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arXiv 2017年

作者： Vidal-Codina, F. Nguyen, N.C. Perairea, J. Dept. of Aeronautics and Astronautics Massachusetts Institute of Technology CambridgeMA02139 United States

The interaction of electromagnetic waves with metallic nanostructures generates resonant oscillations of the conduction-band electrons at the metal surface. These resonances can lead to large enhancements of the incident feld and to the confnement of light to small regions, typically several orders of magnitude smaller than the incident wavelength. The accurate prediction of these resonances entails several challenges. Small geometric variations in the plasmonic structure may lead to large variations in the electromagnetic feld responses. Furthermore, the material parameters that characterize the optical behavior of metals at the nanoscale need to be determined experimentally and are consequently subject to measurement errors. It then becomes essential that any predictive tool for the simulation and design of plasmonic structures accounts for fabrication tolerances and measurement uncertainties. In this paper, we develop a reduced order modeling framework that is capable of real-time accurate electromagnetic responses of plasmonic nanogap structures for a wide range of geometry and material parameters. The main ingredients of the proposed method are: (i) the hybridizable discontinuous Galerkin method to numerically solve the equations governing electromagnetic wave propagation in dielectric and metallic media, (ii) a reference domain formulation of the time-harmonic Maxwell's equations to account for arbitrary geometry variations;and (iii) proper orthogonal decomposition and empirical interpolation techniques to construct an efcient reduced model. To demonstrate efectiveness of the models developed, we analyze geometry sensitivities and explore optimal designs of a 3D periodic coaxial nanogap structure. Copyright © 2017, The Authors. All rights reserved.

关键词： Galerkin methods

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Optimal Shell Thickness of Metal@Insulator Nanoparticles for Net Enhancement of Photogenerated Polarons in P3HT Films

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ACS APPLIED MATERIALS & INTERFACES 2016年第4期8卷 2464-2469页

作者： Goh, Wei-Peng Williams, Evan L. Yang, Ren-Bin Koh, Wee-Shing Mhaisalkar, Subodh Ooi, Zi-En ASTAR Inst Mat Res & Engn 2 Fusionopolis WayInnovis 08-03 Singapore 138634 Singapore ASTAR Inst High Performance Comp 1 Fusionopolis Way16-16 Connexis North Singapore 138632 Singapore Nanyang Technol Univ Sch Mat Sci & Engn Mat Technol Div Block N4-1 Nanyang Ave Singapore 639798 Singapore

Embedding metal nanoparticles in the active layer of organic solar cells has been explored as a route for improving charge carrier generation, with localized field enhancement as a proposed mechanism. However, embedded metal nanoparticles can also act as charge recombination sites. To suppress such recombination, the metal nanoparticles are commonly coated with a thin insulating shell. At the same time, this insulating shell limits the extent that the localized enhanced electric field influences charge generation in the organic medium. It is presumed that there is an optimal thickness which maximizes field enhancement effects while suppressing recombination. Atomic Layer Deposition (ALD) was used to deposit Al2O3 layers of different thicknesses onto silver nanoparticles (Ag NPs), in a thin film of P3HT. Photoinduced absorption (PIA) spectroscopy was used to study the dependence of the photogenerated P3HT(+) polaron population on the Al2O3 thickness. The optimal thickness was found to be 35 nm. This knowledge can be further applied in the design of metal nanoparticle-enhanced solar cells.

关键词： metallic nanoparticles insulating oxide polaron generation localized surface plasmons localized field enhancements plasmon enhanced organic photovoltaic cell optical scattering photoinduced absorption spectroscopy

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Assessment of future backhaul and fronthaul networks for HetNet architectures

Assessment of future backhaul and fronthaul networks for Het...

