scholarly journals Broadband terahertz absorber based on dispersion-engineered catenary coupling in dual metasurface

Nanophotonics ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 117-125 ◽  
Author(s):  
Ming Zhang ◽  
Fei Zhang ◽  
Yi Ou ◽  
Jixiang Cai ◽  
Honglin Yu
Keyword(s):  
Optical Model ◽  
Dispersion Management ◽  
Bandwidth Extension ◽  
Limited Bandwidth ◽  
Terahertz Absorber ◽  
Simple Strategy ◽  
Management Ability ◽  
Potential Applications ◽  
Resolution Imaging ◽  
Different Thickness

AbstractTerahertz (THz) absorbers have attracted considerable attention due to their potential applications in high-resolution imaging systems, sensing, and imaging. However, the limited bandwidth of THz absorbers limits their further applications. Recently, the dispersion management of metasurfaces has become a simple strategy for the bandwidth extension of THz devices. In this paper, we used the capability of dispersion management to extend the bandwidth of THz absorbers. As a proof-of-concept, a dual metasurface-based reflective device was proposed for broadband near-unity THz absorber, which was composed of two polarization-independent metasurfaces separated from a metallic ground by dielectric layers with different thickness. Benefiting from the fully released dispersion management ability in adjusting the dimensions of the metasurfaces, we obtained an absorbance above 90% in the frequency range from 0.52 to 4.4 THz and the total thickness for the bandwidth approaching the theoretical Rozanov limit. The experimental results verified the ability of dispersion management in designing broadband absorbers and the performance of the designed absorber. The underlying physical mechanism of dispersion management was interpreted in the general equivalent circuit theory and transmission line model. In addition, the catenary optical model was used to further interpret the physics behind this dual metasurface. Moreover, we found that the alignment deviations between the dual metasurface had little impact on the performance of the designed absorber, which indicates that the dual-metasurface does not require center alignment and is easy to be fabricated. The results of this work could broaden the application areas of THz absorbers.

scholarly journals Gold-coated plant virus as computed tomography imaging contrast agent

2019 ◽  
Vol 10 ◽  
pp. 1983-1993 ◽  
Author(s):  
Alaa A A Aljabali ◽  
Mazhar S Al Zoubi ◽  
Khalid M Al-Batanyeh ◽  
Ali Al-Radaideh ◽  
Mohammad A Obeid ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Agent ◽  
Low Cost ◽  
Cell Types ◽  
Specific Cell ◽  
Scan Time ◽  
Ct Contrast Agent ◽  
Potential Applications ◽  
Resolution Imaging

Chemical modification of the surface of viruses, both the interior and the exterior, imparts new functionalities, that have potential applications in nanomedicine. In this study, we developed novel virus-based nanomaterials as a contrast agent for computed tomography (CT) imaging in vitro. The gold-coated cowpea mosaic virus (Au-CPMV) particles were generated by the electrostatic adsorption of positively charged electrolyte on the virus capsid with the subsequent incubation and reduction of anionic gold complexes. Au-CPMV particles as a CT contrast agent offer a fast scan time (less than 2 min), low cost, and biocompatibility and allow for high-resolution imaging with ca. 150 Hounsfield units (HU). The Au-CPMV surface was further modified allowing for the incorporation of targeting molecules of specific cell types.

scholarly journals Joint 3D-Wind Retrievals with Stereoscopic Views from MODIS and GOES

2019 ◽  
Vol 11 (18) ◽  
pp. 2100 ◽  
Author(s):  
James L. Carr ◽  
Dong L. Wu ◽  
Robert E. Wolfe ◽  
Houria Madani ◽  
Guoqing (Gary) Lin ◽  
...  
Keyword(s):  
Height Measurement ◽  
Wildfire Smoke ◽  
Brightness Temperatures ◽  
Potential Applications ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Wind Retrievals ◽  
Atmospheric Motion Vectors ◽  
Along Track

