We propose a paradigm for the realization of nonreciprocal photonic devices based on time-modulated graphene capacitors coupled to photonic waveguides, without relying on magneto-optic effects. The resulting hybrid gr...
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We propose a paradigm for the realization of nonreciprocal photonic devices based on time-modulated graphene capacitors coupled to photonic waveguides, without relying on magneto-optic effects. The resulting hybrid graphene-dielectric platform is low loss, silicon compatible, robust against graphene imperfections, scalable from terahertz to near-infrared frequencies, and it exhibits large nonreciprocal responses using realistic biasing schemes. We introduce an analytical framework based on solving the eigenstates of the modulated structure and on spatial coupled mode theory, unveiling the physical mechanisms that enable nonreciprocity and enabling a quick analysis and design of optimal isolator geometries based on synthetic linear and angular momentum bias. Our results, validated through harmonic-balance full-wave simulations, confirm the feasibility of the introduced low-loss (<3 dB) platform to realize large photonic isolation through various mechanisms, such as narrow-band asymmetric band gaps and interband photonic transitions that allow multiple isolation frequencies and large bandwidths. We envision that this technology may pave the wave to magnetic-free, fully integrated, and CMOS–compatible nonreciprocal components with wide applications in photonic networks and thermal management.
作者:
Bobb, KamauProgram Officer
National Science Foundation Directorate of Computer and Information Science and Engineering 4201 Wilson Boulevard ArlingtonVA22230 United States
For many important network types (e.g., sensor networks in complex harsh environments and social networks) physical coordinate systems (e.g., Cartesian), and physical distances (e.g., Euclidean), are either difficult ...
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Having both avian-like receptors (?±2,3-linked sialic acid, SA2,3Gal) and human-like receptors (?±2,6-linked sialic acid, SA2,6Gal), swine are proposed as??úmixing vessel??ùfor generating influenza...
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Having both avian-like receptors (?±2,3-linked sialic acid, SA2,3Gal) and human-like receptors (?±2,6-linked sialic acid, SA2,6Gal), swine are proposed as??úmixing vessel??ùfor generating influenza pandemic strains. Laboratory experiments suggested all HA subtypes of influenza A virus (IAV) can infect swine. However, only sporadic cases of avian
We report the magnetic response of Pt/Au/GdFeCo trilayers to optical irradiation of the Pt surface. For trilayers with Au thickness greater than 50 nm, the great majority of energy is absorbed by the Pt layer, creatin...
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We report the magnetic response of Pt/Au/GdFeCo trilayers to optical irradiation of the Pt surface. For trilayers with Au thickness greater than 50 nm, the great majority of energy is absorbed by the Pt layer, creating an initial temperature differential of thousands of kelvin between the Pt/Au layers and the GdFeCo layer. The resulting electronic heat current across the metal multilayer lasts for several picoseconds with energy flux in excess of 2TWm−2 and provides sufficient heating to the GdFeCo electrons to induce deterministic reversal of the magnetic moment.
The human visual system employs a mechanism of visual attention, which selects only part of the incoming information for further processing. Through this mechanism, the brain avoids overloading its limited cognitive c...
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We report the magnetic response of Co/Pt multilayers to picosecond electrical heating. Using photoconductive Auston switches, we generate electrical pulses with 5.5 ps duration and hundreds of pico-Joules to pass thro...
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We report the magnetic response of Co/Pt multilayers to picosecond electrical heating. Using photoconductive Auston switches, we generate electrical pulses with 5.5 ps duration and hundreds of pico-Joules to pass through Co/Pt multilayers. The electrical pulse heats the electrons in the Co/Pt multilayers and causes an ultrafast reduction in the magnetic moment. A comparison between optical and electrically induced demagnetization of the Co/Pt multilayers reveals significantly different dynamics for optical vs electrical heating. We attribute the disparate dynamics to the dependence of the electron-phonon interaction on the average energy and the total number of initially excited electrons.
Image retargeting has seen many applications in areas such as content adaptation for small displays and thumbnailing for image database browsing. Most retargeting methods, however, are too expensive computationally to...
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Chemical-genetic approaches offer the potential for unbiased functional annotation of chemical libraries. Mutations can alter the response of cells in the presence of a compound, revealing chemical-genetic interaction...
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Chemical-genetic approaches offer the potential for unbiased functional annotation of chemical libraries. Mutations can alter the response of cells in the presence of a compound, revealing chemical-genetic interactions that can elucidate a compound’s mode of action. We developed a highly parallel, unbiased yeast chemical-genetic screening system involving three key components. First, in a drug-sensitive genetic background, we constructed an optimized diagnostic mutant collection that is predictive for all major yeast biological processes. Second, we implemented a multiplexed (768-plex) barcode-sequencing protocol, enabling the assembly of thousands of chemical-genetic profiles. Finally, based on comparison of the chemical-genetic profiles with a compendium of genome-wide genetic interaction profiles, we predicted compound functionality. Applying this high-throughput approach, we screened seven different compound libraries and annotated their functional diversity. We further validated biological process predictions, prioritized a diverse set of compounds, and identified compounds that appear to have dual modes of action.
Dielectric film capacitors with high energy density represent some of the most pervasive devices used in electrical and electronic systems. With the rapid growing demands in electrification, new polymer film dielectri...
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ISBN:
(纸本)9781538611951
Dielectric film capacitors with high energy density represent some of the most pervasive devices used in electrical and electronic systems. With the rapid growing demands in electrification, new polymer film dielectrics with high dielectric constant and high breakdown strength are needed. A toluene diisocyanate (TDI) based organic polymer with a flexible diaminoether backbone (EDR148™) was synthesized and fabricated into ~10 μm films by a blade cast method. Systematic dielectric spectroscopy study was performed to characterize the complex dielectric spectra over a broad range of frequencies and temperatures to probe global, segmental, and local relaxations. Furthermore, high field characterizations were conducted by using a D-E polarization loop tester and a specially designed pre-breakdown conduction measurement system for the fundamental understanding of the relationship between molecular structure and high filed polarization and breakdown. TDI-EDR148 exhibited a high dielectric constant of > 6 with a low loss factor of ~1.5% and a high breakdown strength of >600 MV/m. These properties represent a high energy density of ~12 J/cc for this aromatic polyuria film. The result was compared with a previously studied high K polymer to correlate and reveal mechanism leading to the design of polymers with high dipolar energy density.
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