scholarly journals Broadband Near-Infrared Absorber Based on All Metallic Metasurface

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3568 ◽  
Author(s):  
Zhang ◽  
Deng ◽  
Song ◽  
Zhang
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Incident Angle ◽  
Incident Light ◽  
Electron Transition ◽  
Normal Incidence ◽  
Localized Surface Plasmon ◽  
Metal Nanostructures ◽  
High Loss ◽  
High Absorption

Perfect broadband absorbers have increasingly been considered as important components for controllable thermal emission, energy harvesting, modulators, etc. However, perfect absorbers which can operate over a wide optical regime is still a big challenge to achieve. Here, we propose and numerically investigate a perfect broadband near-infrared absorber based on periodic array of four isosceles trapezoid prism (FITP) unit cell made of titanium (Ti) over a continuous silver film. The structure operates with low quality (Q) factor of the localized surface plasmon resonance (LSPR) because of the intrinsic high loss, which is the foundation of the broadband absorption. The high absorption of metal nanostructures mainly comes from the power loss caused by the continuous electron transition excited by the incident light inside the metal, and the resistance loss depends on the enhanced localized electric field caused by the FITP structure. Under normal incidence, the simulated absorption is over 90% in the spectrum ranging from 895 nm to 2269 nm. The absorber is polarization-independent at normal incidence, and has more than 80% high absorption persisting up to the incident angle of ~45° at TM polarization.

Optical Analysis of Hole Patterned Ag Nanoparticle Structure

2021 ◽  
Vol 21 (8) ◽  
pp. 4192-4199
Author(s):  
Hyun-Ji Jeon ◽  
Ji-Yeon Kim ◽  
Jinnil Choi
Keyword(s):  
Metal Nanoparticles ◽  
Optical Transmission ◽  
Incident Angle ◽  
Incident Light ◽  
Localized Surface Plasmon ◽  
Optical Analysis ◽  
Optical Noise ◽  
Hole Configuration ◽  
Nanoparticle Structure ◽  
Sub Wavelength

A structure with periodic sub-wavelength nanohole patterns interacts with incident light and causes extraordinary optical transmission (EOT), with metal nanoparticles leading to localized surface plasmon resonance (LSPR) phenomena. To explore the effects of metal nanoparticles (NPs), optical analysis is performed for metal NP layers with periodic hole patterns. Investigation of Ag NP arrangements and comparisons with metal film structures are presented. Ag NP structures with different hole configuration are explored. Also, the effects of increasing light incident angle are investigated for metal NP structures where EOT peak at 460 nm wavelength is observed. Moreover, electric field distributions at each transmittance peak wavelengths and optical noise are analyzed. As a result, optical characteristics of metal NP structures are obtained and differences in resonance at each wavelength are highlighted.

scholarly journals Dual-Tunable Broadband Terahertz Absorber Based on a Hybrid Graphene-Dirac Semimetal Structure

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1096
Author(s):  
Jiali Wu ◽  
Xueguang Yuan ◽  
Yangan Zhang ◽  
Xin Yan ◽  
Xia Zhang
Keyword(s):  
Fermi Energy ◽  
Incident Angle ◽  
Normal Incidence ◽  
Surface Conductivity ◽  
Chemical Doping ◽  
Absorption Bandwidth ◽  
Terahertz Absorber ◽  
Dirac Semimetal ◽  
High Absorption ◽  
Broadband Terahertz

A dual-controlled tunable broadband terahertz absorber based on a hybrid graphene-Dirac semimetal structure is designed and studied. Owing to the flexible tunability of the surface conductivity of graphene and relative permittivity of Dirac semimetal, the absorption bandwidth can be tuned independently or jointly by shifting the Fermi energy through chemical doping or applying gate voltage. Under normal incidence, the device exhibits a high absorption larger than 90% over a broad range of 4.06–10.7 THz for both TE and TM polarizations. Moreover, the absorber is insensitive to incident angles, yielding a high absorption over 90% at a large incident angle of 60° and 70° for TE and TM modes, respectively. The structure shows great potential in miniaturized ultra-broadband terahertz absorbers and related applications.