Atmospheric motion vectors (AMVs), derived by tracking patterns, represent the winds in a layer characteristic of the pattern. AMV height (or pressure), important for applications in atmospheric research and operational meteorology, is usually assigned using observed IR brightness temperatures with a modeled atmosphere and can be inaccurate. Stereoscopic tracking provides a direct geometric height measurement of the pattern that an AMV represents. We extend our previous work with multi-angle imaging spectro–radiometer (MISR) and GOES to moderate resolution imaging spectroradiometer (MODIS) and the GOES-R series advanced baseline imager (ABI). MISR is a unique satellite instrument for stereoscopy with nine angular views along track, but its images have a narrow (380 km) swath and no thermal IR channels. MODIS provides a much wider (2330 km) swath and eight thermal IR channels that pair well with all but two ABI channels, offering a rich set of potential applications. Given the similarities between MODIS and VIIRS, our methods should also yield similar performance with VIIRS. Our methods, as enabled by advanced sensors like MODIS and ABI, require high-accuracy geographic registration in both systems but no synchronization of observations. AMVs are retrieved jointly with their heights from the disparities between triplets of ABI scenes and the paired MODIS granule. We validate our retrievals against MISR-GOES retrievals, operational GOES wind products, and by tracking clear-sky terrain. We demonstrate that the 3D-wind algorithm can produce high-quality AMV and height measurements for applications from the planetary boundary layer (PBL) to the upper troposphere, including cold-air outbreaks, wildfire smoke plumes, and hurricanes.

scholarly journals Three-dimensional printing of functionally graded liquid crystal elastomer

2020 ◽  
Vol 6 (39) ◽  
pp. eabc0034 ◽  
Author(s):  
Zijun Wang ◽  
Zhijian Wang ◽  
Yue Zheng ◽  
Qiguang He ◽  
Yang Wang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Glass Plate ◽  
Three Dimensional ◽  
Functionally Graded ◽  
Structure Property ◽  
Three Dimensional Printing ◽  
Liquid Crystal Elastomer ◽  
Simple Strategy ◽  
Potential Applications ◽  
Dimensional Printing

As a promising actuating material, liquid crystal elastomer (LCE) has been intensively explored in building diverse active structures and devices. Recently, direct ink writing technique has been developed to print LCE structures with various geometries and actuation behaviors. Despite the advancement in printing LCE, it remains challenging to print three-dimensional (3D) LCE structures with graded properties. Here, we report a facile method to tailor both the actuation behavior and mechanical properties of printed LCE filaments by varying printing parameters. On the basis of the comprehensive processing-structure-property relationship, we propose a simple strategy to print functionally graded LCEs, which greatly increases the design space for creating active morphing structures. We further demonstrate mitigation of stress concentration near the interface between an actuatable LCE tube and a rigid glass plate through gradient printing. The strategy developed here will facilitate potential applications of LCEs in different fields.

Study on the Specific Harmonic Suppression of Active Power Filter

2014 ◽  
Vol 556-562 ◽  
pp. 1945-1949
Author(s):  
Xiong Rui ◽  
Zi Qiang Xi ◽  
Miao Zhou
Keyword(s):  
Steady State ◽  
Error Control ◽  
Active Power Filter ◽  
Active Power ◽  
Harmonic Suppression ◽  
Limited Bandwidth ◽  
Power Filter ◽  
Simple Strategy ◽  
Current Coupling ◽  
State Error

Aiming at the problems that the traditional active power filter (APF) which is with limited bandwidth and is difficult to realize zero steady-state error control, we use a strategy based on multiple synchronous rotating coordinate for each harmonic separation to achieve the detection of selective harmonic and proportion-integral (PI) control. Then it’s able to implement zero steady-state error compensation. After establishing the mathematical model of harmonic rotating coordinate for the APF, we proposed a simple strategy of current coupling and decoupling. The simulation results and the prototypes’ practical operations proved that the control strategy can compensate for the selective harmonic effectively and respond to the changes of the conditions in time. Meanwhile it has good characteristics in dynamic response.

scholarly journals Confocal Endomicroscopy of Colorectal Polyps

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Vivian M. Ussui ◽  
Michael B. Wallace
Keyword(s):  
Real Time ◽  
Disease Surveillance ◽  
Colorectal Polyps ◽  
Confocal Laser Endomicroscopy ◽  
Confocal Laser ◽  
Disruptive Technology ◽  
Living Tissue ◽  
Potential Applications ◽  
Resolution Imaging ◽  
Capillary Circulation

