Large Effective Area Research Articles

Design of non-zero dispersion shifted fiber with large effective area based on variational method

The determination of design parameters of large effective area fiber with segmented-core profile is presented by using simple variational method to obtain the effective area, mode field diameter, and dispersion of the fiber. The designed fiber has a large effective area of 171.1 μm2 with mode field diameter, dispersion, and normalized cut off frequency of 9.7 μm, 2.85 ps/nm.km, 2.491, respectively. The results have shown that the fiber with a bending radius of 35 mm, has a very low bending loss of 0.0053 dB/km. The calculated of parameters values of designed non-zero dispersion-shifted fiber (NZDSF) have shown that with a segmented-core profile of radius 3.5 μm, with a ring width of 0.2 μm, the core effective area Aeff increases from 152.3 μm2 to 189 μm2, which in practical point of view, is an achievement to reduce the nonlinearity effects in the NZDSF as transmission medium.

Recent Progress in Non-Enzymatic Electroanalytical Detection of Pesticides Based on the Use of Functional Nanomaterials as Electrode Modifiers.

This review presents recent advances in the non-enzymatic electrochemical detection and quantification of pesticides, focusing on the use of nanomaterial-based electrode modifiers and their corresponding analytical response. The use of bare glassy carbon electrodes, carbon paste electrodes, screen-printed electrodes, and other electrodes in this research area is presented. The sensors were modified with single nanomaterials, a binary composite, or triple and multiple nanocomposites applied to the electrodes’ surfaces using various application techniques. Regardless of the type of electrode used and the class of pesticides analysed, carbon-based nanomaterials, metal, and metal oxide nanoparticles are investigated mainly for electrochemical analysis because they have a high surface-to-volume ratio and, thus, a large effective area, high conductivity, and (electro)-chemical stability. This work demonstrates the progress made in recent years in the non-enzymatic electrochemical analysis of pesticides. The need for simultaneous detection of multiple pesticides with high sensitivity, low limit of detection, high precision, and high accuracy remains a challenge in analytical chemistry.

Impact of Fiber Attenuation and Effective Area on Spectrum Efficiency of Elastic Optical Networks

The ultra-low-loss optical fibers becoming available now offer large effective areas with much better transmission performance than conventional standard single-mode fibers (SSMFs). However, how low the attenuation should be and how large the effective area has to be to benefit the transmission performance of a fiber-optic system have been open questions until now. In the context of an elastic optical network (EON), this paper evaluates for the first time the extent to which both fiber attenuation and effective area impact the network capacity. We first present an optical signal-to-noise ratio (OSNR) model to evaluate the performance of a lightpath considering various optical transmission impairments. We also propose different service-provisioning approaches based on this OSNR model. Simulation studies show that a spectrum-dependent provisioning scheme that considers different levels of cross-channel interference (XCI) requires minimum spectrum resources when provisioning incremental demands, and a margin-reservation scheme that considers different alternate routes shows the lowest bandwidth blocking probability (BBP) when provisioning dynamic lightpath demands. We also estimate optimal launch powers needed by lightpaths for different fiber attenuations and effective areas. Under different launch powers, it is found that lowering fiber attenuation and increasing fiber effective area demonstrate saturation in performance improvement, i.e., initially decreasing fiber attenuation and increasing effective area can significantly improve the network service provisioning performance, but the improvement is much less when the fiber attenuation and effective area are lower than 0.165 dB/km and greater than 110 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively. This implies that it is not necessary to fabricate a fiber with extremely low attenuation and large effective area for the best cost-to-performance ratio.

