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Sample records for near-field coupled processes

  1. Panel discussion on near-field coupled processes with emphasis on performance assessment

    SciTech Connect

    Codell, R.B.; Baca, R.G.; Ahola, M.P.

    1996-04-01

    The presentations in this panel discussion involve the general topic of near-field coupled processes and postclosure performance assessment with an emphasis on rock mechanics. The potential impact of near-field rock mass deformation on repository performance was discussed, as well as topics including long term excavation deterioration, the performance of geologic seals, and coupled processes concerning rock mechanics in performance assessments.

  2. Modeled near-field environment porosity modifications due to coupled thermohydrologic and geochemical processes

    SciTech Connect

    Glassley, W. E.; Nitao, J. J.

    1998-10-30

    Heat deposited by waste packages in nuclear waste repositories can modify rock properties by instigating mineral dissolution and precipitation along hydrothermal flow pathways. Modeling this reactive transport requires coupling fluid flow to permeability changes resulting from dissolution and precipitation. Modification of the NUFT thermohydrologic (TH) code package to account for this coupling in a simplified geochemical system has been used to model the time- dependent change in porosity, permeability, matrix and fracture saturation, and temperature in the vicinity of waste-emplacement drifts, using conditions anticipated for the potential Yucca Mountain repository. The results show, within a few hundred years, dramatic porosity reduction approximately 10 m above emplacement drifts. Most of this reduction is attributed to deposition of solute load at the boiling front, although some of it also results from decreasing temperature along the flow path. The actual distribution of the nearly sealed region is sensitive to the time- dependent characteristics of the thermal load imposed on the environment and suggests that the geometry of the sealed region can be engineered by managing the waste-emplacement strategy.

  3. Near Field Environment Process Model Report

    SciTech Connect

    R.A. Wagner

    2000-11-14

    Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.

  4. Source near-field effects on HPM coupling

    SciTech Connect

    King, R.J.; Hudson, H.G.

    1988-08-01

    This report gives an overview of many of these issues and cites examples. It is part of an on-going effort to investigate all aspects of the phenomenology of HPM interactions with systems. Experimental results are given for near-field coupling into generic test systems. While we do not exhaustively answer all of these questions, certain trends are observed. From these, some general conclusions are drawn to guide the use of HPM simulators for testing full systems. 3 refs., 43 figs., 2 tabs.

  5. Nonadiabatic photodissociation process using an optical near field.

    PubMed

    Kawazoe, Tadashi; Kobayashi, Kiyoshi; Takubo, Satoru; Ohtsu, Motoichi

    2005-01-01

    We demonstrated the deposition of nanometric Zn dots using photodissociation with gas-phase diethylzinc and an optical near field under nonresonant conditions. To explain the experimental results, we proposed an exciton-phonon polariton model, and discuss the quantitative experimental dependence of the deposition rate on the optical power and photon energy based on photodissociation involving multiple-step excitation via molecular vibration modes. The physical basis of this process, which seems to violate the Franck-Condon principle, is the optically nonadiabatic excitation of the molecular vibration mode due to the steep spatial gradient of the optical near-field energy. PMID:15638622

  6. Near-field environment/processes working group summary

    SciTech Connect

    Murphy, W.M.

    1995-09-01

    This article is a summary of the proceedings of a group discussion which took place at the Workshop on the Role of Natural Analogs in Geologic Disposal of High-Level Nuclear Waste in San Antonio, Texas on July 22-25, 1991. The working group concentrated on the subject of the near-field environment to geologic repositories for high-level nuclear waste. The near-field environment may be affected by thermal perturbations from the waste, and by disturbances caused by the introduction of exotic materials during construction of the repository. This group also discussed the application of modelling of performance-related processes.

  7. Active control of near-field coupling in conductively coupled microelectromechanical system metamaterial devices

    NASA Astrophysics Data System (ADS)

    Pitchappa, Prakash; Manjappa, Manukumara; Ho, Chong Pei; Qian, You; Singh, Ranjan; Singh, Navab; Lee, Chengkuo

    2016-03-01

    We experimentally report a structurally reconfigurable metamaterial for active switching of near-field coupling in conductively coupled, orthogonally twisted split ring resonators (SRRs) operating in the terahertz spectral region. Out-of-plane reconfigurable microcantilevers integrated into the dark SRR geometry are used to provide active frequency tuning of dark SRR resonance. The geometrical parameters of individual SRRs are designed to have identical inductive-capacitive resonant frequency. This allows for the excitation of classical analogue of electromagnetically induced transparency (EIT) due to the strong conductive coupling between the SRRs. When the microcantilevers are curved up, the resonant frequency of dark SRR blue-shifts and the EIT peak is completely modulated while the SRRs are still conductively connected. EIT modulation contrast of ˜50% is experimentally achieved with actively switchable group delay of ˜2.5 ps. Electrical control, miniaturized size, and readily integrable fabrication process of the proposed structurally reconfigurable metamaterial make it an ideal candidate for the realization of various terahertz communication devices such as electrically controllable terahertz delay lines, buffers, and tunable data-rate channels.

  8. Thermodynamic coupling of heat and matter flows in near-field regions of nuclear waste repositories

    SciTech Connect

    Carnahan, C.L.

    1983-11-01

    In near-field regions of nuclear waste repositories, thermodynamically coupled flows of heat and matter can occur in addition to the independent flows in the presence of gradients of temperature, hydraulic potential, and composition. The following coupled effects can occur: thermal osmosis, thermal diffusion, chemical osmosis, thermal filtration, diffusion thermal effect, ultrafiltration, and coupled diffusion. Flows of heat and matter associated with these effects can modify the flows predictable from the direct effects, which are expressed by Fourier's law, Darcy's law, and Fick's law. The coupled effects can be treated quantitatively together with the direct effects by the methods of the thermodynamics of irreversible processes. The extent of departure of fully coupled flows from predictions based only on consideration of direct effects depends on the strengths of the gradients driving flows, and may be significant at early times in backfills and in near-field geologic environments of repositories. Approximate calculations using data from the literature and reasonable assumptions of repository conditions indicate that thermal-osmotic and chemical-osmotic flows of water in semipermeable backfills may exceed Darcian flows by two to three orders of magnitude, while flows of solutes may be reduced greatly by ultrafiltration and chemical osmosis, relative to the flows predicted by advection and diffusion alone. In permeable materials, thermal diffusion may contribute to solute flows to a smaller, but still significant, extent.

  9. Resonance hybridization and near field properties of strongly coupled plasmonic ring dimer-rod nanosystem

    SciTech Connect

    Koya, Alemayehu Nana; Ji, Boyu; Hao, Zuoqiang; Lin, Jingquan

    2015-09-21

    Combined effects of polarization, split gap, and rod width on the resonance hybridization and near field properties of strongly coupled gold dimer-rod nanosystem are comparatively investigated in the light of the constituent nanostructures. By aligning polarization of the incident light parallel to the long axis of the nanorod, introducing small split gaps to the dimer walls, and varying width of the nanorod, we have simultaneously achieved resonance mode coupling, huge near field enhancement, and prolonged plasmon lifetime. As a result of strong coupling between the nanostructures and due to an intense confinement of near fields at the split and dimer-rod gaps, the extinction spectrum of the coupled nanosystem shows an increase in intensity and blueshift in wavelength. Consequently, the near field lifespan of the split-nanosystem is prolonged in contrast to the constituent nanostructures and unsplit-nanosystem. On the other hand, for polarization of the light perpendicular to the long axis of the nanorod, the effect of split gap on the optical responses of the coupled nanosystem is found to be insignificant compared to the parallel polarization. These findings and such geometries suggest that coupling an array of metallic split-ring dimer with long nanorod can resolve the huge radiative loss problem of plasmonic waveguide. In addition, the Fano-like resonances and immense near field enhancements at the split and dimer-rod gaps imply the potentials of the nanosystem for practical applications in localized surface plasmon resonance spectroscopy and sensing.

  10. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    NASA Astrophysics Data System (ADS)

    Elliott, Stephen J.; Ni, Guangjian

    2015-12-01

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a "coupling mass" effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  11. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    SciTech Connect

    Elliott, Stephen J.; Ni, Guangjian

    2015-12-31

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a “coupling mass” effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  12. Near-field coupling model between PCB and grounded transmission line based on plane wave spectrum

    NASA Astrophysics Data System (ADS)

    Leseigneur, Christelle; Baudry, David; Ravelo, Blaise; Louis, Anne

    2013-10-01

    This article presents an explicit model of electromagnetic (EM) coupling between electronic circuits and metallic wire placed above the ground plane. The model is based on the interaction between the EM near-field (NF) that has been treated with plane wave spectrum (PWS) and the Taylor model. The routine process illustrating the methodology is addressed is this article. The practicability of the model developed was upheld with different analytical and real demonstrators. First, the NF coupling between a straight transmission line (TL) and 1 GHz Wilkinson power divider (PWD) designed and implemented in planar technology was provided. Subsequently, simulations with a powerful commercial tool and measurements from 0.2 GHz to 2 GHz revealed a good agreement between the coupling voltages from the proposed model. As a second proof of concept, a printed circuit board incorporating a 40 MHz RF oscillator was placed 5 mm above the grounded TL. Once again, coupling voltages matched measurements were observed with magnitude relative difference lower than 5 dB. The hereby model presents huge benefits not only in terms of flexibility in the design process but it can also be run with very less computation time compared to the existing standard simulators. The model can be potentially a good candidate for investigating complex systems EMC engineering.

  13. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-01

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  14. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    SciTech Connect

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-14

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  15. Accurate near-field calculation in the rigorous coupled-wave analysis method

    NASA Astrophysics Data System (ADS)

    Weismann, Martin; Gallagher, Dominic F. G.; Panoiu, Nicolae C.

    2015-12-01

    The rigorous coupled-wave analysis (RCWA) is one of the most successful and widely used methods for modeling periodic optical structures. It yields fast convergence of the electromagnetic far-field and has been adapted to model various optical devices and wave configurations. In this article, we investigate the accuracy with which the electromagnetic near-field can be calculated by using RCWA and explain the observed slow convergence and numerical artifacts from which it suffers, namely unphysical oscillations at material boundaries due to the Gibbs phenomenon. In order to alleviate these shortcomings, we also introduce a mathematical formulation for accurate near-field calculation in RCWA, for one- and two-dimensional straight and slanted diffraction gratings. This accurate near-field computational approach is tested and evaluated for several representative test-structures and configurations in order to illustrate the advantages provided by the proposed modified formulation of the RCWA.

  16. Fano profiles induced by near-field coupling in heterogeneous dimers of gold and silver nanoparticles.

    PubMed

    Bachelier, G; Russier-Antoine, I; Benichou, E; Jonin, C; Del Fatti, N; Vallée, F; Brevet, P-F

    2008-11-01

    The near-field coupling between a gold and a silver spherical nanoparticle is investigated theoretically. Fano profiles are observed in the absorption cross section of the gold nanoparticle due to the coupling between the spectrally localized surface plasmon resonance of the silver nanoparticle and the continuum of interband transitions of the gold one. The effect of dimer internal characteristics (particle sizes and distance), surrounding medium (through the refractive index), and external excitation (polarization and propagation directions) are addressed. In particular, it is shown that the near-field coupling can be tuned from the weak to the strong regime by rotating the polarization direction, and that the Fano profiles are sensitive to the shadowing effect even for small particle sizes. PMID:19113308

  17. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials.

    PubMed

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S; Zhang, Lin

    2016-10-14

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate. PMID:27607837

  18. Temporal coupled-mode theory model for resonant near-field thermophotovoltaics

    SciTech Connect

    Karalis, Aristeidis; Joannopoulos, J. D.

    2015-10-05

    A temporal Coupled-Mode Theory model is developed to predict performance of resonant near-field ThermoPhotoVoltaic systems, which typically requires numerically intensive calculations. It is formulated for both orthogonal and non-orthogonal (coupled) modes and includes load-voltage dependencies and non-idealities, such as background absorption and radiation losses. Its good accuracy is confirmed by comparing with exact transfer-matrix calculations for two simple planar systems: a plasmonic emitter across a bulk semiconductor absorber and a metal-backed thin-film semiconductor emitter across an identical absorber.

  19. Near-Field Infrared Pump-Probe Imaging of Surface Phonon Coupling in Boron Nitride Nanotubes.

    PubMed

    Gilburd, Leonid; Xu, Xiaoji G; Bando, Yoshio; Golberg, Dmitri; Walker, Gilbert C

    2016-01-21

    Surface phonon modes are lattice vibrational modes of a solid surface. Two common surface modes, called longitudinal and transverse optical modes, exhibit lattice vibration along or perpendicular to the direction of the wave. We report a two-color, infrared pump-infrared probe technique based on scattering type near-field optical microscopy (s-SNOM) to spatially resolve coupling between surface phonon modes. Spatially varying couplings between the longitudinal optical and surface phonon polariton modes of boron nitride nanotubes are observed, and a simple model is proposed. PMID:26727539

  20. Light transport in dense composite media: role of near-field coupling

    NASA Astrophysics Data System (ADS)

    Rezvani Naraghi, Roxana; Sukhov, Sergey; Sáenz, Juan José; Dogariu, Aristide

    In scattering media, optical waves comprise both homogeneous and evanescent components. At very high concentrations of scatterers, particles are located in close proximity and interact through evanescent near fields. Thus, in this regime the energy is not only carried by propagating waves but it also evolves through evanescent coupling between individual scatterers. We have shown that in dense composite media additional transmission channels open because of these near-field interactions between close proximity scatters and, consequently, a new regime of transport emerges. This is clearly beyond simple descriptions of scatterers acting independently of their environment and framed in terms of far-field characteristics such as Mie cross-sections. We will show that, because in the dense media the energy can transfer through both diffusion and evanescent channels, the total transmittance is T =TCS +TNF = 1 1 L (lCS* +lNF*) L (lCS* +lNF*) . Correcting the total transmission in this manner is appealing because it is done in terms of physically meaningful and measurable quantities such a near-field (NF) scattering cross-section σNF.

  1. Collective properties and strong coupling in the near-field of a meta-surface

    NASA Astrophysics Data System (ADS)

    Felbacq, Didier

    2015-08-01

    Meta{surfaces or 2D metamaterials are generally seen as a device able to control the far-field behavior of light. Several studies have shown the possibility of controlling the polarization state, the directivity, the light-by-light manipulation or the generation of second harmonic signal. However, because of their resonant properties, meta{ surfaces also have interesting properties in the near-field. In the present work, a meta{surface made of a set of parallel line distributed dipoles was studied. The coupling of a quantum emitter with the photonic surface modes supported by the meta{surface is investigated.

  2. An ab-initio coupled mode theory for near field radiative thermal transfer.

    PubMed

    Chalabi, Hamidreza; Hasman, Erez; Brongersma, Mark L

    2014-12-01

    We investigate the thermal transfer between finite-thickness planar slabs which support surface phonon polariton modes (SPhPs). The thickness-dependent dispersion of SPhPs in such layered materials provides a unique opportunity to manipulate and enhance the near field thermal transfer. The key accomplishment of this paper is the development of an ab-initio coupled mode theory that accurately describes all of its thermal transfer properties. We illustrate how the coupled mode parameters can be obtained in a direct fashion from the dispersion relation of the relevant modes of the system. This is illustrated for the specific case of a semi-infinite SiC substrate placed in close proximity to a thin slab of SiC. This is a system that exhibits rich physics in terms of its thermal transfer properties, despite the seemingly simple geometry. This includes a universal scaling behavior of the thermal conductance with the slab thickness and spacing. The work highlights and further increases the value of coupled mode theories in rapidly calculating and intuitively understanding near-field transfer. PMID:25606933

  3. Hybrid modelling of near-field coupling onto grounded wire under ultra-short duration perturbation

    NASA Astrophysics Data System (ADS)

    Ravelo, B.; Liu, Y.

    2014-10-01

    A time-frequency (TF) hybrid model (HM) for investigating the interaction between EM near-field (NF) aggression and grounded wire is addressed. The HM is based on the combination of techniques for extracting the EM NF radiated by electronic structures and the calculation of electrical disturbances across the wire due to EM coupling. The computation method is fundamentally inspired from transmission line (TL) theory under EM illumination. The methodology including flow chart interpreting the routine algorithm based on the combination of frequency and time domain approaches is featured. An experimental result showing the EM coupling between patch antenna-wire from 1.5-3.5GHz reveals the efficiency of the HM in frequency domain. The relevance of this HM was illustrated with a structure comprised of 20cm aggressor and 5cm victim I-shaped wires placed above a planar ground plane. The aggressor was excited with 40ns duration perturbation signal. After Matlab implementation of the HM, the disturbance voltages across the extremity of the victim wire were extracted. This simple and fast HM is useful for the EMC engineering during the design and fabrication phases of electrical and electronic systems.

  4. From near-field to far-field coupling in the third dimension: retarded interaction of particle plasmons.

    PubMed

    Taubert, Richard; Ameling, Ralf; Weiss, Thomas; Christ, André; Giessen, Harald

    2011-10-12

    We study the transition from the near-field to the far-field coupling regime of particle plasmons in a three-dimensional geometry. In the far-field regime, retardation plays the dominant role and the plasmonic resonances are radiatively coupled. When the spatial arrangement of the oscillators is matched to their resonance wavelength, superradiant-like effects are observed. PMID:21879724

  5. Coupled near-field and far-field exposure assessment framework for chemicals in consumer products.

    PubMed

    Fantke, Peter; Ernstoff, Alexi S; Huang, Lei; Csiszar, Susan A; Jolliet, Olivier

    2016-09-01

    Humans can be exposed to chemicals in consumer products through product use and environmental emissions over the product life cycle. Exposure pathways are often complex, where chemicals can transfer directly from products to humans during use or exchange between various indoor and outdoor compartments until sub-fractions reach humans. To consistently evaluate exposure pathways along product life cycles, a flexible mass balance-based assessment framework is presented structuring multimedia chemical transfers in a matrix of direct inter-compartmental transfer fractions. By matrix inversion, we quantify cumulative multimedia transfer fractions and exposure pathway-specific product intake fractions defined as chemical mass taken in by humans per unit mass of chemical in a product. Combining product intake fractions with chemical mass in the product yields intake estimates for use in life cycle impact assessment and chemical alternatives assessment, or daily intake doses for use in risk-based assessment and high-throughput screening. Two illustrative examples of chemicals used in personal care products and flooring materials demonstrate how this matrix-based framework offers a consistent and efficient way to rapidly compare exposure pathways for adult and child users and for the general population. This framework constitutes a user-friendly approach to develop, compare and interpret multiple human exposure scenarios in a coupled system of near-field ('user' environment), far-field and human intake compartments, and helps understand the contribution of individual pathways to overall human exposure in various product application contexts to inform decisions in different science-policy fields for which exposure quantification is relevant. PMID:27318619

  6. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-03-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials.

  7. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays

    PubMed Central

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-01-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials. PMID:26983501

  8. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays.

    PubMed

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-01-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials. PMID:26983501

  9. Modeling of the Near Field Coupling Between an External Loop and an Implantable Spiral Chip Antennas in Biosensor Systems

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Miranda, Felix A.

    2006-01-01

    In this paper, the near field coupling between an external hand-held loop antenna and an implantable miniature (1x1 mm) printed square spiral chip antenna used in bio-MEMS sensors for contact-less powering and RF telemetry is investigated. The loop and the spiral are inductively coupled and effectively form a transformer. The numerical results include the quasi-stationary magnetic field pattern of the implanted antenna, near zone wave impedance as a function of the radial distance and the values of the lumped elements in the equivalent circuit model for the transformer.

  10. Enhanced near-field radiative heat transfer between a nanosphere and a hyperbolic metamaterial mediated by coupled surface phonon polaritons

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Jiang, Yongyuan; Liu, Linhua

    2015-06-01

    We study the near-field radiative heat transfer between a silicon carbide (SiC) nanosphere and a SiC-SiO2 multi-layered hyperbolic metamaterial (HMM) by means of fluctuational electrodynamics. Results show that the absorbed mean power at the volume resonant frequency of the SiC nanosphere is one order of magnitude stronger than that of bulk SiC medium. This enhancement of near-field radiative heat transfer is mediated by the coupled surface phonon polaritons at the forbidden region of the Bloch mode. Moreover, the forbidden region of the Bloch mode is tuned by the geometry structure of the multi-layered HMM and overlapped with the volume resonant frequency of the SiC nanosphere, thus generating stronger absorption.

  11. Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

    SciTech Connect

    Li, Hai-ming; Liu, Shao-bin Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun; Wang, Shen-yun

    2015-03-16

    In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

  12. Density controlled nanophotonic waveguide gratings for efficient on-chip out-coupling in the near field (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Vercruysse, Dries; Mukund, Vignesh; Jansen, Roelof; Stahl, Richard; Van Dorpe, Pol; Lagae, Liesbet; Rottenberg, Xavier

    2016-05-01

    Waveguide optics takes up a prominent role in the progressing miniaturization of optical devices. Chip integrated photonic waveguides especially allow for complex routing schemes of light across a chip. In/out-coupling diffraction gratings form an essential tool in waveguide systems, as they facilitate the interaction between the waveguide system and the near or far-field.[1,2] Ideally, these gratings would couple out all light in the waveguide into a beam with a predefined polarization and, phase and intensity profile. As such they should be able to produce any functional beam that is typically prepared by free space optics. Yet, in practice there is typically a design trade-off between beam quality and out-coupling efficiency.[2] Light in the waveguide has to travel laterally through the grating to be coupled out. The light therefore decays exponentially over the grating, causing much more light to be coupled out at the start of the grating than at the end. This asymmetry results in a warped out-coupling intensity that heavily influences the light beam's intensity profile. Especially when the grating is addressing points in the near field, as is the case for focusing waveguide grating couplers, this effect can be highly disruptive. In this work we present a grating constructed from a field of sub-wavelength scatterers, rather than full grating lines. By tuning the position and the density of the scatterers, the phase and the intensity of the out-coupled light can be set precisely over large grating areas. An iterative design algorithm is developed that carefully tunes the density so as to control the light intensity in the waveguide and the amount of out-coupled light. Using FDTD simulations we show that these gratings can efficiently couple out light into a nearly diffraction limited spot with an even angular intensity. We verify this experimentally by fabricating these gratings in the SiN/SiO2 system using e-beam lithography. In addition, we also show that

  13. Detection and processing of electromagnetic and near-field acoustic signals in elasmobranch fishes.

    PubMed Central

    Kalmijn, A D

    2000-01-01

    The acoustic near field of quietly moving underwater objects and the bio-electric field of aquatic animals exhibit great similarity, as both are predominantly governed by Laplace's equation. The acoustic and electrical sensory modalities thus may, in directing fishes to their prey, employ analogous processing algorithms, suggesting a common evolutionary design, founded on the salient physical features shared by the respective stimulus fields. Sharks and rays are capable of orientating to the earth's magnetic field and, hence, have a magnetic sense. The electromagnetic theory of orientation offers strong arguments for the animals using the electric fields induced by ocean currents and by their own motions in the earth's magnetic field. In the animal's frame of reference, in which the sense organs are at rest, the classical concept of motional electricity must be interpreted in relativistic terms. In the ampullae of Lorenzini, weak electric fields cause the ciliated apical receptor-cell membranes to produce graded, negative receptor currents opposite in direction to the fields applied. The observed currents form part of a positive-feedback mechanism, supporting the generation of receptor potentials much larger than the input signal. Acting across the basal cell membranes, the receptor potentials control the process of synaptic transmission. PMID:11079385

  14. Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling

    PubMed Central

    Kehr, S.C.; Liu, Y.M.; Martin, L.W.; Yu, P.; Gajek, M.; Yang, S.-Y.; Yang, C.-H.; Wenzel, M.T.; Jacob, R.; von Ribbeck, H.-G.; Helm, M.; Zhang, X.; Eng, L.M.; Ramesh, R.

    2011-01-01

    A planar slab of negative-index material works as a superlens with sub-diffraction-limited resolution, as propagating waves are focused and, moreover, evanescent waves are reconstructed in the image plane. Here we demonstrate a superlens for electric evanescent fields with low losses using perovskites in the mid-infrared regime. The combination of near-field microscopy with a tunable free-electron laser allows us to address precisely the polariton modes, which are critical for super-resolution imaging. We spectrally study the lateral and vertical distributions of evanescent waves around the image plane of such a lens, and achieve imaging resolution of λ/14 at the superlensing wavelength. Interestingly, at certain distances between the probe and sample surface, we observe a maximum of these evanescent fields. Comparisons with numerical simulations indicate that this maximum originates from an enhanced coupling between probe and object, which might be applicable for multifunctional circuits, infrared spectroscopy and thermal sensors. PMID:21427720

  15. Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling.

    PubMed

    Kehr, S C; Liu, Y M; Martin, L W; Yu, P; Gajek, M; Yang, S-Y; Yang, C-H; Wenzel, M T; Jacob, R; von Ribbeck, H-G; Helm, M; Zhang, X; Eng, L M; Ramesh, R

    2011-01-01

    A planar slab of negative-index material works as a superlens with sub-diffraction-limited resolution, as propagating waves are focused and, moreover, evanescent waves are reconstructed in the image plane. Here we demonstrate a superlens for electric evanescent fields with low losses using perovskites in the mid-infrared regime. The combination of near-field microscopy with a tunable free-electron laser allows us to address precisely the polariton modes, which are critical for super-resolution imaging. We spectrally study the lateral and vertical distributions of evanescent waves around the image plane of such a lens, and achieve imaging resolution of λ/14 at the superlensing wavelength. Interestingly, at certain distances between the probe and sample surface, we observe a maximum of these evanescent fields. Comparisons with numerical simulations indicate that this maximum originates from an enhanced coupling between probe and object, which might be applicable for multifunctional circuits, infrared spectroscopy and thermal sensors. PMID:21427720

  16. Note: Quasi-real-time analysis of dynamic near field scattering data using a graphics processing unit

    NASA Astrophysics Data System (ADS)

    Cerchiari, G.; Croccolo, F.; Cardinaux, F.; Scheffold, F.

    2012-10-01

    We present an implementation of the analysis of dynamic near field scattering (NFS) data using a graphics processing unit. We introduce an optimized data management scheme thereby limiting the number of operations required. Overall, we reduce the processing time from hours to minutes, for typical experimental conditions. Previously the limiting step in such experiments, the processing time is now comparable to the data acquisition time. Our approach is applicable to various dynamic NFS methods, including shadowgraph, Schlieren and differential dynamic microscopy.

  17. Optical security based on near-field processes at the nanoscale

    NASA Astrophysics Data System (ADS)

    Naruse, Makoto; Tate, Naoya; Ohtsu, Motoichi

    2012-09-01

    Optics has been playing crucial roles in security applications ranging from authentication and watermarks to anti-counterfeiting. However, since the fundamental physical principle involves optical far-fields, or propagating light, diffraction of light causes severe difficulties, for example in device scaling and system integration. Moreover, conventional security technologies in use today have been facing increasingly stringent demands to safeguard against threats such as counterfeiting of holograms, requiring innovative physical principles and technologies to overcome their limitations. Nanophotonics, which utilizes interactions between light and matter at the nanometer scale via optical near-field interactions, can break through the diffraction limit of conventional propagating light. Moreover, nanophotonics has some unique physical attributes, such as localized optical energy transfer and the hierarchical nature of optical near-field interactions, which pave the way for novel security functionalities. This paper reviews the physical principles and describes some experimental demonstrations of systems based on nanophotonics with respect to security applications such as tamper resistance against non-invasive and invasive attacks, hierarchical information retrieval, hierarchical holograms, authentication, and traceability.

  18. A coupled soil-fluid-structure simulation of the near-field earthquake effects on gravity type quay-walls

    NASA Astrophysics Data System (ADS)

    Zeinoddini, M.; Matin Nikoo, H.; Ahmadpour, F.

    2013-08-01

    This study focuses on non-linear seismic response of concrete gravity quay-wall structures subjected to near-fault ground motions, a subject which seems not to have received much attention in the literature. A two-dimensional coupled fluid-structure-soil finite element modelling is employed to obtain the quay-wall response. The seawater medium is represented by acoustic type, potential based fluid elements. The elasto-plastic behavior of the soil medium is idealized using Drucker-Prager yield criterion based on associated flow rule assumption. Four nodded plane strain elements are used to model the concrete wall, foundation, subsoil, backfill and seabed zones. Fluid Structure Interface (FSI) elements are considered between the seawater interfaces with the quay-wall and the seabed. Frictional contact elements are employed between the wall and soil interfaces. The numerical model is validated using field measurements available for permanent drifts in a quay-wall damaged during Kobe earthquake. Reasonable agreements are obtained between the model predictions and the field measurements. Non-linear seismic analyses of the selected quay-wall subjected to both near-fault and far-fault ground motions are performed. An incremental dynamic analysis approach (IDA) is used. In general, at least for models examined in the current study, the gravity quay-walls are found to be more vulnerable to near-field, in comparison with the corresponding far-field, earthquakes.