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International Conference on Transparent optical Networks

作者： Dirk Breuer Erik Weis Sandro Krauß Jakob Belschner Frank Geilhardt Deutsche Telekom AG Laboratories Berlin Germany Deutsche Telekom AG Laboratories 10781 Berlin Germany

Mobile traffic is heavily increasing in the last years and a massive continuous growth is forecasted for the next decade. To cope with this significant traffic increase in mobile networks and the further evolving competitive market situation, operators are looking for solutions to increase the capacity of their mobile networks, while keeping the cost low. Besides enhancements of mobile radio technology and adding new spectrum to the existing sites, densification of radio sites, by so called small cells, is considered as a very promising option to increase capacity. Adding small cells to the already existing macro cell layer lead to heterogeneous networks (HetNet). Because of the scarce radio spectrum it is most likely that the radio sites in HetNets will use the same frequencies and therefore create interferences. To mitigate this impact different coordination methods have been proposed creating new challenging requirements on the transport network compared to today's backhaul. Cost effective and scalable transport solutions are an important fundament for wide and successful deployment of HetNets. This paper investigates and assesses techno-economically different architectures for backhaul and fronthaul transport of existing and newly deployed radio sites in HetNet architectures taking requirements from interference co-ordination into account.

关键词： Mobile communication Mobile computing Convergence optical fiber networks optical fiber cables optical fiber devices Computer architecture

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Simulating Surface-Enhanced Raman optical Activity Using Atomistic Electrodynamics-Quantum Mechanical Models

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JOURNAL OF PHYSICAL CHEMISTRY A 2014年第39期118卷 9069-9079页

作者： Chulhai, Dhabih V. Jensen, Lasse Penn State Univ Dept Chem University Pk PA 16802 USA

Raman optical activity has proven to be a powerful tool for probing the geometry of small organic and biomolecules. It has therefore been expected that the same mechanisms responsible for surface-enhanced Raman scattering may allow for similar enhancements in surface-enhanced Raman optical activity (SEROA). However, SEROA has proved to be an experimental challenge and mirror-image SEROA spectra of enantiomers have so far not been measured. There exists a handful of theories to simulate SEROA, all of which treat the perturbed molecule as a point-dipole object. To go beyond these approximations, we present two new methods to simulate SEROA: the first is a dressed-tensors model that treats the molecule as a point-dipole and point-quadrupole object;the second method is the discrete interaction model/quantum mechanical (DIM/QM) model, which considers the entire charge density of the molecule. We show that although the first method is acceptable for small molecules, it fails for a medium-sized one such as 2-bromohexahelicene. We also show that the SEROA mode intensities and signs are highly sensitive to the nature of the local electric field and gradient, the orientation of the molecule, and the surface plasmon frequency width. Our findings give some insight into why experimental SEROA, and in particular observing mirror-image SEROA for enantiomers, has been difficult.

关键词： QUANTUM electrodynamics SURFACE enhanced Raman effect optical rotation QUANTUM mechanics BIOMOLECULES SURFACE plasmons

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A Practical Low-Power Nonregular Interconnect Design With Manufacturing for Design Approach

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IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS 2012年第2期2卷 322-332页

作者： Zhang, Hongbo Wong, Martin D. F. KevinChao, Kai-Yuan Deng, Liang Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA Intel Corp Intel Architecture Grp Hillsboro OR 97124 USA Broadcom Corp Santa Clara CA 95054 USA

Wire shaping for delay/power minimization has been extensively studied. Due to the perceived high design and manufacturing costs for using nonregular wire shapes, wire shaping is generally considered to be impractical. In this paper, we present a practical wire shaping method to reduce power consumption of interconnect. Nonregular wire shapes are directly implemented on silicon wafer instead of in GDSII during design. We present novel enhancements to existing optical proximity correction (OPC) technology to accurately print nonregular wire shapes. Experimental results show that the post-OPC mask complexities of uniform wire and nonregular wire are comparable. With minimal impact on the design and manufacturing flows and minimal additional design and manufacturing costs, we demonstrate that wire shaping can help to obtain substantial reduction of interconnect dynamic power without affecting timing closure. Our wire shaping methodology is an excellent example of Manufacturing for Design.