Ultra-low loss polymer-based photonic crystal fiber supporting 242 OAM modes with high bending tolerance for multimode THz communication

A novel polymer-based ring-core circular photonic crystal fiber (C-PCF) is proposed and investigated. The solid core C-PCF structure is composed of Topas as background material, a high refractive index (RI) Kapton polymer as a ring material and four layers of air hole patterns. Numerical simulation is used to optimize the PCF geometry to support maximum stable modes with minimum losses. The proposed C-PCF supports 242 stable OAM modes near 1.9 THz with mode purity >0.9. The fiber exhibit low confinement loss (CL) ∼10-9 dB/cm, large effective mode area ∼ 10-2 mm2, low dispersion <1 ps/THz/cm and high effective mode index difference (Δneff) >10-3 in the range 1.5 THz to 3.5 THz. Attenuation, mode stability, material dispersion and fiber bending tolerance of PCF are analyzed to increase the transmission capacity. The detailed experimental feasibility and design sensitivity are theoretically addressed. The proposed PCF supports stable modes and works at a wider spectrum then the previously reported studies. The fiber has the potential to be employed for next-generation THz multimode communication systems.

Plasma-assisted three-dimensional lightscribe graphene as high-performance supercapacitors

Graphene-based supercapacitors demonstrate extraordinary energy storage capacity due to their layered structure, large effective surface area, high electrical conductivity and acceptable chemical stability. Herein, reduced graphene oxide (rGO)-based supercapacitors were introduced in a simple, and fast method with considerable performance. For this purpose, graphene oxide (GO) was synthesized by the modified Hummers’ method and then easily reduced to desired patterns of rGO using a commercial LightScribe DVD drive. In order to increase the effective surface area, as well as the electrical conductivity of rGO layers, oxygen/sulfur hexafluoride plasma was applied to the rGO followed by laser irradiation. By performing such sequential processes, an rGO-based supercapacitor was introduced with a capacitance of about 10.2 F/cm3, which had high stability for more than 1000 consecutive charge–discharge cycles. The fabrication steps of the electrodes were investigated by different analyses such as SEM, TEM, Raman, surface resistance, BET, and XPS measurements. Results showed that these rGO-based electrodes fabricated by sequential processes are very interesting for practical applications of energy storage.

Are Brazilian catchments gaining or losing water? The effective area of tropical catchments

AbstractSimilar to most countries, the Brazilian water resources management considers topographically delineated catchment as a territorial unit for policy implementation. Yet, previous studies have shown that catchments are not hydrologically isolated, and topographic limits often neglect the groundwater boundaries. Thus, studies on effective catchment areas are promising for shedding light on inter‐catchment groundwater flow. Here, we investigated the deviation between the topographic and effective areas across Brazil. We applied the effective catchment area index (ECI) to 733 Brazilian catchments and identified the most influencing attributes on the ECI by using principal component and random forest analyses (PCA and RFA, respectively). Further analysis was carried out by contrasting the ECI values against the expected range of the Budyko curve, considering both topographic and effective catchment areas (classic and adjusted framework, respectively). We noted that nearly 32% of the Brazilian catchments presented more than 30% of difference between the effective area and its topographic boundaries. In general, the more arid biomes in Brazil—the Cerrado and Caatinga—are prone to have smaller effective areas while larger effective areas were mostly found in the Atlantic Forest biome, a humid tropical region with a higher mean elevation. Our findings indicate that the aridity index was the main driving factor and negatively correlated with ECI followed by mean slope, precipitation seasonality, and mean elevation. We highlight the potential of adopting a pooling of catchments based on their interconnectivity to minimize management costs while maximizing synergies and lessening trade‐offs between ecosystem functioning and water transfer processes. Our results contribute to a better country‐wide understanding of hydrological connectivity among catchments and highlight the need to consider the effective catchment area to overcome water‐food‐energy security challenges on multiple scales.

AstroSat detection of a quasi-periodic oscillation at ∼42 Hz in Cygnus X-2

ABSTRACT We report the results of AstroSat observations of Cygnus X-2 during 2016 February. The source’s power density spectrum generated using Large Area X-ray Proportional Counter (LAXPC) data revealed the presence of a prominent quasi-periodic oscillation (QPO) at ∼42 Hz with broad-band continuum noise at lower frequencies at ∼10 Hz. The large effective area of LAXPC at ≳30 keV allowed for an unprecedented study of the energy dependence of the QPO and the broad noise continuum. The fractional rms increases with energy, and its shape is similar for both the QPO and the continuum noise, suggesting a common radiative origin. However, while the QPO exhibits hard time-lags, with the high-energy photons lagging the low ones by a few milliseconds, the continuum noise shows the opposite behaviour. The photon spectrum from Soft X-ray Imaging Telescope and LAXPC in 0.7–30 keV band comprises the soft component from a disc and a hard Comptonized component from a hot corona. While the energy dependence of the rms shows that the QPO and the continuum noise variability are dominated by the Comptonized component, the change in sign of the time-lag suggests that the dynamic origin of the QPO may be in the disc while the noise continuum may originate from the corona.