  19. Adaptive and robust statistical methods for processing near-field scanning microwave microscopy images.

    PubMed

    Coakley, K J; Imtiaz, A; Wallis, T M; Weber, J C; Berweger, S; Kabos, P

    2015-03-01

    Near-field scanning microwave microscopy offers great potential to facilitate characterization, development and modeling of materials. By acquiring microwave images at multiple frequencies and amplitudes (along with the other modalities) one can study material and device physics at different lateral and depth scales. Images are typically noisy and contaminated by artifacts that can vary from scan line to scan line and planar-like trends due to sample tilt errors. Here, we level images based on an estimate of a smooth 2-d trend determined with a robust implementation of a local regression method. In this robust approach, features and outliers which are not due to the trend are automatically downweighted. We denoise images with the Adaptive Weights Smoothing method. This method smooths out additive noise while preserving edge-like features in images. We demonstrate the feasibility of our methods on topography images and microwave |S11| images. For one challenging test case, we demonstrate that our method outperforms alternative methods from the scanning probe microscopy data analysis software package Gwyddion. Our methods should be useful for massive image data sets where manual selection of landmarks or image subsets by a user is impractical. PMID:25463325

  20. Direct-write PVDF nonwoven fiber fabric energy harvesters via the hollow cylindrical near-field electrospinning process

    NASA Astrophysics Data System (ADS)

    Liu, Z. H.; Pan, C. T.; Lin, L. W.; Huang, J. C.; Ou, Z. Y.

    2014-02-01

    One-dimensional piezoelectric nanomaterials have attracted great attention in recent years for their possible applications in mechanical energy scavenging devices. However, it is difficult to control the structural diameter, length, and density of these fibers fabricated by micro/nano-technologies. This work presents a hollow cylindrical near-field electrospinning (HCNFES) process to address production and performance issues encountered previously in either far-field electrospinning (FFES) or near-field electrospinning (NFES) processes. Oriented polyvinylidene fluoride (PVDF) fibers in the form of nonwoven fabric have been directly written on a glass tube for aligned piezoelectricity. Under a high in situ electrical poling field and strong mechanical stretching (the tangential speed on the glass tube collector is about 1989.3 mm s-1), the HCNFES process is able to uniformly deposit large arrays of PVDF fibers with good concentrations of piezoelectric β-phase. The nonwoven fiber fabric (NFF) is transferred onto a polyethylene terephthalate (PET) substrate and fixed at both ends using copper foil electrodes as a flexible textile-fiber-based PVDF energy harvester. Repeated stretching and releasing of PVDF NFF with a strain of 0.05% at 7 Hz produces a maximum peak voltage and current at 76 mV and 39 nA, respectively.

  1. Source processes of near-field deformation accompanying recent lava lake level decrease at Nyiragongo, DR. Congo

    NASA Astrophysics Data System (ADS)

    Geirsson, Halldor; Smets, Benoît; d'Oreye, Nicolas; Cayol, Valerie; Samsonov, Sergey; De Rauw, Dominique; Kervyn, Francois

    2016-04-01

    Nyiragongo volcano in the Democratic Republic of Congo, Central Africa, is one of the rare volcanoes that host a long-living lava lake. The evolution of this lava lake is very dynamic, with height changes spanning hundreds of meters over the past decades and including drastic height changes in relation to flank eruptions of the volcano in 1977 and 2002 (Smets et al., this meeting). Since September 30, 2011, the level of the lava lake has been progressively falling, reaching ~70 m below the lowest platform (termed "platform P3" hereafter) in July 2014. Platform P3 is constructed from successive overflows of the lava lake from 2002 to 2011, amounting to ~400 m thickness since the emptying of the lava lake following the 2002 flank eruption. Coinciding with the recent fall of the lava lake, differences of photogrammetry-derived DEM models, and InSAR time series, show a very near-field (out to ~200-300 m distance from the ~200 m-wide lava lake, i.e. on platform P3) deformation signal with up to meter-scale deformation near the crater. Ring-fractures have also formed in platform P3. Here we compare and contrast plausible models of processes contributing to this near-field deformation, including thermal contraction, elastic response, block rotation, structural weaknesses, and subsurface shape of the lava lake.

  2. Nano-material processing with laser radiation in the near field of a scanning probe tip

    NASA Astrophysics Data System (ADS)

    Jersch, J.; Demming, F.; Hildenhagen, J.; Dickmann, K.

    1998-04-01

    We report preliminary results of using a scanning probe microscope/laser combination to perform nanostructuring on insulator and metal surfaces in air. This technique enables processing of structures with a lateral resolution of approximately 10 nm. In this paper we present our last structuring results with both scanning tunnelling and scanning force microscopy. Some possible interaction mechanisms responsible for the structuring will be discussed.

  3. Departures from plane-wave-like coupling to a Maverick missile in the radiating near-field region of a horn antenna

    NASA Astrophysics Data System (ADS)

    Voss, D. E.; Koslover, R. A.; Cremer, C. D.; Silvestro, J.; Miner, L. M.

    1990-05-01

    The High Power Microwaves (HPM) susceptibility testing often requires irradiating test objects at the highest fluences possible. For aperture antennas, the highest fluences are generally found in the radiating near field region. For valid effects testing, the energy coupled to the object interior must accurately replicate that which would occur in a true weapon environment (plane wave illumination). Some believe that valid testing requires object placement at distances from the aperture exceeding 2 D squared/lambda (D=antenna effective diameter). Many also believe testing at farther away than 2 D squared/lambda guarantees plane wave-like coupling conditions. Neither view is correct. Testing in the reactive field region (less than lambda from the aperture) is generally invalid due to dominance of reactive coupling. For testing in the radiating near field, determination of validity is less trivial. An investigation was performed quantifying deviations from plane wave coupling. The measurements, using an instrumented Maverick missile in an anechoic chamber, and supported by theory, indicate conditions for which testing the Maverick missile accurately simulates plane wave coupling.

  4. Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks

    SciTech Connect

    Rutqvist, J.; Chijimatsu, M.; Jing, L.; Millard, A.; Nguyen,T.S.; Rejeb, A.; Sugita, Y.; Tsang, C.F.

    2004-09-09

    BENCHPAR project, the impact of thermal-hydrological-mechanical (THM) couplings on the performance of a bentonite-back-filled nuclear waste repository in near-field crystalline rocks is evaluated in a Bench-Mark Test problem (BMT1) and the results are presented in a series of three companion papers in this issue. This is the third paper with focus on the effects of THM processes at a repository located in a sparsely fractured rock. Several independent coupled THM analyses presented in this paper show that THM couplings have the most significant impact on the mechanical stress evolution, which is important for repository design, construction and post-closure monitoring considerations. The results show that the stress evolution in the bentonite-back-filled excavations and the surrounding rock depends on the post-closure evolution of both fields of temperature and fluid pressure.It is further shown that the time required to full resaturation may play an important role for the mechanical integrity of the repository drifts.In this sense, the presence of hydraulically conducting fractures in the near-field rock might actually improve the mechanical performance of the repository. Hydraulically conducting fractures in the near-field rocks enhances the water supply to the buffers/back-fills, which promotes a more timely process of resaturation and development of swelling pressures in the back-fill, thus provides timely confining stress and support to the rock walls. In one particular case simulated in this study, it was shown that failure in the drift walls could be prevented if the compressive stresses in back-fill were fully developed within 50 years,which is when thermally induced rock strain begins to create high differential (failure-prone) stresses in the near-field rocks.

  5. Imaging cervical cytology with scanning near-field optical microscopy (SNOM) coupled with an IR-FEL.

    PubMed

    Halliwell, Diane E; Morais, Camilo L M; Lima, Kássio M G; Trevisan, Julio; Siggel-King, Michele R F; Craig, Tim; Ingham, James; Martin, David S; Heys, Kelly A; Kyrgiou, Maria; Mitra, Anita; Paraskevaidis, Evangelos; Theophilou, Georgios; Martin-Hirsch, Pierre L; Cricenti, Antonio; Luce, Marco; Weightman, Peter; Martin, Francis L

    2016-01-01

    Cervical cancer remains a major cause of morbidity and mortality among women, especially in the developing world. Increased synthesis of proteins, lipids and nucleic acids is a pre-condition for the rapid proliferation of cancer cells. We show that scanning near-field optical microscopy, in combination with an infrared free electron laser (SNOM-IR-FEL), is able to distinguish between normal and squamous low-grade and high-grade dyskaryosis, and between normal and mixed squamous/glandular pre-invasive and adenocarcinoma cervical lesions, at designated wavelengths associated with DNA, Amide I/II and lipids. These findings evidence the promise of the SNOM-IR-FEL technique in obtaining chemical information relevant to the detection of cervical cell abnormalities and cancer diagnosis at spatial resolutions below the diffraction limit (≥0.2 μm). We compare these results with analyses following attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy; although this latter approach has been demonstrated to detect underlying cervical atypia missed by conventional cytology, it is limited by a spatial resolution of ~3 μm to 30 μm due to the optical diffraction limit. PMID:27406404

  6. Imaging cervical cytology with scanning near-field optical microscopy (SNOM) coupled with an IR-FEL

    PubMed Central

    Halliwell, Diane E.; Morais, Camilo L. M.; Lima, Kássio M. G.; Trevisan, Julio; Siggel-King, Michele R. F.; Craig, Tim; Ingham, James; Martin, David S.; Heys, Kelly A.; Kyrgiou, Maria; Mitra, Anita; Paraskevaidis, Evangelos; Theophilou, Georgios; Martin-Hirsch, Pierre L.; Cricenti, Antonio; Luce, Marco; Weightman, Peter; Martin, Francis L.

    2016-01-01

    Cervical cancer remains a major cause of morbidity and mortality among women, especially in the developing world. Increased synthesis of proteins, lipids and nucleic acids is a pre-condition for the rapid proliferation of cancer cells. We show that scanning near-field optical microscopy, in combination with an infrared free electron laser (SNOM-IR-FEL), is able to distinguish between normal and squamous low-grade and high-grade dyskaryosis, and between normal and mixed squamous/glandular pre-invasive and adenocarcinoma cervical lesions, at designated wavelengths associated with DNA, Amide I/II and lipids. These findings evidence the promise of the SNOM-IR-FEL technique in obtaining chemical information relevant to the detection of cervical cell abnormalities and cancer diagnosis at spatial resolutions below the diffraction limit (≥0.2 μm). We compare these results with analyses following attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy; although this latter approach has been demonstrated to detect underlying cervical atypia missed by conventional cytology, it is limited by a spatial resolution of ~3 μm to 30 μm due to the optical diffraction limit. PMID:27406404

  7. Simulation of near-field and far-field optical properties of electromagnetically coupled multi-layered nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Hongxing; Käll, Mikael

    2001-03-01

    Recent studies of nanoparticle-oligonucleotide conjugates^1 and “hot sites” in single-molecule surface-enhanced Raman scattering (SERS)^2 have highlighted the importance of clustering effects for the optical properties of metal nanoparticles. However, many applications in the life-sciences require coated nanoparticles, e.g. in order to induce biocompatibility or biorecognition. Such a coating will change the optical properties of the nanoparticle system. We here describe a calculational procedure that can be used to model the optical response of clusters composed of shelled spherical nanoparticles. Both far-field (e.g. extinction cross section) and near-field (e.g. SERS effect) optical properties can be evaluated. We will discuss how the wavelength dependent optical properties are influenced by core nanoparticle size and composition; surrounding medium; shell thickness and dielectric constant, and interparticle separation distance. ^1R. Elghanian et al., Science, 277, 1078 (1997); ^2H. Xu et al., Phys. Rev. Lett., 83, 4357 (1999) and Phys. Rev. E, 62, 4318 (2000)

  8. Simulations of near-field and far-field optical properties of electromagnetically coupled multi-layered nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Hongxing

    2004-03-01

    Recent studies of nanoparticle-oligonucleotide conjugates[1] and "hot sites" in single-molecule surface-enhanced Raman scattering(SERS)[2] have highlighted the importance of clustering effects for the optical properties of metal nanoparticles. However, many applications in the life-sciences require coated nanoparticles, e.g. in order to induce biocompatibility or biorecognition. Such a coating will change the optical properties of nanoparticle system. We here describe a recursive method based on the extended Mie theory, which can be used to model the optical response clusters of shelled spherical nanoparticles. Both far-field (e.g. extinction cross section) and near-field (e.g. SERS effect) optical properties can be evaluated. We will discuss how the wavelength dependent optical properties are influenced by core nanoparticle size and composition; surrounding medium; shell thickness and dielectric constant, and interparticle separation distance. [1]R. Elghanian et al., Science, 277, 1078(1997); [2]H. Xu et al., Phys. Rev. Lett., 83, 4357(1999) and Phys. Rev. E, 62, 4318(2000)

  9. Some important mechanisms and processes in the near field of the Swedish repository for spent nuclear fuel

    SciTech Connect

    Neretnieks, I.

    1993-12-31

    In repositories for nuclear waste there are many processes that will be instrumental in damaging the canisters and releasing the nuclides. Based on experiences from studies of the performance of repositories and of an actual design, the major mechanisms influencing the integrity and performance of a repository are described and discussed. The paper addresses only conditions in crystalline rock repositories. The low water flow rate in fractures and channels plays a dominant role in limiting the interaction between water and waste. Molecular diffusion in the backfill and rock matrix, as well as in the mobile water, is an important transport process, but actually limits the exchange rate because diffusive transport is slow. Solubility limits of both waste matrix and of individual nuclides are also important. Complicating processes include alpha-radiolysis, which may change the water chemistry in the near-field. The sizes and locations of water flowpaths and damages in the canisters considerably influence the release rates. Uncertainties in data are large. Nevertheless the system is very robust in the sense that practically no reasonably conceivable assumptions or data will lead to large nuclide releases. Several natural analogues have been found to exhibit similarities with a waste repository and help to validate concepts and to increase our confidence that all major issues have been considered.

  10. A case study on the influence of THM coupling on the near field safety of a spent fuel repository in sparsely fractured granite

    SciTech Connect

    Nguyen, T.S.; Borgesson, L.; Chijimatsu, M.; Hernelind, J.; Jing, L.; Kobayashi, A.; Rutqvist, J.

    2009-03-01

    In order to demonstrate the feasibility of geological disposal of spent CANDU fuel in Canada, a safety assessment was performed for a hypothetical repository in the Canadian Shield. The assessment shows that such repository would meet international criteria for dose rate; however, uncertainties in the assumed evolution of the repository were identified. Such uncertainties could be resolved by the consideration of coupled Thermal-Hydro-Mechanical-Chemical (THMC) processes. In Task A of the DECOVALEX-THMC project, THM models were developed within the framework of the theory of poroelasticity. Such model development was performed in an iterative manner, using experimental data from laboratory and field tests. The models were used to perform near-field simulations of the evolution of the repository in order to address the above uncertainties. This paper presents the definition and rationale of task A and the results of the simulations. From a repository safety point of view, the simulations predict that the maximum temperature would be well below the design target of 100 C, however the load on the container can marginally exceed the design value of 15 MPa. However, the most important finding from the simulations is that a rock damage zone could form around the emplacement borehole. Such damage zone can extend a few metres from the walls of the emplacement holes, with permeability values that are orders of magnitude higher than the initial values. The damage zone has the potential to increase the radionuclide transport flux from the geosphere; the effect of such an increase should be taken into account in the safety assessment and mitigated if necessary by the provision of sealing systems.

  11. A case study on the influence of THM coupling on the near field safety of a spent fuel repository in sparsely fractured granite

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh Son; Börgesson, Lennart; Chijimatsu, Masakazu; Hernelind, Jan; Jing, Lanru; Kobayashi, Akira; Rutqvist, Jonny

    2009-05-01

    In order to demonstrate the feasibility of geological disposal of spent CANDU fuel in Canada, a safety assessment was performed for a hypothetical repository in the Canadian Shield. The assessment shows that the maximum long term radionuclide release from such repository would meet international criteria for dose rate; however, uncertainties in the assumed evolution of the repository were identified. Such uncertainties could be resolved by the consideration of coupled Thermal-Hydro-Mechanical-Chemical (THMC) processes. In Task A of the DECOVALEX-THMC project, THM models were developed within the framework of the theory of poroelasticity. Such model development was performed in an iterative manner, using experimental data from laboratory and field tests. The models were used to perform near-field simulations of the evolution of the repository in order to address the above-mentioned uncertainties. This paper presents the definition and rationale of task A and the results of the simulations. From a repository safety point of view, the simulations predict that the maximum temperature would be well below the design target of 100°C; however, the stress on the container can marginally exceed the design value of 15 MPa. However, the most important finding from the simulations is that a rock damage zone could form around the emplacement borehole. Such damage zone can extend a few metres from the walls of the emplacement holes, with permeability values that are orders of magnitude higher than the initial values. The damage zone has the potential to increase the radionuclide transport flux from the geosphere; the effect of such an increase should be taken into account in the safety assessment and mitigated if necessary by the provision of sealing systems.

  12. Joint inversion of teleseismic, geodetic, and near-field waveform datasets for rupture process of the 2015 Gorkha, Nepal, earthquake

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hiroaki; Koketsu, Kazuki; Miyake, Hiroe; Takai, Nobuo; Shigefuji, Michiko; Bhattarai, Mukunda; Sapkota, Soma Nath

    2016-04-01

    The 2015 Gorkha earthquake and its aftershocks caused severe damage mostly in Nepal, while countries around the Himalayan region were warned for decades about large Himalayan earthquakes and the seismic vulnerability of these countries. However, the magnitude of the Gorkha earthquake was smaller than those of historical earthquakes in Nepal, and the most severe damage occurred in the north and northeast of Kathmandu. We explore reasons for these unexpected features by performing a joint source inversion of teleseismic, geodetic, and near-field waveform datasets to investigate the rupture process. Results indicate that the source fault was limited to the northern part of central Nepal and did not reach the Main Frontal Thrust. The zone of large slip was located in the north of Kathmandu, and the fault rupture propagated eastward with an almost constant velocity. Changes in the Coulomb failure function (ΔCFF) due to the Gorkha earthquake were computed, indicating that southern and western regions neighboring the source fault are potential source regions for future earthquakes related to the Gorkha earthquake. These two regions may correspond to the historical earthquakes of 1866 and 1344. Possible future earthquakes in the regions are predicted, and the warning for Himalayan seismic hazards remains high even after the Gorkha earthquake.

  13. Plasmon-induced transparency in metamaterials: Active near field coupling between bright superconducting and dark metallic mode resonators

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Singh, Ranjan; Zhang, Caihong; Han, Jiaguang; Tonouchi, Masayoshi; Zhang, Weili

    2013-09-01

    Structured plasmonic metamaterial devices offer the design flexibility to be size scaled for operation across the electromagnetic spectrum and are extremely attractive for generating electromagnetically induced transparency and slow-light behaviors via coupling of bright and dark subwavelength resonators. Here, we experimentally demonstrate a thermally active superconductor-metal coupled resonator based hybrid terahertz metamaterial on a sapphire substrate that shows tunable transparency and slow light behavior as the metamaterial chip is cooled below the high-temperature superconducting phase transition temperature. This hybrid metamaterial opens up the avenues for designing micro-sized active circuitry with switching, modulation, and "slowing down terahertz light" capabilities.

  14. Bayesian exploration of coseismic seafloor deformation process during the 2011 Tohoku-Oki earthquake using near-field tsunami records

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Simons, M.

    2014-12-01

    The diverse range of data for the 2011 Mw 9.0 Tohoku-oki earthquake are unprecedented. However, several models using joint data sets still disagree on the estimated slip distribution due to (1) choice of fault geometry and elastic structure; (2) choice of regularization scheme in optimization approaches; (3) lack or under-estimation of model prediction error due to imperfect forward modeling. Some important questions therefore remain unresolved, e.g., what is the profile of fault slip as one approaches the trench, and how much of the co-seismic signals is recorded in seafloor geodetic measurements. To obtain robust and detailed features of the co-seismic process, we present an approach to invert for the seafloor deformation field using only tsunami waveforms recorded by near-field stations, including GPS buoys, ocean bottom pressure gauges, cable pressure gauges and open ocean DART buoys. In addition to observational error, we incorporate model prediction error by considering the uncertainty in dispersion characteristics of tsunami propagation simulations. We adopt an analytical Bayesian approach to derive the posterior distributions for the coseismic seafloor deformation with minimal a priori assumptions. The analytical approach provides fast and robust characterization of coseismic seafloor deformation using the first arrivals of tsunami waveforms with potential for real-time applications. Our models show that large seafloor uplift is required at the trench, with maximum seafloor uplift occurring about 50 km from the trench. The actual fault slip depends on the assumed elastic structure and fault geometry; in the case of a homogeneous half-space and simplified fault geometry, slip decreases towards the trench. This method also provides direct comparisons with seafloor geodetic measurements and a quantitative estimation of the respective contributions from co- and post-seismic processes.

  15. The Role of Turbulence in Chemical and Dynamical Processes in the Near-Field Wake of Subsonic Aircraft

    NASA Technical Reports Server (NTRS)

    Lewellen, D. C.; Lewellen, W. Steve

    2002-01-01

    During this grant, covering the period from September 1998 to December 2001, we continued the investigation of the role of turbulent mixing in the wake of subsonic aircraft initiated in 1994 for NASA's Atmospheric Effects of Aviation Project. The goal of the research has been to provide sufficient understanding and quantitative analytical capability to assess the dynamical, chemical, and microphysical interactions in the near-field wake that have the greatest potential to influence the global atmospheric impact of the projected fleet of subsonic aircraft. Through large-eddy simulations we have shown that turbulence in the early wake dynamics can have a strong effect on both the ice microphysics of contrail evolution and on wake chemistry. The wake vortex dynamics are the primary determinant of the vertical extent of the contrail; this together with the local wind shear largely determines the horizontal extent. The fraction of the initial ice crystals surviving the wake vortex dynamics, their spatial distribution, and the ice mass distribution are all sensitive to the aircraft type, assumed initial ice crystal number, and ambient humidity and turbulence conditions. Our model indicates that there is a significant range of conditions for which a smaller aircraft such as a B737 produces as significant a persistent contrail as a larger aircraft such as a B747, even though the latter consumes almost five times as much fuel. Large-eddy simulations of the near wake of a B757 provided a fine-grained chemical-dynamical representation of simplified NOx - HOx chemistry in wakes of ages from a few seconds to several minutes. By sampling the simulated data in a manner similar to that of in situ aircraft measurements it was possible to provide a likely explanation for a puzzle uncovered in the 1996 SUCCESS flight measurements of OH and HO2 The results illustrate the importance of considering fluid dynamics effects in interpreting chemistry results when mixing rates and species

  16. Communication: dynamical embedding: correct quantum response from coupling TDDFT for a small cluster with classical near-field electrodynamics for an extended region.

    PubMed

    Gao, Yi; Neuhauser, Daniel

    2013-05-14

    We show how to obtain the correct electronic response of a large system by embedding; a small region is propagated by TDDFT (time-dependent density functional theory) simultaneously with a classical electrodynamics evolution using the Near-Field method over a larger external region. The propagations are coupled through a combined time-dependent density yielding a common Coulomb potential. We show that the embedding correctly describes the plasmonic response of a Mg(0001) slab and its influence on the dynamical charge transfer between an adsorbed H2O molecule and the substrate, giving the same spectral shape as full TDDFT (similar plasmon peak and molecular-dependent differential spectra) with much less computational effort. The results demonstrate that atomistic embedding electrodynamics is promising for nanoplasmonics and nanopolaritonics. PMID:23676021

  17. Communication: Dynamical embedding: Correct quantum response from coupling TDDFT for a small cluster with classical near-field electrodynamics for an extended region

    SciTech Connect

    Gao Yi; Neuhauser, Daniel

    2013-05-14

    We show how to obtain the correct electronic response of a large system by embedding; a small region is propagated by TDDFT (time-dependent density functional theory) simultaneously with a classical electrodynamics evolution using the Near-Field method over a larger external region. The propagations are coupled through a combined time-dependent density yielding a common Coulomb potential. We show that the embedding correctly describes the plasmonic response of a Mg(0001) slab and its influence on the dynamical charge transfer between an adsorbed H{sub 2}O molecule and the substrate, giving the same spectral shape as full TDDFT (similar plasmon peak and molecular-dependent differential spectra) with much less computational effort. The results demonstrate that atomistic embedding electrodynamics is promising for nanoplasmonics and nanopolaritonics.

  18. Coupling diffusion and high-pH precipitation/dissolution in the near field of a HLW repository in clay by means of reactive solute transport models

    NASA Astrophysics Data System (ADS)

    Samper, J.; Font, I.; Yang, C.; Montenegro, L.

    2004-12-01

    The reference concept for a HLW repository in clay in Spain includes a 75 cm thick bentonite buffer which surrounds canisters. A concrete sustainment 20 cm thick is foreseen between the bentonite buffer and the clay formation. The long term geochemical evolution of the near field is affected by a high-pH hyperalkaline plume induced by concrete. Numerical models of multicomponent reactive transport have been developped in order to quantify the evolution of the system over 1 Ma. Water flow is negligible once the bentonite buffer is saturated after about 20 years. Therefore, solute transport occurs mainly by diffusion. Models account for aqueous complexation, acid-base and redox reactions, cation exchange, and mineral dissolution precipitation in the bentonite, the concrete and the clay formation. Numerical results obtained witth CORE2D indicate that the high-pH plume causes significant changes in porewater chemistry both in the bentonite buffer and the clay formation. Porosity changes caused by mineral dissolution/precipitation are extremely important. Therefore, coupled modes of diffusion and reactive transport accounting for changes in porosity caused by mineral precipitation are required in order to obtain realistic predictions.

  19. Nanofabrication using near-field optical probes

    PubMed Central

    McLeod, Euan; Ozcan, Aydogan

    2012-01-01

    Nanofabrication using near-field optical probes is an established technique for rapid prototyping and automated maskless fabrication of nanostructured devices. In this review, we present the primary types of near-field probes and their physical processing mechanisms. Highlights of recent developments include improved resolution by optimizing the probe shape, incorporation of surface plasmonics in probe design, broader use in biological and magnetic storage applications, and increased throughput using probe arrays as well as high speed writing and patterning. PMID:22713756

  20. Land subsidence, structures and processes at the Dead Sea shoreline as revealed by a near-field photogrammetry survey at Ghor Haditha, Jordan

    NASA Astrophysics Data System (ADS)

    Al-Halbouni, Djamil; Holohan, Eoghan P.; Walter, Thomas; Alrshdan, Hussam; Sawarieh, Ali; Dahm, Torsten

    2015-04-01

    Rapid recession of the Dead Sea in the last few decades has led to an increasing rate of sinkhole formation around the lake shore. The development of these sinkholes and other land subsidence phenomena poses a major geological hazard to the local population, agriculture and industry. For a better understanding of the underlying physical processes and for determining current and future areas of sinkhole hazard, we conducted field investigations and a first low altitude ("near-field") aerial photogrammetric survey with a Helikite Balloon at Ghor Haditha, Jordan, in October 2014. From the near-field photogrammetry, we generated a high resolution Digital Elevation Model of the surveyed area. This enables a detailed quantification of sinkhole sizes and distribution as well of morphological parameters such as the sinkhole depth/diameter ratio (D). Values of the latter are generally greater in the mechanically stronger alluvial fan sediments (D = 3.0 - 0.4) than in the weaker muds of the former Dead Sea lakebed (D = 0.3 - 0.1). Importantly, the point of emanation of a very recent and sediment-laden stream at c. 10m below the former floor of the Dead Sea can be structurally and morphologically connected to the main sinkhole area. This provides evidence for channelised subterranean groundwater flows beneath this area. From our observations, two processes were identified as key factors for the development of large land subsidence structures and local sinkhole clusters: (1) Subrosion of weak material due to groundwater following preferred flow paths of ancient and current wadi riverbeds and (2) rapid dissolution of soluble material (salt) in this aragonite-rich mud. The heterogeneous geology and alternation of aquifers (alluvial fan sediments) and aquicludes (mud-flats) lead to the formation of complex subsurface flow channels that represent the secondary porosity of the internal structure of karst aquifers. As a consequence of these subterranean channels, local bending and

  1. DECOVALEX-THMC Task D: Long-Term Permeability/Porosity Changes inthe EDZ and Near Field due to THM and THC Processes in Volcanic andCrystaline-Bentonite Systems, Status Report October 2005

    SciTech Connect

    Birkholzer, J.; Rutqvist, J.; Sonnenthal, E.; Barr, D.