关键词： Interconnect manufacturing for design optical proximity correction (OPC) power minimization wire tapering

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The load balancing problem in extended OTIS-n-cube interconnection networks

The load balancing problem in extended OTIS-n-cube interconn...

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11th IEEE International Conference on Trust, Security and Privacy in computing and Communications, TrustCom-2012

作者： Al-Sadi, Jehad Information Technology and Computing Department Arab Open University Amman Jordan

ISBN: (纸本)9780769547459

The new era of the OTIS (optical Transpose Interconnection System) optoelectronic interconnection network architecture is a promising and an interesting alternative for future-generation parallel processing systems. Many enhancements were presented on OTIS topologies included the Extended OTIS-n-Cube interconnection networks. Therefore, all performance improvement characteristics of such a promising architecture need to be investigated;one of which is load balancing technique. This paper focuses on devising an efficient algorithm for load balancing on the promising Extended OTIS-n-Cube interconnection networks. The proposed algorithm is called Factor-optical-Factor Exchange Model (FOFEM). The proposed algorithm in terms of various parameters, including execution time, load balancing accuracy, number of communication steps, and speed is introduced on OTIS-n-Cube interconnection networks is efficient since it can reach the load balancing final state in 2n+1 communication steps. © 2012 IEEE.

关键词： Network architecture

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The Load Balancing Problem in Extended OTIS-n-Cube Interconnection Networks

The Load Balancing Problem in Extended OTIS-n-Cube Interconn...

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IEEE International Conference on Trust, Security and Privacy in computing and Communications (TrustCom)

作者： Jehad Al-Sadi Information Technology and Computing Department Arab Open University Amman Jordan

ISBN: (纸本)9781467321723

The new era of the OTIS (optical Transpose Interconnection System) optoelectronic interconnection network architecture is a promising and an interesting alternative for future-generation parallel processing systems. Many enhancements were presented on OTIS topologies included the Extended OTIS-n-Cube interconnection networks. Therefore, all performance improvement characteristics of such a promising architecture need to be investigated; one of which is load balancing technique. This paper focuses on devising an efficient algorithm for load balancing on the promising Extended OTIS-n-Cube interconnection networks. The proposed algorithm is called Factor-optical-Factor Exchange Model (FOFEM). The proposed algorithm in terms of various parameters, including execution time, load balancing accuracy, number of communication steps, and speed is introduced on OTIS-n-Cube interconnection networks is efficient since it can reach the load balancing final state in 2n+1 communication steps.

关键词： Load management Program processors optical fiber communication Algorithm design and analysis Hypercubes Approximation algorithms

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Theoretical aspects on the evaluation and interpretation of the third-order nonlinear optical properties of diradical compounds

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AIP Conference Proceedings 2012年第1期1504卷 844-847页

作者： Benoı̂t Champagne Edith Botek Akihiro Shimizu Takashi Kubo Kenji Kamada Koji Ohta Ryohei Kishi Hitoshi Fukui Hideaki Takahashi Masayoshi Nakano Laboratoire de Chimie Théorique Appliquée Facultés Universitaires Notre-Dame de la Paix (FUNDP) rue de Bruxelles 61 5000 Namur Belgium Department of Chemistry Graduate School of Science Osaka University Toyonaka Osaka 560-0043 Japan Photonics Research Institute National Institute of Advanced Industrial Science and Technology (AIST) Ikeda Osaka 563-8577 Japan Department of Materials Engineering Science Graduate School of Engineering Science Osaka University Toyonaka Osaka 560-8531 Japan