A design of dual guided modes ring-based photonic crystal fiber supporting 170 + 62 OAM modes with large effective mode field area

A design of dual guided modes ring-based photonic crystal fiber supporting 170 + 62 OAM modes with large effective mode field area

Co-assembly of soluble metal–organic polyhedrons for high-flux thin-film nanocomposite membranes

Well-developed pore channels and large effective permeation area are sorely needed in developing highly permeable synthetic membranes for the reduction of energy consumption in separation processes. Herein, water stable, soluble and reactive amino-functionalized metal–organic polyhedron (MOP) ZrT-1-NH2 with intrinsic porosity is co-assembled with lysine (Lys) into a new kind of thin-film nanocomposite (TFN) membranes through in situ interfacial polymerization (IP) with trimesoyl chloride (TMC). Striped structure on the membrane surface is induced by the participation of the amino-MOP in polymerization, which greatly enhances the effective permeation area of the separation layer compared with the membranes feature smooth surface. Meanwhile, the suitable pore aperture of the introduced ZrT-1-NH2 can also benefit the diffusion of water molecules and block the transport of molecules with bulkier molecular volumes. The results showed that the formed membrane exhibits significantly improved water permeance (27.3 L m−2 h−1 bar−1, 480% increase) compared with that of the pristine Lys/TMC membrane (4.7 L m−2 h−1 bar−1). The compositing of ZrT-1-NH2 also leads to an increase in the rejection selectivity of dye and salt, rejection selectivity of dye/salt mixture, as well as in antifouling and antibacterial properties, making the ZrT-1-NH2-Lys/TMC composite membrane a potential choice for dye/salt separation. Moreover, this work demonstrates the bright prospects of applying soluble and reactive porous cages in the development of high-loading defect-less TFN membranes for efficient molecular separations.

Chapter 5 Dark Matter and New Physics Beyond the Standard Model with LHAASO

In order to reveal the nature of dark matter, it is crucial to detect its non-gravitational interactions with the standard model particles. The traditional dark matter searches focused on the so-called weakly interacting massive particles. However, this paradigm is strongly constrained by the null results of current experiments with high precision. Therefore there is a renewed interest of searches for heavy dark matter particles above TeV scale. The Large High Altitude Air Shower Observatory (LHAASO) with large effective area and strong background rejection power is very suitable to investigate the gamma-ray signals induced by dark matter annihilation or decay above TeV scale. In this document, we review the theoretical motivations and background of heavy dark matter. We review the prospects of searching for the gamma-ray signals resulted from dark matter in the dwarf spheroidal satellites and Galactic halo for LHAASO, and present the projected sensitivities. We also review the prospects of searching for the axion-like particles, which are a kind of well motivated light pseudo-scalars, through the LHAASO measurement of the very high energy gamma-ray spectra of astrophysical sources.

100-m/3-Gbps underwater wireless optical transmission using a wideband photomultiplier tube (PMT).

In this paper, a wideband photomultiplier tube (PMT)-based underwater wireless optical communication (UWOC) system is proposed and a comprehensive experimental study of the proposed PMT-based UWOC system is conducted, in which the transmission distance, data rate, and attenuation length (AL) is pushed to 100.6 meters, 3 Gbps, and 6.62, respectively. The receiver sensitivity at 100.6-meter underwater transmission is as low as -40 dBm for the 1.5-Gbps on-off keying (OOK) modulation signal. To the best of our knowledge, this is the first Gbps-class UWOC experimental demonstration in >100-meter transmission that has ever been reported. To further minimize the complexity of channel equalization, a sparsity-aware equalizer with orthogonal matching pursuit is adopted to reduce the number of the filter coefficients by more than 50% while keeping slight performance penalty. Furthermore, the performance of the proposed PMT-based UWOC system in different turbidity waters is investigated, which shows the robustness of the proposed scheme. Thanks to the great sensitivity (approaching the quantum limit) and a relatively larger effective area, benefits of misalignment tolerance contributed by the PMT is verified through a proof-of-concept UWOC experiment.