    2005-11-01

    The DECOVALEX project is an international cooperativeproject initiated by SKI, the Swedish Nuclear Power Inspectorate, withparticipation of about 10 international organizations. The name DECOVALEXstands for DEvelopment of COupled models and their VALidation againstExperiments. The general goal of this project is to encouragemultidisciplinary interactive and cooperative research on modelingcoupled processes in geologic formations in support of the performanceassessment for underground storage of radioactive waste. Three multi-yearproject stages of DECOVALEX have been completed in the past decade,mainly focusing on coupled thermal-hydrological-mechanicalprocesses.Currently, a fourth three-year project stage of DECOVALEX isunder way, referred to as DECOVALEX-THMC. THMC stands for Thermal,Hydrological, Mechanical, and Chemical processes. The new project stageaims at expanding the traditional geomechanical scope of the previousDECOVALEX project stages by incorporating geochemical processes importantfor repository performance. The U.S. Department of Energy (DOE) leadsTask D of the new DECOVALEX phase, entitled "Long-termPermeability/Porosity Changes in the EDZ and Near Field due to THC andTHM Processes for Volcanic and Crystalline-Bentonite Systems." In itsleadership role for Task D, DOE coordinates and sets the direction forthe cooperative research activities of the international research teamsengaged in Task D.

  2. Abstraction of Drift-Scale Coupled Processes

    SciTech Connect

    N.D. Francis; D. Sassani

    2000-03-31

    This Analysis/Model Report (AMR) describes an abstraction, for the performance assessment total system model, of the near-field host rock water chemistry and gas-phase composition. It also provides an abstracted process model analysis of potentially important differences in the thermal hydrologic (TH) variables used to describe the performance of a geologic repository obtained from models that include fully coupled reactive transport with thermal hydrology and those that include thermal hydrology alone. Specifically, the motivation of the process-level model comparison between fully coupled thermal-hydrologic-chemical (THC) and thermal-hydrologic-only (TH-only) is to provide the necessary justification as to why the in-drift thermodynamic environment and the near-field host rock percolation flux, the essential TH variables used to describe the performance of a geologic repository, can be obtained using a TH-only model and applied directly into a TSPA abstraction without recourse to a fully coupled reactive transport model. Abstraction as used in the context of this AMR refers to an extraction of essential data or information from the process-level model. The abstraction analysis reproduces and bounds the results of the underlying detailed process-level model. The primary purpose of this AMR is to abstract the results of the fully-coupled, THC model (CRWMS M&O 2000a) for effects on water and gas-phase composition adjacent to the drift wall (in the near-field host rock). It is assumed that drift wall fracture water and gas compositions may enter the emplacement drift before, during, and after the heating period. The heating period includes both the preclosure, in which the repository drifts are ventilated, and the postclosure periods, with backfill and drip shield emplacement at the time of repository closure. Although the preclosure period (50 years) is included in the process models, the postclosure performance assessment starts at the end of this initial period

  3. Novel concepts in near-field optics: from magnetic near-field to optical forces

    NASA Astrophysics Data System (ADS)

    Yang, Honghua

    near-field response of a linear rod antenna is studied with Babinet's principle. Babinet's principle connects the magnetic field of a structure to the electric field of its complement structure. Using combined far- and near-field spectroscopy, imaging, and theory, I identify magnetic dipole and higher order bright and dark magnetic resonances at mid-infrared frequencies. From resonant length scaling and spatial field distributions, I confirm that the theoretical requirement of Babinet's principle for a structure to be infinitely thin and perfectly conducting is still fulfilled to a good approximation in the mid-infrared. Thus Babinet's principle provides access to spatial and spectral magnetic field properties, leading to targeted design and control of magnetic optical antennas. Lastly, a novel form of nanoscale optical spectroscopy based on mechanical detection of optical gradient force is explored. It is to measure the optical gradient force between induced dipole moments of a sample and an atomic force microscope (AFM) tip. My study provides the theoretical basis in terms of spectral behavior, resonant enhancement, and distance dependence of the optical gradient force from numerical simulations for a coupled nanoparticle model geometry. I show that the optical gradient force is dispersive for local electronic and vibrational resonances, yet can be absorptive for collective polaronic excitations. This spectral behavior together with the distance dependence scaling provides the key characteristics for its measurement and distinction from competing processes such as thermal expansion. Furthermore, I provide a perspective for resonant enhancement and control of optical forces in general.

  4. Near-field optical microscopy nanoarray

    NASA Astrophysics Data System (ADS)

    Semin, David J.; Ambrose, W. Patrick; Goodwin, Peter M.; Wendt, Joel R.; Keller, Richard A.

    1997-04-01

    Multiplexing near-field scanning optical microscopy (NSOM) by the use of a nanoarray with parallel imaging is studied. The fabrication, characterization, and utilization of nanoarrays with approximately 100 nm diameter apertures spaced 500 nm center-to-center is presented. Extremely uniform nanoarrays with approximately 108 apertures were fabricated by electron beam lithography and reactive ion etching. The nanoarrays were characterized by atomic force microscopy and scanning electron microscopy. In this paper we utilize these nanoarrays in a laser-illuminated microscope with parallel detection on a charge-coupled device. Detection of B-phycoerythrin molecules using near- field illumination is presented. In principle, our system can be used to obtain high lateral resolution NSOM images over a wide-field of view (e.g. 50 - 100 micrometers ) within seconds.

  5. A near-field optical microscopy nanoarray

    SciTech Connect

    Semin, D.J.; Ambrose, W.P.; Goodwin, P.M.; Kwller, A.; Wendt, J.R.

    1996-12-31

    Multiplexing near-field scanning optical microscopy (NSOM) by the use of a nanoarray with parallel imaging is studied. The fabrication, characterization, and utilization of nanoarrays with {approximately} 100 nm diameter apertures spaced 500 nm center-to- center is presented. Extremely uniform nanoarrays with {approximately} 10{sup 8} apertures were fabricated by electron beam lithography and reactive ion etching. The nanoarrays were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In this paper we utilize these nanoarrays in a laser-illuminated microscope with parallel detection on a charge- coupled device (CCD). Detection of B-phycoerythrin (B-PE) molecules using near-field illumination is presented. In principle, our system can be used to obtain high lateral resolution NSOM images over a wide-field of view (e.g. 50-100 {mu}m) within seconds.

  6. Antenna Near-Field Probe Station Scanner

    NASA Technical Reports Server (NTRS)

    Zaman, Afroz J. (Inventor); Lee, Richard Q. (Inventor); Darby, William G. (Inventor); Barr, Philip J. (Inventor); Lambert, Kevin M (Inventor); Miranda, Felix A. (Inventor)

    2011-01-01

    A miniaturized antenna system is characterized non-destructively through the use of a scanner that measures its near-field radiated power performance. When taking measurements, the scanner can be moved linearly along the x, y and z axis, as well as rotationally relative to the antenna. The data obtained from the characterization are processed to determine the far-field properties of the system and to optimize the system. Each antenna is excited using a probe station system while a scanning probe scans the space above the antenna to measure the near field signals. Upon completion of the scan, the near-field patterns are transformed into far-field patterns. Along with taking data, this system also allows for extensive graphing and analysis of both the near-field and far-field data. The details of the probe station as well as the procedures for setting up a test, conducting a test, and analyzing the resulting data are also described.

  7. Near-field/altered-zone models report

    SciTech Connect

    Hardin, E. L., LLNL

    1998-03-01

    lithophysal units. These units are made up of moderately to densely welded, devitrified, fractured tuff. The rock's chemical composition is comparable to that of typical granite, but has textural features and mineralogical characteristics of large-scale, silicic volcanism. Because the repository horizon will be approximately 300 m below the ground surface and 200 m above the water table, the repository will be partially saturated. The welded tuff matrix in the host units is highly impermeable, but water and gas flow readily through fractures. The degree of fracturing in these units is highly variable, and the hydrologic significance of fracturing is an important aspect of site investigation. This report describes the characterization and modeling of a region around the potential repository--the altered zone--a region in which the temperature will be increased significantly by waste-generated heat. Numerical simulation has shown that, depending on the boundary conditions, rock properties, and repository design features incorporated in the models, the altered zone (AZ) may extend from the water table to the ground surface. This report also describes models of the near field, the region comprising the repository emplacement drifts and the surrounding rock, which are critical to the performance of engineered components. Investigations of near-field and altered-zone (NF/AZ) processes support the design of underground repository facilities and engineered barriers and also provide constraint data for probabilistic calculations of waste-isolation performance (i.e., performance assessment). The approach to investigation, which is an iterative process involving hypothesis testing and experimentation, has relied on conceptualizing engineered barriers and on performance analysis. This report is a collection, emphasizing conceptual and numerical models, of the recent results contributed from studies of NF/AZ processes and of quantitative measures of NF/AZ performance. The selection and

  8. Radiation Entropy and Near-Field Thermophotovoltaics

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuomin M.

    2008-08-01

    Radiation entropy was key to the original derivation of Planck's law of blackbody radiation, in 1900. This discovery opened the door to quantum mechanical theory and Planck was awarded the Nobel Prize in Physics in 1918. Thermal radiation plays an important role in incandescent lamps, solar energy utilization, temperature measurements, materials processing, remote sensing for astronomy and space exploration, combustion and furnace design, food processing, cryogenic engineering, as well as numerous agricultural, health, and military applications. While Planck's law has been fruitfully applied to a large number of engineering problems for over 100 years, questions have been raised about its limitation in micro/nano systems, especially at subwavelength distances or in the near field. When two objects are located closer than the characteristic wavelength, wave interference and photon tunneling occurs that can result in significant enhancement of the radiative transfer. Recent studies have shown that the near-field effects can realize emerging technologies, such as superlens, sub-wavelength light source, polariton-assisted nanolithography, thermophotovoltaic (TPV) systems, scanning tunneling thermal microscopy, etc. The concept of entropy has also been applied to explain laser cooling of solids as well as the second law efficiency of devices that utilize thermal radiation to produce electricity. However, little is known as regards the nature of entropy in near-field radiation. Some history and recent advances are reviewed in this presentation with a call for research of radiation entropy in the near field, due to the important applications in the optimization of thermophotovoltaic converters and in the design of practical systems that can harvest photon energies efficiently.

  9. Ionic contrast terahertz near field imaging

    NASA Astrophysics Data System (ADS)

    Gallot, Guilhem

    2013-09-01

    We demonstrated the direct and noninvasive imaging of functional neurons by Ionic Contrast Terahertz (ICT) near-field microscopy. This technique provides quantitative measurements of ionic concentrations in both the intracellular and extracellular compartments and opens the way to direct noninvasive imaging of neurons during electrical, toxin, or thermal stresses. Furthermore, neuronal activity results from both a precise control of transient variations in ionic conductance and a much less studied water exchange between the extracellular matrix and the intraaxonal compartment. The developed ICT technique associated with a full three-dimensional simulation of the axon-aperture near-field system allows a precise measurement of the axon geometry and therefore the direct visualization of neuron swelling induced by temperature change or neurotoxin poisoning. We also developed Terahertz Attenuated Total Reflection (ATR) devices perfectly suited for studying cell layers. Inserted in a terahertz time-domain system, and using a high resistivity low loss silicon prism to couple the terahertz wave into the sample, the detection scheme is based on the relative differential spectral phase of two orthogonal polarizations. Biological sample imaging as well as subwavelength (λ/16) longitudinal resolution are demonstrated.

  10. NASA-JSC antenna near-field measurement system

    NASA Technical Reports Server (NTRS)

    Cooke, W. P.; Friederich, P. G.; Jenkins, B. M.; Jameson, C. R.; Estrada, J. P.

    1988-01-01

    Work was completed on the near-field range control software. The capabilities of the data processing software were expanded with the addition of probe compensation. In addition, the user can process the measured data from the same computer terminal used for range control. The design of the laser metrology system was completed. It provides precise measruement of probe location during near-field measurements as well as position data for control of the translation beam and probe cart. A near-field range measurement system was designed, fabricated, and tested.

  11. Near field zones of quiet

    NASA Astrophysics Data System (ADS)

    Joseph, P.; Elliott, S. J.; Nelson, P. A.

    1994-05-01

    This paper examines the consequences of driving a single secondary loudspeaker to cancel the pressure due to some primary source at a point in its near field. This simple technique has been applied to the sound field in a highly reverberant room to produce zones of quiet in the vicinity of the loudspeaker, which have diameters that are typically equal to one-tenth of the acoustic wavelength, within which the sound pressure level is attenuated by at least 10 dB. The principal advantage gained with this strategy over other active techniques for controlling the sound field in rooms is that the sound pressure level well away from the control point is largely unaffected, an increase of only a small fraction of one dB being typical. Such a loudspeaker-microphone configuration could be located, for example, in the head rests of cars or aeroplanes, or indeed anywhere where the listener is seated for significant lengths of time and subjected to high ambient noise levels such that auditory comfort may be disturbed.

  12. Report of near field group

    SciTech Connect

    Palmer, R.B.; Baggett, N.; Claus, J.; Fernow, R.; Stumer, I.; Figueroa, H.; Kroll, N.; Funk, W.; Lee-Whiting, G.; Pickup, M.

    1985-04-01

    Substantial progress since the Los Alamos Workshop two years ago is reported. A radio-frequency model of a grating accelerator has been tested at Cornell, and extensive calculations compared with observations. Alternative structures consisting of either hemispherical bumps on a plane, or conducting spheres in space, have also been rf modeled. The use of liquid droplets to form such structures has been proposed and a conceptual design studied. Calculations and experiments have examined the effects of surface plasmas, and shown that in this case the reflectivity is low. However, calculations and observations suggest that gradients in excess of 1 GeV/meter should be obtainable without forming such plasma. An examination of wake fields shows that, with Landau damping, these are independent of wavelength. The use of near field structures to act as high gradient focusing elements has been studied and shows promise, independent of the acceleration mechanism. A proposal has been made to establish a facility that would enable ''proof of principle experiments'' to be performed on these and other laser driven accelerator mechanisms. 11 refs., 10 figs.

  13. Near-field thermodynamics and nanoscale energy harvesting

    NASA Astrophysics Data System (ADS)

    Latella, Ivan; Pérez-Madrid, Agustín; Lapas, Luciano C.; Rubi, J. Miguel

    2015-10-01

    We study the thermodynamics of near-field thermal radiation between two identical polar media at different temperatures. As an application, we consider an idealized energy harvesting process from sources at near room temperature at the nanoscale. We compute the maximum work flux that can be extracted from the radiation in the near-field regime and compare it with the corresponding maximum work flux in the blackbody regime. This work flux is considerably higher in the near-field regime. For materials that support surface phonon polaritons, explicit expressions for the work flux and an upper bound for the efficiency as functions of the surface wave frequency are obtained.

  14. Signal of microstrip scanning near-field optical microscope in far- and near-field zones.

    PubMed

    Morozov, Yevhenii M; Lapchuk, Anatoliy S

    2016-05-01

    An analytical model of interference between an electromagnetic field of fundamental quasi-TM(EH)00-mode and an electromagnetic field of background radiation at the apex of a near-field probe based on an optical plasmon microstrip line (microstrip probe) has been proposed. The condition of the occurrence of electromagnetic energy reverse flux at the apex of the microstrip probe was obtained. It has been shown that the nature of the interference depends on the length of the probe. Numerical simulation of the sample scanning process was conducted in illumination-reflection and illumination-collection modes. Results of numerical simulation have shown that interference affects the scanning signal in both modes. However, in illumination-collection mode (pure near-field mode), the signal shape and its polarity are practically insensible to probe length change; only signal amplitude (contrast) is slightly changed. However, changing the probe length strongly affects the signal amplitude and shape in the illumination-reflection mode (the signal formed in the far-field zone). Thus, we can conclude that even small background radiation can significantly influence the signal in the far-field zone and has practically no influence on a pure near-field signal. PMID:27140358

  15. Near Field Communication: Introduction and Implications

    ERIC Educational Resources Information Center

    McHugh, Sheli; Yarmey, Kristen

    2012-01-01

    Near field communication is an emerging technology that allows objects, such as mobile phones, computers, tags, or posters, to exchange information wirelessly across a small distance. Though primarily associated with mobile payment, near field communication has many different potential commercial applications, ranging from marketing to nutrition,…

  16. Source Rupture Process for the February 21, 2011, Mw6.1, New Zealand Earthquake and the Characteristics of Near-field Strong Ground Motion

    NASA Astrophysics Data System (ADS)

    Meng, L.; Shi, B.

    2011-12-01

    time duration to the observations, especially for the vertical component. Synthetics Fourier spectra are reasonably similar to the recordings. The simulated PGA values of vertical and S26W components are consistent with the recorded, and for the S64E component, the PGA derived from our simulation is smaller than that from observation. The resultant Fourier spectra both for the synthetic and observation is much similar with each other for three components of acceleration time histories, except for the vertical component, where the derived spectra from synthetic data is smaller than that resultant from observation when the frequency is above 10 Hz. Both theoretical study and numerical simulation indicate that, for the 2011 Mw 6.1, New Zealand Earthquake, the higher dynamic stress drop during the source rupture process could play an important role to the anomalous ground-motion amplification beside to the other site-related seismic effects. The composite source modeling based on the simple Brune's pulse model could approximately provide us a good insight into earthquake source related rupture processes for a moderate-sized earthquake.

  17. Attosecond nanoscale near-field sampling

    NASA Astrophysics Data System (ADS)

    Förg, B.; Schötz, J.; Süßmann, F.; Förster, M.; Krüger, M.; Ahn, B.; Okell, W. A.; Wintersperger, K.; Zherebtsov, S.; Guggenmos, A.; Pervak, V.; Kessel, A.; Trushin, S. A.; Azzeer, A. M.; Stockman, M. I.; Kim, D.; Krausz, F.; Hommelhoff, P.; Kling, M. F.

    2016-05-01

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. By comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted.

  18. Attosecond nanoscale near-field sampling.

    PubMed

    Förg, B; Schötz, J; Süßmann, F; Förster, M; Krüger, M; Ahn, B; Okell, W A; Wintersperger, K; Zherebtsov, S; Guggenmos, A; Pervak, V; Kessel, A; Trushin, S A; Azzeer, A M; Stockman, M I; Kim, D; Krausz, F; Hommelhoff, P; Kling, M F

    2016-01-01

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. By comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted. PMID:27241851

  19. Attosecond nanoscale near-field sampling

    PubMed Central

    Förg, B.; Schötz, J.; Süßmann, F.; Förster, M.; Krüger, M.; Ahn, B.; Okell, W. A.; Wintersperger, K.; Zherebtsov, S.; Guggenmos, A.; Pervak, V.; Kessel, A.; Trushin, S. A.; Azzeer, A. M.; Stockman, M. I.; Kim, D.; Krausz, F.; Hommelhoff, P.; Kling, M. F.

    2016-01-01

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. By comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted. PMID:27241851

  20. Attosecond nanoscale near-field sampling

    DOE PAGESBeta

    Forg, B.; Schotz, J.; SuBmann, F.; Forster, M.; Kruger, M.; Ahn, B.; Okell, W. A.; Wintersperger, K.; Zherebtsov, S.; Guggenmos, A.; et al

    2016-05-31

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. Furthermore, by comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted.

  1. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    SciTech Connect

    E. Gonnenthal; N. Spyoher

    2001-02-05

    The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M and O) 2000 [153447]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M and O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: (1) Performance Assessment (PA); (2) Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); (3) UZ Flow and Transport Process Model Report (PMR); and (4) Near-Field Environment (NFE) PMR. The work scope for this activity is presented in the TWPs cited above, and summarized as follows: continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in

  2. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    SciTech Connect

    E. Sonnenthale

    2001-04-16

    The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M&O) 2000 [1534471]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M&O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: Performance Assessment (PA); Near-Field Environment (NFE) PMR; Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); and UZ Flow and Transport Process Model Report (PMR). The work scope for this activity is presented in the TWPs cited above, and summarized as follows: Continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in this AMR are required

  3. Near field heat transfer in superlattices

    NASA Astrophysics Data System (ADS)

    Esquivel-Sirvent, Raul

    2015-03-01

    I present a theoretical calculation of the near field heat transfer between super lattices made of alternative layers of both metallic and semiconducting materials. The calculation of the near field transfer requires the knowledge of the reflectivities, that are obtained by calculating the surface impedance of the super lattice. Depending on the periodicity of the lattice and the dielectric function of the materials the near field heat transfer can be modulated or engineered. Additional control on the heat transfer is achieved by introducing defects in the superlattice. The results are extended to include photonic hypercrystals that effectively behave like a hyperbolic metamaterial even in the near field (1), where the tuning of the heat transfer is modified by Partial Support from DGAPA-UNAM project IN 111214.

  4. Millimeter wave near-field study

    NASA Technical Reports Server (NTRS)

    Kefauver, Neill

    1990-01-01

    The possibility is evaluated of current technology measuring large aperture millimeter wave antennas. Included are a mathematical modeling of system errors, experimental data supporting error model, predictions of system accuracy at millimeter wavelengths, advantage of near-field measurements, and a cost estimate for a facility upgrade. The use is emphasized of software compensation and other inexpensive alternatives to develop a near optimum solution to near-field measurement problems at millimeter wavelengths.

  5. Quantitative imaging of the optical near field.

    PubMed

    Kühler, Paul; García de Abajo, F Javier; Leiprecht, Philipp; Kolloch, Andreas; Solis, Javier; Leiderer, Paul; Siegel, Jan

    2012-09-24

    When exposing small particles on a substrate to a light plane wave, the scattered optical near field is spatially modulated and highly complex. We show, for the particular case of dielectric microspheres, that it is possible to image these optical near-field distributions in a quantitative way. By placing a single microsphere on a thin film of the photosensitive phase change material Ge(2)Sb(5)Te(5) and exposing it to a single short laser pulse, the spatial intensity modulation of the near field is imprinted into the film as a pattern of different material phases. The resulting patterns are investigated by using optical as well as high-resolution scanning electron microscopy. Quantitative information on the local optical near field at each location is obtained by calibrating the material response to pulsed laser irradiation. We discuss the influence of polarization and angle of incidence of the laser beam as well as particle size on the field distribution. The experimental results are in good quantitative agreement with a model based on a rigorous solution of Maxwell's equations. Our results have potential application to near-field optical lithography and experimental determination of near fields in complex nanostructures. PMID:23037356

  6. Thermal infrared near-field spectroscopy.

    PubMed

    Jones, Andrew C; Raschke, Markus B

    2012-03-14

    Despite the seminal contributions of Kirchhoff and Planck describing far-field thermal emission, fundamentally distinct spectral characteristics of the electromagnetic thermal near-field have been predicted. However, due to their evanescent nature their direct experimental characterization has remained elusive. Combining scattering scanning near-field optical microscopy with Fourier-transform spectroscopy using a heated atomic force microscope tip as both a local thermal source and scattering probe, we spectroscopically characterize the thermal near-field in the mid-infrared. We observe the spectrally distinct and orders of magnitude enhanced resonant spectral near-field energy density associated with vibrational, phonon, and phonon-polariton modes. We describe this behavior and the associated distinct on- and off-resonance nanoscale field localization with model calculations of the near-field electromagnetic local density of states. Our results provide a basis for intrinsic and extrinsic resonant manipulation of optical forces, control of nanoscale radiative heat transfer with optical antennas, and use of this new technique of thermal infrared near-field spectroscopy for broadband chemical nanospectroscopy. PMID:22280474

  7. Near-field thermodynamics: Useful work, efficiency, and energy harvesting

    SciTech Connect

    Latella, Ivan Pérez-Madrid, Agustín; Lapas, Luciano C.; Miguel Rubi, J.

    2014-03-28

    We show that the maximum work that can be obtained from the thermal radiation emitted between two planar sources in the near-field regime is much larger than that corresponding to the blackbody limit. This quantity, as well as an upper bound, for the efficiency of the process is computed from the formulation of thermodynamics in the near-field regime. The case when the difference of temperatures of the hot source and the environment is small, relevant for energy harvesting, is studied in detail. We also show that thermal radiation energy conversion can be more efficient in the near-field regime. These results open new possibilities for the design of energy converters that can be used to harvest energy from sources of moderate temperature at the nanoscale.

  8. Near-Field Photothermal Heating with a Plasmonic Nanofocusing Probe

    NASA Astrophysics Data System (ADS)

    Chen, Xiang; Dong, Biqing; Balogun, Oluwaseyi

    2016-03-01

    Noble metal nanostructures support plasmon resonances—collective oscillation of charge carriers at optical frequencies—and serve as effective tools to create bright light sources at the nanoscale. These sources are useful in broad application areas including, super-resolution imaging and spectroscopy, nanolithography, and near-field optomechanical transducers. The feasibility of these applications relies on efficient conversion of free-space propagating light to plasmons. Recently, we demonstrated a hybrid nanofocusing scheme for efficient coupling of light to plasmons at the apex of a scanning probe. In the approach, free-space light is coupled to propagating surface plasmon polaritons (SPPs) on the tapered shaft of the scanning probe. The SPPs propagate adiabatically towards the probe tip where they are coupled to localized plasmons (LSPs). The nanofocusing scheme was explored in a near-field scanning optical microscope for super-resolution imaging, near-field transduction of nanomechanical vibrations, and local detection of ultrasound. Owing to the strong concentration of light at the probe, significant heating of the tip and a sample positioned in the optical near-field is expected. This paper investigates the local heating produced by the plasmonic nanofocusing probe under steady-state conditions using the tip-enhanced Raman scattering approach. In addition, a finite element model is explored to study the coupling of free propagating light to LSPs, and to estimate the temperature rise expected in a halfspace heated by absorption of the LSPs. This study has implications for exploring the plasmonic nanofocusing probe in heat-assisted nanofabrication and fundamental studies of nanoscale heat transport in materials.

  9. Parallel scanning near-field photolithography: the snomipede.

    PubMed

    ul Haq, Ehtsham; Liu, Zhuming; Zhang, Yuan; Ahmad, Shahrul A Alang; Wong, Lu-Shin; Armes, Steven P; Hobbs, Jamie K; Leggett, Graham J; Micklefield, Jason; Roberts, Clive J; Weaver, John M R

    2010-11-10

    The “Millipede”, developed by Binnig and co-workers (Bining, G. K.; et al. IBM J. Res. Devel. 2000, 44, 323.), elegantly solves the problem of the serial nature of scanning probe lithography processes, by deploying massive parallelism. Here we fuse the “Millipede” concept with scanning near-field photolithography to yield a “Snomipede” that is capable of executing parallel chemical transformations at high resolution over macroscopic areas. Our prototype has sixteen probes that are separately controllable using a methodology that is, in principle, scalable to much larger arrays. Light beams generated by a spatial modulator or a zone plate array are coupled to arrays of cantilever probes with hollow, pyramidal tips. We demonstrate selective photodeprotection of nitrophenylpropyloxycarbonyl-protected aminosiloxane monolayers on silicon dioxide and subsequent growth of nanostructured polymer brushes by atom-transfer radical polymerization, and the fabrication of 70 nm structures in photoresist by a Snomipede probe array immersed under water. Such approaches offer a powerful means of integrating the top-down and bottom-up fabrication paradigms, facilitating the reactive processing of materials at nanometer resolution over macroscopic areas. PMID:20945880

  10. Active Extraction of Near-field Thermal Radiation

    NASA Astrophysics Data System (ADS)

    Ding, Ding; Kim, Taeyong; Minnich, Austin

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at sub-wavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active radiative cooling (ARC) scheme to extract these modes to the far-field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far-field. We also provide further insights into our ARC scheme by applying the theoretical framework used for laser cooling of solids (LCS) to ARC. We show that LCS and ARC can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ARC. Using this framework, we examine the predictions of the formalism for LCS and ARC using realistic parameters and find that ARC can achieve higher efficiency and extracted power over a wide range of conditions. Our study demonstrates a new approach to manipulate near-field thermal radiation for thermal management.