Confocal laser endomicroscopy (CLE) is one of several novel methods that provide real-time, high-resolution imaging at a micron scale via endoscopes. CLE has the potential to be a disruptive technology in that it can change the current algorithms that depend on biopsy to perform surveillance of high-risk conditions. Furthermore, it allows on-table decision making that has the potential to guide therapy in real time and reduce the need for repeated procedures. CLE and related technologies are often termed “virtual biopsy” as they simulate the images seen in traditional histology. However, the imaging of living tissue allows more than just pragmatic convenience; it also allows imaging of living tissue such as active capillary circulation, cellular death, and vascular and endothelial translocation, thus extending beyond what is capable in traditional biopsy. Immediate potential applications of CLE are to guide biopsy sampling in Barrett's esophagus and inflammatory bowel disease surveillance, evaluation of colorectal polyps, and intraductal imaging of the pancreas and bile duct. Data on these applications is rapidly emerging, and more is needed to clearly demonstrate the optimal applications of CLE. In this paper, we will focus on the role of CLE as applied to colorectal polyps detected during colonoscopy.

scholarly journals Bandwidth and BER Improvement Employing a Pre-Equalization Circuit with White LED Arrays in a MISO VLC System

2019 ◽  
Vol 9 (5) ◽  
pp. 986 ◽  
Author(s):  
Monette Khadr ◽  
Ahmed Abd El Aziz ◽  
Heba Fayed ◽  
Moustafa Aly
Keyword(s):  
Signal To Noise Ratio ◽  
Visible Light Communication ◽  
Bandwidth Extension ◽  
Bandwidth Enhancement ◽  
White Leds ◽  
Limited Bandwidth ◽  
Single Output ◽  
Data Rates ◽  
The Impact ◽  
Led Arrays

This paper aims to extend the limited bandwidth of phosphorescent white LEDs for a multiple-input single-output (MISO) visible light communication (VLC) system. A proposed LED arrangement model is presented, resulting in improved results as compared to those previously discussed in the literature. In this paper, the impact of the receiver field of view (FOV) angle, the LED transmission angle, and the number of LED arrays used on the transmission are studied at different speeds. The system performance is measured by the signal to noise ratio (SNR) and the corresponding bit error rate (BER) at different data rates. The obtained results show that the proposed model is able to improve the illumination uniformity across the room with a higher SNR using the same number of LEDs in the investigated indoor environment. The paper also introduces a pre-equalization circuit in the transmitter end in order to extend the limited bandwidth of the used white LEDs. This bandwidth extension using the proposed circuit results in an increased data rate with the aid of a blue filter. A number of experiments are executed to optimize the key parameters for maximum bandwidth enhancement. The proposed circuit offers 28% bandwidth enhancement over the most recent study in this area while eradicating the BER at 200 Mb/s when compared to un-equalized LED circuits.

scholarly journals A Dual-Band Terahertz Absorber with Two Passbands Based on Periodic Patterned Graphene

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3016 ◽  
Author(s):  
Ximeng Zhang ◽  
Weiwei Wu ◽  
Chenxin Li ◽  
Chang Wang ◽  
Yuhong Ma ◽  
...  
Keyword(s):  
Chemical Potential ◽  
Transmission Rate ◽  
Frequency Selective Surface ◽  
Transverse Magnetic ◽  
Dual Band ◽  
Center Frequency ◽  
Absorption Bands ◽  
Terahertz Absorber ◽  
Potential Applications ◽  
Incident Waves

In this paper, a dual-band terahertz absorber with two passbands is proposed. The absorber is composed of periodic patterned graphene arrays on the top of a SiO 2 substrate and a frequency selective surface (FSS) on the bottom of the substrate. The simulated results indicate that there are two absorption bands (absorption greater than 90%) ranging from 0.54 to 0.84 THz and 2.13 to 2.29 THz. It is almost transparent to incident waves (transmission greater than 50%) below 0.19 THz and between 1.3 and 1.67 THz with a center frequency of 1.49 THz. The absorber has a good tolerance to the transverse electric (TE) and transverse magnetic (TM) polarized wave oblique incidence, and the transmission rate of the passbands remains greater than 50% within 70 degrees. Moreover, the absorption rate of the absorber can be tuned by the chemical potential of graphene. The structure with absorption and transmission properties has potential applications in filtering, sensing, detecting and antenna stealth.