Understanding the Extraordinary Flexibility of Polydimethylsiloxane through Single-Molecule Mechanics

Linear (un-cross-linked) polydimethylsiloxane (PDMS) exists as a viscous fluid at room temperature even though its molecular weight reaches a high level (105 Da). Accordingly, one can infer the extraordinary flexibility of PDMS. However, the mechanism of the extraordinary flexibility is still unclear at present. Herein the single-chain mechanics of PDMS is measured by single-molecule atomic force microscopy, which is consistent with the results from quantum mechanical calculations. Then, the effects of several factors of microscopic structures of PDMS on the macroscopic mechanical properties are qualitatively analyzed. With the extremely low elasticity of the individual chain, the large effective cross-sectional area, and the very weak intra/interchain noncovalent interactions and their synergistic effect, the relatively small modulus of PDMS is reasonable. We further propose a method to estimate the modulus of an extended chain crystal of a polymer from the single-chain force–extension curve. For the polymer crystals in which only van der Waals forces are involved in the intra/interchain noncovalent interactions, the estimated moduli are very close to the measured values, which indicates that this method should be valid for PDMS. It is found that the estimated modulus of PDMS is smaller than those of most polymers, which directly shows its extraordinary flexibility at the macroscopic level. This work may be helpful for bridging the gap between the single-molecule and macroscopic properties of polymer materials.

A kind of single trench 19-core single-mode heterogeneous fiber with low crosstalk and anti-bending performance

The rapid growth of the demand for optical communication capacity promotes optical fiber communication technology. As a method to break through the capacity limitation of conventional single-mode fiber, multi-core fiber based on space division multiplexing technology has attracted extensive attention. In order to respond to the capacity of traditional single-mode fiber positively, we design a scheme of single-mode multi-core fiber combining the arrangement of heterogeneous fiber cores with secondary structure of low refractive index trench. The scheme consists of nineteen fiber cores arranged in a hexagonal closed-packed structure. Heterogeneous trench-assisted multi-core fiber (Hetero-TA-MCF) has low inter-core crosstalk and excellent anti-bending performance. Compared with conventional single-mode fiber, the Hetero-TA-MCF has the large transmission capacity and average effective area of each core of about 80 μm&lt;sup&gt;2&lt;/sup&gt;. The transmission capacity of 19 cores is equivalent to the sum of the transmission capacities of 19 single-core single-mode fibers. We use COMSOL Multiphysics to simulate the fiber structure, finding the parameters that affect the properties of the fiber, selecting parameters and structures for optimal performance. Then we calculate the transmission characteristics by the finite element method,and the results of substantive simulating compute are as follows. The Hetero-TA-MCF achieves a low inter-core crosstalk (XT) of about –39 dB/100 km so that each core can be transmitted as a separate channe. It meets the standard of multi-core fiber long distance transmission. The XT of the heterogeneous 19-core single-mode fiber is suitable for multi-core fiber long distance transmission standards. The bending loss of the outermost fiber core is –7.7×10&lt;sup&gt;–5&lt;/sup&gt; dB/m when the bending radius is 10 cm, which reflects the low loss characteristics of the structure. The nonlinear coefficients of three kinds of core are 1.28 W&lt;sup&gt;–1&lt;/sup&gt;·km&lt;sup&gt;–1&lt;/sup&gt;, 1.31 W&lt;sup&gt;–1&lt;/sup&gt;·km&lt;sup&gt;–1&lt;/sup&gt;, and 1.30 W&lt;sup&gt;–1&lt;/sup&gt;·km&lt;sup&gt;–1&lt;/sup&gt; respectively, reducing the nonlinear effect of optical fiber effectively; the dispersions of three kinds of cores are less than 24 ps/(nm·km). In addition, the steady single-mode transmission is achieved in &lt;i&gt;C&lt;/i&gt;+&lt;i&gt;L&lt;/i&gt; band. Compared with traditional single-mode fiber and single-trench homogeneous fiber, the proposed fiber in this work has low crosstalk, good bending resistance and large mode field area, which is suitable for long distance and large capacity transmission in space division multiplexing system.