  11. Controllable near-field intensity and spot size of hybrid terahertz metamaterial.

    PubMed

    Meng, Dejia; Hoque, M N F; Wang, Wei; Fan, Zhaoyang; Wang, Kejia; Lai, Jianjun; Chen, Changhong

    2015-04-15

    We report controllable near fields around split-ring resonator (SRR) gaps of an active terahertz metamaterial. As extension of parallel-plate capacitors, patterned VO2 is integrated into the metallic SRRs to manipulate the near-field intensity and hot spot size through its metal-insulator transition. This design enhances the device reliability by preventing VO2 dielectric breakdown at a strongly enhanced near field. The near-field intensity and spot size are tunable in broad ranges, and the device is demonstrated to be capable of compensating resonant frequency drift arisen from different interactions due to near-field coupling. It provides an effective method to actively manipulate the light-matter interaction through the strongly enhanced and tunable near fields. PMID:25872063

  12. Volumetric Near-Field Microwave Plasma Generation

    NASA Technical Reports Server (NTRS)

    Exton, R. J.; Balla, R. Jeffrey; Herring, G. C.; Popovic, S.; Vuskovic, L.

    2003-01-01

    A periodic series of microwave-induced plasmoids is generated using the outgoing wave from a microwave horn and the reflected wave from a nearby on-axis concave reflector. The plasmoids are spaced at half-wavelength separations according to a standing-wave pattern. The plasmoids are enhanced by an effective focusing in the near field of the horn (Fresnel region) as a result of a diffractive narrowing. Optical imaging, electron density, and rotational temperature measurements characterize the near field plasma region. Volumetric microwave discharges may have application to combustion ignition in scramjet engines.

  13. Near-field scanning study for radio frequency interference estimation

    NASA Astrophysics Data System (ADS)

    Pan, Jingnan

    This dissertation discusses the novel techniques using near-fields scanning to do radio frequency interference (RFI) estimation. As the electronic products are becoming more and more complicated, the radio frequency (RF) receiver in the system is very likely interfered by multiple noise sources simultaneously. A method is proposed to identify the interference from different noise sources separately, even when they are radiating at the same time. This method is very helpful for engineers to identify the contribution of the coupling from different sources and further solve the electromagnetic interference issues efficiently. On the other hand, the equivalent dipole-moment models and a decomposition method based on reciprocity theory can also be used together to estimate the coupling from the noise source to the victim antennas. This proposed method provides convenience to estimate RFI issues in the early design stage and saves the time of RFI simulation and measurements. The finite element method and image theory can also predict the far fields of the radiation source, locating above a ground plane. This method applies the finite element method (FEM) to get the equivalent current sources from the tangential magnetic near fields. With the equivalent current sources, the far-field radiation can be calculated based on Huygens's Principle and image theory. By using only the magnetic near fields on the simplified Huygens's surface, the proposed method significantly saves measurement time and cost while also retaining good far-field prediction.

  14. Near-field compact dielectric optics

    NASA Astrophysics Data System (ADS)

    Feuermann, Daniel; Gordon, Jeffrey M.; Ng, Tuck Wah

    2006-08-01

    Aplanatic optics crafted from transparent dielectrics can approach the etendue limit for radiative transfer in pragmatic near-field systems. Illustrations are presented for the more demanding realm of high numerical aperture (NA) at the source and/or target. These light couplers can alleviate difficulties in aligning system components, and can achieve the fundamental compactness limit for optical devices that satisfy Fermat's principle.

  15. Near-field NanoThermoMechanical memory

    SciTech Connect

    Elzouka, Mahmoud; Ndao, Sidy

    2014-12-15

    In this letter, we introduce the concept of NanoThermoMechanical Memory. Unlike electronic memory, a NanoThermoMechanical memory device uses heat instead of electricity to record, store, and recover data. Memory function is achieved through the coupling of near-field thermal radiation and thermal expansion resulting in negative differential thermal resistance and thermal latching. Here, we demonstrate theoretically via numerical modeling the concept of near-field thermal radiation enabled negative differential thermal resistance that achieves bistable states. Design and implementation of a practical silicon based NanoThermoMechanical memory device are proposed along with a study of its dynamic response under write/read cycles. With more than 50% of the world's energy losses being in the form of heat along with the ever increasing need to develop computer technologies which can operate in harsh environments (e.g., very high temperatures), NanoThermoMechanical memory and logic devices may hold the answer.

  16. Active thermal extraction of near-field thermal radiation

    NASA Astrophysics Data System (ADS)

    Ding, D.; Kim, T.; Minnich, A. J.

    2016-02-01

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at subwavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active scheme to extract these modes to the far field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far field. Our study demonstrates an approach to manipulate thermal radiation that could find applications in thermal management.

  17. Near-field heat transfer between gold nanoparticle arrays

    SciTech Connect

    Phan, Anh D.; Phan, The-Long; Woods, Lilia M.

    2013-12-07

    The radiative heat transfer between gold nanoparticle layers is presented using the coupled dipole method. Gold nanoparticles are modelled as effective electric and magnetic dipoles interacting via electromagnetic fluctuations. The effect of higher-order multipoles is implemented in the expression of electric polarizability to calculate the interactions at short distances. Our findings show that the near-field radiation reduces as the radius of the nanoparticles is increased. Also, the magnetic dipole contribution to the heat exchange becomes more important for larger particles. When one layer is displayed in parallel with respect to the other layer, the near-field heat transfer exhibits oscillatory-like features due to the influence of the individual nanostructures. Further details about the effect of the nanoparticles size are also discussed.

  18. Coping Processes of Couples Experiencing Infertility

    ERIC Educational Resources Information Center

    Peterson, Brennan D.; Newton, Christopher R.; Rosen, Karen H.; Schulman, Robert S.

    2006-01-01

    This study explored the coping processes of couples experiencing infertility. Participants included 420 couples referred for advanced reproductive treatments. Couples were divided into groups based on the frequency of their use of eight coping strategies. Findings suggest that coping processes, which are beneficial to individuals, may be…

  19. Noise analysis for near-field 3D FM-CW radar imaging systems

    NASA Astrophysics Data System (ADS)

    Sheen, David M.

    2015-05-01

    Near field radar imaging systems are used for demanding security applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit performance in several ways. Practical imaging systems can employ arrays with low gain antennas and relatively large signal distribution networks that have substantial losses which limit transmit power and increase the effective noise figure of the receiver chain, resulting in substantial thermal noise. Phase noise can also limit system performance. The signal coupled from transmitter to receiver is much larger than expected target signals. Phase noise from this coupled signal can set the system noise floor if the oscillator is too noisy. Frequency modulated continuous wave (FM-CW) radar transceivers used in short range systems are relatively immune to the effects of the coupled phase noise due to range correlation effects. This effect can reduce the phase-noise floor such that it is below the thermal noise floor for moderate performance oscillators. Phase noise is also manifested in the range response around bright targets, and can cause smaller targets to be obscured. Noise in synthetic aperture imaging systems is mitigated by the processing gain of the system. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.

  20. From classical to modern near-field optics and the future

    NASA Astrophysics Data System (ADS)

    Ohtsu, Motoichi

    2014-11-01

    This paper reviews the framework of classical near-field optics and recent progress in modern near-field optics. Some applications are also reviewed, including novel optical functional devices, nano-fabrication technologies, energy conversion technologies, and information processing systems. Novel theoretical models based on mathematical science are also presented, as well as an outlook for the future, hinting at the possibilities of near-field optics.

  1. Evaluation of near-field earthquake effects

    SciTech Connect

    Shrivastava, H.P.

    1994-11-01

    Structures and equipment, which are qualified for the design basis earthquake (DBE) and have anchorage designed for the DBE loading, do not require an evaluation of the near-field earthquake (NFE) effects. However, safety class 1 acceleration sensitive equipment such as electrical relays must be evaluated for both NFE and DBE since they are known to malfunction when excited by high frequency seismic motions.

  2. Hill Ciphers over Near-Fields

    ERIC Educational Resources Information Center

    Farag, Mark

    2007-01-01

    Hill ciphers are linear codes that use as input a "plaintext" vector [p-right arrow above] of size n, which is encrypted with an invertible n x n matrix E to produce a "ciphertext" vector [c-right arrow above] = E [middle dot] [p-right arrow above]. Informally, a near-field is a triple [left angle bracket]N; +, *[right angle bracket] that…

  3. Bicollimated near-field Gregorian reflector antenna

    NASA Astrophysics Data System (ADS)

    Rao, J. B. L.

    1983-02-01

    A bicollimated near-field Gregorian reflector is structurally similar to a classical confocal parabolic reflector, but its surfaces are shaped to have better scan capability. A geometrical optics procedure is used in designing the reflector surfaces. A three dimensional ray tracing procedure is used in analyzing the aperture phase errors as the beam is scanned to different angles. The results show that the bicollimated configuration has about 45% greater angular scanning range than the corresponding confocal parabolic dual-reflector system.

  4. Near-field radiofrequency electromagnetic exposure assessment.

    PubMed

    Rubtsova, Nina; Perov, Sergey; Belaya, Olga; Kuster, Niels; Balzano, Quirino

    2015-09-01

    Personal wireless telecommunication devices, such as radiofrequency (RF) electromagnetic field (EMF) sources operated in vicinity of human body, have possible adverse health effects. Therefore, the correct EMF assessment is necessary in their near field. According to international near-field measurement criteria, the specific absorption rate (SAR) is used for absorbed energy distribution assessment in tissue simulating liquid phantoms. The aim of this investigation is to validate the relationship between the H-field of incident EMF and absorbed energy in phantoms. Three typical wireless telecommunication system frequencies are considered (900, 1800 and 2450 MHz). The EMF source at each frequency is an appropriate half-wave dipole antenna and the absorbing medium is a flat phantom filled with the suitable tissue simulating liquid. Two methods for SAR estimation have been used: standard procedure based on E-field measured in tissue simulating medium and a proposed evaluation by measuring the incident H-field. Compared SAR estimations were performed for various distances between sources and phantom. Also, these research data were compared with simulation results, obtained by using finite-difference time-domain method. The acquired data help to determine the source near-field space characterized by the smallest deviation between SAR estimation methods. So, this region near the RF source is suitable for correct RF energy absorption assessment using the magnetic component of the RF fields. PMID:26444190

  5. Ideal near-field thermophotovoltaic cells

    NASA Astrophysics Data System (ADS)

    Molesky, Sean; Jacob, Zubin

    2015-05-01

    We ask the question, what are the ideal characteristics of a near-field thermophotovoltaic cell? Our search leads us to a reformulation of near-field radiative heat transfer in terms of the joint density of electronic states of the emitter-absorber pair in the thermophotovoltaic system. This form reveals that semiconducting materials with narrowband absorption spectra are critical to the energy-conversion efficiency. This essential feature is unavailable in conventional bulk semiconductor cells but can be obtained using low-dimensional materials. Our results show that the presence of matched van Hove singularities resulting from quantum confinement in the emitter and absorber of a thermophotovoltaic cell boosts both the magnitude and spectral selectivity of radiative heat transfer, dramatically improving energy-conversion efficiency. We provide a model near-field thermophotovoltaic system design making use of this idea by employing the van Hove singularities present in carbon nanotubes. Shockley-Queisser analysis shows that the predicted heat transfer characteristics of this model device are fundamentally better than existing thermophotovoltaic designs. Our work paves the way for the use of quantum dots, quantum wells, two-dimensional semiconductors, semiconductor nanowires, and carbon nanotubes as future materials for thermophotovoltaic cells.

  6. Near-field millimeter - wave imaging of nonmetallic materials

    SciTech Connect

    Gopalsami, N.; Bakhtiari, S.; Raptis, A.C.

    1996-12-31

    A near-field millimeter-wave (mm-wave) imaging system has been designed and built in the 94-GHz range for on-line inspection of nonmetallic (dielectric) materials. The imaging system consists of a transceiver block coupled to an antenna that scans the material to be imaged; a reflector plate is placed behind the material. A quadrature IF mixer in the transceiver block enables measurement of in-phase and quadrature-phase components of reflected signals with respect to the transmitted signal. All transceiver components, with the exception of the Gunn-diode oscillator and antenna, were fabricated in uniform blocks and integrated and packaged into a compact unit (12.7 x 10.2 x 2.5 cm). The objective of this work is to test the applicability of a near-field compact mm-wave sensor for on-line inspection of sheetlike materials such as paper, fabrics, and plastics. This paper presents initial near-field mm-wave images of paper and fabric samples containing known artifacts.

  7. Tip-enhanced near-field optical microscopy

    PubMed Central

    Mauser, Nina; Hartschuh, Achim

    2013-01-01

    Tip-enhanced near-field optical microscopy (TENOM) is a scanning probe technique capable of providing a broad range of spectroscopic information on single objects and structured surfaces at nanometer spatial resolution and with highest detection sensitivity. In this review, we first illustrate the physical principle of TENOM that utilizes the antenna function of a sharp probe to efficiently couple light to excitations on nanometer length scales. We then discuss the antenna-induced enhancement of different optical sample responses including Raman scattering, fluorescence, generation of photocurrent and electroluminescence. Different experimental realizations are presented and several recent examples that demonstrate the capabilities of the technique are reviewed. PMID:24100541

  8. Evaluation of near field rock treatment during constructions (LADSfeature #22)

    SciTech Connect

    Sonnenthal, Eric; Spycher, Nicolas

    1998-11-24

    The purpose of this report is to evaluate the effect of near-field rock treatment by injection of reactive material (calcite) above the drift for the purpose of decreasing postclosure drift seepage. The method used for the calculation was a coupled reaction-transport numerical model for gas-water-rock interaction. This includes the mass conservation of heat, liquid and gas for thermohydrological calculations, of aqueous and gaseous species for advective and diffusive transport, and the kinetics of mineral-water reactions.

  9. Near-field Interferometric Imaging of Lightning

    NASA Astrophysics Data System (ADS)

    Stock, M.; Wu, T.; Akiyama, Y.; Kawasaki, Z.; Ushio, T.

    2015-12-01

    In the past, lightning interferometric mapping systems assumed that a source is very far from the measurement location. The assumption greatly simplifies the mathematics needed to locate the source, but the resulting source positions are limited to two spatial dimensions (azimuth and elevation). For short baseline systems, this assumption is very good because the source is almost always much farther away than the diameter of the array, making three-dimensional location all but impossible. By removing the far-field assumption, if the array is large enough it is possible to locate the source in three spatial dimensions using purely interferometric techniques. The purely interferometric method is quite different from the more typical time-of-arrival method. Instead of measuring arrival times or time differences of the radiation arriving at each station, a volume is imaged over a some integration period and then searched for a source. It is not necessary to know that a source exists in the integration period for the interferometric imaging technique to produce a well defined solution. Interferometric imaging can locate sources buried in noise, can locate both continuous and impulsive emission, and is capable of locating multiple simultaneously radiating sources. If the waveforms are corrected for propagation delay to the search volume, the integration period can be made arbitrarily small (limited only by the frequencies being observed), allowing the progression of lightning to be examined in detail. Near-field interferometry works equally well on a wide range of different signal types, from the LF to VHF bands in radio, or even on acoustic emissions from lightning. Near-field imaging can be used to correct the angular locations of short baseline systems when a source is very close to the array, or to produce full three-dimensional maps of lightning with long baseline arrays. Presented here are preliminary results of applying near-field interferometric imaging to the

  10. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, Xiao-Dong; Schultz, Peter G.; Wei, Tao

    1998-01-01

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an endwall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity.

  11. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, X.D.; Schultz, P.G.; Wei, T.

    1998-10-13

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an end wall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity. 17 figs.

  12. Earthquake-Ionosphere Coupling Processes

    NASA Astrophysics Data System (ADS)

    Kamogawa, Masashi

    an ionospheric phenomenon attributed to tsunami, termed tsunamigenic ionospheric hole (TIH) [Kakinami and Kamogwa et al., GRL, 2012]. After the TEC depression accompanying a monoperiodic variation with approximately 4-minute period as an acoustic resonance between the ionosphere and the solid earth, the TIH gradually recovered. In addition, geomagnetic pulsations with the periods of 150, 180 and 210 seconds were observed on the ground in Japan approximately 5 minutes after the mainshock. Since the variation with the period of 180 seconds was simultaneously detected at the magnetic conjugate of points of Japan, namely Australia, field aligned currents along the magnetic field line were excited. The field aligned currents might be excited due to E and F region dynamo current caused by acoustic waves originating from the tsunami. This result implies that a large earthquake generates seismogenic field aligned currents. Furthermore, monoperiodical geomagnetic oscillation pointing to the epicenter of which velocity corresponds to Rayleigh waves occurs. This may occur due to seismogenic arc-current in E region. Removing such magnetic oscillations from the observed data, clear tsunami dynamo effect was found. This result implies that a large EQ generates seismogenic field aligned currents, seismogenic arc-current and tsunami dynamo current which disturb geomagnetic field. Thus, we found the complex coupling process between a large EQ and an ionosphere from the results of Tohoku EQ.

  13. Active Thermal Extraction and Temperature Sensing of Near-field Thermal Radiation

    PubMed Central

    Ding, D.; Kim, T.; Minnich, A. J.

    2016-01-01

    Recently, we proposed an active thermal extraction (ATX) scheme that enables thermally populated surface phonon polaritons to escape into the far-field. The concept is based on a fluorescence upconversion process that also occurs in laser cooling of solids (LCS). Here, we present a generalized analysis of our scheme using the theoretical framework for LCS. We show that both LCS and ATX can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ATX. Using this framework, we compare the ideal efficiency and power extracted for the two schemes and examine the parasitic loss mechanisms. This work advances the application of ATX to manipulate near-field thermal radiation for applications such as temperature sensing and active radiative cooling. PMID:27595609

  14. Active Thermal Extraction and Temperature Sensing of Near-field Thermal Radiation.

    PubMed

    Ding, D; Kim, T; Minnich, A J

    2016-01-01

    Recently, we proposed an active thermal extraction (ATX) scheme that enables thermally populated surface phonon polaritons to escape into the far-field. The concept is based on a fluorescence upconversion process that also occurs in laser cooling of solids (LCS). Here, we present a generalized analysis of our scheme using the theoretical framework for LCS. We show that both LCS and ATX can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ATX. Using this framework, we compare the ideal efficiency and power extracted for the two schemes and examine the parasitic loss mechanisms. This work advances the application of ATX to manipulate near-field thermal radiation for applications such as temperature sensing and active radiative cooling. PMID:27595609

  15. Curved laser microjet in near field.

    PubMed

    Kotlyar, Victor V; Stafeev, Sergey S; Kovalev, Alexey A

    2013-06-20

    With the use of the finite-difference time-domain-based simulation and a scanning near-field optical microscope that has a metal cantilever tip, the diffraction of a linearly polarized plane wave of wavelength λ by a glass corner step of height 2λ is shown to generate a low divergence laser jet of a root-parabolic form: over a distance of 4.7λ on the optical axis, the beam path is shifted by 2.1λ. The curved laser jet of the FWHM length depth of focus=9.5λ has the diameter FWHM=1.94λ over the distance 5.5λ, and the intensity maximum is 5 times higher than the incident wave intensity. The discrepancy between the analytical and the experimental results amounts to 11%. PMID:23842153

  16. MOUNTAIN-SCALE COUPLED PROCESSES (TH/THC/THM)MODELS

    SciTech Connect

    Y.S. Wu

    2005-08-24

    This report documents the development and validation of the mountain-scale thermal-hydrologic (TH), thermal-hydrologic-chemical (THC), and thermal-hydrologic-mechanical (THM) models. These models provide technical support for screening of features, events, and processes (FEPs) related to the effects of coupled TH/THC/THM processes on mountain-scale unsaturated zone (UZ) and saturated zone (SZ) flow at Yucca Mountain, Nevada (BSC 2005 [DIRS 174842], Section 2.1.1.1). The purpose and validation criteria for these models are specified in ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Drift-Scale Abstraction) Model Report Integration'' (BSC 2005 [DIRS 174842]). Model results are used to support exclusion of certain FEPs from the total system performance assessment for the license application (TSPA-LA) model on the basis of low consequence, consistent with the requirements of 10 CFR 63.342 [DIRS 173273]. Outputs from this report are not direct feeds to the TSPA-LA. All the FEPs related to the effects of coupled TH/THC/THM processes on mountain-scale UZ and SZ flow are discussed in Sections 6 and 7 of this report. The mountain-scale coupled TH/THC/THM processes models numerically simulate the impact of nuclear waste heat release on the natural hydrogeological system, including a representation of heat-driven processes occurring in the far field. The mountain-scale TH simulations provide predictions for thermally affected liquid saturation, gas- and liquid-phase fluxes, and water and rock temperature (together called the flow fields). The main focus of the TH model is to predict the changes in water flux driven by evaporation/condensation processes, and drainage between drifts. The TH model captures mountain-scale three-dimensional flow effects, including lateral diversion and mountain-scale flow patterns. The mountain-scale THC model evaluates TH effects on water and gas

  17. Surface wave multipath signals in near-field microwave imaging.

    PubMed

    Meaney, Paul M; Shubitidze, Fridon; Fanning, Margaret W; Kmiec, Maciej; Epstein, Neil R; Paulsen, Keith D

    2012-01-01

    Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations. PMID:22566992

  18. Surface Wave Multipath Signals in Near-Field Microwave Imaging

    PubMed Central

    Meaney, Paul M.; Shubitidze, Fridon; Fanning, Margaret W.; Kmiec, Maciej; Epstein, Neil R.; Paulsen, Keith D.

    2012-01-01

    Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations. PMID:22566992

  19. Near-field thermoacoustic tomography of small animals

    NASA Astrophysics Data System (ADS)

    Kellnberger, Stephan; Hajiaboli, Amir; Razansky, Daniel; Ntziachristos, Vasilis

    2011-06-01

    Near-field radiofrequency thermoacoustic (NRT) tomography is a new imaging method that was developed to mitigate limitations of conventional thermoacoustic imaging approaches, related to hard compromises between signal strength and spatial resolution. By utilizing ultrahigh-energy electromagnetic impulses at ~20 ns duration along with improved energy absorption coupling in the near-field, this method can deliver high-resolution images without compromising signal to noise ratio. NRT is a promising modality, offering cost-effectiveness and ease of implementation and it can be conveniently scaled to image small animals and humans. However, several of the performance metrics of the method are not yet documented. In this paper, we characterize the expected imaging performance via numerical simulations based on a finite-integration time-domain (FITD) technique and experiments using tissue mimicking phantoms and different biological samples. Furthermore, we show for the first time whole-body tomographic imaging results from mice, revealing clear anatomical details along with highly dissipative inclusions introduced for control. The best spatial resolution achieved for those experiments was 150 µm.

  20. Near-field performance assessment for the Saltstone Disposal Facility

    SciTech Connect

    Seitz, R.R.; Dicke, C.A.; Walton, J.C.

    1993-12-31

    A near-field performance assessment (PA) was conducted for the Saltstone Disposal Facility (SDF) at the Savannah River Site in South Carolina. The analysis was conducted in four parts: general screening calculations, degradation calculations, and flow and transport through the fractured and nonfractured facility. Modeling approaches and example sensitivity analysis results from the simulations of the fractured facility are discussed. Design considerations that may not be apparent without addressing flow and transport through fractures and lessons learned during the process are also presented.

  1. Electrooptic sensor module fabrication for near-field intrabody communication

    NASA Astrophysics Data System (ADS)

    Furuya, Akinori; Sasaki, Ai-ichiro; Morimura, Hiroki; Kagami, Osamu; Shinagawa, Mitsuru

    2014-09-01

    In this paper, we describe how to obtain a low cost electrooptic (EO) sensor module for the mass production of near-field intrabody communication devices. In our previous study, we used a bulk cleavage technique to fabricate EO modulators without the need for any optical polishing or washing processes. In this study, we fabricated EO modulators as a miniaturized chip sensor without a base portion, and clarified the feasibility of assembling optical components by only a passive alignment technique with a compact housing.

  2. Infrared near-field imaging and spectroscopy based on thermal or synchrotron radiation

    SciTech Connect

    Peragut, Florian; De Wilde, Yannick; Brubach, Jean-Blaise; Roy, Pascale

    2014-06-23

    We demonstrate the coupling of a scattering near-field scanning optical microscope combined with a Fourier transform infrared spectrometer. The set-up operates using either the near-field thermal emission from the sample itself, which is proportional to the electromagnetic local density of states, or with an external infrared synchrotron source, which is broadband and highly brilliant. We perform imaging and spectroscopy measurements with sub-wavelength spatial resolution in the mid-infrared range on surfaces made of silicon carbide and gold and demonstrate the capabilities of the two configurations for super-resolved near-field mid-infrared hyperspectral imaging and that the simple use of a properly chosen bandpass filter on the detector allows one to image the spatial distribution of materials with sub-wavelength resolution by studying the contrast in the near-field images.

  3. The Survey on Near Field Communication.

    PubMed

    Coskun, Vedat; Ozdenizci, Busra; Ok, Kerem

    2015-01-01

    Near Field Communication (NFC) is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of applications into one single smartphone. NFC technology has emerged recently, and consequently not much academic data are available yet, although the number of academic research studies carried out in the past two years has already surpassed the total number of the prior works combined. This paper presents the concept of NFC technology in a holistic approach from different perspectives, including hardware improvement and optimization, communication essentials and standards, applications, secure elements, privacy and security, usability analysis, and ecosystem and business issues. Further research opportunities in terms of the academic and business points of view are also explored and discussed at the end of each section. This comprehensive survey will be a valuable guide for researchers and academicians, as well as for business in the NFC technology and ecosystem. PMID:26057043

  4. The Survey on Near Field Communication

    PubMed Central

    Coskun, Vedat; Ozdenizci, Busra; Ok, Kerem

    2015-01-01

    Near Field Communication (NFC) is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of applications into one single smartphone. NFC technology has emerged recently, and consequently not much academic data are available yet, although the number of academic research studies carried out in the past two years has already surpassed the total number of the prior works combined. This paper presents the concept of NFC technology in a holistic approach from different perspectives, including hardware improvement and optimization, communication essentials and standards, applications, secure elements, privacy and security, usability analysis, and ecosystem and business issues. Further research opportunities in terms of the academic and business points of view are also explored and discussed at the end of each section. This comprehensive survey will be a valuable guide for researchers and academicians, as well as for business in the NFC technology and ecosystem. PMID:26057043

  5. Gold Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.; Witherow, William K.

    2000-01-01

    We report what is believed to be the first experimental demonstration of gold coating by a chemical baking process on tapered fiber tips used in near-field scanning optical microscopy. Many tips can be simultaneously coated.

  6. Tuning near-field enhancements on an off-resonance nanorod dimer via temporally shaped femtosecond laser

    NASA Astrophysics Data System (ADS)

    Du, Guangqing; Yang, Qing; Chen, Feng; Lu, Yu; Wu, Yanmin; Ou, Yan; Hou, Xun

    2015-11-01

    We theoretically investigated ultrafast thermal dynamics tuning of near-field enhancements on an off-resonance gold nanorod dimer via temporally shaped femtosecond (fs) laser double pulses. The nonequilibrium thermal excitation is self-consistently coupled into a near-field scattering model for exploring the ultrafast near-field enhancement effects. It is revealed that the near electric-field localized within the gold nanorod dimer can be largely promoted via optimizing the temporal separation and the pulse energy ratio of temporally shaped femtosecond laser double pulses. The results are explained as thermal dynamics manipulation of plasmon resonances in the nanorod dimer via tailoring temporally shaped femtosecond laser. This study provides basic understanding for tuning near-field properties on poorly fabricated metallic nano-structures via temporally shaped femtosecond laser, which can find potential applications in the fields such as fs super-resolution near-field imaging, near-field optical tweezers, and fs photothermal therapy.

  7. Coupled transport processes in semipermeable media

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1990-03-01

    The thermodynamics of irreversible processes leads to nonlinear governing equations for direct and coupled mass transport processes. Analytical solutions of linearized versions of these equations can be used to verify numerical solutions of the nonlinear equations under conditions such that nonlinear terms are relatively small. This report presents derivations of the analytical solutions for one-dimensional and axisymmetric geometries. 7 refs.

  8. Coupled processes associated with nuclear waste repositories

    SciTech Connect

    Tsang, C.F.

    1987-01-01

    This book deals with coupled processes which affect a nuclear waste repository. While there are many descriptive accounts of environmental degradation resulting from various land uses, the author emphasizes the geomorphic processes responsible for such changes and the reasons why various reclamation practices are valuable in environmental management.

