain method was used to calculate the magnitudes of reflectance, and then the induced surface current and power loss distributions were demonstrated to analyze the insight physical picture of the multi-band resonant feature. By optimizing the simulation results, the absorptivities of two absorption peaks are all above 98% when the number of copper loops is two, 95% for three absorption peaks of three loops, and 87% for four absorption peaks of four loops.

scholarly journals Cascaded Nanorod Arrays for Ultrabroadband, Omnidirectional and Polarization-Insensitive Absorption

2020 ◽  
Vol 10 (11) ◽  
pp. 3878
Author(s):  
Xun Wang ◽  
Tian Sang ◽  
Honglong Qi ◽  
Guoqing Li ◽  
Xin Yin ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Near Infrared ◽  
Structural Parameters ◽  
Resonant Cavity ◽  
Dielectric Materials ◽  
Localized Surface Plasmon ◽  
Nanorod Arrays ◽  
Absorption Properties ◽  
Polarization Insensitive ◽  
Absorption Performance

An ultrabroadband, omnidirectional, and polarization-insensitive absorber based on cascaded nanorod arrays (CNAs) is numerically demonstrated, and an average absorptivity of 98.2% with a relative absorption bandwidth (RAB) of 149.8% can be achieved in the 0.38–2.65 μm wavelength range. The proposed CNA-based absorber requires only several pairs of multilayers to achieve excellent absorption performance. More significantly, the physical mechanism for this intriguing ultrabroadband absorption results from the synergistic effect of localized surface plasmon (LSP) and plasmonic resonant cavity (PRC) modes, which is fundamentally different from the tapered metal/dielectric multilayer-based absorbers associated with the slow-light mode. We investigated the absorption properties of the CNA-based metasurface by using the impedance theory, which indicates that the impedance of the structure matches well with the impedance of the free space from the visible to near-infrared wavelength range. In addition, the absorption properties of the CNA-based metasurface are robust to the variation of the structural parameters and the metal/dielectric materials, and ultrabroadband absorption performance can be maintained within 0–60° for both TM and TE modes.

Phase Resonance Tuning and Multi-Band Absorption Via Graphene-Covered Compound Metallic Gratings

2017 ◽  
Vol 53 (5) ◽  
pp. 1-10 ◽  
Author(s):  
Omid Hemmatyar ◽  
Babak Rahmani ◽  
Amirmasood Bagheri ◽  
Amin Khavasi
Keyword(s):  
Resonance Tuning ◽  
Metallic Gratings ◽  
Band Absorption ◽  
Phase Resonance ◽  
Multi Band

Perfect Selective Metamaterial Absorber With Thin-Film of GaAs Layer In The Visible Region For Solar Cell Applications

2021 ◽  
Author(s):  
Raj Kumar ◽  
Bipin K Singh ◽  
Rajesh K Tiwari ◽  
Praveen C Pandey
Keyword(s):  
Structural Parameters ◽  
Short Circuit ◽  
Effective Permittivity ◽  
Visible Region ◽  
Special Kind ◽  
Short Circuit Current ◽  
Gaas Layer ◽  
Visible Range ◽  
Perfect Absorber ◽  
Perfect Absorption

Abstract In this paper, we have presented a new design of a metamaterial perfect absorber (MPA) consisting of three layers of metal-dielectric-metal in which the top layer is considered of special kind square patches at different places in a unit cell. This MPA exhibits wideband, wide-angle, and polarization-independent absorption performance in the visible region. This structure originates the plasmonic resonance which is responsible for the perfect absorption in the optical region. Under a specific condition, this simulated absorber structure exhibits an extremely high broadband absorption between 591.54 nm to 704.40 nm wavelength range with near-unity absorption, and a single peak observed at 385.33 nm with absorption 94.16%. We extracted the impedance of the absorber and matched it with free space, and also demonstrated the effective permittivity and permeability. Moreover, the parametric study of the resonators, dielectric layer, and multi-band topology has also been investigated. The polarization-insensitive-based metamaterial may be utilized to improve the efficiency of different devices in the visible range. Furthermore, we have calculated the absorption of the proposed MPA under the solar radiation (AM1.5) for different structural parameters. The proposed absorber greatly enhances the conversion efficiency which is highly useful for solar cells. We also determined the short circuit current density of this absorber for different thicknesses of the GaAs layer. Al metal patches at meta-surface provide nearly similar performance in comparison with other costly metals. Therefore, the proposed structure with cheaper Al metal may be used for different devices as the perfect absorber.

Synthesis and Infrared Multi‐band Absorption Properties of Core‐shell NaYF 4 :Yb 3+ , Er 3+ @SiO 2 Nanoparticles

2019 ◽  
Vol 645 (21) ◽  
pp. 1240-1246
Author(s):  
Lu Yuan ◽  
Ming Kang ◽  
Guanjun Chang ◽  
Xiangmeng Lv ◽  
Simin Shen ◽  
...  
Keyword(s):  
Core Shell ◽  
Absorption Properties ◽  
Band Absorption ◽  
Multi Band

scholarly journals Inversion Method Characterization of Graphene-Based Coordination Absorbers Incorporating Periodically Patterned Metal Ring Metasurfaces

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1102
Author(s):  
Zhiyu Bao ◽  
Yang Tang ◽  
Zheng-Da Hu ◽  
Chengliang Zhang ◽  
Aliaksei Balmakou ◽  
...  
Keyword(s):  
High Performance ◽  
Inversion Method ◽  
Metal Ring ◽  
Perfect Absorption ◽  
Broadband Absorption ◽  
Equivalent Impedance ◽  
Parametric Inversion ◽  
Band Absorption ◽  
The Individual ◽  
Multi Band

In this paper, we propose a tunable coordinated multi-band absorber that combines graphene with metal–dielectric–metal structures for the realization of multiple toward perfect absorption. The parametric inversion method is used to extract the equivalent impedance and explain the phenomena of multiple-peak absorption. With the change of the Fermi level, equivalent impedances were extracted, and the peculiarities of the individual multiple absorption peaks to change were determined. By changing the structure parameters of gold rings, we obtain either multiple narrow-band absorption peaks or a broadband absorption peak, with the bandwidth of 0.8 μm where the absorptance is near 100%. Therefore, our results provide new insights into the development of tunable multi-band absorbers and broadband absorbers that can be applied to terahertz imaging in high-performance coordinate sensors and other promising optoelectronic devices.

scholarly journals Multi Band Metamaterials Absorber for Stealth Applications

2019 ◽  
Vol 11 (1) ◽  
pp. 133-144 ◽  
Author(s):  
Khalid Saeed Lateef Al-badri
Keyword(s):  
Electromagnetic Waves ◽  
Computer Software ◽  
Metamaterial Absorber ◽  
Perfect Absorption ◽  
Stealth Technology ◽  
Band Absorption ◽  
Perfect Metamaterial Absorber ◽  
Ground Plate ◽  
Good Agreement ◽  
Multi Band

Purpose – This paper presents a simulation study using CST microwave studio computer software. Methodology/approach/design – A simple structure based on metamaterial are used to construct a perfect metamaterial absorber. It is made of just one uncompleted square patch copper placed on top of dielectric layer to separate it from a copper ground plate. Findings – This design provides four perfect absorption regions with absorption peaks of an average of 93%. The characteristic study of parameters such as copper dimensions and dielectric properties led to an expected result in the synthesis of resonant frequency. Practical implications – The multi-band absorption can be used in energy harvesting applications, protection from the effects of electromagnetic waves, radar stealth technology and thermal imaging. Moreover, the experimental results show good agreement with CST simulation.

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