30-Day and 1-Year Outcomes With HYDRA Self-Expanding TranscatheterAortic Valve: The Hydra CE Study.

This study sought to evaluate the 30-day and 1-year safety and performance of the Hydra transcatheter aortic valve (THV) (in the treatment of symptomatic severe aortic stenosis in patients at high or extreme surgical risk. The Hydra THV is a novel repositionable self-expanding system with supra-annular bovine pericardial leaflets. The Hydra CE study was a premarket, prospective, multicenter, single-arm study conducted across 18 study centers in Europe and Asia-Pacific countries. The primary endpoint was all-cause mortality at 30days. All endpoints were adjudicated by an independent clinical events committee. A total of 157 patients (79.2 ± 7.1 years of age, 58.6% female; Society of Thoracic Surgeons score 4.7 ± 3.4%) were enrolled. Successful implantation was achieved in 94.3% cases. At 30days, there were 11 (7.0%) deaths, including 9 (5.7%) cardiovascular deaths, of which 5 (3.2%) were device related. At 1 year, there were 23 (14.6%) deaths, including 13 (8.3%) cardiovascular deaths. At 30days, there were significant improvement of effective orifice area (from 0.7 ± 0.2cm2 to 1.9 ± 0.6cm2) and mean aortic valve gradient (from 49.5 ± 18.5mmHg to 8.1 ± 3.7mmHg), which were sustained up to 1 year. Moderate or severe paravalvular leak was observed in 6.3% of patients at 30days and 6.9% of patients at 1 year. The rate of new permanent pacemaker implantation was 11.7% at 30days and 12.4% at 1 year. The Hydra CE study demonstrated that transcatheter aortic valve replacement with Hydra THV offered favorable efficacy at 1 year, providing large effective orifice area and low transvalvular gradient as well as acceptable complication rates with regard to new permanent pacemaker and paravalvular leak. (A Clinical Evaluation of the HYDRA Self Expanding Transcatheter Aortic Valve; NCT02434263).

Design and Fabrication of Novel Large Effective Area Non-Zero Dispersion-Shifted Optical Fiber Based on Outside Vapor Deposition

Design and Fabrication of Novel Large Effective Area Non-Zero Dispersion-Shifted Optical Fiber Based on Outside Vapor Deposition

Multi-Wavelength Continuous-Wave Convertor Driven by Forward Brillouin Scattering in Large Effective Area Fiber

Multi-Wavelength Continuous-Wave Convertor Driven by Forward Brillouin Scattering in Large Effective Area Fiber

Multicore raised cosine fibers for next generation space division multiplexing systems

Space division multiplexing (SDM) is a promising solution for improving the transmission capacity and increasing the spectral efficiency. SDM over few mode multicore fibers (FM-MCFs) is an attractive approach that observes increasing interest. In this work, after reviewing the basic guidelines for FM-MCFs design, we address, for the first time, the Raised Cosine (RC) profile to multicore fibers context. We optimize the single core RC profile in order to support exactly 6 linearly polarized (LP) modes with large effective mode area (min Aeff = 96 μm2), with low differential mode delay (DMD) (max DMD = 33 ps⧹km) and high intermodal separation (⩾2×10−4). Once achieved, we investigate the induced crosstalk between twin RC cores and twin trenched RC (TRC) cores. We then propose four 6 modes 7 cores RC⧹TRC fibers. Their crosstalk and their relative core multiplicity are analysed and compared with those reported in recently graded index-FM-MCFs. The selected designs could be promising candidates for short and medium haul interconnects.