  9. Near-field imaging of optical antenna modes in the mid-infrared.

    PubMed

    Olmon, Robert L; Krenz, Peter M; Jones, Andrew C; Boreman, Glenn D; Raschke, Markus B

    2008-12-01

    Optical antennas can enhance the coupling between free-space propagating light and the localized excitation of nanoscopic light emitters or receivers, thus forming the basis of many nanophotonic applications. Their functionality relies on an understanding of the relationship between the geometric parameters and the resulting near-field antenna modes. Using scattering-type scanning near-field optical microscopy (s-SNOM) with interferometric homodyne detection, we investigate the resonances of linear Au wire antennas designed for the mid-IR by probing specific vector near-field components. A simple effective wavelength scaling is observed for single wires with lambda(eff) = lambda /(2.0+/- 0.2), specific to the geometric and material parameters used. The disruption of the coherent current oscillation by introducing a gap gives rise to an effective multipolar mode for the two near-field coupled segments. Using antenna theory and numerical electrodynamics simulations two distinct coupling regimes are considered that scale with gap width or reactive near-field decay length, respectively. The results emphasize the distinct antenna behavior at optical frequencies compared to impedance matched radio frequency (RF) antennas and provide experimental confirmation of theoretically predicted scaling laws at optical frequencies. PMID:19065168

  10. Far-field subwavelength imaging with near-field resonant metalens scanning at microwave frequencies

    PubMed Central

    Wang, Ren; Wang, Bing-Zhong; Gong, Zhi-Shuang; Ding, Xiao

    2015-01-01

    A method for far-field subwavelength imaging at microwave frequencies using near-field resonant metalens scanning is proposed. The resonant metalens is composed of switchable split-ring resonators (SRRs). The on-SRR has a strong magnetic coupling ability and can convert evanescent waves into propagating waves using the localized resonant modes. In contrast, the off-SRR cannot achieve an effective conversion. By changing the switch status of each cell, we can obtain position information regarding the subwavelength source targets from the far field. Because the spatial response and Green’s function do not need to be measured and evaluated and only a narrow frequency band is required for the entire imaging process, this method is convenient and adaptable to various environment. This method can be used for many applications, such as subwavelength imaging, detection, and electromagnetic monitoring, in both free space and complex environments. PMID:26053074

  11. Vibrational near-field mapping of planar and buried three-dimensional plasmonic nanostructures.

    PubMed

    Dregely, Daniel; Neubrech, Frank; Duan, Huigao; Vogelgesang, Ralf; Giessen, Harald

    2013-01-01

    Nanoantennas confine electromagnetic fields at visible and infrared wavelengths to volumes of only a few cubic nanometres. Assessing their near-field distribution offers fundamental insight into light-matter coupling and is of special interest for applications such as radiation engineering, attomolar sensing and nonlinear optics. Most experimental approaches to measure near-fields employ either diffraction-limited far-field methods or intricate near-field scanning techniques. Here, using diffraction-unlimited far-field spectroscopy in the infrared, we directly map the intensity of the electric field close to plasmonic nanoantennas. We place a patch of probe molecules with 10 nm accuracy at different locations in the near-field of a resonant antenna and extract the molecular vibrational excitation. We map the field intensity along a dipole antenna and gap-type antennas. Moreover, this method is able to assess the near-field intensity of complex buried plasmonic structures. We demonstrate this by measuring for the first time the near-field intensity of a three-dimensional plasmonic electromagnetically induced transparency structure. PMID:23892519

  12. Dynamic near-field optical interaction between oscillating nanomechanical structures

    PubMed Central

    Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi

    2015-01-01

    Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequency demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45 pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20 nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129 MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures. PMID:26014599

  13. Dynamic near-field optical interaction between oscillating nanomechanical structures

    SciTech Connect

    Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi

    2015-05-27

    Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequency demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures.

  14. Dynamic near-field optical interaction between oscillating nanomechanical structures

    DOE PAGESBeta

    Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi

    2015-05-27

    Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequencymore » demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures.« less

  15. Assessment of Near-Field Sonic Boom Simulation Tools

    NASA Technical Reports Server (NTRS)

    Casper, J. H.; Cliff, S. E.; Thomas, S. D.; Park, M. A.; McMullen, M. S.; Melton, J. E.; Durston, D. A.

    2008-01-01

    A recent study for the Supersonics Project, within the National Aeronautics and Space Administration, has been conducted to assess current in-house capabilities for the prediction of near-field sonic boom. Such capabilities are required to simulate the highly nonlinear flow near an aircraft, wherein a sonic-boom signature is generated. There are many available computational fluid dynamics codes that could be used to provide the near-field flow for a sonic boom calculation. However, such codes have typically been developed for applications involving aerodynamic configuration, for which an efficiently generated computational mesh is usually not optimum for a sonic boom prediction. Preliminary guidelines are suggested to characterize a state-of-the-art sonic boom prediction methodology. The available simulation tools that are best suited to incorporate into that methodology are identified; preliminary test cases are presented in support of the selection. During this phase of process definition and tool selection, parallel research was conducted in an attempt to establish criteria that link the properties of a computational mesh to the accuracy of a sonic boom prediction. Such properties include sufficient grid density near shocks and within the zone of influence, which are achieved by adaptation and mesh refinement strategies. Prediction accuracy is validated by comparison with wind tunnel data.

  16. Coupling environmental models and geospatial data processing

    NASA Astrophysics Data System (ADS)

    Brandmeyer, Jo Ellen

    2000-10-01

    This research investigated geospatial functions for solving environmental problems from the perspective of the environmental modeler. Its purpose is to better understand the different approaches to coupling complex models and geospatial data processing, plus the implications for the coupled system. To this end, various coupling methodologies were systematically explored using a geographic information system (GIS) and an emissions processor (SMOKE) for air quality models (AQMs). SMOKE converts an emissions inventory into the format required by an AQM. A GIS creates a file describing the spatial distribution of emissions among the cells in a modeling domain. To demonstrate advantages of a coupled GIS---environmental model system, two methods of spatially distributing on-road mobile emissions to cells were examined. The existing method calculates emissions for each road class, but distributes emissions to the cells using population density. For the new method a GIS builds road density by class and then distributes the emissions using road density. Comparing these methods reveals a significantly different spatial pattern of emissions. Next, various model-coupling methodologies were analyzed, revealing numerous coupling approaches, some of which were categorized in the literature. Critiquing these categorizations while comparing them with documented implementations led to the development of a new coupling hierarchy. The properties of each hierarchical level are discussed with the advantages and limitations of each design. To successfully couple models, the spatial and temporal scales of all models in the coupled system and the spatiotemporal extents of the data must be reconciled. Finally, a case study demonstrated methodologies for coupling SMOKE and a GIS. One methodology required a new approach utilizing dynamically linked libraries. Consequently, emissions were processed using SMOKE from a GIS. Also, a new method of converting data from netCDF files into a database

  17. Experimental characterization of Fabry-Perot resonances of magnetostatic volume waves in near-field metamaterials

    NASA Astrophysics Data System (ADS)

    Chabalko, Matthew J.; Ricketts, David S.

    2015-02-01

    In this work, we report on the experimental demonstration of magnetoquasistatic volume wave resonances in a 2-dimensional near field metamaterial (MM). Previous works have described only theoretically the magnetostatic waves in near field MMs and have reported peaks and valleys in the mutual coupling of MM enhanced wireless power transfer that they have attributed to Fabry-Perot resonances, however, neither has been experimentally measured nor characterized. We report on the direct magnetic field measurement of magnetostatic volume waves in a 2D near-field MM and show that the periodic peaks and valleys in mutual coupling observed previously are indeed due to a Fabry-Perot oscillation. In addition, we show that these resonances can be predicted from experimentally extracted permeability and the dimensions of the system.

  18. DRIFT-SCALE COUPLED PROCESSES (DST AND TH SEEPAGE) MODELS

    SciTech Connect

    J.T. Birkholzer; S. Mukhopadhyay

    2005-01-13

    The purpose of this report is to document drift-scale modeling work performed to evaluate the thermal-hydrological (TH) behavior in Yucca Mountain fractured rock close to waste emplacement drifts. The heat generated by the decay of radioactive waste results in rock temperatures elevated from ambient for thousands of years after emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, giving rise to water redistribution and altered flow paths. The predictive simulations described in this report are intended to investigate fluid flow in the vicinity of an emplacement drift for a range of thermal loads. Understanding the TH coupled processes is important for the performance of the repository because the thermally driven water saturation changes affect the potential seepage of water into waste emplacement drifts. Seepage of water is important because if enough water gets into the emplacement drifts and comes into contact with any exposed radionuclides, it may then be possible for the radionuclides to be transported out of the drifts and to the groundwater below the drifts. For above-boiling rock temperatures, vaporization of percolating water in the fractured rock overlying the repository can provide an important barrier capability that greatly reduces (and possibly eliminates) the potential of water seeping into the emplacement drifts. In addition to this thermal process, water is inhibited from entering the drift opening by capillary forces, which occur under both ambient and thermal conditions (capillary barrier). The combined barrier capability of vaporization processes and capillary forces in the near-field rock during the thermal period of the repository is analyzed and discussed in this report.

  19. Drift-Scale Coupled Processes (DST and TH Seepage) Models

    SciTech Connect

    J. Birkholzer; S. Mukhopadhyay

    2004-09-29

    The purpose of this report is to document drift-scale modeling work performed to evaluate the thermal-hydrological (TH) behavior in Yucca Mountain fractured rock close to waste emplacement drifts. The heat generated by the decay of radioactive waste results in rock temperatures elevated from ambient for thousands of years after emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, giving rise to water redistribution and altered flow paths. The predictive simulations described in this report are intended to investigate fluid flow in the vicinity of an emplacement drift for a range of thermal loads. Understanding the TH coupled processes is important for the performance of the repository because the thermally driven water saturation changes affect the potential seepage of water into waste emplacement drifts. Seepage of water is important because if enough water gets into the emplacement drifts and comes into contact with any exposed radionuclides, it may then be possible for the radionuclides to be transported out of the drifts and to the groundwater below the drifts. For above-boiling rock temperatures, vaporization of percolating water in the fractured rock overlying the repository can provide an important barrier capability that greatly reduces (and possibly eliminates) the potential of water seeping into the emplacement drifts. In addition to this thermal process, water is inhibited from entering the drift opening by capillary forces, which occur under both ambient and thermal conditions (capillary barrier). The combined barrier capability of vaporization processes and capillary forces in the near-field rock during the thermal period of the repository is analyzed and discussed in this report.

  20. A unidirectional subwavelength focusing near-field plate

    SciTech Connect

    Imani, Mohammadreza F.; Grbic, Anthony

    2014-01-28

    Near-field plates consist of non-periodically patterned surfaces that can overcome the diffraction limit and confine electromagnetic fields to subwavelength dimensions. Previous near-field plates experimentally demonstrated extreme field tailoring capabilities. However, their performance suffered from radiation/reflection in undesired directions, those other than the subwavelength focus. This issue can limit the practical use of near-field plates. In this paper, we address this issue by designing a unidirectional near-field plate that can form a subwavelength focal pattern, while suppressing the field radiated/reflected in other directions. The design and operation of the proposed unidirectional near-field plate are verified through full-wave simulation. The unidirectional near-field plate may find application in high resolution imaging and probing, high density data storage, and wireless power transfer systems. As an example, its utility as a high resolution probe is demonstrated through full-wave electromagnetic simulation.

  1. Near-field imaging techniques for surface inspection

    NASA Astrophysics Data System (ADS)

    Dannenberg, Florian; Hahlweg, Cornelius; Pescoller, Lukas; Zhao, Wenjing

    2014-09-01

    Following the recent work on the characterization of flexo-printing plates a concept for inspection of glossy surfaces using a defined out of focus image of the surface under parallel illumination is presented, which in principle represents a near field distribution of the reflection function of the surface. The image turns out to be equivalent to a focussed shadowgraph as used for the investigation of processes in transparent media. Beside the plain 'reflected shadow imaging' several degrees of freedom can be exploited for configuration of the feature emphasis. The method is especially interesting for the quality control of printed matter. In the paper the definition of the system, the mechanism of the imaging process and its relation to the real image of the surface itself are considered. Further, questions of resolution, extractable features and extended applications are discussed.

  2. CAD/CAM-coupled image processing systems

    NASA Astrophysics Data System (ADS)

    Ahlers, Rolf-Juergen; Rauh, W.

    1990-08-01

    Image processing systems have found wide application in industry. For most computer integrated manufacturing faci- lities it is necessary to adapt these systems thus that they can automate the interaction with and the integration of CAD and CAM Systems. In this paper new approaches will be described that make use of the coupling of CAD and image processing as well as the automatic generation of programmes for the machining of products.

  3. Induction coupled thermomagnetic processing: A disruptive technology

    DOE PAGESBeta

    Ahmad, Aquil; Mackiewicz-Ludtka, Gail; Pfaffmann, George; Ludtka, Gerard Michael

    2016-06-01

    Here, one of the major goals of the U.S. Department of Energy (DoE) is to achieve energy savings with a corresponding reduction in the carbon footprint. With this in mind, the DoE sponsored the Induction Coupled Thermomagnetic Processing (ITMP) project with major partners Eaton Corp., Ajax Tocco Magnethermic, and Oak Ridge National Laboratory (ORNL) to evaluate the viability of processing metals in a strong magnetic field.

  4. Near field interactions in terahertz metamaterials

    NASA Astrophysics Data System (ADS)

    Keiser, George R.

    Terahertz (THz) frequencies comprise the portion of the electromagnetic spectrum more energetic than microwaves, but less energetic than infrared light. The THz band presents many opportunities for condensed matter physics and optics engineering. From the physics perspective, advances in the generation and detection of THz radiation have opened the door for spectroscopic studies of a range of solid-state phenomena that manifest at THz frequencies. From an engineering perspective, THz frequencies are an under-used spectral region, ripe for the development of new devices. In both cases, the challenge for researchers is to overcome a lack of sources, detectors, and optics for THz light, termed the THz Gap. Metamaterials (MMs), composite structures with engineered index of refraction, n, and impedance, Z, provide one path towards realizing THz optics. MMs are an ideal platform for the design of local EM field distributions, and far-field optical properties. This is especially true at THz frequencies, where fabrication of inclusions is easily accomplished with photolithography. Historically, MM designs have been based around static configurations of resonant inclusions that work only in a narrow frequency band, limiting applications. Broadband and tunable MMs are needed to overcome this limit. This dissertation focuses on creating tunable and controllable MM structures through the manipulation of electromagnetic interactions between MM inclusions. We introduce three novel MM systems. Each system is studied computationally with CST-Studio, and experimentally via THz spectroscopy. First, we look at the tunable transmission spectrum of two coupled split ring resonators (SRRs) with different resonant frequencies. We show that introducing a lateral displacement between the two component resonators lowers the electromagnetic coupling between the SRRs, activating a new resonance. Second, we study an SRR array, coupled to a non-resonant closed ring array. We show that lowering

  5. Nanospectrofluorometry inside single living cell by scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Lei, F. H.; Shang, G. Y.; Troyon, M.; Spajer, M.; Morjani, H.; Angiboust, J. F.; Manfait, M.

    2001-10-01

    Near-field fluorescence spectra with subdiffraction limit spatial resolution have been taken in the proximity of mitochondrial membrane inside breast adenocarcinoma cells (MCF7) treated with the fluorescent dye (JC-1) by using a scanning near-field optical microscope coupled with a confocal laser microspectrofluorometer. The probe-sample distance control is based on a piezoelectric bimorph shear force sensor having a static spring constant k=5 μN/nm and a quality factor Q=40 in a physiological medium of viscosity η=1.0 cp. The sensitivity of the force sensor has been tested by imaging a MCF7 cell surface.

  6. Heat flux splitter for near-field thermal radiation

    SciTech Connect

    Ben-Abdallah, P.; Belarouci, A.; Frechette, L.; Biehs, S.-A.

    2015-08-03

    We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the development of an active control of propagation directions for heat fluxes exchanged in the near field throughout integrated nanostructured networks.

  7. Coupled transport processes in semipermeable media

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1990-04-01

    A numerical simulator has been developed to investigate the effects of coupled processes on heat and mass transport in semipermeable media. The governing equations on which the simulator is based were derived using the thermodynamics of irreversible processes. The equations are nonlinear and have been solved numerically using the n-dimensional Newton's method. As an example of an application, the numerical simulator has been used to investigate heat and solute transport in the vicinity of a heat source buried in a saturated clay-like medium, in part to study solute transport in bentonite packing material surrounding a nuclear waste canister. The coupled processes considered were thermal filtration, thermal osmosis, chemical osmosis and ultrafiltration. In the simulations, heat transport by coupled processes was negligible compared to heat conduction, but pressure and solute migration were affected. Solute migration was retarded relative to the uncoupled case when only chemical osmosis was considered. When both chemical osmosis and thermal osmosis were included, solute migration was enhanced. 18 refs., 20 figs.

  8. Mesoscopic near-field radiative heat transfer at low temperatures

    NASA Astrophysics Data System (ADS)

    Maasilta, Ilari; Geng, Zhuoran; Chaudhuri, Saumyadip; Koppinen, Panu

    2015-03-01

    Near-field radiative heat transfer has mostly been discussed at room temperatures and/or macroscopic scale geometries. Here, we discuss our recent theoretical and experimental advances in understanding near-field transfer at ultra-low temperatures below 1K. As the thermal wavelengths increase with lowering temperature, we show that with sensitive tunnel junction bolometers it is possible to study near-field transfer up to distances ~ 10 μm currently, even though the power levels are low. In addition, these type of experiments correspond to the extreme near-field limit, as the near-field region starts at ~ mm distances at 0.1 K, and could have theoretical power enhancement factors of the order of 1010. Preliminary results on heat transfer between two parallel metallic wires are presented. We also comment on possible areas were such heat transfer might be relevant, such as densely packed arrays of low-temperature detectors.

  9. Modeling of Inner Magnetosphere Coupling Processes

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.

    2011-01-01

    The Ring Current (RC) is the biggest energy player in the inner magnetosphere. It is the source of free energy for Electromagnetic Ion Cyclotron (EMIC) wave excitation provided by a temperature anisotropy of RC ions, which develops naturally during inward E B convection from the plasmasheet. The cold plasmasphere, which is under the strong influence of the magnetospheric electric field, strongly mediates the RC-EMIC wave-particle-coupling process and ultimately becomes part of the particle and energy interplay. On the other hand, there is a strong influence of the RC on the inner magnetospheric electric and magnetic field configurations and these configurations, in turn, are important to RC dynamics. Therefore, one of the biggest needs for inner magnetospheric research is the continued progression toward a coupled, interconnected system with the inclusion of nonlinear feedback mechanisms between the plasma populations, the electric and magnetic fields, and plasma waves. As we clearly demonstrated in our studies, EMIC waves strongly interact with electrons and ions of energies ranging from approx.1 eV to approx.10 MeV, and that these waves strongly affect the dynamics of resonant RC ions, thermal electrons and ions, and the outer RB relativistic electrons. As we found, the rate of ion and electron scattering/heating in the Earth's magnetosphere is not only controlled by the wave intensity-spatial-temporal distribution but also strongly depends on the spectral distribution of the wave power. The latter is also a function of the plasmaspheric heavy ion content, and the plasma density and temperature distributions along the magnetic field lines. The above discussion places RC-EMIC wave coupling dynamics in context with inner magnetospheric coupling processes and, ultimately, relates RC studies with plasmaspheric and Superthermal Electrons formation processes as well as with outer RB physics.

  10. Coupled transport processes in semipermeable media

    SciTech Connect

    Carnahan, C.L.; Jacobsen, J.S.

    1990-04-01

    The thermodynamics of irreversible processes (TTIP) is used to derive governing equations and phenomenological equations for transport processes and chemical reactions in water-saturated semipermeable media. TTIP is based on three fundamental postulates. The first postulate, the assumption of local equilibrium, allows the formulation of balance equations for entropy. These equations are the bases for the derivation of governing equations for the thermodynamic variables, temperature, pressure, and composition. The governing equations involve vector fluxes of heat and mass and scalar rates of chemical reactions; in accordance with the second postulate of TTIP, these fluxes and rates are related, respectively, to all scalar driving forces (gradients of thermodynamic variables) acting within the system. The third postulate of TTIP states equality (the Onsager reciprocal relations) between certain of the phenomenological coefficients relating forces and fluxes. The description by TTIP of a system undergoing irreversible processes allows consideration of coupled transport processes such as thermal osmosis, chemical osmosis, and ultrafiltration. The coupled processes can make significant contributions to flows of mass and energy in slightly permeable, permselective geological materials such as clays and shales.

  11. Atomic force microscope based near-field imaging for probing cell surface interactions

    NASA Astrophysics Data System (ADS)

    Amini, Sina

    Near-membrane and trans-membrane proteins and their interactions with the extracellular matrix (ECM) can yield valuable information about cell dynamics. However, advances in the field of nanoscale cellular processes have been hindered, in part, due to limits imposed by current technology. In this work, a novel evanescent field (EF) imaging technique is designed, modeled, created and tested for near-field imaging in the apical surface of cells. This technique and Forster resonance energy transfer (FRET) were used to investigate interactions between integrins on the cell surface and the ECM protein, fibronectin. The goal was to monitor changes in the integrin density at the cell surface as a function of clustering after binding to fibronectin on the microsphere surface. For the EF technique, quantum dot (QD)-embedded polystyrene microspheres were used to couple light into whispering gallery modes (WGMs) inside the microspheres; the resulting EF at the surface of the microsphere was used as a near-field excitation source with ~50 nm axial resolution for exciting fluorescently-labeled integrins. For FRET measurements (~10 nm axial resolution), QDs (donors) were coated on the surface of microspheres and energy transfer to red fluorescent protein (RFP)-integrin constructs (acceptors) studied. In both techniques, the QD-modified microspheres were mounted on atomic force microscope (AFM) cantilevers, functionalized with fibronectin, and brought into contact with fluorescently-labeled HeLa or vascular smooth muscle (VSM) cells. The results obtained from both methods show the clustering and activity of the integrins and are in good agreement with each other. Amsterdam discrete dipole approximation (ADDA) was used to study the effects of inhomogeneous surrounding refractive index on the quality factor and position of the WGMs due to the attachment of a microsphere to an AFM cantilever. WGMs of various QD-embedded microspheres mounted on AFM cantilevers were experimentally

  12. Synthesis report on thermally driven coupled processes

    SciTech Connect

    Hardin, E.L.

    1997-10-15

    The main purpose of this report is to document observations and data on thermally coupled processes for conditions that are expected to occur within and around a repository at Yucca Mountain. Some attempt is made to summarize values of properties (e.g., thermal properties, hydrologic properties) that can be measured in the laboratory on intact samples of the rock matrix. Variation of these properties with temperature, or with conditions likely to be encountered at elevated temperature in the host rock, is of particular interest. However, the main emphasis of this report is on direct observation of thermally coupled processes at various scales. Direct phenomenological observations are vitally important in developing and testing conceptual models. If the mathematical implementation of a conceptual model predicts a consequence that is not observed, either (1) the parameters or the boundary conditions used in the calculation are incorrect or (2) the conceptual basis of the model does not fit the experiment; in either case, the model must be revised. For example, the effective continuum model that has been used in thermohydrology studies combines matrix and fracture flow in a way that is equivalent to an assumption that water is imbibed instantaneously from fractures into adjacent, partially saturated matrix. Based on this approximation, the continuum-flow response that is analogous to fracture flow will not occur until the effective continuum is almost completely saturated. This approximation is not entirely consistent with some of the experimental data presented in this report. This report documents laboratory work and field studies undertaken in FY96 and FY97 to investigate thermally coupled processes such as heat pipes and fracture-matrix coupling. In addition, relevant activities from past years, and work undertaken outside the Yucca Mountain project are summarized and discussed. Natural and artificial analogs are also discussed to provide a convenient source of

  13. Near field wireless power transfer using curved relay resonators for extended transfer distance

    NASA Astrophysics Data System (ADS)

    Zhu, D.; Clare, L.; Stark, B. H.; Beeby, S. P.

    2015-12-01

    This paper investigates the performance of a near field wireless power transfer system that uses curved relay resonator to extend transfer distance. Near field wireless power transfer operates based on the near-field electromagnetic coupling of coils. Such a system can transfer energy over a relatively short distance which is of the same order of dimensions of the coupled coils. The energy transfer distance can be increased using flat relay resonators. Recent developments in printing electronics and e-textiles have seen increasing demand of embedding electronics into fabrics. Near field wireless power transfer is one of the most promising methods to power electronics on fabrics. The concept can be applied to body-worn textiles by, for example, integrating a transmitter coil into upholstery, and a flexible receiver coil into garments. Flexible textile coils take on the shape of the supporting materials such as garments, and therefore curved resonator and receiver coils are investigated in this work. Experimental results showed that using curved relay resonator can effectively extend the wireless power transfer distance. However, as the curvature of the coil increases, the performance of the wireless power transfer, especially the maximum received power, deteriorates.

  14. Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Taguchi, Y.; Saiki, T.; Nagasaka, Y.

    2012-12-01

    A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

  15. Near-Field Scanning Optical Microscopy and Raman Microscopy.

    NASA Astrophysics Data System (ADS)

    Harootunian, Alec Tate

    1987-09-01

    Both a one dimensional near-field scanning optical microscope and Raman microprobe were constructed. In near -field scanning optical microscopy (NSOM) a subwavelength aperture is scanned in the near-field of the object. Radiation transmitted through the aperture is collected to form an image as the aperture scans over the object. The resolution of an NSOM system is essentially wavelength independent and is limited by the diameter of the aperture used to scan the object. NSOM was developed in an effort to provide a nondestructive in situ high spatial resolution probe while still utilizing photons at optical wavelengths. The Raman microprobe constructed provided vibrational Raman information with spatial resolution equivalent that of a conventional diffraction limited microscope. Both transmission studies and near-field diffration studies of subwavelength apertures were performed. Diffraction theories for a small aperture in an infinitely thin conducting screen, a slit in a thick conducting screen, and an aperture in a black screen were examined. All three theories indicate collimation of radiation to the size to the size of the subwavelength aperture or slit in the near-field. Theoretical calculations and experimental results indicate that light transmitted through subwavelength apertures is readily detectable. Light of wavelength 4579 (ANGSTROM) was transmitted through apertures with diameters as small as 300 (ANGSTROM). These studies indicate the feasibility of constructing an NSOM system. One dimensional transmission and fluorescence NSOM systems were constructed. Apertures in the tips of metallized glass pipettes width inner diameters of less than 1000 (ANGSTROM) were used as a light source in the NSOM system. A tunneling current was used to maintain the aperture position in the near-field. Fluorescence NSOM was demonstrated for the first time. Microspectroscopic and Raman microscopic studies of turtle cone oil droplets were performed. Both the Raman vibrational

  16. Non-contact transportation using near-field acoustic levitation

    PubMed

    Ueha; Hashimoto; Koike

    2000-03-01

    Near-field acoustic levitation, where planar objects 10 kg in weight can levitate stably near the vibrating plate, is successfully applied both to non-contact transportation of objects and to a non-contact ultrasonic motor. Transporting apparatuses and an ultrasonic motor have been fabricated and their characteristics measured. The theory of near-field acoustic levitation both for a piston-like sound source and a flexural vibration source is also briefly described. PMID:10829622

  17. Near-field scanning optical microscopy investigations of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Dearo, Jessie Ann

    The Near-Field Scanning Optical Microscopy (NSOM) studies of novel, optically active, conjugated polymers are presented. NSOM is a relatively new technique which produces super resolution (˜50--100 nm) optical images simultaneously with topography. The conjugated polymer poly(p-phenylene vinylene) (PPV) and derivatives of PPV are organic semiconductor-like materials with interesting and unique optical properties. Derivatives of PPV have been used in LEDs and have potential in other optoelectronic devices. NSOM provides a tool for investigation of the photoluminescence, absorption/reflection, photo-dynamics and photoconductivity of films of PPV and PPV derivatives on the length scale that these properties are fundamentally defined. The NSOM experiments have revealed mesoscale domains (˜100 nm) of varying photoluminescence emission and average molecular order in drop cast films of PPV. NSOM of stretch-oriented PPV have shown domains of perpendicular molecular orientation with low photoluminescence emission. Near-field photoconductivity experiments of stretch-oriented PPV have correlated the mesoscale topography with the photoconductivity properties of the polymer. NSOM experiments of films of poly(2-methoxy, 5-(2'-(ethyl(hexyloxy)-p-phenylene vinylene) (MEH-PPV) have shown that there is mesoscale spatial inhomogeneity in the photo-oxidation process which reduces photoluminescence emission. NSOM has also been used to create nanoscale photo-patterning in MEH-PPV films. The NSOM experiments of blended films of MEH-PPV in polystyrene have shown mesoscale phase separation directly correlated to variations in the optical properties of the film. Derivatives of PPV, stretch-oriented in polyethylene, show photoluminescence intensity variations perpendicular and parallel to the stretch-direction correlated to topography features. As a complement to the NSOM studies of conjugated polymers, single polymer molecule experiments of MEH-PPV are also presented. The

  18. Near-field ptychography using lateral and longitudinal shifts

    NASA Astrophysics Data System (ADS)

    Robisch, A.-L.; Kröger, K.; Rack, A.; Salditt, T.