scholarly journals FDTD Modelling of Silver Nanoparticles Embedded in Phase Separation Interface of H-PDLC

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Kun Gui ◽  
Jihong Zheng ◽  
Kangni Wang ◽  
Daoping Li ◽  
Songlin Zhuang
Keyword(s):  
Silver Nanoparticles ◽  
Phase Separation ◽  
Incident Angle ◽  
Incident Light ◽  
Near Field ◽  
Double Resonance ◽  
Blue Shift ◽  
Resonance Peak ◽  
Localized Surface Plasmon ◽  
Silver Nps

We report localized surface plasmon resonance (LSPR) of silver nanoparticles (NPs) embedded in interface of phase separation of holographic polymer-dispersed liquid crystal (H-PDLC) gratings using Finite-Difference Time Domain method. We show that silver NPs exhibit double resonance peak at the interface, and these peaks are influenced by the angle of incident light. We observe a blue shift of the wavelength of resonance peak as the incident angle increases. However, the location of silver NPs at the interface has nearly no effect on the wavelength of resonance peak. Also we show near-field and far-field properties surrounding silver NPs and find that field distribution can be controlled through rotation of incident angle. Therefore, LSPR properties of silver NPs within H-PDLC gratings can be excited by appropriate wavelength and angle of the incident light.

Polarization angular-resolved transmission spectroscopy of opal films

2016 ◽  
Vol 25 (02) ◽  
pp. 1650015
Author(s):  
M. Muldarisnur ◽  
F. Marlow
Keyword(s):  
Light Propagation ◽  
Light Transmission ◽  
Incident Angle ◽  
Incident Light ◽  
Normal Incidence ◽  
Diffraction Theory ◽  
Deposition Method ◽  
High Quality ◽  
Diffraction Peaks ◽  
Angular Shift

In this paper, we investigated the angular behavior of light transmission through opal films over a broad range of wavelengths and angles. The opal films were prepared using the capillary deposition method (CDM). The observation of many well-defined diffraction peaks indicates that the CDM results in opal films with high quality. Peaks overlapping at normal incidence split when samples are rotated. The angular shift of these peaks was found to satisfy the kinematical diffraction theory very well. Furthermore, the variation of intensity with incident angle can be interpreted in terms of a simplified dynamical diffraction theory. Moreover, the presence of two differently oriented domains in CDM-made opal films is essential in discussing the measured spectra. These domains can be assigned to parallel microscopic stripes of ABC and ACB type fcc structures. Angular-resolved spectroscopy with polarized incident light shows interesting polarization dependence of light propagation inside opals.

Directional Characteristics of Near Infrared Light Reflected from Wood

Holzforschung ◽  
2001 ◽  
Vol 55 (5) ◽  
pp. 534-540 ◽  
Author(s):  
Satoru Tsuchikawa ◽  
Misato Torii ◽  
Shigeaki Tsutsumi
Keyword(s):  
Cellular Structure ◽  
Near Infrared ◽  
Incident Angle ◽  
Incident Light ◽  
Sample Thickness ◽  
The Other ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Reflected Light ◽  
Directional Characteristics

Summary A near infrared auto-goniophotometer was designed to acquire detailed information on optical characteristics of a biological material which had a cellular structure, such as wood. The reflected light, which originated from the irradiation of polarized near infrared light, was separated into an unpolarized and a polarized component by using two polarizing filters. The standardized reflected intensities of each component at various incident angles θ and observation angles η, ρup (θ, η) and ρp (θ, η), were measured. Sitka spruce samples with various thicknesses were used. The measurements showed that the directional characteristics of the unpolarized component were affected significantly by the irradiation conditions and the sample thickness. Particularly, these varied with the wavelength of incident light λ. This shows that the directional characteristics models we proposed previously are reasonable. On the other hand, matrices of the directional characteristics for polarized components typically show an elliptical shape which is strongly affected by incident angle and only slightly by λ. Based on these results, the effects of sample thickness on the spectral directional characteristics were determined.

scholarly journals New Approach in the Application of Conjugated Polymers: The Light-Activated Source of Versatile Singlet Oxygen Molecule

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1098
Author(s):  
Agata Blacha-Grzechnik
Keyword(s):  
Conjugated Polymers ◽  
Singlet Oxygen ◽  
Near Infrared ◽  
Photophysical Properties ◽  
Short Review ◽  
The Novel ◽  
New Approach ◽  
Intermolecular Energy ◽  
Intermolecular Energy Transfer ◽  
High Absorption

For many years, the research on conjugated polymers (CPs) has been mainly focused on their application in organic electronics. Recent works, however, show that due to the unique optical and photophysical properties of CPs, such as high absorption in UV–Vis or even near-infrared (NIR) region and efficient intra-/intermolecular energy transfer, which can be relatively easily optimized, CPs can be considered as an effective light-activated source of versatile and highly reactive singlet oxygen for medical or catalytic use. The aim of this short review is to present the novel possibilities that lie dormant in those exceptional polymers with the extended system of π-conjugated bonds.

scholarly journals Shoreline Changes along Northern Ibaraki Coast after the Great East Japan Earthquake of 2011

2021 ◽  
Vol 13 (7) ◽  
pp. 1399
Author(s):  
Quang Nguyen Hao ◽  
Satoshi Takewaka
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Sandy Beaches ◽  
Great East Japan Earthquake ◽  
Shoreline Changes ◽  
Run Up ◽  
Tsunami Run Up ◽  
Sentinel 2 ◽  
Infrared Radiometer

In this study, we analyze the influence of the Great East Japan Earthquake, which occurred on 11 March 2011, on the shoreline of the northern Ibaraki Coast. After the earthquake, the area experienced subsidence of approximately 0.4 m. Shoreline changes at eight sandy beaches along the coast are estimated using various satellite images, including the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), ALOS AVNIR-2 (Advanced Land Observing Satellite, Advanced Visible and Near-infrared Radiometer type 2), and Sentinel-2 (a multispectral sensor). Before the earthquake (for the period March 2001–January 2011), even though fluctuations in the shoreline position were observed, shorelines were quite stable, with the averaged change rates in the range of ±1.5 m/year. The shoreline suddenly retreated due to the earthquake by 20–40 m. Generally, the amount of retreat shows a strong correlation with the amount of land subsidence caused by the earthquake, and a moderate correlation with tsunami run-up height. The ground started to uplift gradually after the sudden subsidence, and shoreline positions advanced accordingly. The recovery speed of the beaches varied from +2.6 m/year to +6.6 m/year, depending on the beach conditions.

High-energy organic group-induced spectrally pure upconversion emission in novel zirconate-/hafnate-based nanocrystals

CrystEngComm ◽  
2015 ◽  
Vol 17 (37) ◽  
pp. 7169-7174 ◽  
Author(s):  
Xianghong He ◽  
Bing Yan
Keyword(s):  
Pump Power ◽  
Near Infrared ◽  
Incident Light ◽  
Upconversion Emission ◽  
High Energy ◽  
Single Band ◽  
Organic Group ◽  
Red Fluorescence

A series of novel fluoride-based nanophosphors (NPs) exhibiting spectrally pure upconversion (UC) red fluorescence upon near-infrared (980 nm) excitation. The single-band deep-red UC luminescence feature of K3MF7:Yb3+,Er3+ (M = Zr, Hf) NPs is independent of the doping levels of Yb3+–Er3+ and the pump power of incident light.

scholarly journals NEAR-INFRARED THERMAL EMISSION DETECTIONS OF A NUMBER OF HOT JUPITERS AND THE SYSTEMATICS OF GROUND-BASED NEAR-INFRARED PHOTOMETRY

2015 ◽  
Vol 802 (1) ◽  
pp. 28 ◽  
Author(s):  
Bryce Croll ◽  
Loic Albert ◽  
Ray Jayawardhana ◽  
Michael Cushing ◽  
Claire Moutou ◽  
...  
Keyword(s):  
Near Infrared ◽  
Thermal Emission ◽  
Infrared Photometry ◽  
Hot Jupiters
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