Low‐temperature synthesis of ZnO/ZnS/CuS heterojunction based on solution‐processed nanosheet array with enhanced photocatalytic activity

AbstractZnO/ZnS/CuS net‐like nanosheet (NS) heterojunction array was fabricated via a simple solution method at a low temperature. Morphology and structure of ZnO/ZnS/CuS NS were characterized by scanning electron microscope (SEM) and Transmission electron microscope (TEM). With tiny particles attaching on the rough surface, the thin ZnO/ZnS/CuS NS grew vertically and arranged regularly on Al substrate, providing large effective illumination area and massive active sites. Elemental composition and valence state were confirmed with energy dispersive X‐ray spectrometry and X‐ray photoelectron spectroscopy (XPS), respectively. The UV–vis absorbance spectra indicated that the absorption range of ZnO NS was expanded to the visible region effectively, and the original absorption intensity in the ultraviolet region was also improved after being coated with ZnS and CuS. Photocatalytic activity tests of ZnO, ZnO/ZnS, and ZnO/ZnS/CuS NS were carried out with methyl orange as a simulated pollutant, in which ZnO/ZnS/CuS heterojunction showed great enhancement when making comparison with pure ZnO and ZnO/ZnS NS. After five reuse cycles, photocatalytic performance could still be maintained well, indicating the good catalytic stability. Finally, a probable photocatalytic mechanism was also discussed.

Prospects for the Detection of the Prompt Very-high-energy Emission from γ-ray Bursts with the High Altitude Detection of Astronomical Radiation Experiment

Abstract The observation of very-high-energy (VHE; &gt; 10 GeV) γ-ray emission from γ-ray bursts (GRBs), especially in the prompt phase, will provide critical information for understanding many aspects of their nature including the physical environment, the relativistic bulk motion, the mechanisms of particle acceleration of GRBs, and for studying Lorentz invariance violation, etc. For the afterglow phase, the highest-energy photons detected to date by the imaging atmospheric Cherenkov telescopes extend to the TeV regime. However, for the prompt phase, years of efforts in searching for the VHE emission has yielded no statistically significant detections. A wide field of view and large effective area above tens of GeV are essential for detecting the VHE emissions from GRBs in the prompt phase. The High Altitude Detection of Astronomical Radiation (HADAR) experiment has such merits. In this paper, we report the estimates of its expected annual GRB detection rate, which are obtained by combining the performance of the HADAR instrument with the theoretical calculations based on a phenomenological model to generate the pseudo-GRB population. The expected detectable gamma-ray signal from GRBs above the background is then obtained to give the detection rate. In the spectral model, an extra component is assigned to every GRB event in addition to the Band function. The results indicate that if the energy of the cutoff due to internal absorption is higher than 50 GeV, the detection rate for GRBs for the HADAR experiment is approximately two or three GRBs per year, which varies slightly depending upon the characteristics of the extra component.

Side-Illuminated Photoconductive Semiconductor Switch Based on High Purity Semi-Insulating 4H-SiC

High purity semi-insulating (HPSI) 4H-silicon carbide (SiC) was used to fabricate lateral and vertical photoconductive semiconductor switches (PCSSs). The lateral PCSSs were illuminated from the frontside (fPCSS) or the backside (bPCSS). The side-illuminated vertical PCSS (vPCSS) was designed to increase the light-matter interaction volume. A 532-nm pulsed laser with adjustable energy was utilized to excite the PCSSs. The turn-on time was found to be highly dependent on the optical illumination energy, and the full-width at half-maximum of the PCSSs output waveforms was related to the peak output voltage. The output electrical pulse from the vPCSS exhibited a shorter turn-on time and a larger pulsewidth than the two types of lateral PCSSs. The vPCSS outperformed the fPCSS and bPCSS in terms of minimum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{\scriptscriptstyle ON}$ </tex-math></inline-formula> -state resistance and output pulse amplitude under the same optical illumination energy. The vPCSS, which utilizes a large effective contact area to collect photogenerated carriers, also had higher photon absorption efficiency by arranging the optical path at a right angle to the carrier transport. The vPCSS exhibited a minimum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{\scriptscriptstyle ON}$ </tex-math></inline-formula> -state resistance of 0.34 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> at optical illumination energy of 8 mJ.