    2015-07-01

    Image reconstruction of in-line holography depends crucially on the probing wave front used to illuminate an object. Aberrations inherent to the illumination can mix with the features imposed by the object. Conventional raw data processing methods rely on the division of the measured hologram by the intensity profile of the probe and are not able to fully eliminate artifacts caused by the illumination. Here we present a generalized ptychography approach to simultaneously reconstruct object and probe in the optical near-field. Combining the ideas of ptychographic lateral shifts of the object with variations of the propagation distance by longitudinal shifts, simultaneous reconstruction of object and probe was achieved equally well for a highly aberrated and a mildly disturbed probe without the need for an additional wave front diffuser. The method overcomes the image deterioration by a non-ideal probe and at the same time any restrictions due to linearization of the object’s transmission function or the Fresnel propagator. The method is demonstrated experimentally using visible light and hard x-rays, in both parallel beam and cone beam geometry, which is relevant for high resolution x-ray imaging. It also opens up a new approach to characterize extended wave fronts by phase retrieval.

  19. A novel mathematical model for controllable near-field electrospinning

    SciTech Connect

    Ru, Changhai E-mail: luojun@shu.edu.cn; Chen, Jie; Shao, Zhushuai; Pang, Ming; Luo, Jun E-mail: luojun@shu.edu.cn

    2014-01-15

    Near-field electrospinning (NFES) had better controllability than conventional electrospinning. However, due to the lack of guidance of theoretical model, precise deposition of micro/nano fibers could only accomplished by experience. To analyze the behavior of charged jet in NFES using mathematical model, the momentum balance equation was simplified and a new expression between jet cross-sectional radius and axial position was derived. Using this new expression and mass conservation equation, expressions for jet cross-sectional radius and velocity were derived in terms of axial position and initial jet acceleration in the form of exponential functions. Based on Slender-body theory and Giesekus model, a quadratic equation for initial jet acceleration was acquired. With the proposed model, it was able to accurately predict the diameter and velocity of polymer fibers in NFES, and mathematical analysis rather than experimental methods could be applied to study the effects of the process parameters in NFES. Moreover, the movement velocity of the collector stage can be regulated by mathematical model rather than experience. Therefore, the model proposed in this paper had important guiding significance to precise deposition of polymer fibers.

  20. Three-dimensional near-field MIMO array imaging using range migration techniques.

    PubMed

    Zhuge, Xiaodong; Yarovoy, Alexander G

    2012-06-01

    This paper presents a 3-D near-field imaging algorithm that is formulated for 2-D wideband multiple-input-multiple-output (MIMO) imaging array topology. The proposed MIMO range migration technique performs the image reconstruction procedure in the frequency-wavenumber domain. The algorithm is able to completely compensate the curvature of the wavefront in the near-field through a specifically defined interpolation process and provides extremely high computational efficiency by the application of the fast Fourier transform. The implementation aspects of the algorithm and the sampling criteria of a MIMO aperture are discussed. The image reconstruction performance and computational efficiency of the algorithm are demonstrated both with numerical simulations and measurements using 2-D MIMO arrays. Real-time 3-D near-field imaging can be achieved with a real-aperture array by applying the proposed MIMO range migration techniques. PMID:22345541

  1. Noise analysis for near field 3-D FM-CW radar imaging systems

    SciTech Connect

    Sheen, David M.

    2015-06-19

    Near field radar imaging systems are used for several applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit the performance in several ways including reduction in system sensitivity and reduction of image dynamic range. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.

  2. Planar Near-Field Phase Retrieval Using GPUs for Accurate THz Far-Field Prediction

    NASA Astrophysics Data System (ADS)

    Junkin, Gary

    2013-04-01

    With a view to using Phase Retrieval to accurately predict Terahertz antenna far-field from near-field intensity measurements, this paper reports on three fundamental advances that achieve very low algorithmic error penalties. The first is a new Gaussian beam analysis that provides accurate initial complex aperture estimates including defocus and astigmatic phase errors, based only on first and second moment calculations. The second is a powerful noise tolerant near-field Phase Retrieval algorithm that combines Anderson's Plane-to-Plane (PTP) with Fienup's Hybrid-Input-Output (HIO) and Successive Over-Relaxation (SOR) to achieve increased accuracy at reduced scan separations. The third advance employs teraflop Graphical Processing Units (GPUs) to achieve practically real time near-field phase retrieval and to obtain the optimum aperture constraint without any a priori information.

  3. Far-field patterns of spaceborne antennas from plane-polar near-field measurements

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Y.; Gatti, M. S.

    1985-01-01

    Certain unique features of a recently constructed plane-polar near-field measurement facility for determining the far-field patterns of large and fragile spaceborne antennas are described. In this facility, the horizontally positioned antenna rotates about its axis while the measuring probe is advanced incrementally in a fixed radial direction. The near-field measured data is then processed using a Jacobi-Bessel expansion to obtain the antenna far fields. A summary of the measurement and computational steps is given. Comparisons between the outdoor far-field measurements and the constructed far-field patterns from the near-field measured data are provided for different antenna sizes and frequencies. Application of the substitution method for the absolute gain measurement is discussed. In particular, results are shown for the 4.8-m mesh-deployable high-gain antenna of the Galileo spacecraft which has the mission of orbiting Jupiter in 1988.

  4. Rupture process of the 2010 Mw 7.8 Mentawai tsunami earthquake from joint inversion of near-field hr-GPS and teleseismic body wave recordings constrained by tsunami observations

    NASA Astrophysics Data System (ADS)

    Yue, Han; Lay, Thorne; Rivera, Luis; Bai, Yefei; Yamazaki, Yoshiki; Cheung, Kwok Fai; Hill, Emma M.; Sieh, Kerry; Kongko, Widjo; Muhari, Abdul

    2014-07-01

    The 25 October 2010 Mentawai tsunami earthquake (Mw 7.8) ruptured the shallow portion of the Sunda megathrust seaward of the Mentawai Islands, offshore of Sumatra, Indonesia, generating a strong tsunami that took 509 lives. The rupture zone was updip of those of the 12 September 2007 Mw 8.5 and 7.9 underthrusting earthquakes. High-rate (1 s sampling) GPS instruments of the Sumatra GPS Array network deployed on the Mentawai Islands and Sumatra mainland recorded time-varying and static ground displacements at epicentral distances from 49 to 322 km. Azimuthally distributed tsunami recordings from two deepwater sensors and two tide gauges that have local high-resolution bathymetric information provide additional constraints on the source process. Finite-fault rupture models, obtained by joint inversion of the high-rate (hr)-GPS time series and numerous teleseismic broadband P and S wave seismograms together with iterative forward modeling of the tsunami recordings, indicate rupture propagation ~50 km up dip and ~100 km northwest along strike from the hypocenter, with a rupture velocity of ~1.8 km/s. Subregions with large slip extend from 7 to 10 km depth ~80 km northwest from the hypocenter with a maximum slip of 8 m and from ~5 km depth to beneath thin horizontal sedimentary layers beyond the prism deformation front for ~100 km along strike, with a localized region having >15 m of slip. The seismic moment is 7.2 × 1020 N m. The rupture model indicates that local heterogeneities in the shallow megathrust can accumulate strain that allows some regions near the toe of accretionary prisms to fail in tsunami earthquakes.

  5. Laser wavelength effects in ultrafast near-field laser nanostructuring of Si

    SciTech Connect

    Zormpa, Vasileia; Mao, Xianglei; Russo, Richard E.

    2010-03-18

    We study the effect of laser wavelength (400 nm and 800 nm) on the near-field processing of crystalline silicon (Si) in the femtosecond (fs) pulse duration regime through sub-wavelength apertures. Distinct differences in the obtained nanostructures are found in each case both in terms of their physical sizes as well as their structure which can be tuned between craters and protrusions. A single or a few fs pulses can deliver enough energy on the substrate to induce sub-diffraction limited surface modification, which is among the smallest ever reported in sub-wavelength apertured Near-field Scanning Optical Microscope (NSOM) schemes.

  6. Towards better scanning near-field optical microscopy probes--progress and new developments.

    PubMed

    Heinzelmann, H; Freyland, J M; Eckert, R; Huser, T; Schürmann, G; Noell, W; Staufer, U; De Rooij, N F

    1999-01-01

    Several approaches are described with the aim of producing near-field optical probes with improved properties. Focused ion beam milling allows the fabrication of small apertures in a controlled fashion, resulting in probes with excellent polarization properties and increased transmission. Microfabrication processes are described that allow the production of apertures of 30-50 nm, facilitating the mass-fabrication of apertured tip structures that can be used in a combined force/near-field optical microscope. Finally, possible future developments are outlined. PMID:11388268

  7. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra; Rodriguez, Jose; Danilin, Michael; Scott, Courtney; Shia, Run-Lie; Eluszkiewicz, Junusz; Sze, Nien-Dak

    1999-01-01

    This is the final report. The overall objective of this project is to improve the understanding of coupling processes among atmospheric chemistry, aerosol and climate, all important for quantitative assessments of global change. Among our priority are changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The work emphasizes two important aspects: (1) AER's continued participation in preparation of, and providing scientific input for, various scientific reports connected with assessment of stratospheric ozone and climate. These include participation in various model intercomparison exercises as well as preparation of national and international reports. and (2) Continued development of the AER three-wave interactive model to address how the transport circulation will change as ozone and the thermal properties of the atmosphere change, and assess how these new findings will affect our confidence in the ozone assessment results.

  8. Coupling Processes between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    This is the third semi-annual report for NAS5-97039, covering January through June 1998. The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling for this work are the AER 2-dimensional chemistry-transport model, the AER 2-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strengths and weaknesses of the next generation assessment models.

  9. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER 2-dimensional chemistry-transport model, the AER 2-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strength and weakness of the next generation assessment models.

  10. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strength and weakness of the next generation assessment models.

  11. A near-field scanning microwave microscope based on a superconducting resonator for low power measurements

    NASA Astrophysics Data System (ADS)

    de Graaf, S. E.; Danilov, A. V.; Adamyan, A.; Kubatkin, S. E.

    2013-02-01

    We report on the design and performance of a cryogenic (300 mK) near-field scanning microwave microscope. It uses a microwave resonator as the near-field sensor, operating at a frequency of 6 GHz and microwave probing amplitudes down to 100 {μ V}, approaching low enough photon population (N ˜ 1000) of the resonator such that coherent quantum manipulation becomes feasible. The resonator is made out of a miniaturized distributed fractal superconducting circuit that is integrated with the probing tip, micromachined to be compact enough such that it can be mounted directly on a quartz tuning-fork, and used for parallel operation as an atomic force microscope (AFM). The resonator is magnetically coupled to a transmission line for readout, and to achieve enhanced sensitivity we employ a Pound-Drever-Hall measurement scheme to lock to the resonance frequency. We achieve a well localized near-field around the tip such that the microwave resolution is comparable to the AFM resolution, and a capacitive sensitivity down to 6.4 × 10-20 F/sqrt{Hz}, limited by mechanical noise. We believe that the results presented here are a significant step towards probing quantum systems at the nanoscale using near-field scanning microwave microscopy.

  12. Hybridized plasmon modes and near-field enhancement of metallic nanoparticle-dimer on a mirror.

    PubMed

    Huang, Yu; Ma, Lingwei; Hou, Mengjing; Li, Jianghao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    For the attractive plasmonic structure consisting of metal nanoparticles (NPs) on a mirror, the coexistence of near-field NP-NP and NP-mirror couplings is numerically studied at normal incidence. By mapping their 3D surface charge distributions directly, we have demonstrated two different kinds of mirror-induced bonding dipole plasmon modes and confirmed the bonding hybridizations of the mirror and the NP-dimer which may offer a much stronger near-field enhancement than that of the isolated NP dimers over a broad wavelength range. Further, it is revealed that the huge near-field enhancement of these two modes exhibit different dependence on the NP-NP and NP-mirror hot spots, while both of their near-field resonance wavelengths can be tuned to the blue exponentially by increasing the NP-NP gaps or the NP-mirror separation. Our results here benifit significantly the fundamental understanding and practical applications of metallic NPs on a mirror in plasmonics. PMID:27418039

  13. A near-field scanning microwave microscope based on a superconducting resonator for low power measurements.

    PubMed

    de Graaf, S E; Danilov, A V; Adamyan, A; Kubatkin, S E

    2013-02-01

    We report on the design and performance of a cryogenic (300 mK) near-field scanning microwave microscope. It uses a microwave resonator as the near-field sensor, operating at a frequency of 6 GHz and microwave probing amplitudes down to 100 μV, approaching low enough photon population (N ∼ 1000) of the resonator such that coherent quantum manipulation becomes feasible. The resonator is made out of a miniaturized distributed fractal superconducting circuit that is integrated with the probing tip, micromachined to be compact enough such that it can be mounted directly on a quartz tuning-fork, and used for parallel operation as an atomic force microscope (AFM). The resonator is magnetically coupled to a transmission line for readout, and to achieve enhanced sensitivity we employ a Pound-Drever-Hall measurement scheme to lock to the resonance frequency. We achieve a well localized near-field around the tip such that the microwave resolution is comparable to the AFM resolution, and a capacitive sensitivity down to 6.4 × 10(-20) F/Hz, limited by mechanical noise. We believe that the results presented here are a significant step towards probing quantum systems at the nanoscale using near-field scanning microwave microscopy. PMID:23464217

  14. Near-field thermal radiation between homogeneous dual uniaxial electromagnetic metamaterials

    NASA Astrophysics Data System (ADS)

    Chang, Jui-Yung; Basu, Soumyadipta; Yang, Yue; Wang, Liping

    2016-06-01

    Recently, near-field thermal radiation has attracted much attention in several fields since it can exceed the Planck blackbody limit through the coupling of evanescent waves. In this work, near-field radiative heat transfer between two semi-infinite dual uniaxial electromagnetic metamaterials with two different material property sets is theoretically analyzed. The near-field radiative heat transfer is calculated using fluctuational electrodynamics incorporated with anisotropic wave optics. The underlying mechanisms, namely, magnetic hyperbolic mode, magnetic surface polariton, electrical hyperbolic mode, and electrical surface polariton, between two homogeneous dual uniaxial electromagnetic metamaterials are investigated by examining the transmission coefficient and the spectral heat flux. The effect of vacuum gap distance is also studied, which shows that the enhancement at smaller vacuum gap is mainly due to hyperbolic mode and surface plasmon polariton modes. In addition, the results show that the contribution of s-polarized waves is significant and should not be excluded due to the strong magnetic response regardless of vacuum gap distances. The fundamental understanding and insights obtained here will facilitate the finding and application of novel materials for near-field thermal radiation.

  15. Near-field imaging and spectroscopy of hybridized plasmons (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Aeschlimann, Martin

    2015-09-01

    Understanding light-matter interactions such as the dynamic response of a metal to incident light is essential for advancing fundamental research and technological applications e.g. designing plasmonic devices such as nanoantenna directional emitters. The near-field response is determined on a length scale that is intrinsically smaller than the optical diffraction limit and so we use electrons to image the near-field distribution. We combine photoemission electron microscopy (PEEM) with a variable wavelength laser light source, an optical parametric oscillator (OPO), to perform near-field imaging and spectroscopy of whispering gallery resonator (WGR)1 arrays. These ultrahigh spatially and spectrally resolved measurements show characteristic spectral peaks and near-field mode distributions due to the excitation of different plasmon resonances. Controlling the interference between dipole and quadrupole modes allows us to direct the emission from the nanoantenna. Additionally we perform femtosecond 2-dimensional coherence spectroscopy2 on a microcavity system containing two well separated WGR nanoantennas. Hybridization of a propagating surface plasmon polariton and the localized surface plasmon in a cavity enables energy transfer between the two coupled nanoantennas. [1] E. J. R. Vessseur, F. J. García de Abajo and A. Polman Nano Letters 9 3147 (2009) [2] M. Aeschlimann et al, Science 333, 1723 (2011)

  16. Hybridized plasmon modes and near-field enhancement of metallic nanoparticle-dimer on a mirror

    PubMed Central

    Huang, Yu; Ma, Lingwei; Hou, Mengjing; Li, Jianghao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    For the attractive plasmonic structure consisting of metal nanoparticles (NPs) on a mirror, the coexistence of near-field NP-NP and NP-mirror couplings is numerically studied at normal incidence. By mapping their 3D surface charge distributions directly, we have demonstrated two different kinds of mirror-induced bonding dipole plasmon modes and confirmed the bonding hybridizations of the mirror and the NP-dimer which may offer a much stronger near-field enhancement than that of the isolated NP dimers over a broad wavelength range. Further, it is revealed that the huge near-field enhancement of these two modes exhibit different dependence on the NP-NP and NP-mirror hot spots, while both of their near-field resonance wavelengths can be tuned to the blue exponentially by increasing the NP-NP gaps or the NP-mirror separation. Our results here benifit significantly the fundamental understanding and practical applications of metallic NPs on a mirror in plasmonics. PMID:27418039

  17. Far-Field Super-resolution Detection of Plasmonic Near-Fields.

    PubMed

    Boutelle, Robert Charles; Neuhauser, Daniel; Weiss, Shimon

    2016-08-23

    We demonstrate a far-field single molecule super-resolution method that maps plasmonic near-fields. The method is largely invariant to fluorescence quenching (arising from probe proximity to a metal), has reduced point-spread-function distortion compared to fluorescent dyes (arising from strong coupling to nanoscopic metallic features), and has a large dynamic range (of 2 orders of magnitude) allowing mapping of plasmonic field-enhancements regions. The method takes advantage of the sensitivity of quantum dot (QD) stochastic blinking to plasmonic near-fields. The modulation of the blinking characteristics thus provides an indirect measure of the local field strength. Since QD blinking can be monitored in the far-field, the method can measure localized plasmonic near-fields at high throughput using a simple far-field optical setup. Using this method, propagation lengths and penetration depths were mapped-out for silver nanowires of different diameters and for different dielectric environments, with a spatial accuracy of ∼15 nm. We initially use sparse sampling to ensure single molecule localization for accurate characterization of the plasmonic near-field with plans to increase density of emitters in further studies. The measured propagation lengths and penetration depths values agree well with Maxwell finite-difference time-domain calculations and with published literature values. This method offers advantages such as low cost, high throughput, and superresolved mapping of localized plasmonic fields at high sensitivity and fidelity. PMID:27501216

  18. THz near-field imaging of biological tissues employing synchrotronradiation

    SciTech Connect

    Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried,Daniel

    2004-12-23

    Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking onto the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical wave guides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about lambda/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 mu-m at about 12 wave numbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin.

  19. Infrared spectroscopic near-field mapping of single nanotransistors.

    PubMed

    Huber, A J; Wittborn, J; Hillenbrand, R

    2010-06-11

    We demonstrate the application of scattering-type scanning near-field optical microscopy (s-SNOM) for infrared (IR) spectroscopic material recognition in state-of-the-art semiconductor devices. In particular, we employ s-SNOM for imaging of industrial CMOS transistors with a resolution better than 20 nm, which allows for the first time IR spectroscopic recognition of amorphous SiO(2) and Si(3)N(4) components in a single transistor device. The experimentally recorded near-field spectral signature of amorphous SiO(2) shows excellent agreement with model calculations based on literature dielectric values, verifying that the characteristic near-field contrasts of SiO(2) stem from a phonon-polariton resonant near-field interaction between the probing tip and the SiO(2) nanostructures. Local material recognition by s-SNOM in combination with its capabilities of contact-free and non-invasive conductivity- and strain-mapping makes IR near-field microscopy a versatile metrology technique for nanoscale material characterization and semiconductor device analysis with application potential in research and development, failure analysis and reverse engineering. PMID:20463381

  20. Near-field fiber optic chemical sensors and biological applications

    NASA Astrophysics Data System (ADS)

    Tan, Weihong; Shi, Zhong-You; Thorsrud, Bjorn A.; Harris, C.; Kopelman, Raoul

    1994-03-01

    Near-field optics has been applied in the nanofabrication of subwavelength optical fiber chemical and biological sensors and their operation in chemical and biological analysis. A thousandfold miniaturization of immobilized optical fiber sensors has been achieved by a near- field photo-nanofabrication technique, which is based on nanofabricated optical fiber tips and near-field photopolymerization. This technique has been further developed by multistep near- field nanofabrication and multidye probe fabrication. Multistep nanofabrication can further miniaturize optical fiber sensors, while multidye fabrication results in multifunctional optic and excitonic probes with extremely small size. These probes emit multiwavelength photons or produce excitons of different energy levels, and may have multiple chemical or biological sensitivities. The nondestructive submicrometer sensor has demonstrated its ability to carry out static and dynamic determinations of pH in intact rat conceptuses of varying gestational ages. The ability of the sensors to measure pH changes, in real time, in the intact rat conceptus, demonstrates their potential applications for dynamic analysis in multicellular organisms and single cells. The near-field interaction of photons with matter is discussed.

  1. Near-field energy extraction with hyperbolic metamaterials.

    PubMed

    Shi, Jiawei; Liu, Baoan; Li, Pengfei; Ng, Li Yen; Shen, Sheng

    2015-02-11

    Although blackbody radiation described by Planck's law is commonly regarded as the maximum of thermal radiation, thermal energy transfer in the near-field can exceed the blackbody limit due to the contribution from evanescent waves. Here, we demonstrate experimentally a broadband thermal energy extraction device based on hyperbolic metamaterials that can significantly enhance near-field thermal energy transfer. The thermal extractor made from hyperbolic metamaterials does not absorb or emit any radiation but serves as a transparent pipe guiding the radiative energy from the emitter. At the same gap between an emitter and an absorber, we observe that near-field thermal energy transfer with thermal extraction can be enhanced by around 1 order of magnitude, compared to the case without thermal extraction. The novel thermal extraction scheme has important practical implications in a variety of technologies, e.g., thermophotovoltaic energy conversion, radiative cooling, thermal infrared imaging, and heat assisted magnetic recording. PMID:25622221

  2. Near-field acoustical holography of military jet aircraft noise

    NASA Astrophysics Data System (ADS)

    Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne; Krueger, David W.; Sommerfeldt, Scott D.; James, Michael M.

    2010-10-01

    Noise radiated from high-performance military jet aircraft poses a hearing-loss risk to personnel. Accurate characterization of jet noise can assist in noise prediction and noise reduction techniques. In this work, sound pressure measurements were made in the near field of an F-22 Raptor. With more than 6000 measurement points, this is the most extensive near-field measurement of a high-performance jet to date. A technique called near-field acoustical holography has been used to propagate the complex pressure from a two- dimensional plane to a three-dimensional region in the jet vicinity. Results will be shown and what they reveal about jet noise characteristics will be discussed.

  3. Near-field radiative thermal transport: From theory to experiment

    SciTech Connect

    Song, Bai Fiorino, Anthony; Meyhofer, Edgar; Reddy, Pramod

    2015-05-15

    Radiative thermal transport via the fluctuating electromagnetic near-field has recently attracted increasing attention due to its fundamental importance and its impact on a range of applications from data storage to thermal management and energy conversion. After a brief historical account of radiative thermal transport, we summarize the basics of fluctuational electrodynamics, a theoretical framework for the study of radiative heat transfer in terms of thermally excited propagating and evanescent electromagnetic waves. Various approaches to modeling near-field thermal transport are briefly discussed, together with key results and proposals for manipulation and utilization of radiative heat flow. Subsequently, we review the experimental advances in the characterization of both near-field heat flow and energy density. We conclude with remarks on the opportunities and challenges for future explorations of radiative heat transfer at the nanoscale.

  4. Diagnose human tumors by THz near-field imaging

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Wang, Xiaozhou; Zhao, Tian; Yang, Jinwen

    2014-09-01

    Based on a THz pipe-based near-field imaging system, we demonstrated the capability of THz imaging to diagnose human breast and liver cancers. Through THz near-field mapping of the absorption constants of cancer tissues, the acquired images can not only clearly distinguish cancer from normal tissues fast, automatically, and correctly without pathological H&E staining, but also identify the distribution region of cancer, which matches well with the identification with pathological examination. Due to its capability to perform quantitative analysis, our study indicates the potential of the THz pipe-based near-field imaging for future automation on human tumor pathological examinations and for quick definition of the tumor margins during the surgical procedure such as breast-conserving surgery. With the help of THz imaging, we can expect to economize the use of hospital and human resources.

  5. Processes of Change in Self-Directed Couple Relationship Education

    ERIC Educational Resources Information Center

    Wilson, Keithia L.; Halford, W. Kim

    2008-01-01

    The current study examined the learning processes involved in professionally supported self-directed couple relationship education (CRE). Fifty-nine couples completed Couple CARE, a systematic, self-directed CRE program designed in flexible delivery mode to be completed at home. Couples watched a DVD introducing key relationship ideas and skills…

  6. A sensitive near-field microscope for thermal radiation.

    PubMed

    Kajihara, Yusuke; Kosaka, Keishi; Komiyama, Susumu

    2010-03-01

    A scattering-type scanning near-field optical microscope in long-wavelength infrared (LWIR) region is developed by using an extremely sensitive detector, called the charge-sensitive infrared phototransistor. A tungsten probe attached to a quartz tuning fork is controlled in shear-force mode. Evanescent wave at a sample surface is periodically scattered by slowly (2 Hz) modulating the probe in the direction normal to the sample surface. Near-field microscopy of thermal LWIR radiation from room-temperature Au/GaAs gratings is demonstrated without using any external illumination or excitation. Achieved spatial resolution is better than 300 nm. PMID:20370184

  7. Photonic near-field imaging in multiphoton photoemission electron microscopy

    NASA Astrophysics Data System (ADS)

    Fitzgerald, J. P. S.; Word, R. C.; Saliba, S. D.; Könenkamp, R.

    2013-05-01

    We report the observation of optical near fields in a photonic waveguide of conductive indium tin oxide (ITO) using multiphoton photoemission electron microscopy (PEEM). Nonlinear two-photon photoelectron emission is enhanced at field maxima created by interference between incident 410-nm and coherently excited guided photonic waves, providing strong phase contrast. Guided modes are observed under both transverse magnetic field (TM) and transverse electric field (TE) polarized illuminations and are consistent with classical electromagnetic theory. Implications on the role of multiphoton PEEM in optical near-field imaging are discussed.

  8. Towards phonon photonics: scattering-type near-field optical microscopy reveals phonon-enhanced near-field interaction.

    PubMed

    Hillenbrand, Rainer

    2004-08-01

    Diffraction limits the spatial resolution in classical microscopy or the dimensions of optical circuits to about half the illumination wavelength. Scanning near-field microscopy can overcome this limitation by exploiting the evanescent near fields existing close to any illuminated object. We use a scattering-type near-field optical microscope (s-SNOM) that uses the illuminated metal tip of an atomic force microscope (AFM) to act as scattering near-field probe. The presented images are direct evidence that the s-SNOM enables optical imaging at a spatial resolution on a 10nm scale, independent of the wavelength used (lambda=633 nm and 10 microm). Operating the microscope at specific mid-infrared frequencies we found a tip-induced phonon-polariton resonance on flat polar crystals such as SiC and Si3N4. Being a spectral fingerprint of any polar material such phonon-enhanced near-field interaction has enormous applicability in nondestructive, material-specific infrared microscopy at nanoscale resolution. The potential of s-SNOM to study eigenfields of surface polaritons in nanostructures opens the door to the development of phonon photonics-a proposed infrared nanotechnology that uses localized or propagating surface phonon polaritons for probing, manipulating and guiding infrared light in nanoscale devices, analogous to plasmon photonics. PMID:15231334

  9. Ultrafast nanoelectronics: steering electrons in infrared near-fields (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Herink, Georg; Ropers, Claus

    2015-09-01

    Plasmonic nanostructures can break the diffraction limit and confine optical fields on the nanoscale. The coupling of intense femtosecond transients to the apex of metallic nanotips enables ultrafast electron point sources which find applications in ultrafast electron microscopy and time-resolved diffraction instruments. In this contribution, we demonstrate the impact of near-field localization onto strong-field photoemission and present the control of electron trajectories via the momentary electric near-field. The photoemission dynamics at single gold and tungsten nanotips are experimentally studied over a broad range of excitation frequencies, spanning from 1 - 400 Terahertz (THz). The transition from oscillatory electron acceleration to a field-driven interaction is presented as a result of intense, long-wavelength and localized excitation. The high field enhancement at lower frequencies is demonstrated to induce localized field emission from a nanotip with moderate incident fields as provided by table-top THz sources. Such THz-induced cold field emission can be used, e.g., for the temporal tracking of optically excited hot-electron dynamics in nanostructures. Moreover, the field-driven electron acceleration in the enhanced THz near-field is employed in a pump-probe scheme to temporally map the local THz-response of the nanostructure by projecting the momentary apex near-field onto the kinetic energy of femtosecond electron pulses. Besides the electrical characterization of nanostructures at THz-frequencies, the temporally and spatially confined interaction of free electrons with ultrashort near-fields is expected to enable a novel class of ultrafast vacuum micro- and nanoelectronic devices, and first applications are presented in this talk.