Over the last decades, scientists have designed molecules and materials with unique nonlinear optical (NLO) properties targeting the realization of all-optical computing and signal processing. For many reasons (large response, short response time) organic compounds are of considerable interest. However, suitable materials for practical applications are still missing because the third-order NLO responses and the related molecular second hyperpolarizability (γ) are still too small. Increasing the conjugation length was a first strategy to optimize the third-order nonlinear optical responses while in subsequent approaches appropriate substituents with specific donor and acceptor strengths were selected. More recent strategies consist of varying the shape and dimensionality of the π-electron chromophore and of charging it, for instance by chemical doping. Although these systems are closed-shell molecules, recent studies have demonstrated that open-shell species show potential as materials with high NLO efficiency and in particular, singlet diradical systems with intermediate diradical character (y). For instance, ab initio molecular orbital and density functional theory calculations performed on the p-quinodimethane model showed that γ attains a maximum in the intermediate diradical character region and subsequently that i) π-conjugated diradical systems involving imidazole rings and ii) compounds of the family of thermally stable diphenalenyl diradical systems synthesized display significant enhancements of γ with respect to their analogous closed-shell systems. Then, the dependence of γ value on the spin states makes these compounds attractive for designing multifunctional materials. In this presentation, theoretical aspects on the evaluation and interpretation of the second hyperpolarizabilities of diradical species are discussed.

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High density active optical cable - from a new concept to a prototype

High density active optical cable - from a new concept to a ...

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Conference on Optoelectronic Interconnects and Component Integration XI

作者： Wohlfeld, Denis Lemke, Frank Froening, Holger Schenk, Sven Bruening, Ulrich Heidelberg Univ ZITI Res Grp High Speed Short Range Interconnects B6 26 Mannheim Germany Heidelberg Univ Comp Architecture Grp Mannheim Germany

ISBN: (纸本)9780819484819

Evolution in high performance computing (HPC) leads to increasing demands on bandwidth, connectivity and flexibility. Active optical cables (AOC) are of special interest, combining the benefits of electrical connectors and optical transmission. Optimization and development of AOC solutions requires enhancements concerning different technology barriers. Area and volume occupied by connectors is of special interest within HPC networks. This led to the development of a 12x AOC for the mini-HT connector creating the densest AOC available. In order to integrate electrical optical conversion into a module not higher than 3 mm, a new concept of coupling fibers to VCSELs or photodiodes had to be developed. This unique concept is based on a direct replication process of an integrated fiber coupler consisting of a 90 degrees light deflecting and focusing mirror, a fiber guiding structure, and a fiber funnel. The integrated fiber coupler is directly replicated on top of active components, reducing the distance between active components and fibers to a minimum, thus providing a highly efficient light coupling. As AOC prototype, multi-chip-modules (MCM) including the complete electrical to optical conversion for send and receive connected by two 12x fiber ribbons have been developed. The paper presents the integrated fiber coupling technique and also design and measurement data of the prototype.

关键词： Active optical cables high performance computing fiber coupling parallel optics optical interconnects

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High-performance computer system architectures for embedded computing

High-performance computer system architectures for embedded ...

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作者： Lee, Dongwon Georgia Institute of Technology

学位级别：Ph.D.

The main objective of this thesis is to propose new methods for designing high-performance embedded computer system architectures. To achieve the goal, three major components—multi-core processing elements (PEs), DRAM main memory systems, and on/off-chip interconnection networks—in multi-processor embedded systems are examined in each section respectively. The first section of this thesis presents architectural enhancements to graphics processing units (GPUs), one of the multi- or many-core PEs, for improving performance of embedded applications. An embedded application is first mapped onto GPUs to explore the design space, and then architectural enhancements to existing GPUs are proposed for improving throughput of the embedded application. The second section proposes high-performance buffer mapping methods, which exploit useful features of DRAM main memory systems, in DSP multi-processor systems. The memory wall problem becomes increasingly severe in multiprocessor environments because of communication and synchronization overheads. To alleviate the memory wall problem, this section exploits bank concurrency and page mode access of DRAM main memory systems for increasing the performance of multiprocessor DSP systems. The final section presents a network-centric Turbo decoder and network-centric FFT processors. In the era of multi-processor systems, an interconnection network is another performance bottleneck. To handle heavy communication traffic, this section applies a crossbar switch—one of the indirect networks—to the parallel Turbo decoder, and applies a mesh topology to the parallel FFT processors. When designing the mesh FFT processors, a very different approach is taken to improve performance; an optical fiber is used as a new interconnection medium.

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