Experimental and Theoretical Studies of the Si(100)/SiO2 Interface Formed by Wet and Dry Oxidation

2002 ◽  
Vol 747 ◽  
Author(s):  
A. Roy Chowdhuri ◽  
Dong-Un Jin ◽  
C. G. Takoudis
Keyword(s):  
Optical Model ◽  
Oxide Thickness ◽  
Longitudinal Optical ◽  
Process Conditions ◽  
Silicon Oxides ◽  
Different Temperatures ◽  
Interfacial Strain ◽  
Asymmetric Stretch ◽  
Experimental And Theoretical Studies ◽  
Different Thickness

ABSTRACTInterfacial strain and substoichiometric silicon oxides are the two principal causes that result in the redshift of the transverse and longitudinal optical phonons of the asymmetric stretch of O in the Si-O-Si bridging bond of thermal SiO2 with decreasing oxide thickness. Analyses to comprehend these effects, therefore, require consideration of both strain and interfacial substoichiometry. A method to isolate the contributions of strain and suboxide content towards the observed shifts is proposed. The procedure, which utilizes simple optical model and effective medium approximation, allows estimation of the average strain and suboxide concentration in films of different thickness. Analyses of oxides formed at two different temperatures (550 and 700°C) with dry and wet oxygen reveal how process conditions affect the interface properties.

scholarly journals Thickness-dependent in-plane anisotropy of GaTe phonons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nguyen The Hoang ◽  
Je-Ho Lee ◽  
Thi Hoa Vu ◽  
Sunglae Cho ◽  
Maeng-Je Seong
Keyword(s):  
Monoclinic Crystal ◽  
Monoclinic Crystal Structure ◽  
Gallium Telluride ◽  
Plane Anisotropy ◽  
Parallel Polarization ◽  
Potential Applications ◽  
Raman Modes ◽  
G 12 ◽  
Polarized Raman ◽  
Different Thickness

AbstractGallium Telluride (GaTe), a layered material with monoclinic crystal structure, has recently attracted a lot of attention due to its unique physical properties and potential applications for angle-resolved photonics and electronics, where optical anisotropies are important. Despite a few reports on the in-plane anisotropies of GaTe, a comprehensive understanding of them remained unsatisfactory to date. In this work, we investigated thickness-dependent in-plane anisotropies of the 13 Raman-active modes and one Raman-inactive mode of GaTe by using angle-resolved polarized Raman spectroscopy, under both parallel and perpendicular polarization configurations in the spectral range from 20 to 300 cm−1. Raman modes of GaTe revealed distinctly different thickness-dependent anisotropies in parallel polarization configuration while nearly unchanged for the perpendicular configuration. Especially, three Ag modes at 40.2 ($${\text{A}}_{\text{g}}^{1}$$ A g 1 ), 152.5 ($${\text{A}}_{\text{g}}^{7}$$ A g 7 ), and 283.8 ($${\text{A}}_{\text{g}}^{12}$$ A g 12 ) cm−1 exhibited an evident variation in anisotropic behavior as decreasing thickness down to 9 nm. The observed anisotropies were thoroughly explained by adopting the calculated interference effect and the semiclassical complex Raman tensor analysis.

Results on obtaining structural and analytical information with high lateral resolution in a STEM

1978 ◽  
Vol 36 (1) ◽  
pp. 22-23
Author(s):  
G. Hubert ◽  
B. Krisch ◽  
D. Willasch
Keyword(s):  
Transfer Function ◽  
Phase Contrast ◽  
High Performance ◽  
Chromatic Aberration ◽  
High Lateral Resolution ◽  
Detection Plane ◽  
Potential Applications ◽  
Lattice Images ◽  
Resolution Imaging ◽  
Imaging Conditions

A unique feature of high-performance STEMs is their ability to combine high-resolution imaging with the possibility to perform structural and chemical analysis in areas considerably smaller than 10 nm. The STEM ELMISKOP® ST 100 F has been used to demonstrate some of the potential applications in various modes of operation.Lattice imaging and defect analysis: It is well known that the unit cell charge distribution of certain crystals can be imaged in phase contrast TEM for structure determination and the investigation of lattice defects on an atomic level. In STEM one can obtain similar lattice images in phase contrast using a small-angle detector which samples the interference pattern in the detection plane between the undiffracted and at least one Bragg-diffracted wave (indicated in Fig.la by their wave vectors). Two ways of arranging the detector are possible: For axial (Fig.1a) or symmetrical imaging conditions (Fig.lb). Axial imaging includes instrument-induced chromatic aberration and yields an isotropic transfer function, symmetrical imaging excludes chromatic aberration but leads to an anisotropic transfer function not suitable for most applications.

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