  10. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm; Weisenstein, Debra; Rodriquez, Jose; Danilin, Michael; Scott, Courtney; Shia, Run-Lie; Eluszkiewicz, Janusz; Sze, Nien-Dak; Stewart, Richard W. (Technical Monitor)

    1999-01-01

    This is the final report for NAS5-97039 for work performed between December 1996 and November 1999. The overall objective of this project is to improve the understanding of coupling processes among atmospheric chemistry, aerosol and climate, all important for quantitative assessments of global change. Among our priority are changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The work emphasizes two important aspects: (1) AER's continued participation in preparation of, and providing scientific input for, various scientific reports connected with assessment of stratospheric ozone and climate. These include participation in various model intercomparison exercises as well as preparation of national and international reports. (2) Continued development of the AER three-wave interactive model to address how the transport circulation will change as ozone and the thermal properties of the atmosphere change, and assess how these new findings will affect our confidence in the ozone assessment results.

  11. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Li; Sze, N. D.

    1997-01-01

    This is the first semi-annual report for NAS5-97039 summarizing work performed for January 1997 through June 1997. Work in this project is related to NAS1-20666, also funded by NASA ACMAP. The work funded in this project also benefits from work at AER associated with the AER three-dimensional isentropic transport model funded by NASA AEAP and the AER two-dimensional climate-chemistry model (co-funded by Department of Energy). The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry.

  12. Coupling Processes between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra K.; Shia, Run-Lie; Scott, Courtney J.; Sze, Nien Dak

    1998-01-01

    This is the fourth semi-annual report for NAS5-97039, covering the time period July through December 1998. The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the Atmospheric and Environmental Research (AER) two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. For this six month period, we report on a modeling study of new rate constant which modify the NOx/NOy ratio in the lower stratosphere; sensitivity to changes in stratospheric water vapor in the future atmosphere; a study of N2O and CH4 observations which has allowed us to adjust diffusion in the 2-D CTM in order to obtain appropriate polar vortex isolation; a study of SF6 and age of air with comparisons of models and measurements; and a report on the Models and Measurements II effort.

  13. Near-Field Spectroscopy with Nanoparticles Deposited by AFM

    NASA Technical Reports Server (NTRS)

    Anderson, Mark S.

    2008-01-01

    An alternative approach to apertureless near-field optical spectroscopy involving an atomic-force microscope (AFM) entails less complexity of equipment than does a prior approach. The alternative approach has been demonstrated to be applicable to apertureless near-field optical spectroscopy of the type using an AFM and surface enhanced Raman scattering (SERS), and is expected to be equally applicable in cases in which infrared or fluorescence spectroscopy is used. Apertureless near-field optical spectroscopy is a means of performing spatially resolved analyses of chemical compositions of surface regions of nanostructured materials. In apertureless near-field spectroscopy, it is common practice to utilize nanostructured probe tips or nanoparticles (usually of gold) having shapes and dimensions chosen to exploit plasmon resonances so as to increase spectroscopic-signal strengths. To implement the particular prior approach to which the present approach is an alternative, it is necessary to integrate a Raman spectrometer with an AFM and to utilize a special SERS-active probe tip. The resulting instrumentation system is complex, and the tasks of designing and constructing the system and using the system to acquire spectro-chemical information from nanometer-scale regions on a surface are correspondingly demanding.

  14. Nanostructuring thin polymer films with optical near fields.

    PubMed

    Martín-Fabiani, Ignacio; Siegel, Jan; Riedel, Stephen; Boneberg, Johannes; Ezquerra, Tiberio A; Nogales, Aurora

    2013-11-13

    In the present work, we report on the application of optical near fields to nanostructuring of poly(trimethylene terephthalate) (PTT) thin films. By exposure to a single ultraviolet nanosecond laser pulse, the spatial intensity modulation of the near-field distribution created by a silica microsphere is imprinted into the films. Setting different angles of incidence of the laser, elliptical or circular periodic ring patterns can be produced with periods as small as half the laser wavelength used. These highly complex patterns show optical and topographical contrast and can be characterized by optical microscopy (OM) and atomic force microscopy (AFM). We demonstrate the key role of the laser wavelength and coherence length in achieving smooth, extended patterns in PTT by using excimer laser (193 nm) and Nd:YAG laser (266 nm) pulses. Reference experiments performed in Ge2Sb2Te5 (GST) demonstrate that nanopatterning in PTT is triggered by ablation as opposed to GST, in which nanopatterning originates from laser-induced phase change, accompanied by a small topographical contrast. The experiments presented in this work demonstrate the suitability of optical near fields for structuring polymer films, opening up new possibilities for nanopatterning and paving the way for potential applications where optical near fields and polymer nanostructures are involved. PMID:24127989

  15. Near-Field Noise Computation for a Supersonic Circular Jet

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Hultgren, Lennart S.

    2005-01-01

    A fully expanded, high-Reynolds-number, supersonic circular jet of Mach number 1.4 is simulated, using a 3-D finite-volume Navier-Stokes solver, with emphasis on the near field noise. The numerical results are generally in good agreement with existing experimental findings.

  16. Near-Field Noise Computation for a Subsonic Coannular Jet

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Hultgren, Lennart S.; Jorgenson, Philip C. E.

    2008-01-01

    A high-Reynolds-number, subsonic coannular jet is simulated, using a three-dimensional finite-volume LES method, with emphasis on the near field noise. The nozzle geometry used is the NASA Glenn 3BB baseline model. The numerical results are generally in good agreement with existing experimental findings.

  17. Nano-Scale Fabrication Using Optical-Near-Field

    NASA Astrophysics Data System (ADS)

    Yatsui, Takashi; Ohtsu, Motoichi

    This paper reviews the specific nature of nanophotonics, i.e., a novel optical nano-technology, utilizing dressed photon excited in the nano-material. As examples of nanophotnic fabrication, optical near-field etching and increased spatial homogeneity of contents in compound semiconductors is demonstrated with a self-organized manner.

  18. Near-field analysis of a compressive supersonic ramp

    NASA Astrophysics Data System (ADS)

    Emanuel, George

    1982-07-01

    Steady, two-dimensional, inviscid, supersonic flow is analyzed for a compressive turn where the wall is contoured to provide a centered compression fan. The focal point of the compression is the origin of the usual (primary) oblique shock wave, a slipstream, and a secondary pressure disturbance. This disturbance can be an expansion, a weak solution shock, or a strong solution shock. In the vicinity of the focal point (the near field) there are seven possibilities, one of which is no real solution. For small wall turn angles, there is a unique near-field solution where the primary shock is the weak solution. In this case the secondary disturbance, whose strength is quite small, is either an expansion or a weak solution oblique shock wave. For larger turn angles, two near-field solutions are possible, and for still larger angles, none. At relatively large wall turn angles, where the usual oblique shock equations still provide an attached solution, the near-field equations do not have a solution when the Mach number is sufficiently large.

  19. Photon-induced near-field electron microscopy.

    PubMed

    Barwick, Brett; Flannigan, David J; Zewail, Ahmed H

    2009-12-17

    In materials science and biology, optical near-field microscopies enable spatial resolutions beyond the diffraction limit, but they cannot provide the atomic-scale imaging capabilities of electron microscopy. Given the nature of interactions between electrons and photons, and considering their connections through nanostructures, it should be possible to achieve imaging of evanescent electromagnetic fields with electron pulses when such fields are resolved in both space (nanometre and below) and time (femtosecond). Here we report the development of photon-induced near-field electron microscopy (PINEM), and the associated phenomena. We show that the precise spatiotemporal overlap of femtosecond single-electron packets with intense optical pulses at a nanostructure (individual carbon nanotube or silver nanowire in this instance) results in the direct absorption of integer multiples of photon quanta (nhomega) by the relativistic electrons accelerated to 200 keV. By energy-filtering only those electrons resulting from this absorption, it is possible to image directly in space the near-field electric field distribution, obtain the temporal behaviour of the field on the femtosecond timescale, and map its spatial polarization dependence. We believe that the observation of the photon-induced near-field effect in ultrafast electron microscopy demonstrates the potential for many applications, including those of direct space-time imaging of localized fields at interfaces and visualization of phenomena related to photonics, plasmonics and nanostructures. PMID:20016598

  20. Radiative heat transfer in the extreme near field.

    PubMed

    Kim, Kyeongtae; Song, Bai; Fernández-Hurtado, Víctor; Lee, Woochul; Jeong, Wonho; Cui, Longji; Thompson, Dakotah; Feist, Johannes; Reid, M T Homer; García-Vidal, Francisco J; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2015-12-17

    Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer. PMID:26641312

  1. Approximate Near-Field Blast Theory: A Generalized Approach

    SciTech Connect

    Hutchens, G.J.

    1999-10-25

    A method for analyzing strong shock waves in arbitrary one-dimensional geometry is presented. An approximation to classical Taylor-Sedov theory is extended to the near-field case where source mass is not negligible, accounting for differences in the chemical properties of the source mass and ambient medium. Results from example calculations are compared with previously published analytical formulae.

  2. Measurement of the permittivity and loss of high-loss materials using a Near-Field Scanning Microwave Microscope.

    PubMed

    Gregory, A P; Blackburn, J F; Lees, K; Clarke, R N; Hodgetts, T E; Hanham, S M; Klein, N

    2016-02-01

    In this paper improvements to a Near-Field Scanning Microwave Microscope (NSMM) are presented that allow the loss of high loss dielectric materials to be measured accurately at microwave frequencies. This is demonstrated by measuring polar liquids (loss tangent tanδ≈1) for which traceable data is available. The instrument described uses a wire probe that is electromagnetically coupled to a resonant cavity. An optical beam deflection system is incorporated within the instrument to allow contact mode between samples and the probe tip to be obtained. Liquids are contained in a measurement cell with a window of ultrathin glass. The calibration process for the microscope, which is based on image-charge electrostatic models, has been adapted to use the Laplacian 'complex frequency'. Measurements of the loss tangent of polar liquids that are consistent with reference data were obtained following calibration against single-crystal specimens that have very low loss. PMID:26686660

  3. Generation of single-crystalline domain in nano-scale silicon pillars by near-field short pulsed laser

    NASA Astrophysics Data System (ADS)

    In, Jung Bin; Xiang, Bin; Hwang, David J.; Ryu, Sang-Gil; Kim, Eunpa; Yoo, Jae-Hyuck; Dubon, Oscar; Minor, Andrew M.; Grigoropoulos, Costas P.

    2014-01-01

    We observe laser-induced grain morphology change in silicon nanopillars under a transmission electron microscopy (TEM) environment. We couple the TEM with a near-field scanning optical microscopy pulsed laser processing system. This novel combination enables immediate scrutiny on the grain morphologies that the pulsed laser irradiation produces. We find unusual transformation of the tip of the amorphous or polycrystalline silicon pillar into a single crystalline domain via melt-mediated crystallization. On the basis of the three-dimensional finite difference simulation result and the dark field TEM data, we propose that the creation of the distinct single crystalline tip originates from the dominant grain growth initiated at the apex of the non-planar liquid-solid interface. Our microscopic observation provides a fundamental basis for laser-induced conversion of amorphous nanostructures into coarse-grained crystals.

  4. Sub-10 nm near-field localization by plasmonic metal nanoaperture arrays with ultrashort light pulses

    PubMed Central

    Lee, Hongki; Kim, Chulhong; Kim, Donghyun

    2015-01-01

    Near-field localization by ultrashort femtosecond light pulses has been investigated using simple geometrical nanoapertures. The apertures employ circular, rhombic, and triangular shapes to localize the distribution of surface plasmon. To understand the geometrical effect on the localization, aperture length and period of the nanoapertures were varied. Aperture length was shown to affect the performance more than aperture period due mainly to intra-aperture coupling of near-fields. Triangular apertures provided the strongest spatial localization below 10 nm in size as well as the highest enhancement of field intensity by more than 7000 times compared to the incident light pulse. Use of ultrashort pulses was found to allow much stronger light localization than with continuous-wave light. The results can be used for super-localization sensing and imaging applications where spatially localized fields can break through the limits in achieving improved sensitivity and resolution. PMID:26628326

  5. Sub-10 nm near-field localization by plasmonic metal nanoaperture arrays with ultrashort light pulses.

    PubMed

    Lee, Hongki; Kim, Chulhong; Kim, Donghyun

    2015-01-01

    Near-field localization by ultrashort femtosecond light pulses has been investigated using simple geometrical nanoapertures. The apertures employ circular, rhombic, and triangular shapes to localize the distribution of surface plasmon. To understand the geometrical effect on the localization, aperture length and period of the nanoapertures were varied. Aperture length was shown to affect the performance more than aperture period due mainly to intra-aperture coupling of near-fields. Triangular apertures provided the strongest spatial localization below 10 nm in size as well as the highest enhancement of field intensity by more than 7000 times compared to the incident light pulse. Use of ultrashort pulses was found to allow much stronger light localization than with continuous-wave light. The results can be used for super-localization sensing and imaging applications where spatially localized fields can break through the limits in achieving improved sensitivity and resolution. PMID:26628326

  6. Surface-polariton propagation for scanning near-field optical microscopy application.

    PubMed

    Keilmann, F

    1999-01-01

    Surface plasmon-, phonon- and exciton-polaritons exist on specific materials in specific spectral regions. We assess the properties of such travelling surface-bound electromagnetic waves relevant for scanning near-field optical microscopy applications, i.e. the tightness of surface binding, the attenuation, the phase velocity and the coupling with free-space electromagnetic waves. These quantities can be directly determined by photographic imaging of surface plasmon- and surface phonon-polaritons, in both the visible and mid-infared regions. Focusing of mid-infrared surface plasmons is demonstrated. Surface waveguides to transport and focus photons to the tip of a scanning near-field probe are outlined. PMID:11388308

  7. Electrically tunable near-field radiative heat transfer via ferroelectric materials

    SciTech Connect

    Huang, Yi; Boriskina, Svetlana V.; Chen, Gang

    2014-12-15

    We explore ways to actively control near-field radiative heat transfer between two surfaces that relies on electrical tuning of phonon modes of ferroelectric materials. Ferroelectrics are widely used for tunable electrical devices, such as capacitors and memory devices; however, their tunable properties have not yet been examined for heat transfer applications. We show via simulations that radiative heat transfer between two ferroelectric materials can be enhanced by over two orders of magnitude over the blackbody limit in the near field, and can be tuned as much as 16.5% by modulating the coupling between surface phonon polariton modes at the two surfaces via varying external electric fields. We then discuss how to maximize the modulation contrast for tunable thermal devices using the studied mechanism.

  8. Nonlinear nanoprobes for characterizing ultrafast optical near field

    NASA Astrophysics Data System (ADS)

    Li, Haifeng

    With the rapid development of ultrafast optics and nanophotonics, it is crucial to measure the spatiotemporal evolution of an ultrafast optical near field in nanometer spatial and femtosecond temporal resolution with minimal perturbation. Although near-field scanning optical microscopy (NSOM) can achieve nanoscale spatial resolution and various ultrashort pulse diagnostic tools can characterize femtosecond laser pulses, yet such capability to noninvasively characterize the nanoscale characteristics of femtosecond pulses in all three spatial dimensions remains elusive. In this dissertation, we developed different types of nonlinear optical probes to characterize ultrashort optical pulses. The nonlinear optical probe is composed of three parts, a silica fiber taper, a single nanowire bonded to the end of the fiber and nonlinear nanoparticles attached on the tip of the nanowire. The optical fiber taper can be readily mounted on a mechanical stage and served as a macroscopic interface for handling and positioning control. The single nanowire bridges the dimension gap between the nanocrystals and the fiber taper, and is critical for achieving large aspect ratio and hence minimizing optical scattering and perturbation. The nonlinear nanoparticles give rise to its capability to characterize ultrashort optical pulses. The unique fusion of nanoscale and nonlinear features in developed nonlinear optical probes provides the ability of probing ultrafast optical field in complex 3D microand nano- structures. The demonstration of such ability is crucial for understanding the interaction of ultrafast optical fields and nanoscale systems. The fabrication processes of the nonlinear optical probes are illustrated in detail and the optical properties of the probes are investigated. Two different types of nonlinear optical probes, two-photon fluorescent nanoprobes and Second HARmonic nanoProbes (SHARP), are fabricated. Interferometric autocorrelation measurements near the focal point

  9. Spectrally Enhancing Near-Field Radiative Transfer between Metallic Gratings by Exciting Magnetic Polaritons in Nanometric Vacuum Gaps

    NASA Astrophysics Data System (ADS)

    Yang, Yue; Wang, Liping

    2016-07-01

    In the present Letter, we theoretically demonstrate that near-field radiative transport between one-dimensional periodic grating microstructures separated by nanometer vacuum gaps can be spectrally enhanced by exciting magnetic polaritons. Fluctuational electrodynamics that incorporates scattering matrix theory with rigorous coupled-wave analysis is employed to exactly calculate the near-field radiative flux between two metallic gratings. In addition to the well-known coupled surface plasmon polaritons, the radiative flux can be also spectrally enhanced due to the magnetic polariton, which is excited in the gap between the grating ridges. The mechanism of magnetic polaritons in the near-field radiative transport are elucidated in detail, while the unusual enhancement cannot be predicted by either Derjaguin's or the effective medium approximations. The effects of the vacuum gap distance and grating geometry parameters between the two gratings are investigated. The findings will open a new way to spectrally control near-field radiative transfer by magnetic polaritons with micro- or nanostructured metamaterials, which holds great potential for improving the performance of energy systems like near-field thermophotovoltaics.

  10. Spectrally Enhancing Near-Field Radiative Transfer between Metallic Gratings by Exciting Magnetic Polaritons in Nanometric Vacuum Gaps.

    PubMed

    Yang, Yue; Wang, Liping

    2016-07-22

    In the present Letter, we theoretically demonstrate that near-field radiative transport between one-dimensional periodic grating microstructures separated by nanometer vacuum gaps can be spectrally enhanced by exciting magnetic polaritons. Fluctuational electrodynamics that incorporates scattering matrix theory with rigorous coupled-wave analysis is employed to exactly calculate the near-field radiative flux between two metallic gratings. In addition to the well-known coupled surface plasmon polaritons, the radiative flux can be also spectrally enhanced due to the magnetic polariton, which is excited in the gap between the grating ridges. The mechanism of magnetic polaritons in the near-field radiative transport are elucidated in detail, while the unusual enhancement cannot be predicted by either Derjaguin's or the effective medium approximations. The effects of the vacuum gap distance and grating geometry parameters between the two gratings are investigated. The findings will open a new way to spectrally control near-field radiative transfer by magnetic polaritons with micro- or nanostructured metamaterials, which holds great potential for improving the performance of energy systems like near-field thermophotovoltaics. PMID:27494474

  11. The thermal near-field: Coherence, spectroscopy, heat-transfer, and optical forces

    NASA Astrophysics Data System (ADS)

    Jones, Andrew C.; O'Callahan, Brian T.; Yang, Honghua U.; Raschke, Markus B.

    2013-12-01

    One of the most universal physical processes shared by all matter at finite temperature is the emission of thermal radiation. The experimental characterization and theoretical description of far-field black-body radiation was a cornerstone in the development of modern physics with the groundbreaking contributions from Gustav Kirchhoff and Max Planck. With its origin in thermally driven fluctuations of the charge carriers, thermal radiation reflects the resonant and non-resonant dielectric properties of media, which is the basis for far-field thermal emission spectroscopy. However, associated with the underlying fluctuating optical source polarization are fundamentally distinct spectral, spatial, resonant, and coherence properties of the evanescent thermal near-field. These properties have been recently predicted theoretically and characterized experimentally for systems with thermally excited molecular, surface plasmon polariton (SPP), and surface phonon polariton (SPhP) resonances. We review, starting with the early historical developments, the emergence of theoretical models, and the description of the thermal near-field based on the fluctuation-dissipation theory and in terms of the electromagnetic local density of states (EM-LDOS). We discuss the optical and spectroscopic characterization of distance dependence, magnitude, spectral distribution, and coherence of evanescent thermal fields. Scattering scanning near-field microscopy proved instrumental as an enabling technique for the investigations of several of these fundamental thermal near-field properties. We then discuss the role of thermal fields in nano-scale heat transfer and optical forces, and the correlation to the van der Waals, Casimir, and Casimir-Polder forces. We conclude with an outlook on the possibility of intrinsic and extrinsic resonant manipulation of optical forces, control of nano-scale radiative heat transfer with optical antennas and metamaterials, and the use of thermal infrared near-field

  12. Technical basis and programmatic requirements for laboratory study of hydrological properties of the near-field environment

    SciTech Connect

    Lin, W.

    1993-10-01

    This document contains the technical basis and programmatic requirements for a study plant governs laboratory study of hydrological properties of the near-field environment of a nuclear waste repository. The Study Plan (SP), known as ``Near-Field Environment Hydrological Properties (NFEHP),`` will be reviewed by Yucca Mountain Site Characterization Project Office (YMPO) of the United States Department of Energy (DOE). The final version of the SP may be different from this document. The SP is identified by Work Breakdown Structure (WBS) as WBS 1.2.2.2.2. This study is described in Section 8.3.4.2.4.1 of the Site Characterization Plant (SCP). The purpose and objective of the Near-Field Environment Hydrological Properties study are to understand, at the laboratory scale, hydrological processes expected to occur within the near field of nuclear waste repository after waste package emplacement.

  13. Probe Station and Near-Field Scanner for Testing Antennas

    NASA Technical Reports Server (NTRS)

    Zaman, Afroz; Lee, Richard Q.; Darby, William G.; Barr, Philip J.; Miranda, Felix A.; Lambert, Kevin

    2006-01-01

    A facility that includes a probe station and a scanning open-ended waveguide probe for measuring near electromagnetic fields has been added to Glenn Research Center's suite of antenna-testing facilities, at a small fraction of the cost of the other facilities. This facility is designed specifically for nondestructive characterization of the radiation patterns of miniaturized microwave antennas fabricated on semiconductor and dielectric wafer substrates, including active antennas that are difficult to test in traditional antenna-testing ranges because of fragility, smallness, or severity of DC-bias or test-fixture requirements. By virtue of the simple fact that a greater fraction of radiated power can be captured in a near-field measurement than in a conventional far-field measurement, this near-field facility is convenient for testing miniaturized antennas with low gains.

  14. Mars Pathfinder Near-Field Rock Distribution Re-Evaluation

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Golombek, M. P.

    2003-01-01

    We have completed analysis of a new near-field rock count at the Mars Pathfinder landing site and determined that the previously published rock count suggesting 16% cumulative fractional area (CFA) covered by rocks is incorrect. The earlier value is not so much wrong (our new CFA is 20%), as right for the wrong reason: both the old and the new CFA's are consistent with remote sensing data, however the earlier determination incorrectly calculated rock coverage using apparent width rather than average diameter. Here we present details of the new rock database and the new statistics, as well as the importance of using rock average diameter for rock population statistics. The changes to the near-field data do not affect the far-field rock statistics.

  15. Near-field effects of asteroid impacts in deep water

    SciTech Connect

    Gisler, Galen R; Weaver, Robert P; Gittings, Michael L

    2009-06-11

    Our previous work has shown that ocean impacts of asteroids below 500 m in diameter do not produce devastating long-distance tsunamis. Nevertheless, a significant portion of the ocean lies close enough to land that near-field effects may prove to be the greatest danger from asteroid impacts in the ocean. Crown splashes and central jets that rise up many kilometres into the atmosphere can produce, upon their collapse, highly non-linear breaking waves that could devastate shorelines within a hundred kilometres of the impact site. We present illustrative calculations, in two and three dimensions, of such impacts for a range of asteroid sizes and impact angles. We find that, as for land impacts, the greatest dangers from oceanic impacts are the short-term near-field, and long-term atmospheric effects.

  16. Plasmonic and photonic scattering and near fields of nanoparticles

    PubMed Central

    2014-01-01

    We theoretically compare the scattering and near field of nanoparticles from different types of materials, each characterized by specific optical properties that determine the interaction with light: metals with their free charge carriers giving rise to plasmon resonances, dielectrics showing zero absorption in wide wavelength ranges, and semiconductors combining the two beforehand mentioned properties plus a band gap. Our simulations are based on Mie theory and on full 3D calculations of Maxwell’s equations with the finite element method. Scattering and absorption cross sections, their division into the different order electric and magnetic modes, electromagnetic near field distributions around the nanoparticles at various wavelengths as well as angular distributions of the scattered light were investigated. The combined information from these calculations will give guidelines for choosing adequate nanoparticles when aiming at certain scattering properties. With a special focus on the integration into thin film solar cells, we will evaluate our results. PMID:24475923

  17. Thermal excitation of plasmons for near-field thermophotovoltaics

    SciTech Connect

    Guo, Yu; Molesky, Sean; Hu, Huan; Cortes, Cristian L.; Jacob, Zubin

    2014-08-18

    The traditional approaches of exciting plasmons consist of either using electrons (e.g., electron energy loss spectroscopy) or light (Kretchman and Otto geometry) while more recently plasmons have been excited even by single photons. A different approach: thermal excitation of a plasmon resonance at high temperatures using alternate plasmonic media was proposed by S. Molesky et al. [Opt. Express 21, A96–A110 (2013)]. Here, we show how the long-standing search for a high temperature narrowband near-field emitter for thermophotovoltaics can be fulfilled by thermally exciting plasmons. We also describe a method to control Wein's displacement law in the near-field using high temperature epsilon-near-zero metamaterials. Finally, we show that our work opens up an interesting direction of research for the field of slow light: thermal emission control.

  18. Plasmonic and photonic scattering and near fields of nanoparticles.

    PubMed

    Schmid, Martina; Andrae, Patrick; Manley, Phillip

    2014-01-01

    We theoretically compare the scattering and near field of nanoparticles from different types of materials, each characterized by specific optical properties that determine the interaction with light: metals with their free charge carriers giving rise to plasmon resonances, dielectrics showing zero absorption in wide wavelength ranges, and semiconductors combining the two beforehand mentioned properties plus a band gap. Our simulations are based on Mie theory and on full 3D calculations of Maxwell's equations with the finite element method. Scattering and absorption cross sections, their division into the different order electric and magnetic modes, electromagnetic near field distributions around the nanoparticles at various wavelengths as well as angular distributions of the scattered light were investigated. The combined information from these calculations will give guidelines for choosing adequate nanoparticles when aiming at certain scattering properties. With a special focus on the integration into thin film solar cells, we will evaluate our results. PMID:24475923

  19. Tip-enhanced Raman spectroscopy and near-field polarization

    NASA Astrophysics Data System (ADS)

    Saito, Yuika; Mino, Toshihiro; Verma, Prabhat

    2015-12-01

    Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for High-resolution Raman spectroscopy. In this method, a metal coated nano-tip acts as a plasmonic antenna to enhance the originally weak Raman scattering from a nanometric volume of a sample. The technique enables to detect Raman scattering light from nano-scale area and also enhance the light intensity with combination of near-filed light and localized surface plasmon generated at a metallized tip apex. Nowadays TERS is used to investigate various nano-scale samples, for examples, carbon nanotubes, graphenes DNA and biomaterials. As the TERS developed, there is high demand to investigate the properties of near-field light e.g. polarization properties. We have analyzed the polarization properties of near-field light in TERS and successfully realized the quantitative nano-imaging by visible light.

  20. Near-field imaging of quantum cascade laser transverse modes.

    PubMed

    Yu, Nanfang; Diehl, Laurent; Cubukcu, Ertugrul; Pflügl, Christian; Bour, David; Corzine, Scott; Zhu, Jintian; Höfler, Gloria; Crozier, Kenneth B; Capasso, Federico

    2007-10-01

    We report near field imaging of the transverse lasing modes of quantum cascade lasers. A mid-infrared apertureless near-field scanning optical microscope was used to characterize the modes on the laser facet. A very stable mode pattern corresponding to a TM(00) mode was observed as function of increasing driving current for a narrow active region quantum cascade laser. Higher order modes were observed for devices with a larger active region width-to-wavelength ratio operated in pulsed mode close to threshold. A theoretical model is proposed to explain why specific transverse modes are preferred close to threshold. The model is in good agreement with the experimental results. PMID:19550591

  1. Graphene-enhanced infrared near-field microscopy.

    PubMed

    Li, Peining; Wang, Tao; Böckmann, Hannes; Taubner, Thomas

    2014-08-13

    Graphene is a promising two-dimensional platform for widespread nanophotonic applications. Recent theories have predicted that graphene can also enhance evanescent fields for subdiffraction-limited imaging. Here, for the first time we experimentally demonstrate that monolayer graphene offers a 7-fold enhancement of evanescent information, improving conventional infrared near-field microscopy to resolve buried structures at a 500 nm depth with λ/11-resolution. PMID:25019504

  2. Near-field photometry for organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Li, Rui; Harikumar, Krishnan; Isphording, Alexandar; Venkataramanan, Venkat

    2013-03-01

    Organic Light Emitting Diode (OLED) technology is rapidly maturing to be ready for next generation of light source for general lighting. The current standard test methods for solid state lighting have evolved for semiconductor sources, with point-like emission characteristics. However, OLED devices are extended surface emitters, where spatial uniformity and angular variation of brightness and colour are important. This necessitates advanced test methods to obtain meaningful data for fundamental understanding, lighting product development and deployment. In this work, a near field imaging goniophotometer was used to characterize lighting-class white OLED devices, where luminance and colour information of the pixels on the light sources were measured at a near field distance for various angles. Analysis was performed to obtain angle dependent luminous intensity, CIE chromaticity coordinates and correlated colour temperature (CCT) in the far field. Furthermore, a complete ray set with chromaticity information was generated, so that illuminance at any distance and angle from the light source can be determined. The generated ray set is needed for optical modeling and design of OLED luminaires. Our results show that luminance non-uniformity could potentially affect the luminaire aesthetics and CCT can vary with angle by more than 2000K. This leads to the same source being perceived as warm or cool depending on the viewing angle. As OLEDs are becoming commercially available, this could be a major challenge for lighting designers. Near field measurement can provide detailed specifications and quantitative comparison between OLED products for performance improvement.

  3. Complex Near-Field Plasmonic Response of Au Nanospirals

    NASA Astrophysics Data System (ADS)

    Hachtel, Jordan; Davidson, Roderick; Lupini, Andrew; Lawrie, Benjamin; Haglund, Richard; Pantelides, Sokrates

    Complex metallic nanostructures that support unique near-field surface plasmon modes have shown applications across the fields of photovoltaics, bio-sensing, and even quantum computing. Chiral Au nanospirals not only possess a non-symmetric morphology that results in second-harmonic generation, but possess multiple distinct near-field plasmonic modes that cover a wide range of plasmon frequencies. We use cathodoluminescence (CL) and electron energy loss spectroscopy (EELS) within a scanning transmission electron microscopy (STEM) to study the surface plasmons and map them with nanoscale precision. The two techniques are complementary as EELS measures excitations in the sample, while CL measures the subsequent radiative decays. We STEM-EELS/CL to map and analyze the spatial profile, intensity and polarization response of the intricate near-field plasmon modes in these versatile nanostructures. This work was funded by the Department of Energy Grant DE-FG02-09ER46554 and the Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  4. Near-Field Source Localization by Using Focusing Technique

    NASA Astrophysics Data System (ADS)

    He, Hongyang; Wang, Yide; Saillard, Joseph

    2008-12-01

    We discuss two fast algorithms to localize multiple sources in near field. The symmetry-based method proposed by Zhi and Chia (2007) is first improved by implementing a search-free procedure for the reduction of computation cost. We present then a focusing-based method which does not require symmetric array configuration. By using focusing technique, the near-field signal model is transformed into a model possessing the same structure as in the far-field situation, which allows the bearing estimation with the well-studied far-field methods. With the estimated bearing, the range estimation of each source is consequently obtained by using 1D MUSIC method without parameter pairing. The performance of the improved symmetry-based method and the proposed focusing-based method is compared by Monte Carlo simulations and with Crammer-Rao bound as well. Unlike other near-field algorithms, these two approaches require neither high-computation cost nor high-order statistics.

  5. Sample heating in near-field scanning optical microscopy

    NASA Astrophysics Data System (ADS)

    Erickson, Elizabeth S.; Dunn, Robert C.

    2005-11-01

    Heating near the aperture of aluminum coated, fiber optic near-field scanning optical microscopy probes was studied as a function of input and output powers. Using the shear-force feedback method, near-field probes were positioned nanometers above a thermochromic polymer and spectra were recorded as the input power was varied. Excitation at 405 nm of a thin polymer film incorporating perylene and N-allyl-N-methylaniline leads to dual emission peaks in the spectra. The relative peak intensity is temperature sensitive leading to a ratiometric measurement, which avoids complications based solely on intensity. Using this method, we find that the proximal end of typical near-field probes modestly increase in temperature to 40-45 °C at output powers of a few nanowatts (input power of ˜0.15mW). This increases to 55-65 °C at higher output powers of 50 nW or greater (input power of ˜2-4mW). Thermal heating of the probe at higher powers leads to probe elongation, which limits the heating experienced by the sample.

  6. Near-field thermal electromagnetic transport: An overview

    NASA Astrophysics Data System (ADS)

    Edalatpour, Sheila; DeSutter, John; Francoeur, Mathieu

    2016-07-01

    A general near-field thermal electromagnetic transport formalism that is independent of the size, shape and number of heat sources is derived. The formalism is based on fluctuational electrodynamics, where fluctuating currents due to thermal agitation are added to Maxwell's curl equations, and is thus valid for heat sources in local thermodynamic equilibrium. Using a volume integral formulation, it is shown that the proposed formalism is a generalization of the classical electromagnetic scattering framework in which thermal emission is implicitly assumed to be negligible. The near-field thermal electromagnetic transport formalism is afterwards applied to a problem involving three spheres with size comparable to the wavelength, where all multipolar interactions are taken into account. Using the thermal discrete dipole approximation, it is shown that depending on the dielectric function, the presence of a third sphere slightly affects the spatial distribution of power absorbed compared to the two-sphere case. A transient analysis shows that despite a non-uniform spatial distribution of power absorbed, the sphere temperature remains spatially uniform at any instant due to the fact that the thermal resistance by conduction is much smaller than the resistance by radiation. The formalism proposed in this paper is general, and could be used as a starting point for adapting solution methods employed in traditional electromagnetic scattering problems to near-field thermal electromagnetic transport.

  7. Improved optical fiber probes for scanning near field optical microscopy

    NASA Astrophysics Data System (ADS)

    Wheaton, Bryan R.

    2004-12-01

    The motivation behind this work stems from a combination of my interest in atomic force microscopy (AFM) and the need to apply AFM to several areas of glass research. AFM was used as the main characterization tool in the study of near-field scanning optical microscopy (NSOM) tip formation, evaluation of phase separation in glasses and copper oxide semiconductor film formation. The use of atomic force microscopy (AFM) to evaluate the evolving tip structure of an optical fiber probe for NSOM was studied. This study demonstrates the feasibility of predicting the final tip cone angle, without taking the etching process to completion. Cone angles reported in this study ranged from 58 to 152 degrees, depending on the fiber type and etch conditions. The ability to vary the probe cone angle, and utilize AFM to evaluate the cone angle that results from a set of etch conditions, are valuable additions to the development of NSOM fiber tips. The chemical and spatial variation of phase separated morphologies in glasses can range from a few angstroms to microns, often requiring very high magnification for detection. Historically phase separated glasses have been characterized by transmission electron microscopy (TEM), a time consuming and costly technique. Atomic force microscopy (AFM) provides an inexpensive alternative to TEM and has proven to be a powerful tool in the evaluation of type, degree and scale of phase separation in glasses down to the nanometer level. AFM was used to show that the thickness and uniformity of the CuO films grown in-situ on the surface of copper containing alkali borosilicate glasses increased with time and temperature, however an upper time limit was reached in which no further thickness increases were realized. Tenorite, cuprite and copper metal films were produced depending on the heat treatment environment. XPS was utilized to confirm that copper oxide film formation during heat treatments of glasses near Tg results from the oxidation of copper

  8. Hyperbolic metamaterial-based near-field thermophotovoltaic system for hundreds of nanometer vacuum gap.

    PubMed

    Jin, Seokmin; Lim, Mikyung; Lee, Seung S; Lee, Bong Jae

    2016-03-21

    Artificially designed hyperbolic metamaterial (HMM) possesses extraordinary electromagnetic features different from those of naturally existing materials. In particular, the dispersion relation of waves existing inside the HMM is hyperbolic rather than elliptical; thus, waves that are evanescent in isotropic media become propagating in the HMM. This characteristic of HMMs opens a novel way to spectrally control the near-field thermal radiation in which evanescent waves in the vacuum gap play a critical role. In this paper, we theoretically investigate the performance of a near-field thermophotovoltaic (TPV) energy conversion system in which a W/SiO2-multilayer-based HMM serves as the emitter at 1000 K and InAs works as the TPV cell at 300 K. By carefully designing the thickness of constituent materials of the HMM emitter, the electric power of the near-field TPV devices can be increased by about 6 times at 100-nm vacuum gap as compared to the case of the plain W emitter. Alternatively, in regards to the electric power generation, HMM emitter at experimentally achievable 100-nm vacuum gap performs equivalently to the plain W emitter at 18-nm vacuum gap. We show that the enhancement mechanism of the HMM emitter is due to the coupled surface plasmon modes at multiple metal-dielectric interfaces inside the HMM emitter. With the minority carrier transport model, the optimal p-n junction depth of the TPV cell has also been determined at various vacuum gaps. PMID:27136882

  9. Optical near-field investigations of individual single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hartschuh, Achim

    2009-03-01

    Optical excitation of semiconducting nanotubes creates excitons that determine nearly all light-based applications. Near-field photoluminescence (PL) and Raman imaging with a spatial resolution better than 15 nm was used to probe the spectroscopic properties of excitonic states along single nanotubes on substrates [1,2]. The PL intensity was found to decrease towards the nanotube ends on a length scale of few 10 nm probably caused by exciton transport to localized end states followed by efficient non-radiative recombination. DNA-wrapping of nanotubes results in pronounced emission energy variations on a length scale of few 10 nm indicating the potential of the material for nanoscale sensing applications [3]. Inter-nanotube energy transfer was studied for different pairs of semiconducting nanotubes forming bundles and crossings [4]. Efficient transfer is found to be limited to a few nanometres because of competing fast non-radiative relaxation and can be explained in terms of electromagnetic near-field coupling. We also report on our recent experimental results on time-resolved near-field PL measurements, electrically gated nanotubes and the PL of nanotubes on metal surfaces. [4pt] References: [0pt] [1] A. Hartschuh, Angew. Chem. Int. Ed. 47, 8178 (2008). [0pt] [2] I. O. Maciel et. al, Nature Mat. 7, 878 (2008). [0pt] [3] H. Qian et. al, Nano Lett. 8, 2706 (2008). [0pt] [4] H. Qian et. al, Nano Lett. 8, 1363 (2008).

  10. Phase interpretation for polarization-dependent near-field images of high-density gratings

    NASA Astrophysics Data System (ADS)

    Zheng, Jiangjun; Zhou, Changhe; Wang, Bo

    2008-06-01

    It has been described that the near-field images of a high-density grating at the half self-imaging distance could be different for TE and TM polarization states. We propose that the phases of the diffraction orders play an important role in such polarization dependence. The view is verified through the coincidence of the numerical result of finite-difference time-domain method and the reconstructed results from the rigorous coupled-wave analysis. Field distributions of TE and TM polarizations are given numerically for a grating with period d = 2.3 λ, which are verified through experiments with the scanning near-field optical microscopy technique. The concept of phase interpretation not only explains the polarization dependence at the half self-imaging distance of gratings with a physical view, but also, it could be widely used to describe the near-field diffraction of a variety of periodic diffractive optical elements whose feature size comparable to the wavelength.

  11. On the slow dynamics of near-field acoustically levitated objects under High excitation frequencies

    NASA Astrophysics Data System (ADS)

    Ilssar, Dotan; Bucher, Izhak

    2015-10-01

    This paper introduces a simplified analytical model describing the governing dynamics of near-field acoustically levitated objects. The simplification converts the equation of motion coupled with the partial differential equation of a compressible fluid, into a compact, second order ordinary differential equation, where the local stiffness and damping are transparent. The simplified model allows one to more easily analyse and design near-field acoustic levitation based systems, and it also helps to devise closed-loop controller algorithms for such systems. Near-field acoustic levitation employs fast ultrasonic vibrations of a driving surface and exploits the viscosity and the compressibility of a gaseous medium to achieve average, load carrying pressure. It is demonstrated that the slow dynamics dominates the transient behaviour, while the time-scale associated with the fast, ultrasonic excitation has a small presence in the oscillations of the levitated object. Indeed, the present paper formulates the slow dynamics under an ultrasonic excitation without the need to explicitly consider the latter. The simplified model is compared with a numerical scheme based on Reynolds equation and with experiments, both showing reasonably good results.

  12. Coupling entropy of co-processing model on social networks

    NASA Astrophysics Data System (ADS)

    Zhang, Zhanli

    2015-08-01

    Coupling entropy of co-processing model on social networks is investigated in this paper. As one crucial factor to determine the processing ability of nodes, the information flow with potential time lag is modeled by co-processing diffusion which couples the continuous time processing and the discrete diffusing dynamics. Exact results on master equation and stationary state are achieved to disclose the formation. In order to understand the evolution of the co-processing and design the optimal routing strategy according to the maximal entropic diffusion on networks, we propose the coupling entropy comprehending the structural characteristics and information propagation on social network. Based on the analysis of the co-processing model, we analyze the coupling impact of the structural factor and information propagating factor on the coupling entropy, where the analytical results fit well with the numerical ones on scale-free social networks.

  13. Unified theory of near-field analysis and measurement - Scattering and inverse scattering

    NASA Astrophysics Data System (ADS)

    Wacker, P. F.

    1981-03-01

    The scanning procedures of unified theory of near-field analysis and measurement are adapted to the determination of scattering patterns of electromagnetic and scalar systems from measurements made in the near, intermediate, or far field, with emphasis on high accuracy and efficient data processing. The scanning procedures include spherical, improved plane polar, and many types of plane rectangular, plane radial, and circular cylindrical scanning. Application of group representation to inverse scattering analysis is discussed.

  14. Atomic Response in the Near-Field of Nanostructured Plasmonic Metamaterial.

    PubMed

    Aljunid, Syed Abdullah; Chan, Eng Aik; Adamo, Giorgio; Ducloy, Martial; Wilkowski, David; Zheludev, Nikolay I

    2016-05-11

    We report on reflection spectra of cesium atoms in close vicinity of a nanostructured metallic meta-surface. We show that the hyperfine sub-Doppler spectrum of the 6(2)S1/2-6(2)P3/2 resonance transition at 852 nm is strongly affected by the coupling to the plasmonic resonance of the nanostructure. Fine tuning of dispersion and positions of the atomic lines in the near-field of plasmonic metamaterials could have uses and implications for atom-based metrology, sensing, and the development of atom-on-a-chip devices. PMID:27018806

  15. Concurrent polarization retrieval in multi-heterodyne scanning near-field optical microscopy: validation on silicon form-birefringent grating.

    PubMed

    Yu, L; Sfez, T; Paeder, V; Stenberg, P; Nakagawa, W; Kuittinen, M; Herzig, H P

    2012-10-01

    We demonstrate a concurrent polarization-retrieval algorithm based on a multi-heterodyne scanning near-field optical microscopy (MH-SNOM) measurement system. This method relies on calibration of the polarization properties of the MH-SNOM using an isotropic region of the sample in the vicinity of the nanostructures of interest. We experimentally show the effectiveness of the method on a silicon form-birefringent grating (FBG) with significant polarization diversity. Three spatial dimensional near-field measurements are in agreement with theoretical predictions obtained with rigorous coupled-wave analysis (RCWA). Pseudo-far-field measurements are performed to obtain the effective refractive index of the FBG, emphasizing the validity of the proposed method. This reconstruction algorithm makes the MH-SNOM a powerful tool to analyze concurrently the polarization-dependent near-field optical response of nanostructures with sub wavelength resolution as long as a calibration area is available in close proximity. PMID:23188273

  16. Quantitative and Direct Near-Field Analysis of Plasmonic-Induced Transparency and the Observation of a Plasmonic Breathing Mode.

    PubMed

    Khunsin, Worawut; Dorfmüller, Jens; Esslinger, Moritz; Vogelgesang, Ralf; Rockstuhl, Carsten; Etrich, Christoph; Kern, Klaus

    2016-02-23

    We investigated experimentally and numerically in the optical near-field a plasmonic model system similar to a dolmen-type structure for phenomena such as plasmon-induced transparency. Through engineering of coupling strength, structure orientation, and incident angle and phase of the excitation source it was possible to control near-field excitation of the dark modes. We showed that quantitative analysis of near-field amplitude and excitation strength provided essential information that allowed identifying the interaction between the bright and the dark mode and how it causes the formation of plasmon-induced transparency features and a Fano resonance. In addition, we introduced a mechanism to excite field distributions in plasmonic structures that cannot be accessed directly using far-field illumination and demonstrated the excitation of a dark mode akin to a symmetry-forbidden plasmonic breathing mode using a linearly polarized far-field source. PMID:26789080

  17. Decision making based on optical excitation transfer via near-field interactions between quantum dots

    NASA Astrophysics Data System (ADS)

    Naruse, Makoto; Nomura, Wataru; Aono, Masashi; Ohtsu, Motoichi; Sonnefraud, Yannick; Drezet, Aurélien; Huant, Serge; Kim, Song-Ju

    2014-10-01

    Optical near-field interactions between nanostructured matters, such as quantum dots, result in unidirectional optical excitation transfer when energy dissipation is induced. This results in versatile spatiotemporal dynamics of the optical excitation, which can be controlled by engineering the dissipation processes and exploited to realize intelligent capabilities such as solution searching and decision making. Here, we experimentally demonstrate the ability to solve a decision making problem on the basis of optical excitation transfer via near-field interactions by using colloidal quantum dots of different sizes, formed on a geometry-controlled substrate. We characterize the energy transfer behavior due to multiple control light patterns and experimentally demonstrate the ability to solve the multi-armed bandit problem. Our work makes a decisive step towards the practical design of nanophotonic systems capable of efficient decision making, one of the most important intellectual attributes of the human brain.

  18. Decision making based on optical excitation transfer via near-field interactions between quantum dots

    SciTech Connect

    Naruse, Makoto; Nomura, Wataru; Ohtsu, Motoichi; Aono, Masashi; Sonnefraud, Yannick; Drezet, Aurélien; Huant, Serge; Kim, Song-Ju

    2014-10-21

    Optical near-field interactions between nanostructured matters, such as quantum dots, result in unidirectional optical excitation transfer when energy dissipation is induced. This results in versatile spatiotemporal dynamics of the optical excitation, which can be controlled by engineering the dissipation processes and exploited to realize intelligent capabilities such as solution searching and decision making. Here, we experimentally demonstrate the ability to solve a decision making problem on the basis of optical excitation transfer via near-field interactions by using colloidal quantum dots of different sizes, formed on a geometry-controlled substrate. We characterize the energy transfer behavior due to multiple control light patterns and experimentally demonstrate the ability to solve the multi-armed bandit problem. Our work makes a decisive step towards the practical design of nanophotonic systems capable of efficient decision making, one of the most important intellectual attributes of the human brain.

  19. Exact Reconstruction for Near-Field Three-Dimensional Planar Millimeter-Wave Holographic Imaging

    NASA Astrophysics Data System (ADS)

    Qiao, Lingbo; Wang, Yingxin; Zhao, Ziran; Chen, Zhiqiang

    2015-12-01

    In this paper, an exact reconstruction formula is presented for near-field three-dimensional (3D) planar millimeter-wave (MMW) holographic imaging. The proposed formula is derived based on scalar diffraction theory, and the round-trip imaging process is equivalent to a unidirectional optical field propagation. Because of compensating the propagation loss of the source for the near-field imaging configuration, the inconsistency in range domain of the reconstructed 3D images is avoided. The proposed reconstruction formula also gives a phase correction for the reconstructed complex-valued reflectivity of the target and the range coordinate can be exactly determined. Simulations and laboratory imaging experiments are performed to demonstrate the effectiveness of the proposed reconstruction formula.

  20. Determination of near field excavation disturbance in crystalline rock

    SciTech Connect

    Koopmans, R.; Hughes, R.W.

    1986-01-01

    The computerized dilatometer system has rapidly and economically provided deformation moduli of low and high modulus rock, determined the extent of excavation disturbance surrounding an underground opening and located open fracture within a rock mass. Results from both test sites indicate that the moduli obtained were influenced by the in situ tangential stress field. It has been shown that the near field excavation disturbance is kept to a minimum through the use of careful excavation techniques such as the tunnel boring machine. In turn, the in situ tangential stress levels and deformation moduli are maximized while the corresponding permeability is minimized.

  1. Cryogenic Near-Field Microscopy in Correlated Electronic Systems

    NASA Astrophysics Data System (ADS)

    Gozar, Adrian

    2015-03-01

    We present results on the performance of a scattering-based scanning near-field optical microscope. The instrument was designed for measuring nano-scale complex dielectric properties of materials in a variable-temperature environment. The setup has a 20 - 30 nm spatial resolution with sample temperatures in the 10 - 300 K range. Spectral operation is in the infrared to visible and 0.1 - 1 THz regions. We illustrate these capabilities with results in graphene and ultra-thin sub-surface oxide films.

  2. Near-field spillover from a subreflector: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Lee, S. W.; Acosta, R.; Cherrette, A. R.; Lam, P. T.

    1986-01-01

    In a dual reflector antenna, the spillover from the subreflector is important in determining the accuracy of near-field measurements. This is especially so when some of the feed elements are placed far away from the focus. In this paper, we present a high-frequency GTD analysis of the spillover field over a plane just behind the subreflector. Special attention is given to the field near the incident shadow boundary and the role played by the slope diffraction term. Our computations are in excellent agreement with experimental results.

  3. Magnetic dipole moment determination by near-field analysis

    NASA Technical Reports Server (NTRS)

    Eichhorn, W. L.

    1972-01-01

    A method for determining the magnetic moment of a spacecraft from magnetic field data taken in a limited region of space close to the spacecraft. The spacecraft's magnetic field equations are derived from first principles. With measurements of this field restricted to certain points in space, the near-field equations for the spacecraft are derived. These equations are solved for the dipole moment by a least squares procedure. A method by which one can estimate the magnitude of the error in the calculations is also presented. This technique was thoroughly tested on a computer. The test program is described and evaluated, and partial results are presented.

  4. Focusing properties of near-field time reversal

    NASA Astrophysics Data System (ADS)

    de Rosny, Julien; Fink, Mathias

    2007-12-01

    A time-reversal mirror (TRM) is a plane apparatus that generates the time symmetric of a wave produced by an initial source. Here we look for the conditions to obtain subwavelength focusing when the initial source is in the near field of the TRM and the propagating medium is homogeneous and isotropic. Three variants of TRM are studied: TRM made of monopoles, dipoles, or both of them. The analysis is performed in terms of evanescent and propagative waves. We conclude that only the dipole-TRM leads to subwavelength focusing.

  5. Focusing properties of near-field time reversal

    SciTech Connect

    Rosny, Julien de; Fink, Mathias

    2007-12-15

    A time-reversal mirror (TRM) is a plane apparatus that generates the time symmetric of a wave produced by an initial source. Here we look for the conditions to obtain subwavelength focusing when the initial source is in the near field of the TRM and the propagating medium is homogeneous and isotropic. Three variants of TRM are studied: TRM made of monopoles, dipoles, or both of them. The analysis is performed in terms of evanescent and propagative waves. We conclude that only the dipole-TRM leads to subwavelength focusing.

  6. Simulation study of 'perfect lens' for near-field nanolithography

    NASA Astrophysics Data System (ADS)

    Guo, Xiaowei; Dong, Qiming; Liu, Yong

    2011-09-01

    The near-field perfect lens (NFPL) in imaging chrome gratings is investigated by using finite difference time domain (FDTD) method. The surface plasmon focused effect in and beneath the NFPL layer is demonstrated. The effects of the grating parameters and NFPL permittivity on image fidelity are explored. It is found that the excitation of surface plasmons results in frequency-increased images at large duty cycles and small imaginary part of NFPL permittivities. It is also shown that maximum intensity distributions on image plane occur at some specified pitches and duty cycles. The physics mechanisms are presented to explain these phenomena.

  7. Micromachined photoplastic probe for scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Genolet, G.; Despont, M.; Vettiger, P.; Staufer, U.; Noell, W.; de Rooij, N. F.; Cueni, T.; Bernal, M.-P.; Marquis-Weible, F.

    2001-10-01

    We present a hybrid probe for scanning near-field optical microscopy (SNOM), which consists of a micromachined photoplastic tip with a metallic aperture at the apex that is attached to an optical fiber, thus combining the advantages of optical fiber probes and micromachined tips. The tip and aperture are batch fabricated and assembled to a preetched optical fiber with micrometer centering precision. Rectangular apertures of 50 nm×130 nm have been produced without the need of any postprocessing. Topographical and optical imaging with a probe having an aperture of 300 nm demonstrate the great potential of the photoplastic probe for SNOM applications.

  8. Near Field Imaging at Microwave and Millemeter Wave Frequencies

    SciTech Connect

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    2007-06-03

    Near field imaging at microwave and millimeter wave frequencies is useful for a wide variety of applications including concealed weapon detection, through-wall and inner-wall imaging, ground penetrating radar imaging, radar cross section analysis, and non-destructive evaluation of materials. A variety of novel imaging techniques have been developed for many of these applications at the Pacific Northwest National Laboratory (PNNL) . These techniques make use of wideband holographic wavefront reconstruction methods, and have been developed to optimize the image quality and resolution. This paper will summarize several of these techniques and show imaging results for several interesting application areas.

  9. Plasmonic lithography modeling and measurement of near-field distribution of plasmonic nano-aperture

    NASA Astrophysics Data System (ADS)

    Kim, Yongwoo; Kim, Seok; Jung, Howon; Jang, Jinhee; Lee, Jae Yong; Hahn, Jae W.

    2012-03-01

    In plasmonic nano lithography, a photoresist responds to the localized electric field which decays evanescently in the direction of depth. A simple analytic model is suggested to predict profiles of exposed and finally developed pattern with a finite contrast of photoresist. In this model, the developing process is revisited by accounting the variation of dissolution rate with respect to expose dose distribution. We introduce the concept of nominal developing thickness (NDT) to determine the optimized developing process fitting to the isointensity profile. Based on this model, we obtained three dimensional distribution of near-field of bowtie shaped plasmonic nano aperture in a metal film from the near-field lithography pattern profile. For the near-field exposure, we fabricated a nano aperture in a aluminum metal film which is coated on the contact probe tip. By illuminating 405 nm diode laser source, the positive type photoresist is exposed by the localized electric field produced by nano aperture. The exposed photoresist is developed by the TMAH based solution with a optimum NDT, which leads the developing march encounters the isoexposure contour at threshold dose. From the measurement of developed pattern profile with a atomic force microscope (AFM), the three-dimensional isoexposure (or iso-intensity) surface at the very near region from the exit plane of an aperture (depth: 5 ~ 50 nm) is profiled. Using the threshold dose of photoresist and exposure time, the absolute intensity level is also measured. The experimental results are quantitatively compared with the calculation of FDTD (finite- difference time-domain) method. Concerning with the error in exposure time and threshold dose value, the error in measurement of profile and intensity are less than 6% and 1%, respectively. We expect the lithography model described in this presentation allows more elaborated expectation of developed pattern profile. Furthermore, a methodology of mapping is useful for the

  10. Unidirectional wireless power transfer using near-field plates

    SciTech Connect

    Imani, Mohammadreza F.; Grbic, Anthony

    2015-05-14

    One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency.