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Sample records for near-field optical recording

  1. Ultrahigh-Density Storage Media for Near-Field Optical Recording

    NASA Astrophysics Data System (ADS)

    Hieda, Hiroyuki; Naito, Katsuyuki; Ishino, Takashi; Tanaka, Kuniyoshi; Sakurai, Masatoshi; Kamata, Yoshiyuki; Morita, Seiji; Kikitsu, Akira; Asakawa, Koji

    Two types of recording media possessing nano-dot structures were investigated. The media were prepared by an artificially assisted (or aligned) self-assembling (AASA) method, which includes simple nano-patterning using a nano-imprint and fine nano-patterning using self-assembling organic molecules. The AASA method were successfully applied to fabricate magnetic patterned media for opto-magnetic hybrid recordings and fluorescent organic dye media for near-field optical recording.

  2. Observation of Amorphous Recording Marks Using Reflection-Mode Near-Field Scanning Optical Microscope Supported by Optical Interference Method

    NASA Astrophysics Data System (ADS)

    Sakai, Masaru; Mononobe, Shuji; Yusu, Keiichiro; Tadokoro, Toshiyasu; Saiki, Toshiharu

    2005-09-01

    A signal enhancing technique for a reflection-mode near-field scanning optical microscope (NSOM) is proposed. Optical interference between the signal light, from an aperture at the tip of a tapered optical fiber, and the reflected light, from a metallic coating around the aperture, enhances the signal intensity. We used a rewritable high-definition digital versatile disc (HD DVD) with dual recording layers as a sample medium, and demonstrated observation of amorphous recording marks on the semitransparent (the first) recording layer. In spite of low optical contrast between the crystal region and the amorphous region on this layer, we successfully observed recording marks with good contrast.

  3. Design and control of dual servo actuator for near field optical recording system

    NASA Astrophysics Data System (ADS)

    Jeong, Jaehwa; Choi, Young-Man; Lee, Jun-Hee; Yoon, Hyoung-Kil; Gweon, Dae-Gab

    2005-12-01

    Near field recording (NFR) has been introduced as a new optical data storage method to realize higher data density beyond the diffraction limit. As the data density increases, the track pitch is remarkably reduced to about 400nm. Thus, more precise actuator is required and we propose a dual servo actuator to improve the accuracy of actuator. The proposed dual servo actuator consists of a coarse actuator and a fine actuator, multisegmented magnet array (MSMA) voice coil motor (VCM) and PMN-PT actuator. In design of VCM actuator, a novel magnetic circuit of VCM with MSMA is proposed. It can generate higher air gap flux density than the magnetic circuit of VCM with the conventional magnet array. In design of fine actuator, the fine actuator including PMN-PT single crystal instead of the conventional PZT is proposed. The displacement gain of PMN-PT fine actuator is 26 nm/V and that of PZT fine actuator is 17 nm/V. The displacement gain is increased by 53 %. To evaluate tracking performance of the manufactured dual servo actuator and to assign the proper role to each actuator, the PQ method is selected. From experiment results, the total bandwidth of the dual servo actuator is increased to 2.5kHz and the resolution is 25 nm. Comparing with the resolution of one servo actuator, 70 nm, we can find that the accuracy of actuator is remarkably improved. And the proposed dual servo actuator shows satisfactory performances to be applied to NFR and it can be applied to other future disk drives.

  4. Numerical modeling of the subwavelength phase-change recording using an apertureless scanning near-field optical microscope.

    PubMed

    Grosges, Thomas; Petit, Stéphane; Barchiesi, Dominique; Hudlet, Sylvain

    2004-11-29

    The electromagnetic field enhancement (FE) at the end of the probe of an Apertureless Scanning Near-field Optical Microscope (ASNOM) is used to write nanometric dots in a phase-change medium. The FE acts as a heat source that allows the transition from amorphous to crystalline phase in a Ge2Sb2Te5 layer. Through the 2D Finite Element Method (FEM) we predict the size of the dot as a function of both the illumination duration and the incoming power density. Numerical results are found to be in good agreement with preliminary experimental data. PMID:19488240

  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. 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

  7. 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.

  8. Time-resolved phase-change recording mark formation with zinc oxide near-field optical active layer

    NASA Astrophysics Data System (ADS)

    Kao, Tsung Sheng; Chen, Mu-Ku; Chen, Jia-Wern; Chen, Yi-Hao; Wu, Pei Ru; Tsai, Din Ping

    2015-09-01

    In this paper, an optical active thin film of zinc oxide (ZnOx) nano-composites exploited for the enhancement of optical signals in an ultra-high density recording scheme has been demonstrated. Via the electron microscope investigation, the results display randomly distributed crystalline nanograins in the ZnOx thin films. Optical disks with the ZnOx nanostructured thin films show that the carrier-to-noise ratio (CNR) above 25 dB can be obtained at the mark trains of 100 nm, while the optimal writing power is reduced as a function of the increasing thickness of the ZnOx films. Furthermore, by conducting a series of the optical pump-probe experiments, the optical responses of recording marks on as-deposited phase-change Ge2Sb2Te5 (as-GST) recording layers present that the highly contrast bright recording bits can be acquired with the existence of the ZnOx nanostructured thin films, providing prospective potentials in future data storage and optoelectronic devices.

  9. 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.

  10. 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.

  11. Novel aluminum near field transducer and highly integrated micro-nano-optics design for heat-assisted ultra-high-density magnetic recording.

    PubMed

    Miao, Lingyun; Stoddart, Paul R; Hsiang, Thomas Y

    2014-07-25

    Heat-assisted magnetic recording (HAMR) has attracted increasing attention as one of the most promising future techniques for ultra-high-density magnetic recording beyond the current limit of 1 Tb in(-2). Localized surface plasmon resonance plays an important role in HAMR by providing a highly focused optical spot for heating the recording medium within a small volume. In this work, we report an aluminum near-field transducer (NFT) based on a novel bow-tie design. At an operating wavelength of 450 nm, the proposed transducer can generate a 35 nm spot size inside the magnetic recording medium, corresponding to a recording density of up to 2 Tb in(-2). A highly integrated micro-nano-optics design is also proposed to ensure process compatibility and corrosion-resistance of the aluminum NFT. Our work has demonstrated the feasibility of using aluminum as a plasmonic material for HAMR, with advantages of reduced cost and improved efficiency compared to traditional noble metals. PMID:24981413

  12. High-Speed Gap Servo Control for Solid-Immersion-Lens-Based Near-Field Recording System with a Flexible Optical Disk

    NASA Astrophysics Data System (ADS)

    Hwang, Hyunwoo; Kim, Jung-Gon; Song, Ki Wook; Park, Kyoung-Su; Park, No-cheol; Yang, Hyunseok; Rhim, Yoon-Chul; Park, Young-Pil

    2011-09-01

    Higher data storage capacities and higher data transfer rates will be required in next-generation information storage devices. However, there is a limit to the rotational speeds of conventional disk structures. Hence, conventional disks will not be able to achieve high data transfer rates of over 250 Mbps that is required for next-generation storage devices. To increase the data transfer rate of a disk, flexible optical disks have been studied with the goal of stable rotation at a high speed, using a stabilizer to reduce disk oscillations. If a flexible optical disk is implemented in a near-field recording (NFR) system, simultaneous high data transfer rates and high-density recording should be possible. In an NFR system, it is very important to maintain the gap between the solid immersion lens (SIL) and the disk at distances below tens of nanometers. In this study, to simultaneously achieve high data storage capacity and high data transfer rate, we propose an improved gap servo control system for an SIL-based NFR system with a flexible optical disk. To enable robust control at a high rotational speed, a repetitive controller was designed and applied to the NFR servo algorithm. In both simulation and experiment, the newly designed gap servo controller stably maintained the gap distance in the SIL-based NFR system using a flexible optical disk.

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

    NASA Astrophysics Data System (ADS)

    Yang, Honghua

    Driven by the progress in nanotechnology, imaging and spectroscopy tools with nanometer spatial resolution are needed for in situ material characterizations. Near-field optics provides a unique way to selectively excite and detect elementary electronic and vibrational interactions at the nanometer scale, through interactions of light with matter in the near-field region. This dissertation discusses the development and applications of near-field optical imaging techniques, including plasmonic material characterization, optical spectral nano-imaging and magnetic field detection using scattering-type scanning near-field optical microscopy (s-SNOM), and exploring new modalities of optical spectroscopy based on optical gradient force detection. Firstly, the optical dielectric functions of one of the most common plasmonic materials---silver is measured with ellipsometry, and analyzed with the Drude model over a broad spectral range from visible to mid-infrared. This work was motivated by the conflicting results of previous measurements, and the need for accurate values for a wide range of applications of silver in plasmonics, optical antennas, and metamaterials. This measurement provides a reference for dielectric functions of silver used in metamaterials, plasmonics, and nanophotonics. Secondly, I implemented an infrared s-SNOM instrument for spectroscopic nano-imaging at both room temperature and low temperature. As one of the first cryogenic s-SNOM instruments, the novel design concept and key specifications are discussed. Initial low-temperature and high-temperature performances of the instrument are examined by imaging of optical conductivity of vanadium oxides (VO2 and V2O 3) across their phase transitions. The spectroscopic imaging capability is demonstrated on chemical vibrational resonances of Poly(methyl methacrylate) (PMMA) and other samples. The third part of this dissertation explores imaging of optical magnetic fields. As a proof-of-principle, the magnetic

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. Near-Field Magneto-Optical Microscope

    DOEpatents

    Vlasko-Vlasov, Vitalii; Welp, Ulrich; and Crabtree, George W.

    2005-12-06

    A device and method for mapping magnetic fields of a sample at a resolution less than the wavelength of light without altering the magnetic field of the sample is disclosed. A device having a tapered end portion with a magneto-optically active particle positioned at the distal end thereof in communication with a fiber optic for transferring incoming linearly polarized light from a source thereof to the particle and for transferring reflected light from the particle is provided. The fiber optic has a reflective material trapping light within the fiber optic and in communication with a light detector for determining the polarization of light reflected from the particle as a function of the strength and direction of the magnetic field of the sample. Linearly polarized light from the source thereof transferred to the particle positioned proximate the sample is affected by the magnetic field of the sample sensed by the particle such that the difference in polarization of light entering and leaving the particle is due to the magnetic field of the sample. Relative movement between the particle and sample enables mapping.

  19. Near Field Magneto-Optical Microscope

    DOEpatents

    Vlasko-Vlasov, Vitalii K.; Welp, Ulrich; Crabtree, George W.

    2005-12-06

    A device and method for mapping magnetic fields of a sample at a resolution less than the wavelength of light without altering the magnetic field of the sample is disclosed. A device having a tapered end portion with a magneto-optically active particle positioned at the distal end thereof in communication with a fiber optic for transferring incoming linearly polarized light from a source thereof to the particle and for transferring reflected light from the particle is provided. The fiber optic has a reflective material trapping light within the fiber optic and in communication with a light detector for determining the polarization of light reflected from the particle as a function of the strength and direction of the magnetic field of the sample. Linearly polarized light from the source thereof transferred to the particle positioned proximate the sample is affected by the magnetic field of the sample sensed by the particle such that the difference in polarization of light entering and leaving the particle is due to the magnetic field of the sample. Relative movement between the particle and sample enables mapping.

  20. 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

  1. Imaging Nanoscale Electromagnetic Near-Field Distributions Using Optical Forces.

    PubMed

    Huang, Fei; Tamma, Venkata Ananth; Mardy, Zahra; Burdett, Jonathan; Wickramasinghe, H Kumar

    2015-01-01

    We demonstrate the application of Atomic Force Microscopy (AFM) for mapping optical near-fields with nanometer resolution, limited only by the AFM probe geometry. By detecting the optical force between a gold coated AFM probe and its image dipole on a glass substrate, we profile the electric field distributions of tightly focused laser beams with different polarizations. The experimentally recorded focal force maps agree well with theoretical predictions based on a dipole-dipole interaction model. We experimentally estimate the aspect ratio of the apex of gold coated AFM probe using only optical forces. We also show that the optical force between a sharp gold coated AFM probe and a spherical gold nanoparticle of radius 15 nm, is indicative of the electric field distribution between the two interacting particles. Photo Induced Force Microscopy (PIFM) allows for background free, thermal noise limited mechanical imaging of optical phenomenon over wide range of wavelengths from Visible to RF with detection sensitivity limited only by AFM performance. PMID:26073331

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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

  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 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.

  9. 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

  10. 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

  11. 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

  12. Writing 40 nm marks by using a beaked metallic plate near-field optical probe.

    PubMed

    Matsumoto, T; Anzai, Y; Shintani, T; Nakamura, K; Nishida, T

    2006-01-15

    We have developed a near-field optical probe that uses a triangular metallic plate with a three-dimensionally tapered apex as a light source for thermally assisted magnetic recording. Numerical analysis using a finite-element method shows that the size of the optical spot generated at the apex is 15 nm x 20 nm, and the efficiency (defined as the ratio between the power of the optical near field at the surface of the recording medium and that of the incident light) is 15% when the incident light is focused by a lens with a numerical aperture of 0.8. The metallic plate was fabricated on the surface of a quartz slider and used for writing marks on a phase change recording medium. The marks were observed with a scanning electron microscope, and we confirmed that marks with a diameter of 40 nm were successfully written on the medium. PMID:16441049

  13. 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

  14. Near Field Communication-based telemonitoring with integrated ECG recordings

    PubMed Central

    Morak, J.; Kumpusch, H.; Hayn, D.; Leitner, M.; Scherr, D.; Fruhwald, F.M.; Schreier, G.

    2011-01-01

    Objectives Telemonitoring of vital signs is an established option in treatment of patients with chronic heart failure (CHF). In order to allow for early detection of atrial fibrillation (AF) which is highly prevalent in the CHF population telemonitoring programs should include electrocardiogram (ECG) signals. It was therefore the aim to extend our current home monitoring system based on mobile phones and Near Field Communication technology (NFC) to enable patients acquiring their ECG signals autonomously in an easy-to-use way. Methods We prototypically developed a sensing device for the concurrent acquisition of blood pressure and ECG signals. The design of the device equipped with NFC technology and Bluetooth allowed for intuitive interaction with a mobile phone based patient terminal. This ECG monitoring system was evaluated in the course of a clinical pilot trial to assess the system’s technical feasibility, usability and patient’s adherence to twice daily usage. Results 21 patients (4f, 54 ± 14 years) suffering from CHF were included in the study and were asked to transmit two ECG recordings per day via the telemonitoring system autonomously over a monitoring period of seven days. One patient dropped out from the study. 211 data sets were transmitted over a cumulative monitoring period of 140 days (overall adherence rate 82.2%). 55% and 8% of the transmitted ECG signals were sufficient for ventricular and atrial rhythm assessment, respectively. Conclusions Although ECG signal quality has to be improved for better AF detection the developed communication design of joining Bluetooth and NFC technology in our telemonitoring system allows for ambulatory ECG acquisition with high adherence rates and system usability in heart failure patients. PMID:23616890

  15. Harmonic demodulation and minimum enhancement factors in field-enhanced near-field optical microscopy.

    PubMed

    Scarpettini, A F; Bragas, A V

    2015-01-01

    Field-enhanced scanning optical microscopy relies on the design and fabrication of plasmonic probes which had to provide optical and chemical contrast at the nanoscale. In order to do so, the scattering containing the near-field information recorded in a field-enhanced scanning optical microscopy experiment, has to surpass the background light, always present due to multiple interferences between the macroscopic probe and sample. In this work, we show that when the probe-sample distance is modulated with very low amplitude, the higher the harmonic demodulation is, the better the ratio between the near-field signal and the interferometric background results. The choice of working at a given n harmonic is dictated by the experiment when the signal at the n + 1 harmonic goes below the experimental noise. We demonstrate that the optical contrast comes from the nth derivative of the near-field scattering, amplified by the interferometric background. By modelling the far and near field we calculate the probe-sample approach curves, which fit very well the experimental ones. After taking a great amount of experimental data for different probes and samples, we conclude with a table of the minimum enhancement factors needed to have optical contrast with field-enhanced scanning optical microscopy. PMID:25231792

  16. 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

  17. Imaging Analysis of Near-Field Recording Technique for Observation of Biological Specimens

    NASA Astrophysics Data System (ADS)

    Moriguchi, Chihiro; Ohta, Akihiro; Egami, Chikara; Kawata, Yoshimasa; Terakawa, Susumu; Tsuchimori, Masaaki; Watanabe, Osamu

    2006-07-01

    We present an analysis of the properties of an imaging based on a near-field recording technique in comparison with simulation results. In the system, the optical field distributions localized near the specimens are recorded as the surface topographic distributions of a photosensitive film. It is possible to observe both soft and moving specimens, because the system does not require a scanning probe to obtain the observed image. The imaging properties are evaluated using fine structures of paramecium, and we demonstrate that it is possible to observe minute differences of refractive indices.

  18. 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.

  19. Near-field optical microscopy based on microfabricated probes.

    PubMed

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

    2001-04-01

    We demonstrate high resolution imaging with microfabricated, cantilevered probes, consisting of solid quartz tips on silicon levers. The tips are covered by a 60-nm thick layer of aluminium, which appears to be closed at the apex when investigated by transmission electron microscopy. An instrument specifically built for cantilever probes was used to record images of latex bead projection patterns in transmission as well as single molecule fluorescence. All images were recorded in constant height mode and show optical resolutions down to 32 nm. PMID:11298861

  20. Near field scanning optical microscopy of polycrystalline semiconductors

    NASA Astrophysics Data System (ADS)

    Herndon, Mary Kay

    1999-09-01

    Photovoltaic devices are commonly used for space applications and remote terrestrial power requirements. Polycrystalline solar cell devices often have much lower efficiencies than their crystalline counterparts, but because they can be fabricated much more cheaply, they can still be cost-effective when compared to single crystal devices. The long term goal of this work is to provide information that will lead to higher quality devices with improved cost efficiency. In order to do this, a better understanding of the mechanisms that take place in these materials is needed. The goal of this thesis was to improve our understanding of these devices by adapting a novel characterization technique, Near Field Scanning Optical Microscopy (NSOM), to the study of polycrystalline films. Visible light NSOM is a relatively new technique that allows for optical characterization of materials with resolution beyond the far-field diffraction limit. By using NSOM to study the physical and electrical properties of polycrystalline solar cells, individual grains can be studied and more insight can be gained as to how various properties of the thin films affect the device efficiency. For this research, an NSOM was designed and built to be versatile enough to handle the sorts of samples and measurements required for studying a variety of photovoltaic devices. As a first step, the NSOM was used to characterize single crystal GaAs solar cell devices. Measurements of topography and NSOM-induced photocurrent were obtained simultaneously on cross sections of the material, allowing the p-n junction to be probed. Because the NSOM data could be compared to an expected result, this allowed verification of the new microscope's imaging capabilities and ensured accurate data interpretation. Effects of surface recombination were detected on the cleaved edges. The NSOM was used to characterize surface quality and study the effects of surface passivation treatments. Of the polycrystalline materials

  1. High throughput optical lithography by scanning a massive array of bowtie aperture antennas at near-field

    NASA Astrophysics Data System (ADS)

    Wen, X.; Datta, A.; Traverso, L. M.; Pan, L.; Xu, X.; Moon, E. E.

    2015-11-01

    Optical lithography, the enabling process for defining features, has been widely used in semiconductor industry and many other nanotechnology applications. Advances of nanotechnology require developments of high-throughput optical lithography capabilities to overcome the optical diffraction limit and meet the ever-decreasing device dimensions. We report our recent experimental advancements to scale up diffraction unlimited optical lithography in a massive scale using the near field nanolithography capabilities of bowtie apertures. A record number of near-field optical elements, an array of 1,024 bowtie antenna apertures, are simultaneously employed to generate a large number of patterns by carefully controlling their working distances over the entire array using an optical gap metrology system. Our experimental results reiterated the ability of using massively-parallel near-field devices to achieve high-throughput optical nanolithography, which can be promising for many important nanotechnology applications such as computation, data storage, communication, and energy.

  2. High throughput optical lithography by scanning a massive array of bowtie aperture antennas at near-field

    PubMed Central

    Wen, X.; Datta, A.; Traverso, L. M.; Pan, L.; Xu, X.; Moon, E. E.

    2015-01-01

    Optical lithography, the enabling process for defining features, has been widely used in semiconductor industry and many other nanotechnology applications. Advances of nanotechnology require developments of high-throughput optical lithography capabilities to overcome the optical diffraction limit and meet the ever-decreasing device dimensions. We report our recent experimental advancements to scale up diffraction unlimited optical lithography in a massive scale using the near field nanolithography capabilities of bowtie apertures. A record number of near-field optical elements, an array of 1,024 bowtie antenna apertures, are simultaneously employed to generate a large number of patterns by carefully controlling their working distances over the entire array using an optical gap metrology system. Our experimental results reiterated the ability of using massively-parallel near-field devices to achieve high-throughput optical nanolithography, which can be promising for many important nanotechnology applications such as computation, data storage, communication, and energy. PMID:26525906

  3. Reciprocity theory of apertureless scanning near-field optical microscopy with point-dipole probes.

    PubMed

    Esslinger, Moritz; Vogelgesang, Ralf

    2012-09-25

    Near-field microscopy offers the opportunity to reveal optical contrast at deep subwavelength scales. In scanning near-field optical microscopy (SNOM), the diffraction limit is overcome by a nanoscopic probe in close proximity to the sample. The interaction of the probe with the sample fields necessarily perturbs the bare sample response, and a critical issue is the interpretation of recorded signals. For a few specific SNOM configurations, individual descriptions have been modeled, but a general and intuitive framework is still lacking. Here, we give an exact formulation of the measurable signals in SNOM which is easily applicable to experimental configurations. Our results are in close analogy with the description Tersoff and Hamann have derived for the tunneling currents in scanning tunneling microscopy. For point-like scattering probe tips, such as used in apertureless SNOM, the theory simplifies dramatically to a single scalar relation. We find that the measured signal is directly proportional to the field of the coupled tip-sample system at the position of the tip. For weakly interacting probes, the model thus verifies the empirical findings that the recorded signal is proportional to the unperturbed field of the bare sample. In the more general case, it provides guidance to an intuitive and faithful interpretation of recorded images, facilitating the characterization of tip-related distortions and the evaluation of novel SNOM configurations, both for aperture-based and apertureless SNOM. PMID:22897563

  4. Imaging of optical disc using reflection-mode scattering-type scanning near-field optical microscopy.

    PubMed

    Yamaguchi, M; Sasaki, Y; Sasaki, H; Konada, T; Horikawa, Y; Ebina, A; Umezawa, T; Horiguchi, T

    1999-01-01

    A phase-change optical disc was observed using a reflection-mode scattering-type scanning near-field optical microscope (RS-SNOM). In an a.c.-mode SNOM image, the 1.2 microm x 0.6 microm recording marks were successfully observed although the data were recorded on the groove. In contrast, no recording marks could be resolved in a d.c.-mode SNOM image. These results are in good agreement with those from a numerical simulation using the finite difference time domain method. The resolution was better than 100 nm with a.c.-mode SNOM operation and the results indicate that recording marks in phase-change optical media can be directly observed with the RS-SNOM. PMID:11388305

  5. Generalized method of eigenoscillations for near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Bor-Yuan; Zhang, Lingfeng; Castro Neto, Antonio; Basov, Dimitri; Fogler, Michael

    2015-03-01

    Electromagnetic interaction between a sub-wavelength particle (the ``probe'') and a material surface (the ``sample'') is studied theoretically. The interaction is shown to be governed by a series of resonances (eigenoscillations), corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectric function and geometry of the probe, as well as the surface reflectivity of the material. Calculation of such resonances is carried out for several axisymmetric particle shapes (spherical, spheroidal, and pear-shaped). For spheroids an efficient numerical method is proposed, capable of handling cases of large or strongly momentum-dependent surface reflectivity. The method is applied to modeling near-field spectroscopy studies of various materials. For highly resonant materials such as aluminum oxide (by itself or covered with graphene) a rich structure of the simulated signal is found, including multi-peak spectra and nonmonotonic approach curves. These features have a strong dependence on physical parameters, e.g., the probe shape. For less resonant materials such as silicon oxide the dependence is weaker, and the spheroid model is generally applicable.

  6. 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.

  7. Near field optical probe for critical dimension measurements

    DOEpatents

    Stallard, Brian R.; Kaushik, Sumanth

    1999-01-01

    A resonant planar optical waveguide probe for measuring critical dimensions on an object in the range of 100 nm and below. The optical waveguide includes a central resonant cavity flanked by Bragg reflector layers with input and output means at either end. Light is supplied by a narrow bandwidth laser source. Light resonating in the cavity creates an evanescent electrical field. The object with the structures to be measured is translated past the resonant cavity. The refractive index contrasts presented by the structures perturb the field and cause variations in the intensity of the light in the cavity. The topography of the structures is determined from these variations.

  8. Near field optical probe for critical dimension measurements

    DOEpatents

    Stallard, B.R.; Kaushik, S.

    1999-05-18

    A resonant planar optical waveguide probe for measuring critical dimensions on an object in the range of 100 nm and below is disclosed. The optical waveguide includes a central resonant cavity flanked by Bragg reflector layers with input and output means at either end. Light is supplied by a narrow bandwidth laser source. Light resonating in the cavity creates an evanescent electrical field. The object with the structures to be measured is translated past the resonant cavity. The refractive index contrasts presented by the structures perturb the field and cause variations in the intensity of the light in the cavity. The topography of the structures is determined from these variations. 8 figs.

  9. Background Suppression in Near-field Optical Imaging

    PubMed Central

    Höppener, Christiane; Beams, Ryan; Novotny, Lukas

    2010-01-01

    In several recent studies, antenna-based optical microscopy (e.g. TENOM) has demonstrated its potential to resolve features as small as 10nm. Most studies are concerned with well-separated features on flat surfaces and there are only few studies that deal with samples of high feature density or even three-dimesional objects. The reason is that the external laser irradiation of the optical antenna (e.g. tip or particle) also directly irradiates the sample and therefore gives rise to a background. Here we introduce an efficient background suppression scheme that makes use of feedback modulation. The method is widely applicable and not restricted to cantilever-based scanning schemes. We apply this technique to both dense samples of dye molecules and ion channel proteins in plasma membranes and demonstrate effective background suppression and strongly improved sensitivity. The feedback modulation scheme is expected to find application for biological studies in liquid environments and for investigations of subsurface features in material science. PMID:19170554

  10. Near-Field Optical Microscopy in the Infrared Range

    NASA Astrophysics Data System (ADS)

    de Wilde, Yannick; Lemoine, Paul-Arthur; Babuty, Arthur

    The infrared covers the region of the electromagnetic spectrum with wave numbers (optical frequencies) in the range 13 000 to 10 cm-1, which corresponds to the wavelength range from 780 nm to 1 mm. Infrared frequencies, in particular those in the mid-infrared (2 < λ < 25 μm), are especially attractive for probing materials, for they provide a way of identifying and quantifying their composition and structure, or probing their electronic and thermal properties. The absorption of infrared photons excites molecular vibrations and phonons. It is maximal at those frequencies associated with the vibrational modes, which depend on the kind of molecules and functional groups involved in the vibrations, or the crystal structure. So the frequencies of the absorption maxima form a spectral fingerprint of the material. Other factors such as the electron density and interactions between electrons, in semiconductors, metals, and superconductors, affect the dielectric properties at infrared frequencies, and are studied in the field of condensed matter. Regarding thermal imaging, infrared thermography is used to observe the temperature distribution at the surface of materials. The intensity of the thermal radiation emitted by a material depends on the temperature according to Planck's law. The temperature of a material can be determined by measuring the intensity of the infrared radiation it emits, once its emissivity is known.

  11. Generalized spectral method for near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Jiang, B.-Y.; Zhang, L. M.; Castro Neto, A. H.; Basov, D. N.; Fogler, M. M.

    2016-02-01

    Electromagnetic interaction between a sub-wavelength particle (the "probe") and a material surface (the "sample") is studied theoretically. The interaction is shown to be governed by a series of resonances corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectric function and geometry of the probe as well as on the surface reflectivity of the material. Calculation of such resonances is carried out for several types of axisymmetric probes: spherical, spheroidal, and pear-shaped. For spheroids, an efficient numerical method is developed, capable of handling cases of large or strongly momentum-dependent surface reflectivity. Application of the method to highly resonant materials, such as aluminum oxide (by itself or covered with graphene), reveals a rich structure of multi-peak spectra and nonmonotonic approach curves, i.e., the probe-sample distance dependence. These features also strongly depend on the probe shape and optical constants of the model. For less resonant materials such as silicon oxide, the dependence is weak, so that the spheroidal model is reliable. The calculations are done within the quasistatic approximation with radiative damping included perturbatively.

  12. Phase stabilized homodyne of infrared scattering type scanning near-field optical microscopy

    SciTech Connect

    Xu, Xiaoji G.; Gilburd, Leonid; Walker, Gilbert C.

    2014-12-29

    Scattering type scanning near-field optical microscopy (s-SNOM) allows sub diffraction limited spatial resolution. Interferometric homodyne detection in s-SNOM can amplify the signal and extract vibrational responses based on sample absorption. A stable reference phase is required for a high quality homodyne-detected near-field signal. This work presents the development of a phase stabilization mechanism for s-SNOM to provide stable homodyne conditions. The phase stability is found to be better than 0.05 rad for the mid infrared light source. Phase stabilization results in improved near field images and vibrational spectroscopies. Spatial inhomogeneities of the boron nitride nanotubes are measured and compared.

  13. A quasi-optical vector near-field measurement system at terahertz band.

    PubMed

    Lou, Zheng; Hu, Jie; Zhou, Kang-Min; Miao, Wei; Shi, Sheng-Cai

    2014-06-01

    This paper describes a vector near-field measurement system at terahertz band based on a high sensitivity superconducting receiver equipped with a quasi-optical probe for high resolution near-field sensing. A novel single-receiver rather than commonly used dual-receiver configuration is adopted for vector measurement. Performances of the measurement system including stability and dynamic range are studied. Vector near-field measurement of a diagonal feedhorn at 850 GHz is presented and shows good agreement with simulation and direct far-field measurement. PMID:24985832

  14. Generation of nearly 3D-unpolarized evanescent optical near fields using total internal reflection.

    PubMed

    Hassinen, Timo; Popov, Sergei; Friberg, Ari T; Setälä, Tero

    2016-07-01

    We analyze the time-domain partial polarization of optical fields composed of two evanescent waves created in total internal reflection by random electromagnetic beams with orthogonal planes of incidence. We show that such a two-beam configuration enables to generate nearly unpolarized, genuine three-component (3D) near fields. This result complements earlier studies on spectral polarization, which state that at least three symmetrically propagating beams are required to produce a 3D-unpolarized near field. The degree of polarization of the near field can be controlled by adjusting the polarization states and mutual correlation of the incident beams. PMID:27367071

  15. Near-field study of magneto-optical samples: theoretical comparison of transversal and polar effects

    NASA Astrophysics Data System (ADS)

    Van Labeke, Daniel; Vial, A.; Barchiesi, Dominique

    1996-09-01

    The density of integration of magneto-optical devices is limited by diffraction of light. Recently some groups have proposed to use Near-Field Microscopy to overcome this limitation and some experiments have been performed both in transmission and reflection. In this paper we study theoretically magneto-optical effect in near-field. We consider a magneto-optical sample with details smaller than the wavelength. This sample is modelled as a multilayer rough structure. At least one layer has magneto-optical properties. The corrugation at the interfaces are very small compared to the optical wavelength. We do not consider the writing problem and the experiment is only modelled in the reading mode. Moreover, the magnetic properties are considered in the saturation regime. For this study we use an extension of the method that we used to describe near- field microscope with isotropic sample. The diffracted fields are determined in each layer by using a perturbative version of the Rayleigh method which leads to the resolution of a linear equation for each diffracted wave. The near- field above the sample is thus obtained by summing all the diffracted waves. We consider two geometries for the magnetization: polar effect where the magnetization is perpendicular to the sample and transversal effect where it is in the plane. We compare near-field images obtained in transmission and reflection by changing magnetization orientation. Comparisons with far-field results are also proposed.

  16. 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)

  17. Electroless silver plating for metallization of near-field optical fiber probes

    NASA Astrophysics Data System (ADS)

    Li, Chang'an; Xu, Lina; Gu, Ning

    2007-10-01

    By using mercaptopropyltrimethoxysilane (MPTS) self-assembled monolayers (SAMs), electroless silver plating is developed for the metallization of near-field optical fiber probes. This method has the advantages of controllability, no pinholes, convenience, low cost, and smooth tip surface. The metallized probes are characterized by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDXS).

  18. Point-by-point near-field optical energy deposition around plasmonic nanospheres in absorbing media.

    PubMed

    Harrison, R K; Ben-Yakar, Adela

    2015-08-01

    Here we investigate the effects of absorbing media on plasmon-enhanced near-field optical energy deposition. We find that increasing absorption by the medium results in increased particle scattering at the expense of particle absorption, and that much of this increased particle scattering is absorbed by the medium close to the particle surface. We present an analytical method for evaluating the spatial distribution of near-field enhanced absorption surrounding plasmonic metal nanospheres in absorbing media using a new point-by-point method. We propose criteria to define relevant near-field boundaries and calculate the properties of the local absorption enhancement, which redistributes absorption to the near-field and decays asymptotically as a function of the distance from the particle to background levels. Using this method, we performed a large-scale parametric study to understand the effect of particle size and wavelength on the near-field absorption for gold nanoparticles in aqueous media and silicon, and identified conditions that are relevant to enhanced local infrared absorption in silicon. The presented approach provides insight into the local energy transfer around plasmonic nanoparticles for predicting near-field effects for advanced concepts in optical sensing, thin-film solar cells, nonlinear imaging, and photochemical applications. PMID:26367296

  19. Scattering-type scanning near-field optical microscopy with reconstruction of vertical interaction.

    PubMed

    Wang, Le; Xu, Xiaoji G

    2015-01-01

    Scattering-type scanning near-field optical microscopy provides access to super-resolution spectroscopic imaging of the surfaces of a variety of materials and nanostructures. In addition to chemical identification, it enables observations of nano-optical phenomena, such as mid-infrared plasmons in graphene and phonon polaritons in boron nitride. Despite the high lateral spatial resolution, scattering-type near-field optical microscopy is not able to provide characteristics of near-field responses in the vertical dimension, normal to the sample surface. Here, we present an accurate and fast reconstruction method to obtain vertical characteristics of near-field interactions. For its first application, we investigated the bound electromagnetic field component of surface phonon polaritons on the surface of boron nitride nanotubes and found that it decays within 20 nm with a considerable phase change in the near-field signal. The method is expected to provide characterization of the vertical field distribution of a wide range of nano-optical materials and structures. PMID:26592949

  20. Scattering-type scanning near-field optical microscopy with reconstruction of vertical interaction

    NASA Astrophysics Data System (ADS)

    Wang, Le; Xu, Xiaoji G.

    2015-11-01

    Scattering-type scanning near-field optical microscopy provides access to super-resolution spectroscopic imaging of the surfaces of a variety of materials and nanostructures. In addition to chemical identification, it enables observations of nano-optical phenomena, such as mid-infrared plasmons in graphene and phonon polaritons in boron nitride. Despite the high lateral spatial resolution, scattering-type near-field optical microscopy is not able to provide characteristics of near-field responses in the vertical dimension, normal to the sample surface. Here, we present an accurate and fast reconstruction method to obtain vertical characteristics of near-field interactions. For its first application, we investigated the bound electromagnetic field component of surface phonon polaritons on the surface of boron nitride nanotubes and found that it decays within 20 nm with a considerable phase change in the near-field signal. The method is expected to provide characterization of the vertical field distribution of a wide range of nano-optical materials and structures.

  1. Scattering-type scanning near-field optical microscopy with reconstruction of vertical interaction

    PubMed Central

    Wang, Le; Xu, Xiaoji G.

    2015-01-01

    Scattering-type scanning near-field optical microscopy provides access to super-resolution spectroscopic imaging of the surfaces of a variety of materials and nanostructures. In addition to chemical identification, it enables observations of nano-optical phenomena, such as mid-infrared plasmons in graphene and phonon polaritons in boron nitride. Despite the high lateral spatial resolution, scattering-type near-field optical microscopy is not able to provide characteristics of near-field responses in the vertical dimension, normal to the sample surface. Here, we present an accurate and fast reconstruction method to obtain vertical characteristics of near-field interactions. For its first application, we investigated the bound electromagnetic field component of surface phonon polaritons on the surface of boron nitride nanotubes and found that it decays within 20 nm with a considerable phase change in the near-field signal. The method is expected to provide characterization of the vertical field distribution of a wide range of nano-optical materials and structures. PMID:26592949

  2. 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

  3. Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

    PubMed

    Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

    2015-02-01

    We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of <100 nm. In order to demonstrate the spatiotemporal magnetic imaging capability of this microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz. PMID:25725848

  4. 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.

  5. 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

  6. Cancer cell imaging by stable wet near-field scanning optical microscope with resonance tracking method

    NASA Astrophysics Data System (ADS)

    Park, Kyoung-Duck; Park, Doo Jae; Jeong, Mun Seok; Choi, Geun Chang; Lee, Seung Gol; Byeon, Clare Chisu; Choi, Soo Bong

    2014-05-01

    We report on a successful topographical and optical imaging of various cancer cells in liquid and in air by using a stable wet near-field scanning optical microscope that utilizes a resonance tracking method. We observed a clear dehydration which gives rise to a decrease in the cell volume down to 51%. In addition, a micro-ball lens effect due to the round-shaped young cancer cells was observed from near-field imaging, where the refractive index of young cancer cells was deduced.

  7. Three-dimensional mapping of optical near field of a nanoscale bowtie antenna.

    PubMed

    Guo, Rui; Kinzel, Edward C; Li, Yan; Uppuluri, Sreemanth M; Raman, Arvind; Xu, Xianfan

    2010-03-01

    Ridge nanoscale aperture antennas have been shown to be a high transmission nanoscale light source. They provide a small, polarization-dependent near-field optical spot with much higher transmission efficiency than circularly-shaped apertures with similar field confinement. This provides significant motivations to understand the electromagnetic fields in the immediate proximity to the apertures. This paper describes an experimental three-dimensional optical near-field mapping of a bowtie nano-aperture. The measurements are performed using a home-built near-field scanning optical microscopy (NSOM) system. An aluminum coated Si(3)N(4) probe with a 150 nm hole at the tip is used to collect optical signals. Both contact and constant-height scan (CHS) modes are used to measure the optical intensity at different longitudinal distances. A force-displacement curve is used to determine the tip-sample separation distance allowing the optical intensities to be mapped at distances as small as 50 nm and up to micrometer level. The experimental results also demonstrate the polarization dependence of the transmission through the bowtie aperture. Numerical simulations are also performed to compute the aperture's electromagnetic near-field distribution and are shown to agree with the experimental results. PMID:20389507

  8. 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

  9. Multipass laser amplification with near-field far-field optical separation

    DOEpatents

    Hagen, Wilhelm F.

    1979-01-01

    This invention discloses two classes of optical configurations for high power laser amplification, one allowing near-field and the other allowing far-field optical separation, for the multiple passage of laser pulses through one or more amplifiers over an open optical path. These configurations may reimage the amplifier or any other part of the cavity on itself so as to suppress laser beam intensity ripples that arise from diffraction and/or non-linear effects. The optical cavities combine the features of multiple passes, spatial filtering and optical reimaging and allow sufficient time for laser gain recovery.

  10. 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.

  11. Alterations of single molecule fluorescence lifetimes in near-field optical microscopy

    SciTech Connect

    Ambrose, W.P.; Goodwin, P.M.; Keller, R.A.; Martin, J.C. )

    1994-07-15

    Fluorescence lifetimes of single Rhodamine 6G molecules on silica surfaces were measured with pulsed laser excitation, time-correlated single photon counting, and near-field scanning optical microscopy (NSOM). The fluorescence lifetime varies with the position of a molecule relative to a near-field probe. Qualitative features of lifetime decreases are consistent with molecular excited state quenching effects near metal surfaces. The technique of NSOM provides a means of altering the environment of a single fluorescent molecule and its decay kinetics in a repeatable fashion.

  12. 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.

  13. 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.

  14. Near-field focusing of an optical wave by diffraction gratings

    NASA Astrophysics Data System (ADS)

    Geints, Yu E.; Zemlyanov, A. A.

    2016-07-01

    We report the investigation results for spatially-localised light structures (photonic nanojets) under near-field optical radiation scattering on phase diffraction gratings. Main parameters of photonic nanojets from gratings with sawtooth, rectangular and hemispherical groove profiles are obtained by numerical electrodynamic simulation. It is found that by varying a period, degree of filling, groove shape and parameters of optically contrast coating of the diffraction grating one can control the characteristics of the produced photonic jets in a wide range.

  15. Hyperspectral optical near-field imaging: Looking graded photonic crystals and photonic metamaterials in color

    NASA Astrophysics Data System (ADS)

    Dellinger, Jean; Van Do, K.; Le Roux, Xavier; de Fornel, Frédérique; Cassan, Eric; Cluzel, Benoît

    2012-10-01

    Using a scanning near-field optical microscope operating with a hyperspectral detection scheme, we report the direct observation of the mirage effect within an on-chip integrated artificial material made of a two dimensional graded photonic crystal. The light rainbow due to the material dispersion is quantified experimentally and quantitatively compared to three dimensional plane wave assisted Hamiltonian optics predictions of light propagation.

  16. Nonlinear optical tuning of photonic crystal microcavities by near-field probe

    SciTech Connect

    Vignolini, Silvia; Zani, Margherita; Riboli, Francesco; Vinattieri, Anna; Wiersma, Diederik S.; Gurioli, Massimo; Intonti, Francesca; Balet, Laurent; Li, Lianhe; Colocci, Marcello; Francardi, Marco; Gerardino, Annamaria; Fiore, Andrea

    2008-07-14

    We report on a nonlinear way to control and tune the dielectric environment of photonic crystal microcavities exploiting the local heating induced by near-field laser excitation at different excitation powers. The temperature gradient due to the optical absorption results in an index of refraction gradient which modifies the dielectric surroundings of the cavity and shifts the optical modes. Reversible tuning can be obtained either by changing the excitation power density or by exciting in different points of the photonic crystal microcavity.

  17. Analysis of optical near-field energy transfer by stochastic model unifying architectural dependencies

    SciTech Connect

    Naruse, Makoto; Akahane, Kouichi; Yamamoto, Naokatsu; Holmström, Petter; Thylén, Lars; Huant, Serge; Ohtsu, Motoichi

    2014-04-21

    We theoretically and experimentally demonstrate energy transfer mediated by optical near-field interactions in a multi-layer InAs quantum dot (QD) structure composed of a single layer of larger dots and N layers of smaller ones. We construct a stochastic model in which optical near-field interactions that follow a Yukawa potential, QD size fluctuations, and temperature-dependent energy level broadening are unified, enabling us to examine device-architecture-dependent energy transfer efficiencies. The model results are consistent with the experiments. This study provides an insight into optical energy transfer involving inherent disorders in materials and paves the way to systematic design principles of nanophotonic devices that will allow optimized performance and the realization of designated functions.

  18. Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy.

    PubMed

    Wenzel, Marc Tobias; Härtling, Thomas; Olk, Phillip; Kehr, Susanne C; Grafström, Stefan; Winnerl, Stephan; Helm, Manfred; Eng, Lukas M

    2008-08-01

    We report on the implementation of metal nanoparticles as probes for scattering and apertureless near-field optical investigations in the mid-infrared (mid-IR) spectral regime. At these wavelengths, an efficient electric-field confinement is necessary and achieved here through a gold metal nanoparticle of 80 nm in diameter (Au80-MNP) acting as the optical antenna. The Au80-MNP is attached to a standard AFM cantilever used as the spatial manipulator. When approached to a sample surface while being illuminated with an infrared beam, the Au80-MNP produces a considerably improved spatial confinement of the electric field compared to an ordinary scattering AFM tip. We demonstrate here the confinement normal to the sample surface by making use of a sample-induced phonon polariton resonance in a ferroelectric lithium niobate sample. Our experimental findings are in very good agreement with the quasistatic dipole model and show improved optical resolution via well-selected antenna particles. PMID:18679508

  19. Integrating electron and near-field optics: dual vision for the nanoworld

    NASA Astrophysics Data System (ADS)

    Haegel, Nancy M.

    2014-04-01

    The integration of near-field scanning optical microscopy (NSOM) with the imaging and localized excitation capabilities of electrons in a scanning electron microscope (SEM) offers new capabilities for the observation of highly resolved transport phenomena in the areas of electronic and optical materials characterization, semiconductor nanodevices, plasmonics and integrated nanophotonics. While combined capabilities for atomic force microscopy (AFM) and SEM are of obvious interest to provide localized surface topography in concert with the ease and large spatial dynamic range of SEM and dual beam imaging (e.g., in-situ AFM following focused ion beam modification), integration with near-field optical imaging capability can also provide access to localized transport phenomena beyond the reach of far-field systems. In particular, the flexibility that is achieved with the capability for independent, high resolution placement of an electron source, providing localized excitation in the form of free carriers, photons or plasmons, with scanning of the optical collecting tip allows for unique types of "dual-probe" experiments that directly image energy transfer. We review integrated near-field and electron optics systems to date, highlight applications in a variety of fields and suggest future directions.

  20. Degradation of silver near-field optical probes and its electrochemical reversal

    NASA Astrophysics Data System (ADS)

    Opilik, Lothar; Dogan, Üzeyir; Szczerbiński, Jacek; Zenobi, Renato

    2015-08-01

    Deterioration of the outstanding optical properties of elemental silver due to atmospheric corrosion compromises its use in the field of plasmonics. Therefore, more chemically inert, but more lossy, metals (e.g., gold) are often used as a compromise. Silver tips for near-field optical microscopy are only utilized by specialized laboratories with in-house tip production facilities. This article presents a time-dependent study of the effect of atmospheric corrosion on the electromagnetic enhancement of solid silver tips. It was found that chemical degradation renders them unusable for tip-enhanced Raman spectroscopy (TERS) within the first two days after production. Furthermore, we present a simple electrochemical method for recovering the enhancing effect of corroded silver tips, as well as for storing freshly prepared probes, for example, for easy shipment. The present work greatly simplifies the experimental aspects of near-field optical microscopy, which should make near-field optical techniques, and, in particular, TERS, more accessible to the scientific community.

  1. Optical Near Field Studies of Plasmonic and Optical Antennas For Sensitive and Selective Biosensing Applications

    NASA Astrophysics Data System (ADS)

    Gelfand, Ryan M.

    For biosensing applications a useful device needs at least two properties: high sensitivity and high selectivity. Optical spectroscopy offers unique advantages over other sensing techniques however one big challenge to overcome is the mismatch between wavelength and the size of biologically relevant molecules. In order to have high enough sensitivity to approach the single-molecule limit, the interaction between the light and the molecule should be strong. However, the diffraction limit of light is approximately half the incidence wavelength, on the order of 100 nm for the smallest nondestructive wavelengths. This presents a significant mismatch between the size of the molecule and the smallest focus spot of the light. The photo-excitation should be compressed more than 100 fold to interact strongly. We must use metallic antennas that convert the incidence radiation into plasmonic modes which can then be compressed well below the wavelength diffraction limit. Studying the near field characteristics of these metallic nanostructures will help us gain insight into this emerging field and allow us to better use them in developing next generation devices. We have developed different geometries of these antennas and simulated their performance using Finite Difference Time Domain software. We have concentrated our efforts in the mid-infrared because that is the natural molecular vibration frequency region and also the near infrared because at these frequencies there exists a mature industry for compact sources, detectors, and fiber optic components. Our simulations show a 6,000 fold mode compression for a bowtie antenna and a million fold compression for a plasmonic photonic crystal (ppc) antenna. The bull's-eye antenna does not have as a high a mode compression but it has a natural geometry for molecular sensing due to the central metallic disc. Experimentally, we have measured the near field of these antennas with a custom back reflection apertureless NSOM setup in both

  2. Creating optical near-field orbital angular momentum in a gold metasurface.

    PubMed

    Chen, Ching-Fu; Ku, Chen-Ta; Tai, Yi-Hsin; Wei, Pei-Kuen; Lin, Heh-Nan; Huang, Chen-Bin

    2015-04-01

    Nanocavities inscribed in a gold thin film are optimized and designed to form a metasurface. We demonstrate both numerically and experimentally the creation of surface plasmon (SP) vortex carrying orbital angular momentum in the metasurface under linearly polarized optical excitation that carries no optical angular momentum. Moreover, depending on the orientation of the exciting linearly polarized light, we show that the metasurface is capable of providing dynamic switching between SP vortex formation or SP subwavelength focusing. The resulting SP intensities are experimentally measured using a near-field scanning optical microscope and are found in excellent quantitative agreements as compared to the numerical results. PMID:25798810

  3. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing

    NASA Astrophysics Data System (ADS)

    Li, Peining; Lewin, Martin; Kretinin, Andrey V.; Caldwell, Joshua D.; Novoselov, Kostya S.; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-06-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications.

  4. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing.

    PubMed

    Li, Peining; Lewin, Martin; Kretinin, Andrey V; Caldwell, Joshua D; Novoselov, Kostya S; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-01-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications. PMID:26112474

  5. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing

    PubMed Central

    Li, Peining; Lewin, Martin; Kretinin, Andrey V.; Caldwell, Joshua D.; Novoselov, Kostya S.; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-01-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications. PMID:26112474

  6. Near-field optical microscopy and spectroscopy of few-layer black phosphorous

    NASA Astrophysics Data System (ADS)

    Frenzel, A. J.; Tran, S.; Hinton, J. P.; Sternbach, A. J.; Yang, J.; Gillgren, N.; Lau, C. N.; Basov, D. N.

    Few-layer black phosphorous is a recent addition to the family of two-dimensional (2D) materials which exhibits strongly anisotropic transport and optical properties due to its puckered honeycomb structure. It was recently predicted that this intrinsic anisotropy should manifest in the plasmon dispersion. Additionally, tuning layer number and carrier density can control the dispersion of these collective modes. Scanning near-field optical microscopy (SNOM) has been demonstrated as a powerful method to probe electronic properties, including propagating collective modes, in layered 2D materials. We used SNOM to investigate anisotropic carrier response in few-layer black phosphorous encapsulated by hexagonal boron nitride. In addition to exploring gate-voltage tunability of the electronic response, we demonstrate effective modulation of the near-field signal by ultrafast photoexcitation.

  7. Tuning Localized Surface Plasmon Resonance in Scanning Near-Field Optical Microscopy Probes.

    PubMed

    Vasconcelos, Thiago L; Archanjo, Bráulio S; Fragneaud, Benjamin; Oliveira, Bruno S; Riikonen, Juha; Li, Changfeng; Ribeiro, Douglas S; Rabelo, Cassiano; Rodrigues, Wagner N; Jorio, Ado; Achete, Carlos A; Cançado, Luiz Gustavo

    2015-06-23

    A reproducible route for tuning localized surface plasmon resonance in scattering type near-field optical microscopy probes is presented. The method is based on the production of a focused-ion-beam milled single groove near the apex of electrochemically etched gold tips. Electron energy-loss spectroscopy and scanning transmission electron microscopy are employed to obtain highly spatially and spectroscopically resolved maps of the milled probes, revealing localized surface plasmon resonance at visible and near-infrared wavelengths. By changing the distance L between the groove and the probe apex, the localized surface plasmon resonance energy can be fine-tuned at a desired absorption channel. Tip-enhanced Raman spectroscopy is applied as a test platform, and the results prove the reliability of the method to produce efficient scattering type near-field optical microscopy probes. PMID:26027751

  8. Energy modulation of nonrelativistic electrons in an optical near field on a metal microslit

    NASA Astrophysics Data System (ADS)

    Ishikawa, R.; Bae, J.; Mizuno, K.

    2001-04-01

    Energy modulation of nonrelativistic electrons with a laser beam using a metal microslit as an interaction circuit has been investigated. An optical near field is induced in the proximity of the microslit by illumination of the laser beam. The electrons passing close to the slit are accelerated or decelerated by an evanescent wave contained in the near field whose phase velocity is equal to the velocity of the electrons. The electron-evanescent wave interaction in the microslit has been analyzed theoretically and experimentally. The theory has predicted that electron energy can be modulated at optical frequencies. Experiments performed in the infrared region have verified theoretical predictions. The electron-energy changes of more than ±5 eV with a 10 kW CO2 laser pulse at the wavelength of 10.6 μm has been successfully observed for an electron beam with an energy of less than 80 keV.

  9. Super-resolution imaging and detection of fluorescence from single molecules by scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Meixner, Alfred J.; Zeisel, Dieter; Bopp, A. Martin; Tarrach, Guido

    1995-08-01

    Scanning near-field microscopy (SNOM or NSOM) is a versatile and attractive scanning probe technique for imaging with subdiffraction-limited spatial resolution using visible light. At least three different types of images can be recorded simultaneously of the selected sample area, such as the topography, the near-field optical transmission, and the fluorescence from excited chromophores. We have built such a microscope, especially designed for achieving the high resolution and the sensitivity needed for single molecule detection. We report on optical near- field investigations of surface structures and thin polymer films that are doped with fluorescent dye molecules. The effective aperture diameters of the fiber tips used in the SNOM experiments were determined by a photon-scanning tunneling microscopy (PSTM) giving values between 70 and 160 nm. The transmission imaging of transparent polymer phase gratings reveals the existence of different contrast mechanisms, which are either based on the inherent distance dependence of the optical near field or on the periodic change of boundary conditions for the electric field component of the light between the aperture and the sample. Furthermore, we demonstrate selective irreversible photobleaching of dye molecules at moderate concentration (10-5 M) induced locally by the subwavelength-sized probe tip. Finally, we present fluorescence images showing single molecule detection in a thin solid film. The chromophores (rhodamine 6G) were embedded at low concentration (10-7 M) in a 25-nm thin polyvinylbutyral film. A lateral resolution of 160 nm was achieved. We find that the signal strengths of the brightest fluorescent features vary considerably in a sequence of images (a typical single-molecule behavior), whereas the fluorescence background exhibits the usual photobleaching behavior of a large ensemble.

  10. Direct measurement of optical force induced by near-field plasmonic cavity using dynamic mode AFM

    SciTech Connect

    Guan, Dongshi; Hang, Zhi Hong; Marset, Zsolt; Liu, Hui; Kravchenko, Ivan I.; Chan, Ho Bun; Chan, C. T.; Tong, Penger

    2015-11-20

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. Lastly, the experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.

  11. Direct measurement of optical force induced by near-field plasmonic cavity using dynamic mode AFM

    DOE PAGESBeta

    Guan, Dongshi; Hang, Zhi Hong; Marset, Zsolt; Liu, Hui; Kravchenko, Ivan I.; Chan, Ho Bun; Chan, C. T.; Tong, Penger

    2015-11-20

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength goldmore » disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. Lastly, the experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.« less

  12. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM.

    PubMed

    Guan, Dongshi; Hang, Zhi Hong; Marcet, Zsolt; Liu, Hui; Kravchenko, I I; Chan, C T; Chan, H B; Tong, Penger

    2015-01-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. The experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures. PMID:26586455

  13. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM

    PubMed Central

    Guan, Dongshi; Hang, Zhi Hong; Marcet, Zsolt; Liu, Hui; Kravchenko, I. I.; Chan, C. T.; Chan, H. B.; Tong, Penger

    2015-01-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. The experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures. PMID:26586455

  14. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM

    NASA Astrophysics Data System (ADS)

    Guan, Dongshi; Hang, Zhi Hong; Marcet, Zsolt; Liu, Hui; Kravchenko, I. I.; Chan, C. T.; Chan, H. B.; Tong, Penger

    2015-11-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. The experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.

  15. Improvement of tapping-mode scanning near-field optical microscope

    NASA Astrophysics Data System (ADS)

    Zhuo, Wenjiang; Li, Qin; Sun, Jialin; Xu, Jianhua; Zhao, Jun; Guo, Jihua

    2000-10-01

    The commercial crystal tuning fork glued with an optical fiber probe is used as the sensitive detecting element for the tapping-mode scanning near-field optical microscopy. Firstly, the single-mode optical fiber is etched down to a small diameter to decrease the burden of the tuning fork. Secondary, the fiber is etched for the second time to form the sharp tip with large cone angle. Thirdly, the fiber probe, with nanometric tip and high light throughput, is glued to tuning fork by Cyanoacrylate Adhesive. The measured quality factor, Q, of the tuning fork/optical fiber probe assembly prepared in this way is higher than 300. The optical signal is modulated to the frequency of the tuning fork by optical fiber probe as it is detecting the topography of sample. The high-resolution of the tapping- mode detector is proved by imaging the topography of the grating and biological cell.

  16. Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy.

    PubMed

    Cvitkovic, A; Ocelic, N; Hillenbrand, R

    2007-07-01

    Nanometer-scale mapping of complex optical constants by scattering-type near-field microscopy has been suffering from quantitative discrepancies between the theory and experiments. To resolve this problem, a novel analytical model is presented here. The comparison with experimental data demonstrates that the model quantitatively reproduces approach curves on a Au surface and yields an unprecedented agreement with amplitude and phase spectra recorded on a phonon-polariton resonant SiC sample. The simple closed-form solution derived here should enable the determination of the local complex dielectric function on an unknown sample, thereby identifying its nanoscale chemical composition, crystal structure and conductivity. PMID:19547189

  17. Transverse and longitudinal characterization of electron beams using interaction with optical near-fields.

    PubMed

    Kozák, Martin; McNeur, Joshua; Leedle, Kenneth J; Deng, Huiyang; Schönenberger, Norbert; Ruehl, Axel; Hartl, Ingmar; Hoogland, Heinar; Holzwarth, Ronald; Harris, James S; Byer, Robert L; Hommelhoff, Peter

    2016-08-01

    We demonstrate an experimental technique for both transverse and longitudinal characterization of bunched femtosecond free electron beams. The operation principle is based on monitoring of the current of electrons that obtained an energy gain during the interaction with the synchronized optical near-field wave excited by femtosecond laser pulses. The synchronous accelerating/decelerating fields confined to the surface of a silicon nanostructure are characterized using a highly focused sub-relativistic electron beam. Here the transverse spatial resolution of 450 nm and femtosecond temporal resolution of 480 fs (sub-optical-cycle temporal regime is briefly discussed) achievable by this technique are demonstrated. PMID:27472587

  18. Absorption Coefficient Imaging by Near-Field Scanning Optical Microscopy in Bacteria

    NASA Astrophysics Data System (ADS)

    de Paula, Ana M.; Chaves, Claudilene R.; Silva, Haroldo B.; Weber, Gerald

    2003-06-01

    We present a method for obtaining a position-dependent absorption coefficient from near-field scanning optical transmission microscopy. We show that the optical transmission intensity can be combined with the topography, resulting into an absorption coefficient that simplifies the analysis of different materials within a sample. The method is tested with the dye rhodamine 6G, and we show some analysis in biological samples such as bacteria Klebsiella pneumoniae and Pseudomonas aeruginosa . The calculated absorption coefficient images show important details of the bacteria, in particular for P. aeruginosa , in which membrane vesicles are clearly seen.

  19. 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

  20. Polarization Properties in Apertureless-Type Scanning Near-Field Optical Microscopy.

    PubMed

    Ishibashi, Takayuki; Cai, Yongfu

    2015-12-01

    Polarization properties of apertureless-type scanning near-field optical microscopy (a-SNOM) were measured experimentally and were also analyzed using a finite-difference time-domain (FDTD) simulation. Our study reveals that the polarization properties in the a-SNOM are maintained and the a-SNOM works as a wave plate expressed by a Jones matrix. The measured signals obtained by the lock-in detection technique could be decomposed into signals scattered from near-field region and background signals reflected by tip and sample. Polarization images measured by a-SNOM with an angle resolution of 1° are shown. FDTD analysis also reveals the polarization properties of light in the area between a tip and a sample are p-polarization in most of cases. PMID:26415540

  1. 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.

  2. Power delivery and self-heating in nanoscale near field transducer for heat-assisted magnetic recording.

    PubMed

    Zhou, Nan; Traverso, Luis M; Xu, Xianfan

    2015-03-27

    To keep increasing the storage density in next-generation hard disk drives, heat-assisted magnetic recording is being developed where a nanoscale near field transducer (NFT) locally and temporally heats a sub-diffraction-limited region in the recording medium to reduce the magnetic coercivity. This allows the use of very small grain in the medium while still maintaining data thermal stability. Plasmonic nanostructures made of apertures or antennas are good candidates for NFTs because of their capability of subwavelength light manipulation in optical frequencies. The NFT must simultaneously deliver enough power to the recording medium with as small as possible incident laser power to reduce self-heating in the NFT, which could cause thermal expansion and materials failure that lead to degradation of the overall hard drive performance. In this work, we study the effect of optical properties on the power delivery efficiency of nanoscale bowtie aperture antennas, with the presence of a recording media stack. Heat dissipation and temperature rise in the NFT are also computed to investigate their dependence on materials' properties. The possibility of using alternative plasmonic materials for delivering higher power and/or reducing heating in NFTs is discussed. PMID:25759907

  3. 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).

  4. Toward Nanometer-Scale Optical Photolithography: Utilizing the Near-Field of Bowtie Optical Nanoantennas

    PubMed Central

    Sundaramurthy, Arvind; Kino, Gordon S.; Schuck, P. James; Conley, Nicholas R.; Fromm, David P.; Moerner, W. E.

    2006-01-01

    Optically resonant metallic bowtie nanoantennas are utilized as fabrication tools for the first time, resulting in the production of polymer resist nanostructures <30 nm in diameter at record low incident multiphoton energy densities. The nanofabrication is accomplished via nonlinear photopolymerization, which is initiated by the enhanced, confined optical fields surrounding the nanoantenna. The position, size, and shape of the resist nanostructures directly correlate with rigorous finite-difference time-domain computations of the field distribution, providing a nanometer-scale measurement of the actual field confinement offered by single optical nanoantennas. In addition, the size of the photoresist regions yields strong upper bounds on photoacid diffusion and resist resolution in SU-8, demonstrating a technique that can be generalized to the study of many current and yet-to-be-developed photoresist systems. PMID:16522022

  5. Conference Paper NFO-7:7th International Conference on Near-Field Optics and Related Technologies

    SciTech Connect

    Prof.Dr. Lukas Novotny

    2004-10-18

    The seventh conference in the NFO conference series, held here in Rochester, provided to be the principal forum for advances in sub-wavelength optics, near-field optical microscopy, local field enhancement, instrumental developments and the ever-increasing range of applications. This conference brought together the diverse scientific communities working on the theory and application of near-field optics (NFO) and related techniques.

  6. A single beam near-field laser trap for optical stretching, folding and rotation of erythrocytes

    NASA Astrophysics Data System (ADS)

    Gu, Min; Kuriakose, Smitha; Gan, Xiaosong

    2007-02-01

    To understand the fundamental mechanical and viscoelastic properties of RBCs, one needs laser tweezers in which cells can not only be trapped, but also be stretched, folded, and rotated. Stretching, folding and rotating an RBC is particularly important in order to reveal the shear elasticity of the RBC membrane. Here we show a single beam near-field laser trapping technique under focused evanescent wave illumination for optical stretching, folding and rotation of a single RBC. This multifunctional manipulation method will provide a new platform for measuring cell properties such as the membrane elasticity, viscoelasticity and deformability.

  7. Image formation properties and inverse imaging problem in aperture based scanning near field optical microscopy.

    PubMed

    Schmidt, S; Klein, A E; Paul, T; Gross, H; Diziain, S; Steinert, M; Assafrao, A C; Pertsch, T; Urbach, H P; Rockstuhl, C

    2016-02-22

    Aperture based scanning near field optical microscopes are important instruments to study light at the nanoscale and to understand the optical functionality of photonic nanostructures. In general, a detected image is affected by both the transverse electric and magnetic field components of light. The discrimination of the individual field components is challenging as these four field components are contained within two signals in the case of a polarization resolved measurement. Here, we develop a methodology to solve the inverse imaging problem and to retrieve the vectorial field components from polarization and phase resolved measurements. Our methodology relies on the discussion of the image formation process in aperture based scanning near field optical microscopes. On this basis, we are also able to explain how the relative contributions of the electric and magnetic field components within detected images depend on the chosen probe. We can therefore also describe the influence of geometrical and material parameters of individual probes within the image formation process. This allows probes to be designed that are primarily sensitive either to the electric or magnetic field components of light. PMID:26907063

  8. High-sensitivity piezoelectric tube sensor for shear-force detection in scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Lindfors, K.; Kapulainen, M.; Ryytty, P.; Kaivola, M.

    2004-11-01

    An easy-to-implement non-optical shear-force detection setup for tip-sample distance regulation in scanning near-field optical microscopy is demonstrated. The detection method is based on attaching the near-field probe to a piezoelectric tube resulting in excellent mechanical contact between tip and detector. The main advantages of the method are good signal-to-background contrast and thus potential for high sensitivity. The method is demonstrated by obtaining approach curves of silicon surfaces. The suitability for optical experiments is further shown by measuring the near-field intensity distribution of the emission of a semiconductor laser.

  9. Optical forces on a Rayleigh dielectric particle in a patterned near-field landscape

    NASA Astrophysics Data System (ADS)

    Zelenina, Anna; Quidant, Romain; Petrov, Dmitri; Badenes, Goncal

    2005-07-01

    The trapping of micro-objects by optical radiation forces, so-called optical tweezers, has become widely used in physical, chemical and biological experiments where accurate and non-invasive manipulation is required. Recent advances in beam shaping render it possible for instance to rotate or to dynamically manipulate independently several elements. Today, one of the remaining challenges of conventional optical tweezers is the direct manipulation of systems with sizes belonging to the sub-wavelength or Rayleigh regime. Indeed, the diffraction limit prevents in that case from achieving a commensurable trapping volume and thus does not allow for minimizing the fluctuations in position of the trapped object due to its strong Brownian motion. In order to overcome this limitation, it has been proposed to use evanescent fields instead of the usual propagating fields. Recent advances in optics of noble metal nano-structures have recently provided new configurations to achieve nano-optical tweezers. Especially, tightly localized modes resulting from the coupling between resonant noble metal nanostructures may offer the gradient forces able to trap and manipulate Rayleigh objects. In this work, we calculate the radiation forces exerted on a nanometric dielectric sphere when exposed to a patterned optical near-field landscape at an interface decorated with resonant gold nanostructures. By comparing their magnitude with other forces that affect the movement of the particle, we discuss the practical ability of our configuration for multiple parallel optical manipulation.

  10. Effect of condensed water on scanning near-field optical microscope measurement

    NASA Astrophysics Data System (ADS)

    Douas, M.; Serena, P. A.; Marqués, M. I.

    2013-11-01

    The relevance of the scanning near-field optical microscope (SNOM), for near-field characterization, is often shaded by the appearance of artifacts, especially when geometrical characterization is intended. Artifacts are related to many features such as the feedback system or the scanning mode. For non-vacuum environmental conditions, artifact sources may be related to tip geometry and the pollutants attached, either on the tip or on the studied surfaces, altering the optical image. As an environmental element, water vapor could be treated as a source for artifacts, but could also be used as a tool for chemical characterization of hydrophilic patches. Spontaneous meniscus formation between hydrophilic surfaces, such as the tip and the sample, may guide light from the tip to the sample, enhancing the transmitted signal. This study focuses on the effects that water condensation at the nanoscale has on the signals achieved by SNOM, combining two computational methods (Monte Carlo and finite difference time domain) in order to deal with light propagation through heterogeneous media and water condensation.

  11. Mapping electron-beam-injected trapped charge with scattering scanning near-field optical microscopy.

    PubMed

    Tranca, Denis E; Sánchez-Ortiga, Emilio; Saavedra, Genaro; Martínez-Corral, Manuel; Tofail, Syed A M; Stanciu, Stefan G; Hristu, Radu; Stanciu, George A

    2016-03-01

    Scattering scanning near-field optical microscopy (s-SNOM) has been demonstrated as a valuable tool for mapping the optical and optoelectronic properties of materials with nanoscale resolution. Here we report experimental evidence that trapped electric charges injected by an electron beam at the surface of dielectric samples affect the sample-dipole interaction, which has direct impact on the s-SNOM image content. Nanoscale mapping of the surface trapped charge holds significant potential for the precise tailoring of the electrostatic properties of dielectric and semiconductive samples, such as hydroxyapatite, which has particular importance with respect to biomedical applications. The methodology developed here is highly relevant to semiconductor device fabrication as well. PMID:26974112

  12. Double-resonance probe for near-field scanning optical microscopy

    NASA Astrophysics Data System (ADS)

    Cherkun, A. P.; Serebryakov, D. V.; Sekatskii, S. K.; Morozov, I. V.; Letokhov, V. S.

    2006-03-01

    A surface-contact transducer is developed for scanning probe microscopes, whose operating principle is based on the coincidence between the resonance frequency of a 32kHz quartz tuning fork and that of the probe attached to it. This allows the transducer to have a high quality factor and, if the vibration amplitude of the probe tip exceeds that of the tuning fork prongs, materially improves its force sensitivity. The resonance transducer proposed by us has an experimentally verified force sensitivity of 8pN (rms) in the 300Hz frequency band, which is of the same order of magnitude as the sensitivity of atomic force microscope (AFM) cantilever sensors. The manufacture of such transducers equipped with optical-fiber probes for near-field scanning optical microscopy and with tungsten probes for AFM is described as an example.

  13. Selective trapping or rotation of isotropic dielectric microparticles by optical near field in a plasmonic archimedes spiral.

    PubMed

    Tsai, Wei-Yi; Huang, Jer-Shing; Huang, Chen-Bin

    2014-02-12

    We demonstrate selective trapping or rotation of optically isotropic dielectric microparticles by plasmonic near field in a single gold plasmonic Archimedes spiral. Depending on the handedness of circularly polarized excitation, plasmonic near fields can be selectively engineered into either a focusing spot for particle trapping or a plasmonic vortex for particle rotation. Our design provides a simple solution for subwavelength optical manipulation and may find applications in micromechanical and microfluidic systems. PMID:24392638

  14. Two-dimensional refractive index profiling of optical fibers by modified refractive near-field technique

    NASA Astrophysics Data System (ADS)

    El Sayed, A.; Pilz, Soenke; Ryser, Manuel; Romano, Valerio

    2016-02-01

    The refractive index distribution in the core-cladding region of an optical fiber plays an important role in determining the transmission and dispersion properties of the waveguide. The refracted near-field technique (RNF) is among the most widespread techniques used for measuring the refractive index profile of optical fibers and is based on illuminating the end-facet of a fiber with a focused beam whose vertex angle greatly exceeds the acceptance angle of the fiber, which is immersed in an index matching liquid. What one observes are then the refracted unguided rays rather than the guided rays. Nevertheless, the standard refracted near-field technique cannot be applied to a wide range of optical fibers e.g. if their shapes are not axially symmetric. In this work we demonstrate a modified method which allows 2-D imaging of the refractive index profile and thereby overcoming the axial symmetric limitation of the standard RNF. The new system is operating at 630 nm and based on the same principle of the RNF, but the optical path is reversed so that the light at the fiber end-facet is collected by an objective lens and detected by a CCD camera. The method does not require scanning over the fiber end-facet. Thus the system is faster and less sensitive to vibrations and external conditions compared to the standard RNF, furthermore it allows averaging to improve the signal to noise ratio. The spatial resolution of the system is determined by the numerical aperture of the objective and by the resolution of the CCD camera. To calibrate the setup, a reference multi-step index fiber provided by National Physical Laboratory was used.

  15. Quantitative Imaging of Rapidly Decaying Evanescent Fields Using Plasmonic Near-Field Scanning Optical Microscopy

    PubMed Central

    Zhang, Zhen; Ahn, Phillip; Dong, Biqin; Balogun, Oluwaseyi; Sun, Cheng

    2013-01-01

    Non-propagating evanescent fields play an important role in the development of nano-photonic devices. While detecting the evanescent fields in far-field can be accomplished by coupling it to the propagating waves, in practice they are measured in the presence of unwanted propagating background components. It leads to a poor signal-to-noise ratio and thus to errors in quantitative analysis of the local evanescent fields. Here we report on a plasmonic near-field scanning optical microscopy (p-NSOM) technique that incorporates a nanofocusing probe for adiabatic focusing of propagating surface plasmon polaritons at the probe apex, and for enhanced coupling of evanescent waves to the far-field. In addition, a harmonic demodulation technique is employed to suppress the contribution of the background. Our experimental results show strong evidence of background free near-field imaging using the new p-NSOM technique. Furthermore, we present measurements of surface plasmon cavity modes, and quantify their contributing sources using an analytical model. PMID:24076563

  16. Optical Characterization of Component Wear and Near-Field Plasma of the Hermes Thruster

    NASA Technical Reports Server (NTRS)

    Williams, George J., Jr.; Kamhawi, Hani

    2015-01-01

    Optical emission spectral (OES) data are presented which correlate trends in sputtered species and the near-field plasma with the Hall-Effect Rocket with Magnetic Shielding (HERMeS) thruster operating condition. The relative density of singly-ionized xenon (Xe II) is estimated using a collisional-radiative model. OES data were collected at three radial and several axial locations downstream of the thruster's exit plane. These data were deconvolved to show the structure for the near-field plasma as a function of thruster operating condition. The magnetic field is shown to have a much greater affect on plasma structure than the discharge voltage with the primary ionization/acceleration zone boundary being similar for all nominal operating voltages at constant power. OES measurement of sputtered boron shows that the HERMeS thruster is magnetically shielded across its operating envelope. Preliminary assessment of carbon sputtered from the keeper face suggest it increases significantly with operating voltage, but the uncertainty associated with these measurements is very high.

  17. Nanoscale optical and electrical characterizations of ZnO nanostructures by near-field microscopy

    NASA Astrophysics Data System (ADS)

    Bercu, Bogdan; Giraudet, Louis; Molinari, Michael

    2014-03-01

    The interest in the recent years for nanostructure studies has led to the development of a wide palette of characterization techniques such as the electrical modes in scanning probe microscopy (STM, EFM, KPFM...). Optical characterization at nanoscale remains nevertheless a challenge especially for wide gap semiconductors where high energy is required. In this presentation, we will present our work focusing in the development and the improvement of near-field microscopy techniques to investigate nanoscale properties of ZnO nanostructures and related semiconducting objects. For the optical characterization, cathodoluminescence (CL) studies present many advantages over the classical photoluminescence experiments for ZnO analysis. This contribution presents the development of a scanning near-field cathodoluminescence microscope where a bimorph piezoelectric cantilever is simultaneously used for both actuation and oscillation amplitude detection. Operated inside a scanning electron microscope (SEM) it offers the possibility of performing simultaneous topography and cathodoluminescence charting of the sample surface additionally to the SEM imaging with a resolution in the order of several tenths of nanometers. Different measurements of ZnO nanostructures and related objects will be presented to show the potentiality of our optical characterization setup. Complementary STEM-CL measurements at higher beam energy were performed on the ZnO nanowires confirming the good quality of the investigated nanostructures. As for the electrical characterization, we will focus on the local surface potential mapping of ZnO nanowires used for photoconduction using Kelvin Probe Force Microscopy. While ZnO nanowire photoconduction gains as high as 1010 in the UV region were reported, several issues come into play when it comes to making a precise measurement of a single nanowire. An important issue is the good quality of the injecting contacts on the nanowire and the reproducibility of its

  18. Simulation of near-field scanning optical microscopy using a plasmonic gap probe

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuo; Tanaka, Masahiro; Katayama, Kiyofumi

    2006-10-01

    Imaging by near-field scanning optical microscopy (NSOM) with a plasmonic gap probe (PGP) is simulated to confirm the operation of the recently proposed PGP. The simulations demonstrate that the probe works in illumination, collection-reflection and collection mode, and that is it not necessary to vibrate the probe tip in order to remove background noise. The resolution of the scanned image is also shown to be approximately equal to the diameter of the probe tip. Furthermore, the throughput of the probe is much higher than conventional aperture probes providing similar resolution. The proposed probe thus has the advantages of both aperture probes and scattering probes, and is expected to have excellent characteristics for use as a scanning probe for NSOM.

  19. Desktop near-field thermal-lens microscope for thermo-optical detection in microfluidics.

    PubMed

    Smirnova, Adelina; Proskurnin, Mikhail A; Mawatari, Kazuma; Kitamori, Takehiko

    2012-09-01

    A new compact near-field desktop-sized diode laser thermal-lens microscope for analysis in microfluidics was proposed. A novel beam-alignment and detection systems provided high signal stability and, along with reduced number of optical elements rendered the instrument portable. The detection of nonfluorescent model species (Fe(II)-bathophenanthroline chelate) in water showed good linearity in the range of 5 × 10(-9) to 1 × 10(-4) M, and the limit of detection was 3.5 × 10(-9) M, which corresponded to 3.5 × 10(-7) absorbance units and provided a 20-fold enhancement in sensitivity compared with existing schematic. PMID:22965721

  20. Widely tuneable scattering-type scanning near-field optical microscopy using pulsed quantum cascade lasers

    SciTech Connect

    Yoxall, Edward Rahmani, Mohsen; Maier, Stefan A.; Phillips, Chris C.; Navarro-Cía, Miguel

    2013-11-18

    We demonstrate the use of a pulsed quantum cascade laser, wavelength tuneable between 6 and 10 μm, with a scattering-type scanning near-field optical microscope (s-SNOM). A simple method for calculating the signal-to-noise ratio (SNR) of the s-SNOM measurement is presented. For pulsed lasers, the SNR is shown to be highly dependent on the degree of synchronization between the laser pulse and the sampling circuitry; in measurements on a gold sample, the SNR is 26 with good synchronization and less than 1 without. Simulations and experimental s-SNOM images, with a resolution of 100 nm, corresponding to λ/80, and an acquisition time of less than 90 s, are presented as proof of concept. They show the change in the field profile of plasmon-resonant broadband antennas when they are excited with wavelengths of 7.9 and 9.5 μm.

  1. Evolution of Biomass Burning Aerosol Optical Properties in the Near Field

    NASA Astrophysics Data System (ADS)

    Sedlacek, A. J., III; Arnott, W. P.; Chand, D.; Fortner, E.; Freedman, A.; Kleinman, L. I.; Onasch, T. B.; Shilling, J. E.; Springston, S. R.

    2014-12-01

    Biomass burning (BB) events are known to produce chemically rich environments that can impact the evolution of primary aerosols and influence secondary aerosols production rates. With their increasing in frequency, BB events are expected to exert an ever-increasing impact on climate due to aerosol radiative forcing processes. One area that is still poorly understood is the evolution of these smoke aerosols in the near field. Recent literature suggests that BB aerosols undergo a rapid evolution near their source that is then followed by a slower aging phase. During the summer of 2013, the Department of Energy-sponsored an aircraft field campaign called the Biomass Burning Observation Project (BBOP) that specifically targeted the evolution of smoke aerosols in the near field (< 2 hours). Results examining the evolution of BB optical and microphysical properties will be presented. To probe these properties, the BBOP field campaign deployed a Single Particle Soot Photometer (SP2) to probe the mixing state of refractory black carbon (rBC) and a Soot Particle Aerosol Mass Spectrometer (SP-AMS) to investigate the composition of both non-refractory and rBC-containing particles. Aerosol optical properties were measured in situ using a 355 nm Photoacoustic spectrometer (PAS), a 532 nm photo thermal interferometer (PTI), a 630 nm cavity Attenuation Phase Shifted (CAPS) spectrometer, a 3-λ nephelometer, and a 3-λ PSAP. The BBOP study represented the maiden aircraft deployment for the SP-AMS, the 355 nm PAS and 532 nm PTI. Discussion will be on the near-field evolution of particle mixing state and morphology, chemical composition, and microphysical processes that determine aerosol size distributions and single scattering albedo (SSA) of light absorbing aerosols. In the cases studied, increases in the coating thickness of refractive black carbon (rBC) particles, organic aerosol/rBC ratio, scattering/CO ratio, and aerosol size distributions have been observed. Results will be

  2. Far- and near-field optical properties of gold nanoparticle ensembles

    SciTech Connect

    Nedyalkov, N N; Dikovska, A O; Dimitrov, I; Nikov, Ru; Atanasov, P A; Toshkova, R A; Gardeva, E G; Yossifova, L S; Alexandrov, M T

    2012-12-31

    The optical properties of gold nanoparticle clusters are presented from the point of view of their applications in biophotonics, where the absorption and scattering spectra are crucial. Generalised multiparticle Mie theory and finite difference time domain (FDTD) technique are used for theoretical description of the far- and nearfield optical properties of two dimensional nanoparticle ensembles. The system under consideration consists of spherical gold nanoparticles from 20 to 200 nm in diameter, forming 2D clusters in water. The properties of the far-field absorption and scattering spectra as a function of the cluster size, particle dimensions, and interparticle distance are investigated for ordered hexagonal structure of the particle arrays. It is found that the absorption efficiency can be shifted to the IR spectral range by increasing array size and decreasing interparticle distance. The increase in the array size also results in enhancement of the scattering efficiency while the absorption is reduced. The near-field intensity distribution is inhomogeneous over the array, as formation of zones with intensity enhancement of about two orders of magnitude is observed in specific areas. The optical properties of an ensemble whose configuration is reproduced from real experiments of gold nanoparticle deposition onto cancer cells are also presented. The results obtained can be used in designing of nanoparticle arrays with applications in biophotonics, bioimaging and photothermal therapy. (nanosystems)

  3. Near-Field Scanning Optical Microscopy for High-Resolution Membrane Studies

    PubMed Central

    Huckabay, Heath A.; Armendariz, Kevin P.; Newhart, William H.; Wildgen, Sarah M.; Dunn, Robert C.

    2012-01-01

    The desire to directly probe biological structures on the length scales that they exist has driven the steady development of various high-resolution microscopy techniques. Among these, optical microscopy and, in particular, fluorescence-based approaches continue to occupy dominant roles in biological studies given their favorable attributes. Fluorescence microscopy is both sensitive and specific, is generally noninvasive toward biological samples, has excellent temporal resolution for dynamic studies, and is relatively inexpensive. Light-based microscopies can also exploit a myriad of contrast mechanisms based on spectroscopic signatures, energy transfer, polarization, and lifetimes to further enhance the specificity or information content of a measurement. Historically, however, spatial resolution has been limited to approximately half the wavelength due to the diffraction of light. Near-field scanning optical microscopy (NSOM) is one of several optical approaches currently being developed that combines the favorable attributes of fluorescence microscopy with superior spatial resolution. NSOM is particularly well suited for studies of both model and biological membranes and application to these systems is discussed. PMID:23086886

  4. Optical gecko toe: Optically controlled attractive near-field forces between plasmonic metamaterials and dielectric or metal surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, J.; MacDonald, K. F.; Zheludev, N. I.

    2012-05-01

    On the mesoscopic scale, electromagnetic forces are of fundamental importance to an enormously diverse range of systems, from optical tweezers to the adhesion of gecko toes. Here we show that a strong light-driven force may be generated when a plasmonic metamaterial is illuminated in close proximity to a dielectric or metal surface. This near-field force can exceed radiation pressure and Casimir forces to provide an optically controlled adhesion mechanism mimicking the gecko toe: At illumination intensities of just a few tens of nW/μm2 it is sufficient to overcome the Earth's gravitational pull.

  5. Optical resonance-enhanced absorption-based near-field immunochip biosensor for allergen detection.

    PubMed

    Maier, Irene; Morgan, Michael R A; Lindner, Wolfgang; Pittner, Fritz

    2008-04-15

    An optical immunochip biosensor has been developed as a rapid method for allergen detection in complex food matrixes, and its application evaluated for the detection of the egg white allergens, ovalbumin and ovomucoid. The optical near-field phenomenon underlying the basic principle of the sensor design is called resonance-enhanced absorption (REA), which utilizes gold nanoparticles (Au NPs) as signal transducers in a highly sensitive interferometric setup. Using this approach, a novel, simple, and rapid colorimetric solid-phase immunoassay on a planar chip substrate was realized in direct and sandwich assay formats, with a detection system that does not require any instrumentation for readout. Semiquantitative immunochemical responses are directly visible to the naked eye of the analyst. The biosensor shows concentration-dependent color development by capturing antibody-functionalized Au NPs on allergen-coated chips and has a detection limit of 1 ng/mL. To establish a rapid method, we took advantage of the physicochemical microenvironment of the Au NP-antibody bioconjugate to be bound directly over an interacting poly(styrene-methyl methacrylate) interlayer by an immobilized antigen. In the direct assay format, a coating time with allergen of only 5 min under "soft" nondenaturing conditions was sufficient for accurate reproducibility and sensitivity. In conclusion, the REA-based immunochip sensor is easy to fabricate, is reproducible and selective in its performance, has minimal technical requirements, and will enable high-throughput screening of affinity binding interactions in technological and medical applications. PMID:18358010

  6. Imaging biological molecules with single molecule sensitivity using near-field scanning optical microscopy

    SciTech Connect

    Ambrose, W.P.; Affleck, R.L.; Goodwin, P.M.; Keller, R.A.; Martin, J.C.; Petty, J.T.; Schecker, J.A.; Wu, Ming

    1995-12-01

    We have developed a near-field scanning optical microscope with the sensitivity to detect single fluorescent molecules. Our microscope is based on scanning a sample under a tapered and metal coated fiber optic probe and has an illumination-aperture diameter as small as 100 nm. The microscope simultaneously acquires a shear force image with a height noise of {approximately} 1 nm. We have used this system to demonstrate the detection of single molecules of Rhodamine-6G on silica. In this paper, we explore the use of NSOM for investigations of biological molecules. We have prepared and imaged double-stranded DNA intercalated with thiazole orange homodimer (TOTO); single chromosomes stained with propidium iodide; and {beta}-phycoerythrin proteins on dry, borosilicate-glass surfaces. At very dilute coverages, isolated fluorescent spots are observed for the un-intercalated TOTO dye and for {beta}-phycoerythrin. These fluorescent spots exhibit-emission intensity fluctuations and abrupt bleaching transitions, similar to the intensity behavior observed previously for single Rhodamine 6G molecules on silica.

  7. Near-field characteristics of broad area diode lasers during catastrophic optical damage failure

    NASA Astrophysics Data System (ADS)

    Hempel, Martin; Tomm, Jens W.; Baeumler, Martina; Konstanzer, Helmer; Mukherjee, Jayanta; Elsaesser, Thomas

    2012-06-01

    One of the failure mechanisms preventing diode lasers in reaching ultra high optical output powers is the catastrophic optical damage (COD). It is a sudden degradation mechanism which impairs the device functionality completely. COD is caused by a positive feedback loop of absorbing laser light and increasing temperature at a small portion of the active material, leading to a thermal runaway on a nanosecond timescale. We analyze commercial gain-guided AlGaAs/GaAs quantum well broad area diode lasers in single pulse step tests. The near-field emission on the way to and at the COD is resolved on a picosecond time scale by a streak-camera combined with a microscope. In the final phase of the step tests the COD is occurring at ~50 times threshold current. The growth of the COD defect site is monitored and defect propagation velocities between 30 and 190 μm/μs are determined. The final shape of the damage is verified by opening the device and taking a micro-photoluminescence map of the active layer.

  8. Self-Cleaning Effect of Solid Immersion Lens Using Photocatalyst TiO2 Film for Near-Field Recording

    NASA Astrophysics Data System (ADS)

    Hong, Hyun-Guk; Kim, Young-Joo

    2008-07-01

    A novel approach using the self-cleaning effect of photocatalyst TiO2 film was proposed and studied experimentally to solve the critical contamination issues in solid immersion lens (SIL) based near-field recording (NFR). To evaluate the feasibility of the self-cleaning approach, the surface of a hemispherical (half-ball) SIL and a glass disk were coated with TiO2 film which constituted the final layer of an antireflection (AR) coating for better optical transmittance. The hydrophilic property of the TiO2-coated SIL and disk was confirmed by the contact angle measurement with deionized water after thermal treatment to form an anatase structure and by the irradiation of UV light. To determine the effectiveness of the self-cleaning effect, a removal test was conducted with different contaminants such as a fingerprint and laser toner particles. The effects of the wavelength and intensity of UV light were tested over a range of irradiation times. The air flow during the rotation of the disk was also helpful for removing the contaminants. From the experimental results, it was confirmed that the self-cleaning effect of photocatalyst TiO2 film is very effective for removing organic contaminants from the surfaces of an SIL and disk, which means that this approach can be applied to SIL-based NFR systems.

  9. Modeling the Optical Response to a Near-Field Probe Tip from a Generalized Multilayer Thin Film

    NASA Astrophysics Data System (ADS)

    Lawrence, A. J.

    The contrast mechanism in Kerr imaging is the apparent angle through which the plane of polarization is rotated upon reflection from a magnetic surface. This can be calculated for a well characterized surface given the polarization state of the incident light. As in traditional optical microscopy, the spatial resolution is limited by diffraction to roughly half the wavelength of the illumination light. The diffraction limit can be circumvented through the use of near-field scanning optical microscopy, in which the illumination source is an evanescent field at the tip of a tapered optical fiber. A novel probe design for near-field optical imaging in reflection mode will be proposed, and experimental work on the development of a near-field Kerr microscope performed up to this point will be presented. The complication in merging these two techniques arises from the complex polarization profile of the evanescent field. This profile can be characterized for a given probe geometry with the use of electromagnetic field modeling software, allowing for subsequent modeling of the polarization profile of the optical response. An algorithm for predicting the optical response to a near-field probe tip from a generalized multilayer thin-film is presented.

  10. Highly efficient plasmonic tip design for plasmon nanofocusing in near-field optical microscopy.

    PubMed

    Umakoshi, Takayuki; Saito, Yuika; Verma, Prabhat

    2016-03-14

    Near-field scanning optical microscopy (NSOM) combined with plasmon nanofocusing is a powerful nano-analytical tool due to its attractive feature of efficient background suppression as well as light energy compression to the nanoscale. In plasmon nanofocusing-based NSOM, the metallic tip plays an important role in inducing plasmon nanofocusing. It is, however, very challenging to control plasmonic properties of tips for plasmon nanofocusing with existing tip fabrication methods, even though the plasmonic properties need to be adjusted to experimental environments such as the sample or excitation wavelength. In this study, we propose an efficient tip design and fabrication which enable one to actively control plasmonic properties for efficient plasmon nanofocusing. Because our method offers flexibility in the material and structure of tips, one can easily modify the plasmonic properties depending on the requirements. Importantly, through optimization of the plasmonic properties, we achieve almost 100% reproducibility in plasmon nanofocusing in our experiments. This new approach of tip fabrication makes plasmon nanofocusing-based NSOM practical and reliable, and opens doors for many scientists working in related fields. PMID:26892672

  11. Potential Challenges in Near-Field Scanning Optical Microscopy for Space Applications

    NASA Technical Reports Server (NTRS)

    Vikram, C. S.; Witherow, W.

    2000-01-01

    Near-field scanning optical microscopy is a relatively new but very powerful technique for obtaining several metrological parameters at nanometer range spatial resolution. It is logical to think deploying it into space applications like diagnostics of protein crystal growth under microgravity conditions. One may attempt to deploy existing instrumentation and expect some results. However, the existing technology and commercial instrumentation is tailored to ground based laboratory situations. Even in those laboratory conditions, the role of fluids (common in crystal growth), rough objects (such as a crystal under growth), etc. on the instrumentation is only recently being investigated. These aspects combined with effects of reduced gravity environment are going to make the problem more complex. These technological challenges must be tackled for meaningful system operation in space. Since the microscopy concept has not been attempted so far in space, all of the actual problems are unknown. Nevertheless, based on current literature, some possible problems and potential solutions are described here. One may use the discussion for system modification/optimization during initial use of this kind of microscopy in space.

  12. Indirect interband transition induced by optical near fields with large wave numbers

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Maiku; Nobusada, Katsuyuki

    2016-05-01

    Optical near fields (ONFs) have Fourier components with large wave numbers that are two or three orders of magnitude larger than those of far-field propagating light owing to their nonuniformity in space. By utilizing these large wave numbers, the ONF is expected to induce an indirect interband transition between Bloch states having different wave numbers and directly generate an electron-hole pair without electron-phonon coupling. We perform time-dependent dynamics calculations of a one-dimensional periodic potential with an indirect band-gap structure and demonstrate that the ONF definitely induces an indirect interband transition. Instead of using the general Bloch boundary condition, which is usually imposed in conventional band structure calculations, we adopt an alternative boundary condition, the Born-von Kármán boundary condition, to appropriately treat indirect interband transitions. The calculated absorption spectra for the far-field and ONF excitations show different absorption edges and spectral patterns. We argue that this difference can be experimentally measured as evidence of the effects of the large wave numbers of the ONF.

  13. Highly efficient plasmonic tip design for plasmon nanofocusing in near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Umakoshi, Takayuki; Saito, Yuika; Verma, Prabhat

    2016-03-01

    Near-field scanning optical microscopy (NSOM) combined with plasmon nanofocusing is a powerful nano-analytical tool due to its attractive feature of efficient background suppression as well as light energy compression to the nanoscale. In plasmon nanofocusing-based NSOM, the metallic tip plays an important role in inducing plasmon nanofocusing. It is, however, very challenging to control plasmonic properties of tips for plasmon nanofocusing with existing tip fabrication methods, even though the plasmonic properties need to be adjusted to experimental environments such as the sample or excitation wavelength. In this study, we propose an efficient tip design and fabrication which enable one to actively control plasmonic properties for efficient plasmon nanofocusing. Because our method offers flexibility in the material and structure of tips, one can easily modify the plasmonic properties depending on the requirements. Importantly, through optimization of the plasmonic properties, we achieve almost 100% reproducibility in plasmon nanofocusing in our experiments. This new approach of tip fabrication makes plasmon nanofocusing-based NSOM practical and reliable, and opens doors for many scientists working in related fields.

  14. 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

  15. Optimization and maximum potential of optical antennae in near-field enhancement.

    PubMed

    Chen, PingPing; Liu, Ju; Wang, Li; Jin, Kuijuan; Yin, Yan; Li, ZhiYuan

    2015-06-20

    We investigate four types of gold nanoantennae (the monopole, the dipole, the cone-shaped, and the cone-bowtie antenna), under a fixed working wavelength. The finite-difference time-domain (FDTD) simulations show that the near-field enhancement values do not increase monotonously when the antennae sizes decrease, and optimization conditions vary with the antenna shapes. We also propose a distributed dipole ring model to analytically calculate the near field. The size condition for the strongest enhancement is the compromising result of the total radiated energy and the near-field distribution factor. Assuming the cone-bowtie antenna is the best for high enhancement, the maximum potential in near-field enhancement is 2×10(5) for a linear signal or 4×10(10) for typical nonlinear signals. PMID:26193035

  16. The study of quasi-optical system used in a passive near-field tetrahertz imaging system

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Zhu, Wei-wen; Zhang, Wen-si; Zhang, Cheng-jiang; Ding, Qing; Bi, Xian-ting; Wu, Jui-feng

    2013-08-01

    Passive terahertz imaging technology, which provided blackbody thermal imaging, showed great potential for security applications during the last years. Different research teams in different countries spent a great effort on it for obvious reasons, and first commercial passive THz human imaging system was available. Yet, development of passive THz-imaging system was always limited by the frame rate, spatial resolution and detector cell of it. In this paper, we presented the concept and experimental set-up for a quasi-optical system used in a near-field 0.14THz passive terahertz imaging system. The quasi-optical system was composed of a double-mirror beam-waveguide system and a special feed-horns array. The design of quasi-optical system was based on near-field Gauss optics theory. The double-mirror beam waveguide system was made up of an off-axis ellipsoid mirror and a flat mirror. The influence of angle-scanning of quasi-optics system in near-field THz-imaging was investigated theoretically. Meanwhile, a spatial sparse array-arrangement of feed-horns was applied in quasi-optics system, that the adjacent feed-horns were stagger in the horizontal direction. The influence of this special feed-horns array arrangement on the near-field imaging was also discussed in theory. The quasi-optical system met the requirements of the near-field imaging. The problem of low frame rate of traditional sparse array arrangement was solved by this special array arrangement. And the spatial imaging range of the passive imaging system was also increased. The experimental results of this terahertz imaging system were consistent with our earlier theoretical results. When the detective distance was 3-5m, the experimental spatial resolution of near-field THz imaging was 5cm, and a 5Hz of frame rate was obtained. The quasi-optics system had demonstrated its ability to scan persons and various kinds of objects. We hoped a commercial, user-friendly terahertz imaging system, which could be used

  17. Nano-optical conveyor belt, part II: Demonstration of handoff between near-field optical traps.

    PubMed

    Zheng, Yuxin; Ryan, Jason; Hansen, Paul; Cheng, Yao-Te; Lu, Tsung-Ju; Hesselink, Lambertus

    2014-06-11

    Optical tweezers have been widely used to manipulate biological and colloidal material, but the diffraction limit of far-field optics makes focused beams unsuitable for manipulating nanoscale objects with dimensions much smaller than the wavelength of light. While plasmonic structures have recently been successful in trapping nanoscale objects with high positioning accuracy, using such structures for manipulation over longer range has remained a significant challenge. In this work, we introduce a conveyor belt design based on a novel plasmonic structure, the resonant C-shaped engraving (CSE). We show how long-range manipulation is made possible by means of handoff between neighboring CSEs, and we present a simple technique for controlling handoff by rotating the polarization of laser illumination. We experimentally demonstrate handoff between a pair of CSEs for polystyrene spheres 200, 390, and 500 nm in diameter. We then extend this technique and demonstrate controlled particle transport down a 4.5 μm long "nano-optical conveyor belt." PMID:24807058

  18. High-resolution apertureless near-field optical imaging using gold nanosphere probes.

    PubMed

    Kim, Zee Hwan; Leone, Stephen R

    2006-10-12

    An apertureless near-field scanning optical microscope (ANSOM) that utilizes the enhanced field around a gold nanosphere, which is attached to the end of an atomic force microscope (AFM) tip, is used to image the local dielectric constant of the patterned metallic surfaces and local electric field around plasmonic nanosphere samples. A colloidal gold nanosphere (approximately 50 nm diameter) is linked to the extremity of the conventional etched-silicon probe. The scattering of laser radiation (633 or 532 nm) is modulated by the oscillating nanosphere-functionalized silicon tip, and the scattered radiation is detected. The approach curve (scattering intensity as a function of the tip-sample distance), the polarization dependence (scattering intensity as a function of the excitation polarization direction), and ANSOM image contrast confirm that the spherical nanosphere attached to the silicon tip acts as a point dipole that interacts with the sample surface via a dipole-dipole coupling, in which the dipole created by the field at the tip interacts with its own image dipole in the sample. The image obtained with the nanoparticle functionalized tip provides a dielectric map of the sample surface with a spatial resolution better than 80 nm. In addition, we show that the functionalized tip is capable of imaging the local electric field distribution above the plasmonic nanosphere samples. Overall, the result shows that high-resolution ANSOM is possible without the aid of the lightning-rod effect. With an improved tip-fabrication method, we believe that the method can provide a versatile high-resolution chemical imaging that is not available from usual forms of ANSOM. PMID:17020365

  19. Fluorescence detection of single molecules using pulsed near-field optical excitation and time correlated photon counting

    SciTech Connect

    Ambrose, W.P.; Goodwin, P.M.; Martin, J.C.; Keller, R.A.

    1994-03-01

    Pulsed excitation, time correlated single photon counting and time gated detection are used in near-field optical microscopy to enhance fluorescence images and measure the fluorescence lifetimes of single molecules of Rhodamine 6G on silica surfaces. Time gated detection is used to reject prompt scattered background and to improve the image signal to noise ratio. The excited state lifetime of a single Rhodamine 6G molecule is found to depend on the position of the near-field probe. We attribute the lifetime variations to spontaneous emission rate alterations by the fluorescence reflected from and quenching by the aluminum coated probe.

  20. An Alternative Tapping Scanning Near-Field Optical Microscope Setup Enabling the Study of Biological Systems in Liquid Environment

    NASA Astrophysics Data System (ADS)

    Girasole, M.; Longo, G.; Cricenti, A.

    2006-03-01

    A new aperture scanning near-field optical microscope operating in the intermittent contact mode using a non-bent optical fiber is introduced. The microscope was built modifying a classical scanning near-field optical microscope (SNOM) unit introducing a patented probe-holder (MTP) which contains a piezo-motor and a bimorph-transductor. The main advantages of the present set-up in terms of stability, versatility, optical resolution, and quality of the collected signals are described. The instrument works properly while exerting a minimum perturbation on the sample thus overcoming the major drawbacks of different SNOM-based imaging modes and allowing to study very delicate samples including living cells in physiological environment.

  1. Fabrication of a Near-Field Optical Fiber Probe Based on Electroless Nickel Plating under Ultrasonic Irradiation

    NASA Astrophysics Data System (ADS)

    Mononobe, Shuji; Saito, Yuichi; Ohtsu, Motoichi; Honma, Hideo

    2004-05-01

    We present a method of fabricating a near-field optical probe with a nickel film whose thickness gradually decreases to a few tens of nanometers toward the apex. This method involves etching an optical fiber and electroless nickel plating with ultrasonic agitation. Using 1 MHz ceramic transducers, we have reproducibly fabricated the probe with a tip diameter of less than 40 nm. This reproducibility is high compared to those for Langevin-type transducers.

  2. A Study on Enhancing Data Storage Capacity and Mechanical Reliability of Solid Immersion Lens-Based Near-Field Recording System

    NASA Astrophysics Data System (ADS)

    Park, No-Cheol; Yang, Hyun-Seok; Rhim, Yoon-Cheol; Park, Young-Pil

    2008-08-01

    In this study, several technical issues on solid immersion lens (SIL)-based near-field recording (NFR) are explored, namely, to enhance storage capacity and to guarantee mechanical reliability of the device. For the purpose of enhancing the storage capacity of the NFR system, two optical configurations using radial polarization and dual recording layers are proposed. Through a feasibility analysis of the proposed optical configuration with radial polarization, it was determined that illumination of radial polarization is not a suitable solution to achieve higher areal density. To apply highly focusing characteristics of incidence of radial polarized light to cover-layer protected data storage, an annular pupil filtering method was introduced. Complete field analysis of the proposed dual layered NFR optics verified its feasibility, and the assembly of the SIL of the proposed model was successfully achieved. In addition, to improve mechanical reliability of the SIL-based NFR system, improved near-field (NF) air-gap servo methods and air flow analysis around the low part of the SIL have been evaluated. With improved NF gap servo methods using an error-based disturbance observer (EDOB) on a base air-gap controller, residual gap errors were markebly reduced by 26.26% while controlling the NF air-gap to 30 nm. Air flow near the head media interface was visualized and an undesirable effect of backward flow climbing from the bottom surface of the SIL was ovserved.

  3. Imaging of green fluorescent protein in live plant by scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Xu, Jianhua; Chen, Tao; Sun, Jialin; Guo, Jihua; Zhao, Jun

    2002-04-01

    An auxin/IAA induced in vivo green fluorescent protein (GFP) in a living plant Arabidopsis root has been studied by a scanning near-field microscope in transmission mode. The promising near-field images of the inducible GFPs at sub- surface of a plant cell suggest that they may locate proximity to the cell wall, i.e. both sides of and in the cytoplasm membrane. The clear and faint fluorescent spots with 1-3 micrometers showed that the proteins localized nearer and farther to the cell wall, respectively. All GFP molecules gathered together in a cell, and no individual GFP was observed in the experiment.

  4. Optical singularities and power flux in the near-field region of planar evanescent-field superlenses.

    PubMed

    Perez-Molina, Manuel; Carretero, L; Acebal, P; Blaya, S

    2008-11-01

    We rigorously analyze the optical singularities and power flux in the near-field region of the novel superlenses reported in [Science317, 927 (2007)] For this purpose, we derive near-field expressions and a general criterion to classify the optical singularities in the vacuum, which are valid when the (s- or p-polarized) electromagnetic fields are generated by any planar field distribution with Cartesian or azimuthal symmetry. Such general results are particularized to the superlenses [Science317, 927 (2007)], for which we identify a sequence of optical vortices and saddles that arise from evanescent-field interference. While the saddles are always located around the focal region, the vortex locations depend on the source field. The features of the topological connection between vortices and saddles are also discussed. PMID:18978868

  5. Low Temperature Apertureless Near-field Scanning Optical Microscope for Optical Spectroscopy of Single Ge/Si Quantum Dots

    NASA Astrophysics Data System (ADS)

    Zhu, Henry; Patil, N. G.; Levy, Jeremy

    2001-03-01

    A low-temperature apertureless near-field scanning optical microscope has been designed and constructed for the purpose of investigating the optical properties of individual Ge/Si quantum dots. The microscope fits in the 37 mm bore of a Helium vapor magneto-optic cryostat, allowing operations down to liquid helium temperatures in magnetic fields up to 8 Tesla. An in situ microscope objective focuses light onto the sample, which is scanned in the three spatial directions using a compact modular stage. An AFM/STM tip resides on the top; feedback is achieved using a quartz tuning fork oscillator. Both tip and objective are attached to inertial sliding motors that can move in fine (10 nm) steps to achieve touchdown and focus. A femtosecond optical parametric oscillator is used to excite carriers in the quantum dots both resonantly and non-resonantly; scattered luminescence from the AFM/STM tip is collected and analyzed spectrally using a 1/2 meter imaging spectrometer and a LN_2-cooled InGaAs array. We gratefully acknowledge NSF (DMR-9701725, IMR-9802784) and DARPA (DAAD-16-99-C1036) for financial support of this work.

  6. Optical and mechanical detection of near-field light by atomic force microscopy using a piezoelectric cantilever

    NASA Astrophysics Data System (ADS)

    Satoh, Nobuo; Kobayashi, Kei; Watanabe, Shunji; Fujii, Toru; Matsushige, Kazumi; Yamada, Hirofumi

    2016-08-01

    In this study, we developed an atomic force microscopy (AFM) system with scanning near-field optical microscopy (SNOM) using a microfabricated force-sensing cantilever with a lead zirconate titanate (PZT) thin film. Both optical and mechanical detection techniques were adopted in SNOM to detect scattered light induced by the interaction of the PZT cantilever tip apex and evanescent light, and SNOM images were obtained for each detection scheme. The mechanical detection technique did allow for a clear observation of the light scattered from the PZT cantilever without the interference observed by the optical detection technique, which used an objective lens, a pinhole, and a photomultiplier tube.

  7. Application of evolution strategies for the solution of an inverse problem in near-field optics.

    PubMed

    Macías, Demetrio; Vial, Alexandre; Barchiesi, Dominique

    2004-08-01

    We introduce an inversion procedure for the characterization of a nanostructure from near-field intensity data. The method proposed is based on heuristic arguments and makes use of evolution strategies for the solution of the inverse problem as a nonlinear constrained-optimization problem. By means of some examples we illustrate the performance of our inversion method. We also discuss its possibilities and potential applications. PMID:15330475

  8. Short-range order and near-field effects on optical scattering and structural coloration

    SciTech Connect

    Liew, S.F.; Forster, J.; Noh, H.; Schreck, C.F.; Saranathan, V.; Lu, X.; Yang, L.; Prum, Richard O.; O’Hern, C.S.; Dufresne, E.R.; Cao, H.

    2012-03-26

    We have investigated wavelength-dependent light scattering in biomimetic structures with short-range order. Coherent backscattering experiments are performed to measure the transport mean free path over a wide wavelength range. Overall scattering strength is reduced significantly due to short-range order and near-field effects. Our analysis explains why single scattering of light is dominant over multiple scattering in similar biological structures and is responsible for color generation.

  9. Short-range Order and Near-field Effects on Optical Scattering and Structural Coloration

    SciTech Connect

    S Liew; J Forster; H Noh; C Schreck; V Saranathan; X Lu; L Yang; E Dufresne; H Cao; et al.

    2011-12-31

    We have investigated wavelength-dependent light scattering in biomimetic structures with short-range order. Coherent backscattering experiments are performed to measure the transport mean free path over a wide wavelength range. Overall scattering strength is reduced significantly due to short-range order and near-field effects. Our analysis explains why single scattering of light is dominant over multiple scattering in similar biological structures and is responsible for color generation.

  10. Imaging of quantum Hall edge states under quasiresonant excitation by a near-field scanning optical microscope

    SciTech Connect

    Ito, H.; Shibata, Y.; Mamyoda, S.; Ootuka, Y.; Nomura, S.; Kashiwaya, S.; Yamaguchi, M.; Akazaki, T.; Tamura, H.

    2013-12-04

    A high resolution mapping of quantum Hall edge states has been performed by locally creating electrons with small excess energies with a near-field scanning optical microscope in a dilution refrigerator. We have observed fine structures parallel to the edge in photovoltage signals, which appear only at low temperature. The observed fine structures near sample edges have been seen to shift inward with increase in magnetic field in accordance with Chklovskii Shklovskii, and Glazman model.

  11. Dynamics of a piezoelectric tuning fork/optical fiber assembly in a near-field scanning optical microscope

    NASA Astrophysics Data System (ADS)

    Shelimov, Konstantin B.; Davydov, Dmitri N.; Moskovits, Martin

    2000-02-01

    Factors leading to a decrease in the resonance quality (the Q factor) of quartz microtuning fork/optical fiber assemblies used as sensing elements in near-field scanning optical microscopes were considered using a simple elastomechanical analysis. Experiments to test the predictions of the analysis were carried out and strategies for recovering high Q factors were proposed and tested. Three major factors affecting the magnitude of the Q factor are discussed. The first is the stiffness imparted to the tine of the microtuning fork by the optical fiber attached to it; the second is the location of the attachment point of the fiber along the tine; the third is the resonant vibrational excitation of the fiber tip which acts as an energy dissipative channel. For tapping mode operation using a standard 125 μm diameter fiber, the large longitudinal stiffness of the fiber results in a dramatic Q-factor degradation. This effect can be overcome by reducing the diameter of the fiber cladding, d, and by slightly bending the fiber. Under these conditions, bending rather than longitudinal stretching dominates the fiber dynamics. The effective bending force constant for a thinned fiber is predicted to be proportional to d4. A sharp upturn in the Q factor is observed for d⩽25 μm, consistent with this prediction. The effective stiffness and mass of the fiber are also expected to scale approximately as x3, where x is the distance from the point of attachment of the fiber to the fork's base. Hence, the Q factor can be improved further by attaching the fiber closer to the tuning fork's base. Vibrational coupling between the tuning fork and the probe tip can result in a substantial Q-factor degradation for tips of a certain size. By taking these insights into consideration, we were able to construct tapping mode tuning fork/optical fiber assemblies with Q factors of up to 9000.

  12. Near-field phase-change recording using a GaN laser diode

    NASA Astrophysics Data System (ADS)

    Kishima, Koichiro; Ichimura, Isao; Yamamoto, Kenji; Osato, Kiyoshi; Kuroda, Yuji; Iida, Atsushi; Saito, Kimihiro

    2000-09-01

    We developed a 1.5-Numerical-Aperture optical setup using a GaN blue-violet laser diode. We used a 1.0 mm-diameter super-hemispherical solid immersion lens, and optimized a phase-change disk structure including the cover layer by the method of MTF simulation. The disk surface was polished by tape burnishing technique. An eye-pattern of (1-7)-coded data at the linear density of 80 nm/bit was demonstrated on the phase-change disk below a 50 nm gap height, which was realized through our air-gap servo mechanism.

  13. Solvothermally Synthesized Sb2Te3 Platelets Show Unexpected Optical Contrasts in Mid-Infrared Near-Field Scanning Microscopy.

    PubMed

    Hauer, Benedikt; Saltzmann, Tobias; Simon, Ulrich; Taubner, Thomas

    2015-05-13

    We report nanoscale-resolved optical investigations on the local material properties of Sb2Te3 hexagonal platelets grown by solvothermal synthesis. Using mid-infrared near-field microscopy, we find a highly symmetric pattern, which is correlated to a growth spiral and which extends over the entire platelet. As the origin of the optical contrast, we identify domains with different densities of charge carriers. On Sb2Te3 samples grown by other means, we did not find a comparable domain structure. PMID:25868047

  14. E-beam lithography and optical near-field lithography: new prospects in fabrication of various grating structures

    NASA Astrophysics Data System (ADS)

    Kley, Ernst-Bernhard; Clausnitzer, Tina

    2003-12-01

    Today"s technologies available for the fabrication of micro structured optical elements are well developed for defined classes of structures. Techniques for very complex optical functions or for combinations of optical functions together with others are more or less in the level of research or labs. A promising approach for complex grating fabrication is the use of optical near field holography (NFH) and e-beam writing for unification of the advantages. The paper wants to show the potential of both techniques itself as well as the potential that arises from their teamwork. The paper demonstrates one and two dimensional gratings, chirped and unidirectional gratings fabricated by NFH using e-beam written masks. It shows also possibilities for the fabrication of gratings on binary, multilevel and continuous optical profiles.

  15. Characterization of the near-field and convectional transport behavior of micro and nanoparticles in nanoscale plasmonic optical lattices.

    PubMed

    Yang, Tsang-Po; Yossifon, Gilad; Yang, Ya-Tang

    2016-05-01

    Here, we report the characterization of the transport of micro- and nanospheres in a simple two-dimensional square nanoscale plasmonic optical lattice. The optical potential was created by exciting plasmon resonance by way of illuminating an array of gold nanodiscs with a loosely focused Gaussian beam. This optical potential produced both in-lattice particle transport behavior, which was due to near-field optical gradient forces, and high-velocity (∼μm/s) out-of-lattice particle transport. As a comparison, the natural convection velocity field from a delocalized temperature profile produced by the photothermal heating of the nanoplasmonic array was computed in numerical simulations. This work elucidates the role of photothermal effects on micro- and nanoparticle transport in plasmonic optical lattices. PMID:27226813

  16. Observation of nonlinear bands in near-field scanning optical microscopy of a photonic-crystal waveguide

    SciTech Connect

    Singh, A.; Huisman, S. R.; Ctistis, G. Mosk, A. P.; Pinkse, P. W. H.; Korterik, J. P.; Herek, J. L.

    2015-01-21

    We have measured the photonic bandstructure of GaAs photonic-crystal waveguides with high resolution in energy as well as in momentum using near-field scanning optical microscopy. Intriguingly, we observe additional bands that are not predicted by eigenmode solvers, as was recently demonstrated by Huisman et al. [Phys. Rev. B 86, 155154 (2012)]. We study the presence of these additional bands by performing measurements of these bands while varying the incident light power, revealing a non-linear power dependence. Here, we demonstrate experimentally and theoretically that the observed additional bands are caused by a waveguide-specific near-field tip effect not previously reported, which can significantly phase-modulate the detected field.

  17. Observation of nonlinear bands in near-field scanning optical microscopy of a photonic-crystal waveguide

    NASA Astrophysics Data System (ADS)

    Singh, A.; Ctistis, G.; Huisman, S. R.; Korterik, J. P.; Mosk, A. P.; Herek, J. L.; Pinkse, P. W. H.

    2015-01-01

    We have measured the photonic bandstructure of GaAs photonic-crystal waveguides with high resolution in energy as well as in momentum using near-field scanning optical microscopy. Intriguingly, we observe additional bands that are not predicted by eigenmode solvers, as was recently demonstrated by Huisman et al. [Phys. Rev. B 86, 155154 (2012)]. We study the presence of these additional bands by performing measurements of these bands while varying the incident light power, revealing a non-linear power dependence. Here, we demonstrate experimentally and theoretically that the observed additional bands are caused by a waveguide-specific near-field tip effect not previously reported, which can significantly phase-modulate the detected field.

  18. Optical far- and near-field femtosecond laser ablation of Si for nanoscale chemical analysis

    SciTech Connect

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

    2010-02-02

    Extending spatial resolution in laser-based chemical analysis to the nanoscale becomes increasingly important as nanoscience and nanotechnology develop. Implementation of femtosecond laser pulses arises as a basic strategy for increasing resolution since it is associated with spatially localized material damage. In this work we study femtosecond laser far- and near-field processing of silicon (Si) at two distinct wavelengths (400 and 800 nm), for nanoscale chemical analysis. By tightly focusing femtosecond laser beams in the far-field we were able to produce sub-micrometer craters. In order to further reduce the crater size, similar experiments were performed in the near-field through sub-wavelength apertures, resulting to the formation of sub-30 nm craters. Laser Induced Breakdown Spectroscopy (LIBS) was used for chemical analysis with a goal to identify the minimum crater size from which spectral emission could be measured. Emission from sub-micrometer craters (full-with-at-half-maximum) was possible, which are among the smallest ever reported for femtosecond LIBS.

  19. Photoplastic near-field optical probe with sub-100 nm aperture made by replication from a nanomould.

    PubMed

    Kim, G M; Kim, B J; Ten Have, E S; Segerink, F; Van Hulst, N F; Brugger, J

    2003-03-01

    Polymers have the ability to conform to surface contours down to a few nanometres. We studied the filling of transparent epoxy-type EPON SU-8 into nanoscale apertures made in a thin metal film as a new method for polymer/metal near-field optical structures. Mould replica processes combining silicon micromachining with the photo-curable SU-8 offer great potential for low-cost nanostructure fabrication. In addition to offering a route for mass production, the transparent pyramidal probes are expected to improve light transmission thanks to a wider geometry near the aperture. By combining silicon MEMS, mould geometry tuning by oxidation, anti-adhesion coating by self-assembled monolayer and mechanical release steps, we propose an advanced method for near-field optical probe fabrication. The major improvement is the possibility to fabricate nanoscale apertures directly on wafer scale during the microfabrication process and not on free-standing tips. Optical measurements were performed with the fabricated probes. The full width half maximum after a Gaussian fit of the intensity profile indicates a lateral optical resolution of approximately 60 nm. PMID:12641773

  20. Characterization of surface and sub-surface defects in optical materials using the near field evanescent wave

    SciTech Connect

    Yan, M.; Oberhelman, S.; Wang, L.; Siekhaus, W.; Kozlowski, M.

    1998-12-31

    Optical properties of sub-micron defects at and near the surface are of interest in many applications, e.g. in high power laser systems where initiation of laser induced damage is a critical issue. In-situ scanning atomic force microscopy (AFM) has been used previously to establish a direct correlation between a particular structural surface inhomogeneity (such as a nodular defect in coatings) and the initiation of local laser damage at that inhomogeneity. Near field scanning optical microscopy (NSOM) make it now possible to provide information on both morphology and optical properties of localized defects at and near the surface. The authors have measured the amplitude variation of the near field evanescent wave around nodular defects and sub-surface inclusions in optical coatings and thus detected local laser field intensification. The observed intensity variation of the evanescent wave agrees with theoretical calculations of laser amplification around the inclusion. These findings support the theory that laser damage may be induced by local electrical field enhancement associated with micron and sub-micron defects.

  1. Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy.

    PubMed

    Esslinger, M; Dorfmüller, J; Khunsin, W; Vogelgesang, R; Kern, K

    2012-03-01

    We present advances in experimental techniques of apertureless scanning near-field optical microscopy (aSNOM). The rational alignment procedure we outline is based upon a phase singularity that occurs while scanning polarizers around the nominal cross-polarized configuration of s-polarized excitation and p-polarized detection. We discuss the theoretical origin of this topological feature of the setup, which is robust against small deviations, such as minor tip misalignment or shape variations. Setting the polarizers to this singular configuration point eliminates all background signal, allowing for reproducible plasmonic eigenmode mapping with optimal signal-to-noise ratio. PMID:22462926

  2. Two-photon absorption induced by electric field gradient of optical near-field and its application to photolithography

    SciTech Connect

    Yamaguchi, Maiku; Kawazoe, Tadashi; Yatsui, Takashi; Nobusada, Katsuyuki

    2015-05-11

    An electric field gradient is an inherent property of the optical near-field (ONF). We investigated its effect on electron excitation in a quantum dot via model calculations combining a density matrix formalism and a classical Lorentz model. The electric field gradient of the ONF was found to cause two-photon absorption by an unusual mechanism. Furthermore, the absorption exhibits a nonmonotonic dependence on the spatial arrangement of the nanosystem, completely different from that of conventional two-photon absorption induced by an intense electric field. The present two-photon absorption process was verified in a previous experimental observation by reinterpreting the results of ONF photolithography.

  3. Development of new apertureless near-field scanning optical microscope tip using finite-differential time-domain calculation

    NASA Astrophysics Data System (ADS)

    Kodama, Takashi; Ohtani, Hiroyuki

    2006-12-01

    We calculated the electric field enhancement factor of the apertureless near-field scanning optical microscope (ANSOM) tip using the finite-differential time-domain method. The results revealed that the enhancement factor of the silver tip remarkably decreased as the rounded tip radius increased. On the other hand, aggregated silver nanoparticles resulted in a strong field enhancement. Therefore, we developed a silver nanoparticles immobilized tip for the ANSOM probe and attempted to measure the surface enhanced Raman scattering spectrum of carbon onion molecules using it. We successfully detected the Raman spectra of individual carbon onions with a high sensitivity.

  4. Variable Temperature SiO2 Stripes Spectroscopy Taken by Customized Scattering Type Scanning Near-field Optical Microscopy

    NASA Astrophysics Data System (ADS)

    Li, Chaoran

    Variable temperature scattering-type scanning near-field optical microscopy is the system we built up from basis to explore the phase transition under low temperature. It has advantages of be able to take topography and spectroscopy simultaneously. What the SNOM system measures is the reflective effivient, it is determinde by the dielectric value of the sample, which is an intrinsic chemical propertiy. In this experiment, we taken spectroscopy of a sample with silicon dioxide stripes doped on the silicon substrate, get the contrast of silicon/silison dioxide, which is accord to the prediction of two models. Furthermore, the different contrast under various temperature reveals the temperature dependent dielectric function.

  5. Near-field enhanced optical tweezers utilizing femtosecond-laser nanostructured substrates

    NASA Astrophysics Data System (ADS)

    Kotsifaki, D. G.; Kandyla, M.; Lagoudakis, P. G.

    2015-11-01

    We present experimental evidence of plasmonic-enhanced optical tweezers, of polystyrene beads in deionized water in the vicinity of metal-coated nanostructures. The optical tweezers operate with a continuous wave near-infrared laser. We employ a Cu/Au bilayer that significantly improves dissipation of heat generated by the trapping laser beam and avoid de-trapping from heat convection currents. We investigate the improvement of the optical trapping force and the effective trapping quality factor, and observe an exponential distance dependence of the trapping force from the nanostructures, indicative of evanescent plasmonic enhancement.

  6. Near-field enhanced optical tweezers utilizing femtosecond-laser nanostructured substrates

    SciTech Connect

    Kotsifaki, D. G. Kandyla, M.; Lagoudakis, P. G.

    2015-11-23

    We present experimental evidence of plasmonic-enhanced optical tweezers, of polystyrene beads in deionized water in the vicinity of metal-coated nanostructures. The optical tweezers operate with a continuous wave near-infrared laser. We employ a Cu/Au bilayer that significantly improves dissipation of heat generated by the trapping laser beam and avoid de-trapping from heat convection currents. We investigate the improvement of the optical trapping force and the effective trapping quality factor, and observe an exponential distance dependence of the trapping force from the nanostructures, indicative of evanescent plasmonic enhancement.

  7. Optical fiber characterization: Backscatter, time domain bandwidth, refracted from near field and interlaboratory comparisons, volume 1

    NASA Astrophysics Data System (ADS)

    Danielson, B. L.; Day, G. W.; Franzen, D. L.; Kim, E. M.; Young, M.

    1982-09-01

    Optical fiber waveguide measurements are described. Systems to determine the backscatter, bandwidth, and index profile are covered in detail. Measurement comparisons between laboratories are given for fiber attenuation, bandwidth, numerical aperture, and core diameter.

  8. Near-field optical patterning and structuring based on local-field enhancement at the extremity of a metal tip.

    PubMed

    Royer, Pascal; Barchiesi, Dominique; Lerondel, Gilles; Bachelot, Renaud

    2004-04-15

    We present a particular approach and the associated results allowing the nanostructuration of a thin photosensitive polymer film. This approach based on a scanning near-field optical microscopy configuration uses the field-enhancement (FE) effect, a so-called lightning-rod effect appearing at the extremity of a metallic tip when illuminated with an incident light polarized along the tip axis. The local enhancement of the electromagnetic field straight below the tip's apex is observed directly through a photoisomerization reaction, inducing the growth of a topographical nanodot characterized in situ by atomic-force microscopy using the same probe. From a survey of the literature, we first review the different experimental approaches offered to nanostructure materials by near-field optical techniques. We describe more particularly the FE effect approach. An overview of the theoretical approach of this effect is then given before presenting some experimental results so as theoretical results using the finite-element method. These results show the influence on the nanostructuration of the polymer of a few experimental parameters such as the polarization state, the illumination mode and the tip's geometry. Finally, the potentiality of this technique for some applications in the field of lithography and high-density data storage is shown via the fabrication of nano-patterns. PMID:15306496

  9. Analysis of near-field method for optical data storage using microstrip probe under illumination and illumination-collection mode

    NASA Astrophysics Data System (ADS)

    Morozov, Yevhenii; Kryuchyn, Andriy A.; Petrov, Viacheslav V.; Lapchuk, Anatoliy S.

    2014-09-01

    Results of numerical simulation of near-field optical data storage using microstrip probe are presented. Simulation is carried out on the basis of the finite-difference time-domain method. Features of the information reading process from the ROM and RW (based on the phase transmissions of Ge2Sb2Te5 film) formats of optical discs under illumination and illumination-collection mode are analyzed and considered. Mathematical modeling has shown that the signal from the ROM-format disc under illumination mode, despite the fact that the probe has a significant far-field transmission coefficient, has a large crosstalk and small spatial resolution (significantly worse than a size of probe aperture). Unlike illumination mode, signal under illumination-collection mode (pure near-field method) has a resolution close to the size of the aperture, good amplitude and contrast, as well as relatively low crosstalk. However, information reading under illumination-collection mode from RW-format disc is not able to get the same good quality signal. Therefore the further optimization of the method is required to improve the signal quality of RW format.

  10. Optical near field phenomena in planar and structured organic solar cells

    NASA Astrophysics Data System (ADS)

    Niggemann, M.; Ziegler, T.; Glatthaar, M.; Riede, M.; Zimmermann, B.; Gombert, A.

    2006-04-01

    One key problem in optimizing organic solar cells is to maximize the absorption of incident light and to keep the charge carrier transport paths as short as possible in order to minimize transport losses. The large versatility of organic semiconductors and compositions requires specific optimization of each system. We investigate two model systems, the MDMO-PPV:PCBM blend and the P3HT:PCBM blend. Due to the small thickness of the functional layers in the order of several ten nanometers, coherent optics has to be considered and therefore interference effects play a dominant role. The influence of the thickness of the photoactive layer on the light absorption is investigated and compared with experimental data. The potential of an optical spacer which is introduced between the aluminium electrode and the photoactive layer to enhance the light harvesting is evaluated by optical modelling. Optical modelling becomes more complex for novel solar cell architectures based on nanostructured substrates. Exemplary optical simulations are presented for a nanoelectrode solar cell architecture.

  11. Near-field penetrating optical microscopy: A live cell nanoscale refractive index measurement technique for quantification of internal macromolecular density

    PubMed Central

    Strasser, Samantha Dale; Shekhawat, Gajendra; Rogers, Jeremy D.; Dravid, Vinayak P.; Taflove, Allen; Backman, Vadim

    2012-01-01

    Quantification of intracellular nanoscale macromolecular density distribution is a fundamental aspect to understanding cellular processes. We report a near-field penetrating optical microscopy (NPOM) technique to directly probe the internal nanoscale macromolecular density of biological cells through quantification of intracellular refractive index (RI). NPOM inserts a tapered optical fiber probe to successive depths into an illuminated sample. A 50 nm diameter probe-tip collects signal that exhibits a linear relationship with the sample RI at a spatial resolution of approximately 50 nm for biologically relevant measurements, one order-of-magnitude finer than the Abbe diffraction limit. Live and fixed cell data illustrate the mechanical ability of a 50 nm probe to penetrate biological samples. PMID:22344088

  12. Near-field penetrating optical microscopy: a live cell nanoscale refractive index measurement technique for quantification of internal macromolecular density.

    PubMed

    Strasser, Samantha Dale; Shekhawat, Gajendra; Rogers, Jeremy D; Dravid, Vinayak P; Taflove, Allen; Backman, Vadim

    2012-02-15

    Quantification of intracellular nanoscale macromolecular density distribution is a fundamental aspect to understanding cellular processes. We report a near-field penetrating optical microscopy (NPOM) technique to directly probe the internal nanoscale macromolecular density of biological cells through quantification of intracellular refractive index (RI). NPOM inserts a tapered optical fiber probe to successive depths into an illuminated sample. A 50 nm diameter probe tip collects signal that exhibits a linear relationship with the sample RI at a spatial resolution of approximately 50 nm for biologically relevant measurements, one order of magnitude finer than the Abbe diffraction limit. Live and fixed cell data illustrate the mechanical ability of a 50 nm probe to penetrate biological samples. PMID:22344088

  13. Near-field scanning optical microscopy cross-sectional measurements of crystalline GaAs solar cells

    SciTech Connect

    Herndon, M. K.; Bradford, W. C.; Collins, R. T.; Hawkins, B. E.; Kuech, T. F.; Friedman, D. J.; Kurtz, S. R.

    2000-07-03

    Near-field scanning optical microscopy (NSOM) was used to study cleaved edges of GaAs solar cell devices. Using visible light for excitation, the NSOM acquired spatially resolved traces of the photocurrent response across the various layers in the device. For excitation energies well above the band gap, carrier recombination at the cleaved surface had a strong influence on the photocurrent signal. Decreasing the excitation energy, which increased the optical penetration depth, allowed the effects of surface recombination to be separated from collection by the pn junction. Using this approach, the NSOM measurements directly observed the effects of a buried minority carrier reflector/passivation layer. (c) 2000 American Institute of Physics.

  14. Use of the sampling theorem to speed up near-field physical optics scattering calculations

    NASA Technical Reports Server (NTRS)

    Cramer, P. W.; Imbriale, W. A.

    1994-01-01

    Physical optics scattering calculations performed on the DSN 34-m beam-waveguide antennas at Ka-band (32 GHz) require approximately 12 hr of central processing unit time on a Cray Y-MP2 computer. This is excessive in terms of resource utilization and turnaround time. Typically, the calculations involve five surfaces, and the calculations are done two surfaces at a time. The sampling theorem is used to reduce the number of current values that must be calculated over the second surface by performing a physical optics integration over the first surface. The additional number of current values required on the second surface by subsequent physical optics integrations is obtained by interpolation over the original current values. Time improvements on the order of a factor of 2 to 4 were obtained for typical scattering pairs.

  15. Optical properties of microfabricated fully-metal-coated near-field probes in collection mode.

    PubMed

    Descrovi, Emiliano; Vaccaro, Luciana; Aeschimann, Laure; Nakagawa, Wataru; Staufer, Urs; Herzig, Hans-Peter

    2005-07-01

    A study of the optical properties of microfabricated, fully-metal-coated quartz probes collecting longitudinal and transverse optical fields is presented. The measurements are performed by raster scanning the focal plane of an objective, focusing azimuthally and radially polarized beams by use of two metal-coated quartz probes with different metal coatings. A quantitative estimation of the collection efficiencies and spatial resolutions in imaging both longitudinal and transverse fields is made. Longitudinally polarized fields are collected with a resolution approximately 1.5 times higher as compared with transversely polarized fields, and this behavior is almost independent of the roughness of the probe's metal coating. Moreover, the coating roughness is a critical parameter in the relative collection efficiency of the two field orientations. PMID:16053165

  16. 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)

  17. 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)

  18. 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.

  19. Linear-phase approximation in the triangular facet near-field physical optics computer program

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Hodges, R. E.

    1990-01-01

    Analyses of reflector antenna surfaces use a computer program based on a discrete approximation of the radiation integral. The calculation replaces the actual surface with a triangular facet representation; the physical optics current is assumed to be constant over each facet. Described here is a method of calculation using linear-phase approximation of the surface currents of parabolas, ellipses, and shaped subreflectors and compares results with a previous program that used a constant-phase approximation of the triangular facets. The results show that the linear-phase approximation is a significant improvement over the constant-phase approximation, and enables computation of 100 to 1,000 lambda reflectors within a reasonable time on a Cray computer.

  20. Photodissociation path in H2 + induced by nonuniform optical near fields: Two-step excitation via vibrationally excited states

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Maiku; Nobusada, Katsuyuki

    2016-02-01

    In this paper, effects of the spatial nonuniformity of an optical near field (ONF) on the molecular photodissociation process are presented. The dissociation dynamics of H2 + was theoretically investigated by solving a non-Born-Oppenheimer Schrödinger equation. It was found that in addition to two dissociation mechanisms, which are one-photon and three-photon processes induced by uniform laser light excitation, the nonuniform ONF opens another dissociation path: two-step excitation mediated by vibrationally excited states. The nonuniformity of the ONF causes a transition between vibrational states that is forbidden according to conventional selection rules, leading to the dissociation path. The dependences of photodissociation on the intensity and nonuniformity of the ONF were calculated and the results validated the two-step dissociation mechanism.

  1. Second International Conference on Near-Field Optical Analysis: Photodynamic Therapy and Photobiology Effects

    NASA Technical Reports Server (NTRS)

    Bulgher, Debra L. (Editor); Morrison, Dennis

    2002-01-01

    The International NASA/DARPA Photobiology Conference held at the Johnson Space Center in Houston/TX demonstrated where low level laser therapy (LLLT), respectively low intensity light activated biostimulation (LILAB) and nanotechnological applications employing photobiomodulation techniques will presumably go in the next ten years. The conference was a continuation of the 1st International Conference on Nearfield Optical Analysis organized by Andrei Sommer (ENSOMA Lab, University of Ulm, Germany) in November 2000 at Castle Reisenburg, Germany, which started with a group of ten scientists from eight different countries. The 1st conference was co-sponsored by the American Chemical Society to evaluate the molecular mechanism of accelerated and normal wound healing processes. The 2nd conference was co-sponsored by DARPA, NASA-JSC and the Medical College of Wisconsin. Despite the short time between events, the 2nd conference hosted 40 international experts form universities, research institutes, agencies and the industry. The materials published here are expected to become milestones forming a novel platform in biomedical photobiology. The multidisciplinary group of researchers focused on LLLT/LILAB-applications under extreme conditions expected to have beneficial effects particularly in space, on submarines, and under severe battlefield conditions. The group also focused on novel technologies with possibilities allowing investigating the interaction of light with biological systems, molecular mechanisms of wound healing, bone regeneration, nerve regeneration, pain modulation, as well as biomineralization and biofilm formulation processes induced by nanobacteria.

  2. Polarization-sensitive characterization of the propagating plasmonic modes in silver nanowire waveguide on a glass substrate with a scanning near-field optical microscope.

    PubMed

    Venugopalan, Priyamvada; Zhang, Qiming; Li, Xiangping; Gu, Min

    2013-07-01

    In this paper, we report on the experimental investigation of the polarization properties of the plasmonic modes along a silver nanowire waveguide on a glass substrate. Two orthogonal polarization light components at the distal end of the nanowire are observed in the far-field. The near-field mapping with a scanning near-field optical microscopic probe exhibiting an in-plane polarization sensitivity reveals the two polarization components of the propagating plasmonic modes along the nanowire. PMID:23842310

  3. Effects of Optical Combiner and IPD Change for Convergence on Near-Field Depth Perception in an Optical See-Through HMD.

    PubMed

    Lee, Sangyoon; Hu, Xinda; Hua, Hong

    2016-05-01

    Many error sources have been explored in regards to the depth perception problem in augmented reality environments using optical see-through head-mounted displays (OST-HMDs). Nonetheless, two error sources are commonly neglected: the ray-shift phenomenon and the change in interpupillary distance (IPD). The first source of error arises from the difference in refraction for virtual and see-through optical paths caused by an optical combiner, which is required of OST-HMDs. The second occurs from the change in the viewer's IPD due to eye convergence. In this paper, we analyze the effects of these two error sources on near-field depth perception and propose methods to compensate for these two types of errors. Furthermore, we investigate their effectiveness through an experiment comparing the conditions with and without our error compensation methods applied. In our experiment, participants estimated the egocentric depth of a virtual and a physical object located at seven different near-field distances (40∼200 cm) using a perceptual matching task. Although the experimental results showed different patterns depending on the target distance, the results demonstrated that the near-field depth perception error can be effectively reduced to a very small level (at most 1 percent error) by compensating for the two mentioned error sources. PMID:27045910

  4. Feasibility demonstration of a massively parallelizable optical near-field sensor for sub-wavelength defect detection and imaging

    NASA Astrophysics Data System (ADS)

    Mostafavi, Mahkamehossadat; Diaz, Rodolfo E.

    2016-05-01

    To detect and resolve sub-wavelength features at optical frequencies, beyond the diffraction limit, requires sensors that interact with the electromagnetic near-field of those features. Most instruments operating in this modality scan a single detector element across the surface under inspection because the scattered signals from a multiplicity of such elements would end up interfering with each other. However, an alternative massively parallelized configuration, capable of interrogating multiple adjacent areas of the surface at the same time, was proposed in 2002. Full physics simulations of the photonic antenna detector element that enables this instrument, show that using conventional red laser light (in the 600 nm range) the detector magnifies the signal from an 8 nm particle by up to 1.5 orders of magnitude. The antenna is a shaped slot element in a 60 nm silver film. The ability of this detector element to resolve λ/78 objects is confirmed experimentally at radio frequencies by fabricating an artificial material structure that mimics the optical permittivity of silver scaled to 2 GHz, and “cutting” into it the slot antenna. The experimental set-up is also used to demonstrate the imaging of a patterned surface in which the critical dimensions of the pattern are λ/22 in size.

  5. 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

  6. Feasibility demonstration of a massively parallelizable optical near-field sensor for sub-wavelength defect detection and imaging

    PubMed Central

    Mostafavi, Mahkamehossadat; Diaz, Rodolfo E.

    2016-01-01

    To detect and resolve sub-wavelength features at optical frequencies, beyond the diffraction limit, requires sensors that interact with the electromagnetic near-field of those features. Most instruments operating in this modality scan a single detector element across the surface under inspection because the scattered signals from a multiplicity of such elements would end up interfering with each other. However, an alternative massively parallelized configuration, capable of interrogating multiple adjacent areas of the surface at the same time, was proposed in 2002. Full physics simulations of the photonic antenna detector element that enables this instrument, show that using conventional red laser light (in the 600 nm range) the detector magnifies the signal from an 8 nm particle by up to 1.5 orders of magnitude. The antenna is a shaped slot element in a 60 nm silver film. The ability of this detector element to resolve λ/78 objects is confirmed experimentally at radio frequencies by fabricating an artificial material structure that mimics the optical permittivity of silver scaled to 2 GHz, and “cutting” into it the slot antenna. The experimental set-up is also used to demonstrate the imaging of a patterned surface in which the critical dimensions of the pattern are λ/22 in size. PMID:27185385

  7. 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

  8. Feasibility demonstration of a massively parallelizable optical near-field sensor for sub-wavelength defect detection and imaging.

    PubMed

    Mostafavi, Mahkamehossadat; Diaz, Rodolfo E

    2016-01-01

    To detect and resolve sub-wavelength features at optical frequencies, beyond the diffraction limit, requires sensors that interact with the electromagnetic near-field of those features. Most instruments operating in this modality scan a single detector element across the surface under inspection because the scattered signals from a multiplicity of such elements would end up interfering with each other. However, an alternative massively parallelized configuration, capable of interrogating multiple adjacent areas of the surface at the same time, was proposed in 2002. Full physics simulations of the photonic antenna detector element that enables this instrument, show that using conventional red laser light (in the 600 nm range) the detector magnifies the signal from an 8 nm particle by up to 1.5 orders of magnitude. The antenna is a shaped slot element in a 60 nm silver film. The ability of this detector element to resolve λ/78 objects is confirmed experimentally at radio frequencies by fabricating an artificial material structure that mimics the optical permittivity of silver scaled to 2 GHz, and "cutting" into it the slot antenna. The experimental set-up is also used to demonstrate the imaging of a patterned surface in which the critical dimensions of the pattern are λ/22 in size. PMID:27185385

  9. Local optical absorption spectra of h-BN–MoS2 van der Waals heterostructure revealed by scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Nozaki, Junji; Kobayashi, Yu; Miyata, Yasumitsu; Maniwa, Yutaka; Watanabe, Kenji; Taniguchi, Takashi; Yanagi, Kazuhiro

    2016-06-01

    Van der Waals (vdW) heterostructures, in which different two-dimensional layered materials are stacked, can exhibit unprecedented optical properties. Development of a technique to clarify local optical properties of vdW heterostructures is of great importance for the correct understanding of their backgrounds. Here, we examined local optical absorption spectra of h-BN–MoS2 vdW heterostructures by scanning near-field microscopy measurements with a spatial resolution of 100 nm. In an as-grown sample, there was almost no site dependence of their optical absorption spectra. However, in a degraded sample where defects and deformations were artificially induced, a significant site-dependence of optical absorption spectra was observed.

  10. Writing and reading methodology for biochips with sub-100-nm chemical patterns based on near-field scanning optical microscopy.

    PubMed

    Kobayashi, Yasuhiro; Sakai, Masaru; Ueda, Akio; Maruyama, Kenichi; Saiki, Toshiharu; Suzuki, Koji

    2008-05-01

    This paper demonstrates a writing and reading methodology, which allows both to create and to detect sub-100-nm carboxyl-terminated patterns on light-transmissive quartz substrates by the same instrumental system. Such a technique, capable of creating carboxyl-terminated nanopatterns, offers several benefits for the miniaturization of biochips, since the carboxyl-terminated nanopatterns allow the easy immobilization of biomolecules by amide bond formation. As a consequence, increasingly miniaturized biochips require suitable analytical methods for the detection of nanopatterns. In our approach, carboxyl-terminated nanopatterns of down to 80 nm width were created using a photolabile silane coupling agent and a UV laser coupled to a near-field scanning optical microscope (NSOM). The same NSOM system was then used in a next step to detect the fabricated carboxyl-terminated nanopatterns after modification with a fluorescent label. Furthermore, as a first step towards biochip applications, the successful immobilization of several biomolecules, such as streptavidin, IgG and DNA on carboxyl-terminated nanopatterns was demonstrated. We have shown that our approach has the potential to lead to a new bioanalytical method, which enables one to write and to read biochips on a sub-100-nm scale by the same system. PMID:18469460

  11. Electro-Optical Sensor Fabricated Using a Bulk Cleavage Technique and Its Characteristics for Near-Field Intra-Body Communication

    NASA Astrophysics Data System (ADS)

    Furuya, Akinori; Sasaki, Ai-ichiro; Morimura, Hiroki; Aihara, Kimihisa; Shinagawa, Mitsuru

    2013-09-01

    This paper describes how to obtain a low cost electro-optical (EO) sensor module for the mass production of near-field intra-body communication devices. In this study, we used a bulk cleavage technique to fabricate EO modulators without the need for any optical polishing or washing processes, and clarified the feasibility of assembling optical components using only a passive alignment technique with a compact housing.

  12. Near-field-induced optical force on a metal particle and C{sub 60}: Real-time and real-space electron dynamics simulation

    SciTech Connect

    Iwasa, Takeshi; Nobusada, Katsuyuki

    2010-10-15

    Optical forces induced by a near field are calculated for a 1-mm-sized metal particle mimicked by a jellium model and for C{sub 60} in the framework of real-time and real-space time-dependent density-functional theory combined with a nonuniform light-matter interaction formalism, fully taking account of multipole interaction. A highly localized near field nonuniformly polarizes these molecules. The locally induced polarization charges in the molecules are partly canceled by the screening charges. The polarization and screening charges generally contribute to the attractive and repulsive forces, respectively, and a sensible balance between these charges results in several peaks in the optical force as a function of the frequency of the near field. The resonance excitation does not necessarily maximally induce the net force, and the force exerted on the molecules strongly depends on the details of their electronic structures. The optical force is larger in the metal particle than in C{sub 60}. We also found that the optical force depends linearly on the intensity of the near field.

  13. Observation of amplitude and phase in ridge and photonic crystal waveguides operating at 1.55 microm by use of heterodyne scanning near-field optical microscopy.

    PubMed

    Tortora, P; Abashin, M; Märki, I; Nakagawa, W; Vaccaro, L; Salt, M; Herzig, H P; Levy, U; Fainman, Y

    2005-11-01

    We apply heterodyne scanning near-field optical microscopy (SNOM) to observe with subwavelength resolution the amplitude and phase of optical fields propagating in several microfabricated waveguide devices operating around the 1.55 microm wavelength. Good agreement between the SNOM measurements and predicted optical mode propagation characteristics in standard ridge waveguides demonstrates the validity of the method. In situ observation of the subwavelength-scale distribution and propagation of optical fields in straight and 90 degrees bend photonic crystal waveguides facilitates a more detailed understanding of the optical performance characteristics of these devices and illustrates the usefulness of the technique for investigating nanostructured photonic devices. PMID:16279458

  14. Effects of Configuration of Optical Combiner on Near-Field Depth Perception in Optical See-Through Head-Mounted Displays.

    PubMed

    Lee, Sangyoon; Hua, Hong

    2016-04-01

    The ray-shift phenomenon means the apparent distance shift in the display image plane between virtual and physical objects. It is caused by the difference in the refraction of virtual display and see-through optical paths derived from optical combiners that are necessary to provide a see-through capability in optical see-through head-mounted displays. In this work, through a human-subject experiment, we investigated the effects of ray-shift phenomenon induced by the optical combiner on depth perception for near-field distances (40 cm-100 cm). In our experiment, we considered three different configurations of optical combiner: horizontal-tilt and vertical-tilt configurations (using plate beamsplitters horizontally and vertically tilted by 45°, respectively), and non-tilt configuration (using rectangular solid waveguides). Participants' depth perception errors in these configurations were compared with those in an ordinary condition (i.e., the condition where physical objects are directly shown without the displays) and theoretically estimated ones. According to the experimental results, the measured percentage depth perception errors were similar to the theoretically estimated ones, where the amount of estimated percentage depth errors was greater than 0.3%. Furthermore, the participants showed significantly larger depth perception errors in the horizontal-tilt configuration than in an ordinary condition, while no large errors were found in the vertical-tilt configuration. In the non-tilt configuration, the results were dependent on the thickness of optical combiner and target distance. PMID:26780807

  15. Nanospot soldering polystyrene nanoparticles with an optical fiber probe laser irradiating a metallic AFM probe based on the near-field enhancement effect.

    PubMed

    Cui, Jianlei; Yang, Lijun; Wang, Yang; Mei, Xuesong; Wang, Wenjun; Hou, Chaojian

    2015-02-01

    With the development of nanoscience and nanotechnology for the bottom-up nanofabrication of nanostructures formed from polystyrene nanoparticles, joining technology is an essential step in the manufacturing and assembly of nanodevices and nanostructures in order to provide mechanical integration and connection. To study the nanospot welding of polystyrene nanoparticles, we propose a new nanospot-soldering method using the near-field enhancement effect of a metallic atomic force microscope (AFM) probe tip that is irradiated by an optical fiber probe laser. On the basis of our theoretical analysis of the near-field enhancement effect, we set up an experimental system for nanospot soldering; this approach is carried out by using an optical fiber probe laser to irradiate the AFM probe tip to sinter the nanoparticles, providing a promising technical approach for the application of nanosoldering in nanoscience and nanotechnology. PMID:25582678

  16. Development of a shear-force scanning near-field cathodoluminescence microscope for characterization of nanostructures' optical properties.

    PubMed

    Bercu, N B; Troyon, M; Molinari, M

    2016-09-01

    An original scanning near-field cathodoluminescence microscope for nanostructure characterization has been developed and successfully tested. By using a bimorph piezoelectric stack both as actuator and detector, the developed setup constitutes a real improvement compared to previously reported SEM-based solutions. The technique combines a scanning probe and a scanning electron microscope in order to simultaneously offer near-field cathodoluminescence and topographic images of the sample. Share-force topography and cathodoluminescence measurements on GaN, SiC and ZnO nanostructures using the developed setup are presented showing a nanometric resolution in both topography and cathodoluminescence images with increased sensitivity compared to classical luminescence techniques. PMID:27125561

  17. Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a fiber tip of scanning near-field optical microscopy

    SciTech Connect

    Atie, Elie M.; Xie, Zhihua; El Eter, Ali; Salut, Roland; Baida, Fadi I.; Grosjean, Thierry; Nedeljkovic, Dusan; Tannous, Tony

    2015-04-13

    Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nanometer scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e., in contact to the nanostructures. In this paper, we demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of “remote” (non contact) sensing on the nanometer scale. On the basis of a bowtie-aperture nano-antenna (BNA) integrated at the apex of a SNOM (Scanning Near-field Optical Microscopy) fiber tip, we introduce an ultra-compact, moveable, and background-free optical nanosensor for the remote sensing of a silicon surface (up to distance of 300 nm). Sensitivity of the BNA to its large scale environment is high enough to expect the monitoring and control of the spacing between the nano-antenna and a silicon surface with sub-nanometer accuracy. This work paves the way towards an alternative class of nanopositioning techniques, based on the monitoring of diffraction-free plasmon resonance, that are alternative to nanomechanical and diffraction-limited optical interference-based devices.

  18. Detection of an infrared near-field optical signal by attaching an infrared-excitable phosphor to the end of a photocantilever.

    PubMed

    Tanaka, Y; Fukuzawa, K; Ohwaki, J

    1999-01-01

    To improve the signal-to-noise ratio of near-field scanning optical microscopy, we propose attaching an infrared-excitable phosphor (IEP) to a photocantilever. One source of noise is the light scattered from locations on the sample surface other than that of the probe tip. By detecting only the light scattered from the tip, we can obtain a near-field optical signal without noise. We attached an IEP particle to a photocantilever to convert infrared light to visible light and we used 1550-nm infrared illumination, so the light scattered from the sample was only infrared. The silicon photodiode of the photocantilever is 10(6) times less sensitive to infrared light than to visible light. As a result, only the converted visible light from the IEP particle, i.e. the signal containing the near-field optical information from the tip, was detected. We verified that the photocantilever detected the signal in the evanescent light produced by infrared illumination and that the detected signal was the light converted by the IEP. The experimental results show the feasibility of detecting infrared light and not the background light through the use of the IEP. PMID:11388267

  19. Tip-enhanced near-field optical microscope with side-on and ATR-mode sample excitation for super-resolution Raman imaging of surfaces

    NASA Astrophysics Data System (ADS)

    Heilman, A. L.; Gordon, M. J.

    2016-06-01

    A tip-enhanced near-field optical microscope with side-on and attenuated total reflectance (ATR) excitation and collection is described and used to demonstrate sub-diffraction-limited (super-resolution) optical and chemical characterization of surfaces. ATR illumination is combined with an Au optical antenna tip to show that (i) the tip can quantitatively transduce the optical near-field (evanescent waves) above the surface by scattering photons into the far-field, (ii) the ATR geometry enables excitation and characterization of surface plasmon polaritons (SPPs), whose associated optical fields are shown to enhance Raman scattering from a thin layer of copper phthalocyanine (CuPc), and (iii) SPPs can be used to plasmonically excite the tip for super-resolution chemical imaging of patterned CuPc via tip-enhanced Raman spectroscopy (TERS). ATR-illumination TERS is also quantitatively compared with the more conventional side-on illumination scheme. In both cases, spatial resolution was better than 40 nm and tip on/tip off Raman enhancement factors were >6500. Furthermore, ATR illumination was shown to provide similar Raman signal levels at lower "effective" pump powers due to additional optical energy delivered by SPPs to the active region in the tip-surface gap.

  20. Fabrication and characterization of a silicon cantilever probe with an integrated quartz-glass (fused-silica) tip for scanning near-field optical microscopy.

    PubMed

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

    2001-10-01

    A cantilever-based probe is introduced for use in scanning near-field optical microscopy (SNOM) combined with scanning atomic-force microscopy (AFM). The probes consist of silicon cantilevers with integrated 25-mum-high fused-silica tips. The probes are batch fabricated by microfabrication technology. Transmission electron microscopy reveals that the transparent quartz tips are completely covered with an opaque aluminum layer before the SNOM measurement. Static and dynamic AFM imaging was performed. SNOM imaging in transmission mode of single fluorescent molecules shows an optical resolution better than 32 nm. PMID:18364783

  1. Near-field ground motion of the 2002 Denali fault, Alaska, earthquake recorded at pump station 10

    USGS Publications Warehouse

    Ellsworth, W.L.; Celebi, M.; Evans, J.R.; Jensen, E.G.; Kayen, R.; Metz, M.C.; Nyman, D.J.; Roddick, J.W.; Spudich, P.; Stephens, C.D.

    2004-01-01

    A free-field recording of the Denali fault earthquake was obtained by the Alyeska Pipeline Service Company 3 km from the surface rupture of the Denali fault. The instrument, part of the monitoring and control system for the trans-Alaska pipeline, was located at Pump Station 10, approximately 85 km east of the epicenter. After correction for the measured instrument response, we recover a seismogram that includes a permanent displacement of 3.0 m. The recorded ground motion has relatively low peak acceleration (0.36 g) and very high peak velocity (180 cm/s). Nonlinear soil response may have reduced the peak acceleration to this 0.36 g value. Accelerations in excess of 0.1 g lasted for 10 s, with the most intense motion occurring during a 1.5-s interval when the rupture passed the site. The low acceleration and high velocity observed near the fault in this earthquake agree with observations from other recent large-magnitude earthquakes. ?? 2004, Earthquake Engineering Research Institute.

  2. Optical sedimentation recorder

    DOEpatents

    Bishop, James K.B.

    2014-05-06

    A robotic optical sedimentation recorder is described for the recordation of carbon flux in the oceans wherein both POC and PIC particles are captured at the open end of a submersible sampling platform, the captured particles allowed to drift down onto a collection plate where they can be imaged over time. The particles are imaged using three separate light sources, activated in sequence, one source being a back light, a second source being a side light to provide dark field illumination, and a third source comprising a cross polarized light source to illuminate birefringent particles. The recorder in one embodiment is attached to a buoyancy unit which is capable upon command for bringing the sedimentation recorder to a programmed depth below the ocean surface during recordation mode, and on command returning the unit to the ocean surface for transmission of recorded data and receipt of new instructions. The combined unit is provided with its own power source and is designed to operate autonomously in the ocean for extended periods of time.

  3. Revealing nanoscale optical properties and morphology in perfluoropentacene films by confocal and tip-enhanced near-field optical microscopy and spectroscopy.

    PubMed

    Wang, Xiao; Broch, Katharina; Schreiber, Frank; Meixner, Alfred J; Zhang, Dai

    2016-06-21

    Combining high resolution optical microscopy and spectroscopy, we propose a novel, generally applicable and highly sensitive method for determining the local morphology in organic semiconductor thin films (e.g. perfluoropentacene (PFP)). An azimuthally or radially polarized doughnut mode (APDM or RPDM) laser beam is focused by a high numerical aperture parabolic-mirror to excite a diffraction limited volume of the PFP film with an electric field polarized either exclusively in-plane or dominantly out-of-plane (relative to the substrate). We find two distinct morphologies of thin PFP films: molecular aggregates and crystalline terraces. The well-defined dipole emission patterns observed from the molecular aggregates strongly suggest the presence of localized excitations. For both laser modes, we observe that for the PFP aggregates, the photoluminescence (PL) emission from the main electronic transition is blue-shifted by about 10 meV, as compared to that from the molecular terraces. For the C-C bending modes, the B3g at 1581 cm(-1) (ν1) and the Ag at 1316 cm(-1) (ν0), we observe a decrease of the intensity ratio (Iν1/Iν0) from 0.6 (terrace) to 0.15 (aggregate). Furthermore, the intensity ratios (IAPDM/IRPDM) of ν1 excited by different polarizations increase from 0.12 (terrace) to 0.73 (aggregate). These results indicate that the PFP molecules orient rather parallel to the substrate in the aggregates, whilst more upright in the terraces. Benefiting from the nanometer scale optical resolution offered by the tip-enhanced near-field optical method, we observe clear optical contrasts between the molecular aggregate and the terrace as well as individual layers within a terrace. Tip-enhanced optical spectra locally taken from the molecular terrace and the aggregate show similar blue-shift of the main PL peak and change in the Raman intensity with different polarizations as from the far-field assemble-measurements, which further confirms the different molecular

  4. Local detection efficiency of a NbN superconducting single photon detector explored by a scattering scanning near-field optical microscope.

    PubMed

    Wang, Qiang; Renema, Jelmer J; Engel, Andreas; van Exter, Martin P; de Dood, Michiel J A

    2015-09-21

    We propose an experiment to directly probe the local response of a superconducting single photon detector using a sharp metal tip in a scattering scanning near-field optical microscope. The optical absorption is obtained by simulating the tip-detector system, where the tip-detector is illuminated from the side, with the tip functioning as an optical antenna. The local detection efficiency is calculated by considering the recently introduced position-dependent threshold current in the detector. The calculated response for a 150 nm wide detector shows a peak close to the edge that can be spatially resolved with an estimated resolution of ∼ 20 nm, using a tip with parameters that are experimentally accessible. PMID:26406688

  5. Combining near-field hyperspectral imaging and far-field spectral-angular distribution to develop mid-field white LED optical models with spatial color deviation.

    PubMed

    Lee, Tsung-Xian; Lu, Tsung-Lin; Chen, Bo-Song

    2016-07-11

    The integration of spatial distribution of light intensity and color in the midfield is instrumental for LED optical design. On the basis of this rationale, we proposed an accurate and convenient method for developing white LED optical models. Near-field hyperspectral images and far-field spectral-angular distributions were integrated to illustrate changes in spatial light intensity and color distribution in the mid-field, to the exclusion of the absorption, conversion, and scattering of phosphors. The corresponding optical models were developed for three LED samples under different packaging conditions. Their normalized cross-correlation values for spatial light intensity and correlated-color-temperature distribution between simulation and measurement averaged as high as 0.995 and 0.99 respectively, which validated the accuracy and feasibility of the proposed method. PMID:27410897

  6. Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy

    PubMed Central

    Chen, Y. T.; Karlsson, K. F.; Birch, J.; Holtz, P. O.

    2016-01-01

    Direct measurements of carrier diffusion in GaN nanorods with a designed InGaN/GaN layer-in-a-wire structure by scanning near-field optical microscopy (SNOM) were performed at liquid-helium temperatures of 10 K. Without an applied voltage, intrinsic diffusion lengths of photo-excited carriers were measured as the diameters of the nanorods differ from 50 to 800 nm. The critical diameter of nanorods for carrier diffusion is concluded as 170 nm with a statistical approach. Photoluminescence spectra were acquired for different positions of the SNOM tip on the nanorod, corresponding to the origins of the well-defined luminescence peaks, each being related to recombination-centers. The phenomenon originated from surface oxide by direct comparison of two nanorods with similar diameters in a single map has been observed and investigated. PMID:26876009

  7. Second harmonic generation in a KNbO3 nanorod and its detection by using a near-field scanning optical microscope

    NASA Astrophysics Data System (ADS)

    Park, D. J.; Kang, P. G.; Jung, J. H.; Lee, H. H.; Choi, S. B.

    2016-04-01

    We report on an observation of second harmonic generation in an individual KNbO3 nanorod by using a near-field scanning optical microscope. The second harmonic is successfully generated by irradiating with a femtosecond laser having center wavelengths of 1200, 1100, and 972 nm. Such a second harmonic yield shows a clear dependence on the incident laser polarization, where maximum yield is obtained when the incident laser polarization is parallel to the long axis of an individual nanorod. A spatially-resolved second harmonic image shows a bright spot at the edge of the nanorod, which is attributed to the elaborated intensity of both fundamental laser light and second harmonic light inside the nanowire owing to cavity-mode formation.

  8. Growth and decay dynamics of a stable microbubble produced at the end of a near-field scanning optical microscopy fiber probe

    NASA Astrophysics Data System (ADS)

    Taylor, R. S.; Hnatovsky, C.

    2004-06-01

    Low power cw laser radiation coupled into a near-field scanning optical microscopy fiber probe has been used to generate a stable microbubble in water. A probe tip which was selectively chemically etched and metallized served as a microheater for the generation of the stable bubble. Bubble diameters in the range of 40-400 μm and lifetimes of over an hour have been obtained. The microbubble exhibited a linear growth phase over a period of a few seconds before reaching a maximum diameter which depended on the laser power. When the laser beam was blocked the microbubble decayed with a rate which was inversely proportional to the bubble diameter. The bubble lifetime depended on the square of the initial bubble diameter. Instabilities which transform a large stable bubble into a microjet stream of micron sized bubbles as the laser power was increased is also described.

  9. Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Y. T.; Karlsson, K. F.; Birch, J.; Holtz, P. O.

    2016-02-01

    Direct measurements of carrier diffusion in GaN nanorods with a designed InGaN/GaN layer-in-a-wire structure by scanning near-field optical microscopy (SNOM) were performed at liquid-helium temperatures of 10 K. Without an applied voltage, intrinsic diffusion lengths of photo-excited carriers were measured as the diameters of the nanorods differ from 50 to 800 nm. The critical diameter of nanorods for carrier diffusion is concluded as 170 nm with a statistical approach. Photoluminescence spectra were acquired for different positions of the SNOM tip on the nanorod, corresponding to the origins of the well-defined luminescence peaks, each being related to recombination-centers. The phenomenon originated from surface oxide by direct comparison of two nanorods with similar diameters in a single map has been observed and investigated.

  10. Near-Field Scanning Optical Microscopy of Soft, Biological, or Rough Objects in Aqueous Environment: Challenges and some Remedies to Circumvent

    NASA Technical Reports Server (NTRS)

    Vikram, C. S.; Witherow, W. K.

    1999-01-01

    Near-field scanning optical microscopy is an established technique for sub-wavelength spatial resolution in imaging, spectroscopy, material science, surface chemistry, polarimetry, etc. A significant amount of confidence has been established for thin hard specimens in air. However when soft, biological, rough, in aqueous environment object, or a combination is involved, the progress has been slow. The tip-sample mechanical interaction, heat effects to sample, drag effects to the probe, difficulty in controlling tip-sample separation in case of rough objects, light scattering from sample thickness, etc. create problems. Although these problems are not even fully understood, there have been attempts to study them with the aim of performing reliable operations. In this review we describe these attempts. Starting with general problems encountered, various effects like polarization, thermal, and media are covered. The roles of independent tip-sample distance control tools in the relevant situations are then described. Finally progress in fluid cell aspect has been summarized.

  11. Measuring photoluminescence spectra of self-assembly array nanowire of colloidal CdSe quantum dots using scanning near-field optics microscopy

    NASA Astrophysics Data System (ADS)

    Bai, Zhongchen; Hao, Licai; Zhang, Zhengping; Qin, Shuijie

    2016-05-01

    A novel periodic array CdSe nanowire is prepared on a substrate of the porous titanium dioxide by using a self-assembly method of the colloidal CdSe quantum dots (QDs). The experimental results show that the colloidal CdSe QDs have renewedly assembled on its space scale and direction in process of losing background solvent and form the periodic array nanowire. The main peak wavelength of Photoluminescence (PL) spectra, which is measured by using a 100-nm aperture laser beam spot on a scanning near-field optics microscopy, has shifted 60 nm with compared to the colloidal CdSe QDs. Furthermore, we have measured smaller ordered nanometer structure in thin QDs area as well, a 343-nm periodic nanowire in thick QDs area and the colloidal QDs in edge of well-ordered nanowire.

  12. Membrane specific mapping and colocalization of malarial and host skeletal proteins in the Plasmodium falciparum infected erythrocyte by dual-color near-field scanning optical microscopy.

    PubMed

    Enderle, T; Ha, T; Ogletree, D F; Chemla, D S; Magowan, C; Weiss, S

    1997-01-21

    Accurate localization of proteins within the substructure of cells and cellular organelles enables better understanding of structure-function relationships, including elucidation of protein-protein interactions. We describe the use of a near-field scanning optical microscope (NSOM) to simultaneously map and detect colocalized proteins within a cell, with superresolution. The system we elected to study was that of human red blood cells invaded by the human malaria parasite Plasmodium falciparum. During intraerythrocytic growth, the parasite expresses proteins that are transported to the erythrocyte cell membrane. Association of parasite proteins with host skeletal proteins leads to modification of the erythrocyte membrane. We report on colocalization studies of parasite proteins with an erythrocyte skeletal protein. Host and parasite proteins were selectively labeled in indirect immunofluorescence antibody assays. Simultaneous dual-color excitation and detection with NSOM provided fluorescence maps together with topography of the cell membrane with subwavelength (100 nm) resolution. Colocalization studies with laser scanning confocal microscopy provided lower resolution (310 nm) fluorescence maps of cross sections through the cell. Because the two excitation colors shared the exact same near-field aperture, the two fluorescence images were acquired in perfect, pixel-by-pixel registry, free from chromatic aberrations, which contaminate laser scanning confocal microscopy measurements. Colocalization studies of the protein pairs of mature parasite-infected erythrocyte surface antigen (MESA) (parasite)/protein4.1(host) and P. falciparum histidine rich protein (PfHRP1) (parasite)/protein4.1(host) showed good real-space correlation for the MESA/protein4.1 pair, but relatively poor correlation for the PfHRP1/protein4.1 pair. These data imply that NSOM provides high resolution information on in situ interactions between proteins in biological membranes. This method of

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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

  19. Infrared Scattering Scanning Near-Field Optical Microscopy Using An External Cavity Quantum Cascade Laser For Nanoscale Chemical Imaging And Spectroscopy of Explosive Residues

    SciTech Connect

    Craig, Ian M.; Phillips, Mark C.; Taubman, Matthew S.; Josberger, Erik E.; Raschke, Markus Bernd

    2013-02-04

    Infrared scattering scanning near-field optical microscopy (s-SNOM) is an apertureless superfocusing technique that uses the antenna properties of a conducting atomic force microscope (AFM) tip to achieve infrared spatial resolution below the diffraction limit. The instrument can be used either in imaging mode, where a fixed wavelength light source is tuned to a molecular resonance and the AFM raster scans an image, or in spectroscopy mode where the AFM is held stationary over a feature of interest and the light frequency is varied to obtain a spectrum. In either case, a strong, stable, coherent infrared source is required. Here we demonstrate the integration of a broadly tunable external cavity quantum cascade laser (ECQCL) into an s-SNOM and use it to obtain infrared spectra of microcrystals of chemicals adsorbed onto gold substrates. Residues of the explosive compound tetryl was deposited onto gold substrates. s-SNOM experiments were performed in the 1260-1400 cm-1 tuning range of the ECQCL, corresponding to the NO2 symmetric stretch vibrational fingerprint region. Vibrational infrared spectra were collected on individual chemical domains with a collection area of *500nm2 and compared to ensemble averaged far-field reflection-absorption infrared spectroscopy (RAIRS) results.

  20. Infrared scattering scanning near-field optical microscopy using an external cavity quantum cascade laser for nanoscale chemical imaging and spectroscopy of explosive residues

    NASA Astrophysics Data System (ADS)

    Craig, Ian M.; Phillips, Mark C.; Taubman, Matthew S.; Josberger, Erik E.; Raschke, Markus B.

    2013-01-01

    Infrared scattering scanning near-field optical microscopy (s-SNOM) is an apertureless superfocusing technique that uses the antenna properties of a conducting atomic force microscope (AFM) tip to achieve infrared spatial resolution below the diffraction limit. The instrument can be used either in imaging mode, where a fixed wavelength light source is tuned to a molecular resonance and the AFM raster scans an image, or in spectroscopy mode where the AFM is held stationary over a feature of interest and the light frequency is varied to obtain a spectrum. In either case, a strong, stable, coherent infrared source is required. Here we demonstrate the integration of a broadly tunable external cavity quantum cascade laser (ECQCL) into an s-SNOM and use it to obtain infrared spectra of microcrystals of chemicals adsorbed onto gold substrates. Residues of the explosive compound tetryl was deposited onto gold substrates. s-SNOM experiments were performed in the 1260-1400cm-1 tuning range of the ECQCL, corresponding to the N02 symmetric stretch vibrational fingerprint region. Vibrational infrared spectra were collected on individual chemical domains with a collection area of ~500 nm2 and compared to ensemble averaged far-field reflection-absorption infrared spectroscopy (RAIRS) results.

  1. Fabrication and characterization of fluorescent rare-earth-doped glass-particle-based tips for near-field optical imaging applications.

    PubMed

    Aigouy, Lionel; De Wilde, Yannick; Mortier, Michel; Giérak, Jacques; Bourhis, Eric

    2004-07-01

    Fluorescent rare-earth-doped glass particles glued to the end of an atomic force microscope tip have been used to perform scanning near-field optical measurements on nanostructured samples. The fixation procedure of the fluorescent fragment at the end of the tip is described in detail. The procedure consists of depositing a thin adhesive layer on the tip. Then a tip approach is performed on a fragment that remains stuck near the tip extremity. To displace the particle and position it at the very end of the tip, a nanomanipulation is achieved by use of a second tip mounted on piezoelectric scanners. Afterward, the particle size is reduced by focused ion beam milling. These particles exhibit a strong green luminescence where excited in the near infrared by an upconversion mechanism. Images obtained near a metallic edge show a lateral resolution in the 180-200-nm range. Images we obtained by measuring the light scattered by 250-nm holes show a resolution well below 100 nm. This phenomenon can be explained by a local excitation of the particle and by the nonlinear nature of the excitation. PMID:15250549

  2. 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.

  3. A new optical recording medium

    NASA Technical Reports Server (NTRS)

    Aronson, H.; Loiacono, G. M.

    1973-01-01

    Method has been developed for doping lithium niobiate crystals with transition metal to increase rate at which crystal can record optical data. Discovery may facilitate development of system for analog storage of TV frames, printed pages, photographs, and other visual information.

  4. Parallel generation of nanochannels in fused silica with a single femtosecond laser pulse: Exploiting the optical near fields of triangular nanoparticles

    SciTech Connect

    Hubenthal, F.; Morarescu, R.; Englert, L.; Haag, L.; Baumert, T.; Traeger, F.

    2009-08-10

    We present experiments to prepare highly ordered nanochannels with subdiffraction dimensions on fused silica surfaces with femtosecond laser light. For this purpose, we exploit the strongly enhanced near field of highly ordered triangular gold nanoparticles. We demonstrate that after a single laser shot, 6 {mu}m long nanochannels with a mean depth of 4 nm and an average width of 96 nm, i.e., well below the diffraction limit, are generated. These nanochannels are prepared by ablation, caused by the localization of the near field. The crucial parameters, besides the applied fluence, are the polarization direction of the incoming laser light with respect to the triangular nanoparticles and the size of the nanoparticles.

  5. Rewriteable optical disk recorder development

    NASA Technical Reports Server (NTRS)

    Shull, Thomas A.; Rinsland, Pamela L.

    1991-01-01

    A NASA program to develop a high performance (high rate, high capability) rewriteable optical disk recorder for spaceflight applications is presented. An expandable, adaptable system concept is proposed based on disk Drive modules and a modular Controller. Drive performance goals are 10 gigabyte capacity are up to 1.8 gigabits per second rate with concurrent I/O, synchronous data transfer, and 2 to 5 years operating life in orbit. Technology developments, design concepts, current status, and future plans are presented.

  6. Optothermal property and decomposition characteristics of PtO(x) ultrathin film sandwiched between ZnS-SiO2 for super-resolution near-field recording.

    PubMed

    Her, Yung-Chiun; Liao, Bou-Yin; Hsu, Wei-Chih; Tsai, Song-Yeu

    2007-01-01

    We have investigated the optothermal property and decomposition characteristics of PtO(x) ultrathin film protected by ZnS-SiO2 layers and effects of the constituent phases of PtO(x) on super-resolution capability and read stability of the super-RENS disk. All the ZnS-SiO2/PtO(x)/ZnS-SiO2 multilayers exhibited a steep reflectivity drop at the temperature range between 265 and 350 degrees C, corresponding to the decomposition of PtO(x). The decomposition temperature of the 4-nm-thick PtO(x) ultrathin film protected by ZnS-SiO2 layers was much lower than those obtained in thick PtO(x) films without protection. The activation energy for thermal decomposition was approximately 1.3 eV. Both the decomposition temperature and activation energy for thermal decomposition were unaffected by the constituent phases of PtO(x). Carrier to noise ratios (CNR) of over 40 dB for mark size of 150 nm were achieved in all super-resolution near-field structure (super-RENS) disks, while the super-resolution readout was limited to 2.5 x 10(3) approximately 4.5 x 10(4) cycles. The effect of constituent phases of PtO(x) on the super-resolution capability of super-RENS disk with a PtO(x) mask layer was minimal. However, as the constituent phases of PtO(x) mask layer transformed from a mixture of Pt and PtO, to pure PtO, and then to a mixture of PtO and PtO2, the readout stability of super-RENS disk increased dramatically since less heat was absorbed by the PtO(x) mask layer composed of PtO and PtO2 during the readout process, prohibiting the diffusion of materials inside the bubble to the GeSbTe phase change layer. PMID:17455507

  7. 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.

  8. Spaceflight optical disk recorder development

    NASA Technical Reports Server (NTRS)

    Jurczyk, Stephen G.; Hines, Glenn D.; Shull, Thomas A.

    1992-01-01

    Mass memory systems based on rewriteable optical disk media are expected to play an important role in meeting the data system requirements for future NASA spaceflight missions. NASA has established a program to develop a high performance (high rate, large capacity) optical disk recorder focused on use aboard unmanned Earth orbiting platforms. An expandable, adaptable system concept is proposed based on disk drive modules and a modular controller. Drive performance goals are 10 gigabyte capacity, 300 megabit/s transfer rate, 10 exp -12 corrected bit error rate, and 150 millisec access time. This performance is achieved by writing eight data tracks in parallel on both sides of a 14 in. optical disk using two independent heads. System goals are 160 gigabyte capacity, 1.2 gigabits/s data rate with concurrent I/O, 250 millisec access time, and two to five year operating life on orbit. The system can be configured to meet various applications. This versatility is provided by the controller. The controller provides command processing, multiple drive synchronization, data buffering, basic file management, error processing, and status reporting. Technology developments, design concepts, current status including a computer model of the system and a Controller breadboard, and future plans for the Drive and Controller are presented.

  9. Morphological and biochemical analysis by atomic force microscopy and scanning near-field optical microscopy techniques of human keratinocytes (HaCaT) exposed to extremely low frequency 50 Hz magnetic field

    NASA Astrophysics Data System (ADS)

    Rieti, Sabrina; Manni, Vanessa; Lisi, Antonella; Grimaldi, Settimio; Generosi, Renato; Luce, Marco; Perfetti, Paolo; Cricenti, Antonio; Pozzi, Deleana; Giuliani, Livio

    2002-10-01

    We studied the effect of the interaction of electromagnetic radiation with human keratinocytes (HaCaT), at low (50 Hz, 1 mT) frequency using both atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) techniques. AFM analysis showed modifications in shape and morphology in exposed cells, while SNOM indirect immunofluorescence analysis revealed an increase of segregation of β4 integrin (an adhesion marker) in the cell membrane of the same cells, suggesting that a higher percentage of the exposed cells shows a modified pattern of this adhesion marker.

  10. Nonoptically probing near-field microscopy for the observation of biological living specimens

    NASA Astrophysics Data System (ADS)

    Kawata, Yoshimasa; Murakami, Manabu; Egami, Chikara; Sugihara, Okihiro; Okamoto, Naomichi; Tsuchimori, Masaaki; Watanabe, Osamu; Nakamura, Osamu

    2001-04-01

    We present the observation of living specimens with subwavelength resolution by using the nonoptically probing near-field microscopy we have developed recently. In the near-field microscope, the optical field distributions near the specimens are recorded as the surface topography of a photosensitive film, and the topographical distributions are readout with an atomic-force microscopy. Since the near-field microscope does not require the scanning of a probe tip for illumination or detection or scattering of light, it is possible to observe moving biological specimens and fast phenomena. We demonstrate the observation of a moving paramecium and euglena gracilis with subwavelength resolution. The observation of the nucleus inside a euglena cell was also demonstrated.

  11. Far-Field Spectroscopy and Near-Field Optical Imaging of Coupled Plasmon-Phonon Polaritons in 2D van der Waals Heterostructures.

    PubMed

    Yang, Xiaoxia; Zhai, Feng; Hu, Hai; Hu, Debo; Liu, Ruina; Zhang, Shunping; Sun, Mengtao; Sun, Zhipei; Chen, Jianing; Dai, Qing

    2016-04-01

    A new hybridized plasmon-phonon polariton mode in graphene/h-BN van der Waals heterostructures is presented, featuring the ultrahigh field confinement characteristic of the graphene plasmon and the long lifetime property of the h-BN transverse optical phonon. This enables an ultralong hybrid plasmon lifetime of up to 1.6 ps (with ultrahigh mode confinement up to >l0 (2) /7000 and ultrasmall group velocity down to 0.001c, where c is the speed of light in vacuum), superior to any localized plasmon ever demonstrated. PMID:26889663

  12. 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

  13. Digital optical recorder-reproducer system

    NASA Technical Reports Server (NTRS)

    Reddersen, Brad R. (Inventor); Zech, Richard G. (Inventor); Roberts, Howard N. (Inventor)

    1980-01-01

    A mass archival optical recording and reproduction system includes a recording light source such as a laser beam focussed and directed upon an acousto-optic linear modulator array (or page composer) that receives parallel blocks of data converted from a serial stream of digital data to be stored. The page composer imparts to the laser beam modulation representative of a plurality of parallel channels of data and through focussing optics downstream of the page composer parallel arrays of optical spots are recorded upon a suitable recording medium such as a photographic film floppy disc. The recording medium may be substantially frictionlessly and stably positioned for recording at a record/read station by an air-bearing platen arrangement which is preferably thermodynamically non-throttling so that the recording film may be positioned in the path of the information-carrying light beam in a static or dynamic mode. During readout, the page composer is bypassed and a readout light beam is focussed directly upon the recording medium containing an array of previously recorded digital spots, a sync bit, data positioning bits, and a tracking band. The readout beam which has been directed through the recording medium is then imaged upon a photodetector array, the output of which may be coupled to suitable electronic processing circuitry, such as a digital multiplexer, whereby the parallel spot array is converted back into the original serial data stream.

  14. Shape effects of GeSbTe nanodots on the near-field interaction with a silver triangle antenna

    NASA Astrophysics Data System (ADS)

    Kojima, Naoto; Ota, Norio; Asakawa, Kiyoshi; Shiraishi, Kenji; Yamada, Keisaku

    2015-04-01

    We investigated the shape effects of GeSbTe nanodots on the near-field interaction with a silver triangle antenna using the three-dimensional finite-difference time-domain method, avoiding the difficulty of detecting near-field signals from a single dot that occurs in current measurements. The surface plasmon resonance of silver strengthens the near-field around nanodots made of GeSbTe, commonly used in phase-change recording. Using GeSbTe spheres and pillar dots with various top plane shapes, we investigated the relationship between the inner electric field concentration of GeSbTe nanodots and the radius of curvature of the corners facing the antenna tip. Reducing the radius of curvature strengthens the inner electric field of the dots, enhancing the near-field difference in intensity for the GeSbTe phase change. GeSbTe diamond pillars with a radius of curvature of 1 nm exhibit a near-field difference in intensity of 28% for the phase change. Using the antenna and the GeSbTe nanodot array, optical write-once recording is realized. The preliminary research in this study is expected to realize future optical disk storage using GeSbTe nanodots with diameters below 10 nm.

  15. Characterization of semiconductor materials using synchrotron radiation-based near-field infrared microscopy and nano-FTIR spectroscopy.

    PubMed

    Hermann, Peter; Hoehl, Arne; Ulrich, Georg; Fleischmann, Claudia; Hermelink, Antje; Kästner, Bernd; Patoka, Piotr; Hornemann, Andrea; Beckhoff, Burkhard; Rühl, Eckart; Ulm, Gerhard

    2014-07-28

    We describe the application of scattering-type near-field optical microscopy to characterize various semiconducting materials using the electron storage ring Metrology Light Source (MLS) as a broadband synchrotron radiation source. For verifying high-resolution imaging and nano-FTIR spectroscopy we performed scans across nanoscale Si-based surface structures. The obtained results demonstrate that a spatial resolution below 40 nm can be achieved, despite the use of a radiation source with an extremely broad emission spectrum. This approach allows not only for the collection of optical information but also enables the acquisition of near-field spectral data in the mid-infrared range. The high sensitivity for spectroscopic material discrimination using synchrotron radiation is presented by recording near-field spectra from thin films composed of different materials used in semiconductor technology, such as SiO2, SiC, SixNy, and TiO2. PMID:25089414

  16. 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.

  17. 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.

  18. Optical recording in copper-silica nanocomposite

    NASA Astrophysics Data System (ADS)

    Dmitruk, Igor; Blonskiy, Ivan; Korenyuk, Petro; Kadan, Viktor; Zubrilin, Mykola; Dmytruk, Andriy; Yeshchenko, Oleg; Alexeenko, Alexandr; Kotko, Andriy

    2014-05-01

    The application of field enhancement effect, which takes place when light, interacts with surface plasmon, for optical recording has been suggested. Copper-silica nanocomposite demonstrates possibility of optical writing and erasing under irradiation by second harmonic (400 nm) and fundamental wavelength (800 nm) of femtosecond titanium-sapphire laser, respectively.

  19. 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.

  20. Shaping the nonlinear near field.

    PubMed

    Wolf, Daniela; Schumacher, Thorsten; Lippitz, Markus

    2016-01-01

    Light scattering at plasmonic nanoparticles and their assemblies has led to a wealth of applications in metamaterials and nano-optics. Although shaping of fields around nanostructures is widely studied, the influence of the field inside the nanostructures is often overlooked. The linear field distribution inside the structure taken to the third power causes third-harmonic generation, a nonlinear optical response of matter. Here we demonstrate by a far field Fourier imaging method how this simple fact can be used to shape complex fields around a single particle alone. We employ this scheme to switch the third-harmonic emission from a single point source to two spatially separated but coherent sources, as in Young's double-slit assembly. We envision applications as diverse as coherently feeding antenna arrays and optical spectroscopy of spatially extended electronic states. PMID:26762487

  1. Shaping the nonlinear near field

    PubMed Central

    Wolf, Daniela; Schumacher, Thorsten; Lippitz, Markus

    2016-01-01

    Light scattering at plasmonic nanoparticles and their assemblies has led to a wealth of applications in metamaterials and nano-optics. Although shaping of fields around nanostructures is widely studied, the influence of the field inside the nanostructures is often overlooked. The linear field distribution inside the structure taken to the third power causes third-harmonic generation, a nonlinear optical response of matter. Here we demonstrate by a far field Fourier imaging method how this simple fact can be used to shape complex fields around a single particle alone. We employ this scheme to switch the third-harmonic emission from a single point source to two spatially separated but coherent sources, as in Young's double-slit assembly. We envision applications as diverse as coherently feeding antenna arrays and optical spectroscopy of spatially extended electronic states. PMID:26762487

  2. 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

  3. 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,…

  4. 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.

  5. Using optical metrology to reconstruct sound recordings

    NASA Astrophysics Data System (ADS)

    Cornell, E. W.; Fadeyev, V.; Haber, C.; Jin, J.; Nordmeyer, R.; Golden, M.

    2007-09-01

    Prior to 1950 nearly all sound recordings were made on mechanical media such as wax, foil, shellac, lacquer, and plastic. Some of these older recordings contain material of great historical value or interest but are damaged, decaying, or now considered too delicate to play. Archives seek to preserve and also create broad access to their collections. An ongoing effort at Berkeley Lab has applied methods of optical metrology and image processing to reconstruct sound stored on these mechanical carriers. This approach was inspired by the use of precision optical metrology to align and fabricate silicon tracking arrays for high-energy physics experiments and by track finding and fitting data analysis methods. The technology has matured to the point that an optical metrology system for sound restoration has been designed and built for the Library of Congress.

  6. 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

  7. 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

  8. Electron beam recording of optical disc

    NASA Astrophysics Data System (ADS)

    Cartwright, Giles; Reynolds, Gerald; Baylis, Chris; Pearce, Adrian; Dix, Colin; Ogilvie, Nick

    2002-09-01

    The Nimbus Technology & Engineering e -Beam Mastering System was developed to gain a large improvement in optical disc and structured hard disc recording capacity, significantly more than is possible from deep UV and SIL mastering. The current electron beam recorder is essentially a production machine capable of making full-length exposures at capacities of up to 50 GB with a simple low-cost upgrade path to disc capacities of several hundred gigabytes and beyond and hard disk drives (HDD) with capacities of up to 1 tera bit per square inch.

  9. 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.

  10. 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.

  11. NASA spaceborne optical disk recorder development

    NASA Technical Reports Server (NTRS)

    Shull, Thomas A.; Holloway, Reginald M.; Conway, Bruce A.

    1988-01-01

    Spaceflight application of a high performance (high rate, high capacity) erasable optical disk recorder is discussed. An expandable modular system concept is proposed consisting of multiple drive modules and a modular system controller. A drive contains two 14-inch magneto-optic disks and four electro-optic heads, each containing a nine-diode solid state laser array (eight data tracks, one pilot track). The performance goals of the drive module are 20 gigabyte capacity, 300 megabit per second transfer rate, 10x(Exp-10) corrected BER, and 100 millisecond access time. The system goals are 120 gigabyte capacity at up to 1.8 gigabits per second rate, concurrent 1/0, varying data rates, reconfigurable architecture, and 2 to 5 year operating life in orbit. The system environment and operational scenarios are presented.

  12. 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

  13. Tiled-grating compressor with uncompensated dispersion for near-field-intensity smoothing.

    PubMed

    Huang, H; Kessler, Terrance

    2007-07-01

    A tiled-grating compressor, in which the spatial dispersion is not completely compensated, reduces the near-field-intensity modulation caused by tiling gaps and provides near-field spatial filtering of the input laser beam, thus reducing the laser damage to the final optics. PMID:17603592

  14. Spacecraft optical disk recorder memory buffer control

    NASA Technical Reports Server (NTRS)

    Hodson, Robert F.

    1992-01-01

    The goal of this project is to develop an Application Specific Integrated Circuit (ASIC) for use in the control electronics of the Spacecraft Optical Disk Recorder (SODR). Specifically, this project is to design an extendable memory buffer controller ASIC for rate matching between a system Input/Output port and the SODR's device interface. The aforementioned goal can be partitioned into the following sub-goals: (1) completion of ASIC design and simulation (on-going via ASEE fellowship); (2) ASIC Fabrication (at ASIC manufacturer); and (3) ASIC Testing (NASA/LaRC, Christopher Newport University).

  15. 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.

  16. 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.

  17. 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.

  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. 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.

  20. 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

  1. 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

  2. Mass Replication Of Optically Recorded Holographic Optical Elements

    NASA Astrophysics Data System (ADS)

    Rizzi, M. L.; Delvo, P.

    1987-01-01

    This paper deals with the application to HOE's of the experience acquired by CISE Holographic Labora-tory in the embossing technique of 3D or 2D images. The embossing of HOE's in plastic transparent materials is not able, up to this time, of performing the high diffraction efficiencies associated with HOE's recorded by DCG or photopolymers. However a large number of applications requires the production of great quantity, medium standard, low cost special optical elements to be used in rather complex instruments. Some notes about the embossing process and example of industrial components under development are reported.

  3. 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.

  4. Femtosecond-resolved ablation dynamics of Si in the near field of a small dielectric particle

    PubMed Central

    Kühler, Paul; Puerto, Daniel; Mosbacher, Mario; Leiderer, Paul; Garcia de Abajo, Francisco Javier

    2013-01-01

    Summary In this work we analyze the ablation dynamics of crystalline Si in the intense near field generated by a small dielectric particle located at the material surface when being irradiated with an infrared femtosecond laser pulse (800 nm, 120 fs). The presence of the particle (7.9 μm diameter) leads to a strong local enhancement (ca. 40 times) of the incoming intensity of the pulse. The transient optical response of the material has been analyzed by means of fs-resolved optical microscopy in reflection configuration over a time span from 0.1 ps to about 1 ns. Characteristic phenomena like electron plasma formation, ultrafast melting and ablation, along with their characteristic time scales are observed in the region surrounding the particle. The use of a time resolved imaging technique allows us recording simultaneously the material response at ordinary and large peak power densities enabling a direct comparison between both scenarios. The time resolved images of near field exposed regions are consistent with a remarkable temporal shift of the ablation onset which occurs in the sub-picosend regime, from about 500 to 800 fs after excitation. PMID:24062976

  5. 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.

  6. 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…

  7. 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.

  8. 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

  9. 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.

  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. 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.

  12. Real-Space Mapping of the Chiral Near-Field Distributions in Spiral Antennas and Planar Metasurfaces.

    PubMed

    Schnell, M; Sarriugarte, P; Neuman, T; Khanikaev, A B; Shvets, G; Aizpurua, J; Hillenbrand, R

    2016-01-13

    Chiral antennas and metasurfaces can be designed to react differently to left- and right-handed circularly polarized light, which enables novel optical properties such as giant optical activity and negative refraction. Here, we demonstrate that the underlying chiral near-field distributions can be directly mapped with scattering-type scanning near-field optical microscopy employing circularly polarized illumination. We apply our technique to visualize, for the first time, the circular-polarization selective nanofocusing of infrared light in Archimedean spiral antennas, and explain this chiral optical effect by directional launching of traveling waves in analogy to antenna theory. Moreover, we near-field image single-layer rosette and asymmetric dipole-monopole metasurfaces and find negligible and strong chiral optical near-field contrast, respectively. Our technique paves the way for near-field characterization of optical chirality in metal nanostructures, which will be essential for the future development of chiral antennas and metasurfaces and their applications. PMID:26666399

  13. 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.

  14. Sequence stratigraphy of the ANDRILL Southern McMurdo Sound (SMS) project drillcore, Antarctica: an expanded, near-field record of Antarctic Early to Middle Miocene climate and relative sea-level change

    NASA Astrophysics Data System (ADS)

    Fielding, C. R.; Browne, G. H.; Field, B.; Florindo, F.; Harwood, D. M.; Krissek, L. A.; Levy, R. H.; Panter, K.; Passchier, S.; Pekar, S. F.; SMS Science Team

    2008-12-01

    Present understanding of Antarctic climate change during the Early to Middle Miocene, including definition of major cycles of glacial expansion and contraction, relies in large part on stable isotope proxy records from Ocean Drilling Program cores. Here, we present a sequence stratigraphic analysis of the Southern McMurdo Sound drillcore (AND-2A), which was acquired during the Austral Spring of 2007. This core offers a hitherto unavailable ice-proximal stratigraphic archive of the Early to Middle Miocene from a high-accommodation Antarctic continental margin setting, and provides clear evidence of repeated fluctuations in climate, ice expansion/contraction and attendant sea-level change over the period 20-14 Ma, with a more fragmentary record of the post-14 Ma period. A succession of seventy sequences is recognized, each bounded by a significant facies dislocation (sequence boundary), composed internally of deposits of glacimarine to open shallow marine environments, and each typically dominated by the transgressive systems tract. From changes in facies abundances and sequence character, a series of long-term (m.y.) changes in climate and relative sea-level is identified. The lithostratigraphy can be correlated confidently to glacial events Mi1b and Mi2, to the Miocene Climatic Optimum, and to the global eustatic sea-level curve. SMS provides a detailed, direct, ice-proximal reference point from which to evaluate stable isotope proxy records for Neogene Antarctic paleoclimate.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Legal and records management issue of Optical Disk Storage media

    SciTech Connect

    Nusbaum, A.

    1991-01-01

    The advent of optical storage has made the digital storage of documents a viable option from both a practical and legal perspective. However, the availability of Optical Disk Storage raises questions regarding the destruction of the stored records and standards of longevity, and the admissibility in court of records produced from optical storage has not been tested. This paper will attempt to address these issues. 6 refs.

  2. Near-field fluorescence imaging with 32 nm resolution based on microfabricated cantilevered probes

    NASA Astrophysics Data System (ADS)

    Eckert, Rolf; Freyland, J. Moritz; Gersen, Henkjan; Heinzelmann, Harry; Schürmann, Gregor; Noell, Wilfried; Staufer, Urs; de Rooij, Nico F.

    2000-12-01

    High-resolution near-field optical imaging with microfabricated probes is demonstrated. The probes are made from solid quartz tips fabricated at the end of silicon cantilevers and covered with a 60-nm-thick aluminum film. Transmission electron micrographs indicate a continuous aluminum layer at the tip apex. A specially designed instrument combines the advantages of near-field optical and beam-deflection force microscopy. Near-field optical data of latex bead projection patterns in transmission and of single fluorophores have been obtained in constant-height imaging mode. An artifact-free optical resolution of 31.7±3.6 nm has been deduced from full width at half maximum values of single molecule images.

  3. Optical recording properties of phthalocyanine copper as a write-once read-many recording medium

    SciTech Connect

    Chen, Q.; Gu, D.; Shu, J.; Tang, X.; Gan, F.

    1994-12-31

    The phthalocyanine compounds have received considerable attention because of their good thermal and chemical stability which ensure a long storage life and high readout times as optical storage media. In this paper, the optical spectra and the complex refractive index of phthalocyanine copper (CuPc) have been studied. The optical recording performances of multilayer films are reported.

  4. Near-Field Microscopy Studies of Lung Surfactant Collapse

    NASA Astrophysics Data System (ADS)

    Aga, Rachel; Dunn, Robert

    2003-03-01

    Respiratory distress syndrome (RDS), the fourth leading cause of infant mortality in the United States, arises from an insufficiently developed lung surfactant (LS). Healthy LS, a mixture of lipids and proteins that coats the inner surface of the lungs, reduces the alveolar surface tension to a few millinewtons per meter and, thus, facilitates breathing by stabilizing the large surface area changes associated with respiration. In the absence of an effective LS, surfactant collapse pressure (i.e., monolayer compressibility) and the ability of the monolayer to re-spread during the breathing cycle are reduced, resulting in labored breathing, reduced oxygen transport, and often death in those afflicted. In this study, we investigate the mechanism of collapse and re-spreading of a monolayer formed by a replacement surfactant commonly used in treatment of RDS. Through confocal microscopy fluorescence images obtained at a series of pressures near collapse, we find evidence for multilayer formation in the films. A further understanding of the collapse mechanism is obtained by comparing high resolution fluorescence and topography information measured with near-field scanning optical microscopy. The combined data from both confocal and near-field measurements are used to develop a model of lung surfactant collapse and re-spreading.

  5. 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.

  6. 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

  7. 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

  8. Resolution-limited optical recording in 3D.

    PubMed

    Orlic, Susanna; Dietz, Enrico; Frohmann, Sven; Rass, Jens

    2011-08-15

    We present an optical write/read system for high density optical data storage in 3-D. The microholographic approach relies on submicron-sized reflection gratings that encode the digital data. As in conventional optical data storage, the physical limitations are imposed by both the diffraction of light and resolution of the recording material. We demonstrate resolution-limited volume recording in photopolymer materials sensitive in the green and violet spectral range. The volume occupied by a micrograting scales down by the transition in the write/read wavelength. Readout yields a micrograting width of 306 nm at 532 nm and 197 nm at 405 nm. To our knowledge these are the smallest volume holograms ever recorded. The recordings demonstrate the potential of the technique for volumetric optical structuring, data storage and encryption. PMID:21934972

  9. Polarization holographic optical recording of a new photochromic diarylethene

    NASA Astrophysics Data System (ADS)

    Pu, Shouzhi; Miao, Wenjuan; Chen, Anyin; Cui, Shiqiang

    2008-12-01

    A new symmetrical photochromic diarylethene, 1,2-bis[2-methyl-5-(3-methoxylphenyl)-3-thienyl]perfluorocyclopentene (1a), was synthesized, and its photochromic properties were investigated. The compound exhibited good photochromism both in solution and in PMMA film with alternating irradiation by UV/VIS light, and the maxima absorption of its closed-ring isomer 1b are 582 and 599 nm, respectively. Using diarylethene 1b/PMMA film as recording medium and a He-Ne laser (633 nm) for recording and readout, four types of polarization and angular multiplexing holographic optical recording were performed perfectly. For different types of polarization recording including parallel linear polarization recording, parallel circular polarization recording, orthogonal linear polarization recording and orthogonal circular polarization recording,have been accomplished successfully. The results demonstrated that the orthogonal circular polarization recording is the best method for polarization holographic optical recording when this compound was used as recording material. With angular multiplexing recording technology, two high contrast holograms were recorded in the same place on the film with the dimension of 0.78 μm2.

  10. 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.

  11. Near-field photocurrent nanoscopy on bare and encapsulated graphene

    PubMed Central

    Woessner, Achim; Alonso-González, Pablo; Lundeberg, Mark B.; Gao, Yuanda; Barrios-Vargas, Jose E.; Navickaite, Gabriele; Ma, Qiong; Janner, Davide; Watanabe, Kenji; Cummings, Aron W.; Taniguchi, Takashi; Pruneri, Valerio; Roche, Stephan; Jarillo-Herrero, Pablo; Hone, James; Hillenbrand, Rainer; Koppens, Frank H. L.

    2016-01-01

    Optoelectronic devices utilizing graphene have demonstrated unique capabilities and performances beyond state-of-the-art technologies. However, requirements in terms of device quality and uniformity are demanding. A major roadblock towards high-performance devices are nanoscale variations of the graphene device properties, impacting their macroscopic behaviour. Here we present and apply non-invasive optoelectronic nanoscopy to measure the optical and electronic properties of graphene devices locally. This is achieved by combining scanning near-field infrared nanoscopy with electrical read-out, allowing infrared photocurrent mapping at length scales of tens of nanometres. Using this technique, we study the impact of edges and grain boundaries on the spatial carrier density profiles and local thermoelectric properties. Moreover, we show that the technique can readily be applied to encapsulated graphene devices. We observe charge build-up near the edges and demonstrate a solution to this issue. PMID:26916951

  12. Near-field photocurrent nanoscopy on bare and encapsulated graphene

    NASA Astrophysics Data System (ADS)

    Woessner, Achim; Alonso-González, Pablo; Lundeberg, Mark B.; Gao, Yuanda; Barrios-Vargas, Jose E.; Navickaite, Gabriele; Ma, Qiong; Janner, Davide; Watanabe, Kenji; Cummings, Aron W.; Taniguchi, Takashi; Pruneri, Valerio; Roche, Stephan; Jarillo-Herrero, Pablo; Hone, James; Hillenbrand, Rainer; Koppens, Frank H. L.

    2016-02-01

    Optoelectronic devices utilizing graphene have demonstrated unique capabilities and performances beyond state-of-the-art technologies. However, requirements in terms of device quality and uniformity are demanding. A major roadblock towards high-performance devices are nanoscale variations of the graphene device properties, impacting their macroscopic behaviour. Here we present and apply non-invasive optoelectronic nanoscopy to measure the optical and electronic properties of graphene devices locally. This is achieved by combining scanning near-field infrared nanoscopy with electrical read-out, allowing infrared photocurrent mapping at length scales of tens of nanometres. Using this technique, we study the impact of edges and grain boundaries on the spatial carrier density profiles and local thermoelectric properties. Moreover, we show that the technique can readily be applied to encapsulated graphene devices. We observe charge build-up near the edges and demonstrate a solution to this issue.

  13. Fast optical recording media based on semiconductor nanostructures for image recording and processing

    SciTech Connect

    Kasherininov, P. G. Tomasov, A. A.

    2008-11-15

    Fast optical recording media based on semiconductor nanostructures (CdTe, GaAs) for image recording and processing with a speed to 10{sup 6} cycle/s (which exceeds the speed of known recording media based on metal-insulator-semiconductor-(liquid crystal) (MIS-LC) structures by two to three orders of magnitude), a photosensitivity of 10{sup -2}V/cm{sup 2}, and a spatial resolution of 5-10 (line pairs)/mm are developed. Operating principles of nanostructures as fast optical recording media and methods for reading images recorded in such media are described. Fast optical processors for recording images in incoherent light based on CdTe crystal nanostructures are implemented. The possibility of their application to fabricate image correlators is shown.

  14. 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

  15. Optical Imaging versus Paper Records Storage.

    ERIC Educational Resources Information Center

    Baldygo, Robert

    1999-01-01

    States that the maintenance and storage of paper documents has many inherent weaknesses, including hidden costs and attached risks. Asserts that document imaging is a viable, up-to-date technology that could eliminate many of these costs and risks. Describes the system benefits, scope, requirements, and costs and the legality of optically stored…

  16. Ultrafast dynamics of near-field enhancements at an off-resonance nano-dimer via femtosecond laser excitations

    NASA Astrophysics Data System (ADS)

    Du, GuangQing; Yang, Qing; Chen, Feng; Bian, Hao; Wu, Yanmin; Lu, Yu; Farooq, Umar; Hou, Xun

    2015-04-01

    Giant electric-field enhancements localized on nano-antennas are important for the optical near-field applications in fields such as super-resolution imaging, near-field optical tweezers, and photothermal therapy. Physically, the field enhancement requires plasmon resonance with respect to structure matching. We report a tunable near-field effect, including localized electric-field enhancement and resistive heating at an off-resonance Au nano-sphere dimer via femtosecond laser irradiation. The near field was strongly modified (up to 81 times) with respect to time evolution at a laser fluence of 0.1 \\text{J/cm}2 . The results are explained as thermal dynamics manipulation of the Au nano-sphere dimer plasmon resonances. This study provides a new alternative route to tailoring the near-field enhancement for wide applications in nano-antennas.

  17. 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

  18. 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.

  19. Detection of reflector surface from near field phase measurements

    NASA Technical Reports Server (NTRS)

    Ida, Nathan

    1991-01-01

    The deviation of a reflector antenna surface from a perfect parabolic shape causes degradation of the performance of the antenna. The problem of determining the shape of the reflector surface in a reflector antenna using near field phase measurements is not a new one. A recent issue of the IEEE tansactions on Antennas and Propagation (June 1988) contained numerous descriptions of the use of these measurements: holographic reconstruction or inverse Fourier transform. Holographic reconstruction makes use of measurement of the far field of the reflector and then applies the Fourier transform relationship between the far field and the current distribution on the reflector surface. Inverse Fourier transformation uses the phase measurements to determine the far field pattern using the method of Kerns. After the far field pattern is established, an inverse Fourier transform is used to determine the phases in a plane between the reflector surface and the plane in which the near field measurements were taken. These calculations are time consuming since they involve a relatively large number of operations. A much faster method can be used to determine the position of the reflector. This method makes use of simple geometric optics to determine the path length of the ray from the feed to the reflector and from the reflector to the measurement point. For small physical objects and low frequencies, diffraction effects have a major effect on the error, and the algorithm provides incorrect results. It is believed that the effect is less noticeable for large distortions such as antenna warping, and more noticeable for small, localized distortions such as bumps and depressions such as might be caused by impact damage.

  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. Spacecraft optical disk recorder memory buffer control

    NASA Technical Reports Server (NTRS)

    Hodson, Robert F.

    1993-01-01

    This paper discusses the research completed under the NASA-ASEE summer faculty fellowship program. The project involves development of an Application Specific Integrated Circuit (ASIC) to be used as a Memory Buffer Controller (MBC) in the Spacecraft Optical Disk System (SODR). The SODR system has demanding capacity and data rate specifications requiring specialized electronics to meet processing demands. The system is being designed to support Gigabit transfer rates with Terabit storage capability. The complete SODR system is designed to exceed the capability of all existing mass storage systems today. The ASIC development for SODR consist of developing a 144 pin CMOS device to perform format conversion and data buffering. The final simulations of the MBC were completed during this summer's NASA-ASEE fellowship along with design preparations for fabrication to be performed by an ASIC manufacturer.

  2. Near-field imaging and nano-Fourier-transform infrared spectroscopy using broadband synchrotron radiation.

    PubMed

    Hermann, Peter; Hoehl, Arne; Patoka, Piotr; Huth, Florian; Rühl, Eckart; Ulm, Gerhard

    2013-02-11

    We demonstrate scanning near-field optical microscopy with a spatial resolution below 100 nm by using low intensity broadband synchrotron radiation in the IR regime. The use of such a broadband radiation source opens up the possibility to perform nano-Fourier-transform infrared spectroscopy over a wide spectral range. PMID:23481749

  3. 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

  4. Thermomagnetic recording and magnetic-optic playback system

    NASA Technical Reports Server (NTRS)

    Lewicki, G. W.; Guisinger, J. E. (Inventor)

    1971-01-01

    A magnetic recording and magneto-optic playback system is disclosed wherein thermomagnetic recording is employed. A transparent isotropic film is heated along a continuous path by a focused laser beam. As each successive area of the path is heated locally to the vicinity of its Curie point in the presence of an applied magnetic field, a magneto-optic density is established proportional to the magnetic field and fixed in place as the area cools once the laser beam moves on to an adjacent area. To play back the recorded data, the intensity of the laser beam is reduced to avoid reaching the vicinity of the Curie point of the film as it is scanned by the laser beam in the same manner as for recording. A Faraday effect analyzer and photo detector are employed as a transducer for producing an output signal.

  5. Quantum-dot based nanothermometry in optical plasmonic recording media

    SciTech Connect

    Maestro, Laura Martinez; Zhang, Qiming; Li, Xiangping; Gu, Min; Jaque, Daniel

    2014-11-03

    We report on the direct experimental determination of the temperature increment caused by laser irradiation in a optical recording media constituted by a polymeric film in which gold nanorods have been incorporated. The incorporation of CdSe quantum dots in the recording media allowed for single beam thermal reading of the on-focus temperature from a simple analysis of the two-photon excited fluorescence of quantum dots. Experimental results have been compared with numerical simulations revealing an excellent agreement and opening a promising avenue for further understanding and optimization of optical writing processes and media.

  6. Photon-induced near field electron microscopy

    NASA Astrophysics Data System (ADS)

    Park, Sang Tae; Zewail, Ahmed H.

    2013-09-01

    Ultrafast electron microscopy in the space and time domains utilizes a pulsed electron probe to directly map structural dynamics of nanomaterials initiated by an optical pump pulse, in imaging, di raction, spectroscopy, and their combinations. It has demonstrated its capability in the studies of phase transitions, mechanical vibrations, and chemical reactions. Moreover, electrons can directly interact with photons via the near eld component of light scattering by nanostructures, and either gain or lose light quanta discretely in energy. By energetically selecting those electrons that exchanged photon energies, we can map this photon-electron interaction, and the technique is termed photon-induced near eld electron microscopy (PINEM). Here, we give an account of the theoretical understanding of PINEM. Experimentally, nanostructures such as a sphere, cylinder, strip, and triangle have been investigated. Theoretically, time-dependent Schrodinger and Dirac equations for an electron under light are directly solved to obtain analytical solutions. The interaction probability is expressed by the mechanical work done by an optical wave on a traveling electron, which can be evaluated analytically by the near eld components of the Rayleigh scattering for small spheres and thin cylinders, and numerically by the discrete dipole approximation for other geometries. Application in visualization of plasmon elds is discussed.

  7. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    SciTech Connect

    Liu, X. L.; Zhang, Z. M.

    2014-06-23

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  8. 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.

  9. Near-field magnetophotoluminescence spectroscopy of composition fluctuations in InGaAsN.

    SciTech Connect

    Mintariov, A. M.; Kosel, T. H.; Merz, J. L.; Blagnov, P. A.; Vlasov, A. S.; Ustinov, V. M.; Cook, R. E.; Materials Science Division; Univ. of Notre Dame; Ioffe Physico-Technical Inst.

    2001-12-31

    The localization of excitons on quantum-dot-like compositional fluctuations has been observed in temperature-dependent near-field magnetophotoluminescence spectra of InGaAsN. Localization is driven by the giant bowing parameter of these alloys and manifests itself by the appearance of ultranarrow lines (half-width <1 meV) at temperatures below 70 K. We show how near-field optical scanning microscopy can be used for the estimation of the size, density, and nitrogen excess of individual compositional fluctuations (clusters), thus revealing random versus phase-separation effects in the distribution of nitrogen.

  10. 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.

  11. 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.

  12. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    NASA Astrophysics Data System (ADS)

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-11-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes.

  13. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface.

    PubMed

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-01-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes. PMID:26527420

  14. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    PubMed Central

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-01-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes. PMID:26527420

  15. Optomechanical nanoantenna: far-field control of near-field through mechanical reconfiguration

    NASA Astrophysics Data System (ADS)

    Bonakdar, Alireza; Brown, Robert L.; Jang, Sung Jun; Fathipour, Vala; Hassani Nia, Iman; Rezaei, Mohsen; Mohseni, Hooman

    2015-08-01

    We have introduce optomechanical nanoantennae, which showed dramatic changes in scattering properties by minuscule changes in geometry. These structures are very compact, with a volume 500 times smaller than free space optical wavelength volume. Through these optical elements, far-field can directly control the near-field of antenna by mechanical reconfiguration. Here we present the functionality of the optomechanical nanoantenna and challenges in fabricating and measuring these devices.

  16. Design and Characterization of a Novel Near Field Detector for Three Dimensional X-ray Diffraction

    NASA Astrophysics Data System (ADS)

    Annett, Scott; Margulies, Lawrence; Dale, Darren; Kycia, Stefan

    Three dimensional x-ray diffraction microscopy (3DXRD) is a powerful technique that provides crystallographic and spatial information of a large number of grains in a sample simultaneously. A key component of a 3DXRD experiment is the near field detector which provides high resolution spatial information of the sample. A novel design for a near field detector was developed and characterized. This design, called the Quad Near Field Detector, utilizes four quadrants, each with a dedicated scintillating phosphor and optical microscope. A novel translation stage for focusing the microscopes was developed, tested, and implemented. The near field detector was calibrated and characterized at the Cornell High Energy Synchrotron Source. A flood field correction was developed for the detector to correct for variations in intensity response. Diffraction data of all four quadrants was able to reproduce the crystal orientation of the ruby calibrant. In conclusion, the design and implementation of the Quad Near Field Detector was a success and will be a useful tool for future 3DXRD experiments.

  17. 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.

  18. Two diffusion photopolymer for sharp diffractive optical elements recording.

    PubMed

    Gallego, S; Fernández, R; Márquez, A; Ortuño, M; Neipp, C; Gleeson, M R; Sheridan, J T; Beléndez, A

    2015-07-15

    Photopolymers as recording media are widely used in optical applications. In such materials, changes in the phase of the transmittance function are generated during exposure due to refractive index and thickness modulations. These changes arise primarily as a consequence of photopolymerization and mass transport processes. Characterizing polymers' performance, for example, quantifying the value of monomer diffusion, is therefore very important. Applying index matching, the volume and surface optical effect are separated in an acrylamide/polyvinylalcohol (AA/PVA) material. Using a simplified model that includes the effects of the holes produced during polymerization, both hole and monomer diffusion are analyzed. The analysis presented indicates higher material sensitivity than previously estimated. The results also indicate the possibility of recording sharper diffractive optical elements profiles, like blazed gratings, having diffraction efficiencies higher than 80%. PMID:26176434

  19. Linear laser diode arrays for improvement in optical disk recording

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

    1990-01-01

    The development of individually addressable laser diode arrays for multitrack magneto-optic recorders for space stations is discussed. Three multi-element channeled substrate planar (CSP) arrays with output power greater than 30 mW with linear light vs current characteristics and stable single mode spectra were delivered to NASA. These devices have been used to demonstrate for the first time the simultaneous recording of eight data tracks on a 14-inch magneto-optic erasable disk. The yield of these devices is low, mainly due to non-uniformities inherent to the LPE growth that was used to fabricate them. The authors have recently developed the inverted CSP, based on the much more uniform MOCVD growth techniques, and have made low threshold quantum well arrays requiring about three times less current than the CSP to deliver 30 mW CW in a single spatial mode. The inverted CSP is very promising for use in space flight recorder applications.

  20. 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.

  1. Oxidation resistance of Pb-Te-Se optical recording film

    NASA Astrophysics Data System (ADS)

    Terao, Motoyasu; Horigome, Shinkichi; Shigematsu, Kazuo; Miyauchi, Yasushi; Nakazawa, Masatoshi

    1987-08-01

    The dependence of oxidation resistance of metal-Te-Se optical recording films on film composition is investigated, as well as the effects of oxidation on laser beam recorded hole shape. The films are deposited by vacuum evaporation on substrates with a glass/UV light curing resin/cellulose nitrate structure. The role of Se in the film is to inhibit the oxidation. With at least 14% Se addition, film oxidation is completely inhibited even at 60 °C, relative humidity 95%. Depth profiles of elements in the recording films are analyzed by Auger electron and x-ray photoelectron spectroscopy to clarify the mechanisms of oxidation inhibition by Se addition. A selenium condensed layer is found at the inner part of an oxidized surface layer. The surface Te oxide layer and the Se-rich layer should inhibit the film inside from oxidizing. The role of the metallic elements In, Pb, Sn, Bi, and Sb in the film is to inhibit cracking and to decrease noise in reproduced signals by decreasing the size of crystal grains. Lead is found to be the best among these metallic elements, because the recorded hole shape is clean even when recorded after 15 days accelerated oxidation at 60 °C, relative humidity 95%. A very long storage life is expected for the Pb-Te-Se optical recording film.

  2. Near-field tsunami edge waves and complex earthquake rupture

    USGS Publications Warehouse

    Geist, Eric L.

    2013-01-01

    The effect of distributed coseismic slip on progressive, near-field edge waves is examined for continental shelf tsunamis. Detailed observations of edge waves are difficult to separate from the other tsunami phases that are observed on tide gauge records. In this study, analytic methods are used to compute tsunami edge waves distributed over a finite number of modes and for uniformly sloping bathymetry. Coseismic displacements from static elastic theory are introduced as initial conditions in calculating the evolution of progressive edge-waves. Both simple crack representations (constant stress drop) and stochastic slip models (heterogeneous stress drop) are tested on a fault with geometry similar to that of the M w = 8.8 2010 Chile earthquake. Crack-like ruptures that are beneath or that span the shoreline result in similar longshore patterns of maximum edge-wave amplitude. Ruptures located farther offshore result in reduced edge-wave excitation, consistent with previous studies. Introduction of stress-drop heterogeneity by way of stochastic slip models results in significantly more variability in longshore edge-wave patterns compared to crack-like ruptures for the same offshore source position. In some cases, regions of high slip that are spatially distinct will yield sub-events, in terms of tsunami generation. Constructive interference of both non-trapped and trapped waves can yield significantly larger tsunamis than those that produced by simple earthquake characterizations.

  3. 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.

  4. 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.

  5. Information Content of the Near-Field I: Two-Dimensional Samples

    NASA Technical Reports Server (NTRS)

    Frazin, Richard A.; Fischer, David G.; Carney, P. Scott

    2004-01-01

    Limits on the effective resolution of many optical near-field experiments are investigated. The results are applicable to variants of total-internal-reflection microscopy (TIRM), photon-scanning-tunneling microscopy (PSTM), and near-field-scanning-optical microscopy (NSOM) in which the sample is weakly scattering and the direction of illumination may be controlled. Analytical expressions for the variance of the estimate of the complex susceptibility of an unknown two-dimensional object as a function of spatial frequency are obtained for Gaussian and Poisson noise models, and a model-independent measure is examined. The results are used to explore the transition from near-zone to far-zone detection. It is demonstrated that the information content of the measurements made at a distance of even one wavelength away from the sample is already not much different from the information content of the far field. Copyright 2004 Optical Society of America

  6. Noninvasive, near-field terahertz imaging of hidden objects using a single-pixel detector.

    PubMed

    Stantchev, Rayko Ivanov; Sun, Baoqing; Hornett, Sam M; Hobson, Peter A; Gibson, Graham M; Padgett, Miles J; Hendry, Euan

    2016-06-01

    Terahertz (THz) imaging can see through otherwise opaque materials. However, because of the long wavelengths of THz radiation (λ = 400 μm at 0.75 THz), far-field THz imaging techniques suffer from low resolution compared to visible wavelengths. We demonstrate noninvasive, near-field THz imaging with subwavelength resolution. We project a time-varying, intense (>100 μJ/cm(2)) optical pattern onto a silicon wafer, which spatially modulates the transmission of synchronous pulse of THz radiation. An unknown object is placed on the hidden side of the silicon, and the far-field THz transmission corresponding to each mask is recorded by a single-element detector. Knowledge of the patterns and of the corresponding detector signal are combined to give an image of the object. Using this technique, we image a printed circuit board on the underside of a 115-μm-thick silicon wafer with ~100-μm (λ/4) resolution. With subwavelength resolution and the inherent sensitivity to local conductivity, it is possible to detect fissures in the circuitry wiring of a few micrometers in size. THz imaging systems of this type will have other uses too, where noninvasive measurement or imaging of concealed structures is necessary, such as in semiconductor manufacturing or in ex vivo bioimaging. PMID:27386577

  7. Noninvasive, near-field terahertz imaging of hidden objects using a single-pixel detector

    PubMed Central

    Stantchev, Rayko Ivanov; Sun, Baoqing; Hornett, Sam M.; Hobson, Peter A.; Gibson, Graham M.; Padgett, Miles J.; Hendry, Euan

    2016-01-01

    Terahertz (THz) imaging can see through otherwise opaque materials. However, because of the long wavelengths of THz radiation (λ = 400 μm at 0.75 THz), far-field THz imaging techniques suffer from low resolution compared to visible wavelengths. We demonstrate noninvasive, near-field THz imaging with subwavelength resolution. We project a time-varying, intense (>100 μJ/cm2) optical pattern onto a silicon wafer, which spatially modulates the transmission of synchronous pulse of THz radiation. An unknown object is placed on the hidden side of the silicon, and the far-field THz transmission corresponding to each mask is recorded by a single-element detector. Knowledge of the patterns and of the corresponding detector signal are combined to give an image of the object. Using this technique, we image a printed circuit board on the underside of a 115-μm-thick silicon wafer with ~100-μm (λ/4) resolution. With subwavelength resolution and the inherent sensitivity to local conductivity, it is possible to detect fissures in the circuitry wiring of a few micrometers in size. THz imaging systems of this type will have other uses too, where noninvasive measurement or imaging of concealed structures is necessary, such as in semiconductor manufacturing or in ex vivo bioimaging. PMID:27386577

  8. 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

  9. SEISMIC PERFORMANCE OF RC BRIDGE COLUMNS UNDER VARYING AXIAL FORCE DUE TO NEAR-FIELD VERTICAL GROUND MOTIONS

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Hiroshi; Kumagai, Yuji; Kawashima, Kazuhiko

    Recently, high acceleration and high frequency near-field vertical ground motions were recorded at several sites. The extreme vertical ground motions can induce high frequency varying axial force which develop even tensile force in reinforced concrete bridge columns. Cyclic loading experiments of RC columns were conducted to clarify the seismic performance of RC bridge columns under near-field vertical ground motions. It is shown that core concrete is crushed extensively due to varying axial force after longitudinal bars buckle.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. A polarizing situation: Taking an in-plane perspective for next-generation near-field studies

    NASA Astrophysics Data System (ADS)

    Schuck, P. James; Bao, Wei; Borys, Nicholas J.

    2016-04-01

    By enabling the probing of light-matter interactions at the functionally relevant length scales of most materials, near-field optical imaging and spectroscopy accesses information that is unobtainable with other methods. The advent of apertureless techniques, which exploit the ultralocalized and enhanced near-fields created by sharp metallic tips or plasmonic nanoparticles, has resulted in rapid adoption of near-field approaches for studying novel materials and phenomena, with spatial resolution approaching sub-molecular levels. However, these approaches are generally limited by the dominant out-of-plane polarization response of apertureless tips, restricting the exploration and discovery of many material properties. This has led to recent design and fabrication breakthroughs in near-field tips engineered specifically for enhancing in-plane interactions with near-field light components. This mini-review provides a perspective on recent progress and emerging directions aimed at utilizing and controlling in-plane optical polarization, highlighting key application spaces where in-plane near-field tip responses have enabled recent advancements in the understanding and development of new nanostructured materials and devices.

  15. Multiplexed neural recording along a single optical fiber via optical reflectometry

    NASA Astrophysics Data System (ADS)

    Rodriques, Samuel G.; Marblestone, Adam H.; Scholvin, Jorg; Dapello, Joel; Sarkar, Deblina; Mankin, Max; Gao, Ruixuan; Wood, Lowell; Boyden, Edward S.

    2016-05-01

    We introduce the design and theoretical analysis of a fiber-optic architecture for neural recording without contrast agents, which transduces neural electrical signals into a multiplexed optical readout. Our sensor design is inspired by electro-optic modulators, which modulate the refractive index of a waveguide by applying a voltage across an electro-optic core material. We estimate that this design would allow recording of the activities of individual neurons located at points along a 10-cm length of optical fiber with 40-μm axial resolution and sensitivity down to 100 μV using commercially available optical reflectometers as readout devices. Neural recording sites detect a potential difference against a reference and apply this potential to a capacitor. The waveguide serves as one of the plates of the capacitor, so charge accumulation across the capacitor results in an optical effect. A key concept of the design is that the sensitivity can be improved by increasing the capacitance. To maximize the capacitance, we utilize a microscopic layer of material with high relative permittivity. If suitable materials can be found-possessing high capacitance per unit area as well as favorable properties with respect to toxicity, optical attenuation, ohmic junctions, and surface capacitance-then such sensing fibers could, in principle, be scaled down to few-micron cross-sections for minimally invasive neural interfacing. We study these material requirements and propose potential material choices. Custom-designed multimaterial optical fibers, probed using a reflectometric readout, may, therefore, provide a powerful platform for neural sensing.

  16. Apparatus comprising a tunable nanomechanical near-field grating and method for controlling far-field emission

    DOEpatents

    Carr, Dustin Wade; Bogart, Gregory Robert

    2007-02-06

    A tunable nanomechanical near-field grating is disclosed which is capable of varying the intensity of a diffraction mode of an optical output signal. The tunable nanomechanical near-field grating includes two sub-gratings each having line-elements with width and thickness less than the operating wavelength of light with which the grating interacts. Lateral apertures in the two sub-gratings are formed from the space between one line-element of the first sub-grating and at least one line-element of the second sub-grating. One of the sub-gratings is capable of motion such that at least one of aperture width and aperture depth changes, causing a perturbation to the near-field intensity distribution of the tunable nanomechanical near-field grating and a corresponding change to the far-field emission of thereof.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Image density property of optical information recording microcapsule material

    NASA Astrophysics Data System (ADS)

    Lai, Weidong; Li, Xiaowei; Li, Xinzheng; Fu, Guangsheng

    2009-05-01

    The microcapsules can act as novel optical functional material in which the optical recording substance such as color-forming substance, photoinitiator and prepolymer are encapsulated. In this paper, the microcapsules with average particle diameter of 300nm are prepared with interfacial polymerization method. The optical responding character of the microcapsule is analyzed based on IR spectra and image density technique. Results show that the microcapsule material encapsulated prepolymer TMPTA and photoinitiator Irgacure-ITX, TPO has thermal phase-change at 140°C, at which the penetrability of the microcapsule has the highest efficiency. With the increase of exposure time, the reduction in absorption intensities of the prepolymer TMPTA are observed at 1635cm-1 of C=C stretching and 898cm-1 of C-H stretching on the C=C molecular bond. Such a result can be ascribed to the double bond cleavage process of the prepolymer TMPTA is initiated by the optical-exposed photoinitiator, and superpolymer network is formed. The image density contrast between the unexposed and exposed microcapsule is enhanced with exposure time increased.

  3. Prospects and philosophy for high-density optical recording

    NASA Astrophysics Data System (ADS)

    Milster, Tom D.

    2014-09-01

    In recent years, the commercial impact of optical data storage systems has been displaced by new technologies. Historically, optical data storage displaced older technologies, like consumer magnetic tape, so it is not unexpected that the same fate could pass optical data storage technology into the "retro" domain. In this paper, the basic building blocks of optical data storage are discussed, and limits based on current understanding are presented. Then, conceptual and philosophical arguments are presented to direct intuition toward future possibilities that may provide avenues to develop displacement data storage technology. For example, current understanding puts minimum practical data mark transverse dimensions in the range of 10nm by 10nm, regardless of recording technology. At the conservative assignment of 1 bit per mark area, this mark size equates to about 6,500 Gb/in2 (109 bits per square inch) of surface area. In order to gain the attention of research investment, displacement technologies need to target a 100X improvement in data density or about 1nm by 1nm mark size, with an effective surface data density of over 650,000 Gb/in2. Research and engineering mindsets for displacement data storage technologies should address this goal to be considered significant. Otherwise, advancements in known technologies will probably evolve to satisfy demand.

  4. Recorder/processor apparatus. [for optical data processing

    NASA Technical Reports Server (NTRS)

    Shim, I. H.; Stelben, J. J. (Inventor)

    1973-01-01

    An apparatus is described for recording a data input on, a thermally processible storage medium. A light source, whose intensity is modulated in response to the incoming data input, generates a raster in conformance with incoming timing/control signals so as to expose a latent image of the input information on the storage medium. A rotating drum in conjunction with an incrementally driven lens carriage associated with the laser optical system provides the raster generation. The drum is automatically loaded with the storage medium from a supply means and automatically unloaded to a thermal processor upon completion of recording. The latent image is processed by the controlled application of heat so as to produce an actual displayable image corresponding to the data input at the output of the apparatus.

  5. Chipscale, single-shot gated ultrafast optical recorder.

    PubMed

    Shih, Ta-Ming; Sarantos, Chris H; Haynes, Susan M; Heebner, John E

    2012-01-01

    We introduce a novel, chipscale device capable of single-shot ultrafast recording with picosecond-scale resolution over hundreds of picoseconds of record length. The device consists of two vertically-stacked III-V planar waveguides forming a Mach-Zehnder interferometer, and makes use of a transient, optically-induced phase difference to sample a temporal waveform injected into the waveguides. The pump beam is incident on the chip from above in the form of a diagonally-oriented stripe focused by a cylindrical lens. Due to time-of-flight, this diagonal orientation enables the sampling window to be shifted linearly in time as a function of position across the lateral axis of the waveguides. This time-to-space mapping allows an ordinary camera to record the ultrafast waveform with high fidelity. We investigate the theoretical limits of this technique, present a simulation of device operation, and report a proof-of-concept experiment in GaAs, demonstrating picosecond-scale resolution over 140 ps of record length. PMID:22274365

  6. Recording of incoherent reflective volume Fourier holograms for optical correlators

    NASA Astrophysics Data System (ADS)

    Rodin, Vladislav G.; Starikov, Sergey N.

    2007-01-01

    The scheme of recording of reflective volume Fourier holograms in monochromatic light with partial spatial coherence is presented. The scheme contains posed on one optical axis an illuminated or self-luminous object, Fourier-objective, photosensitive medium and concave mirror. The light is proposed to be monochromatic with partial spatial coherence. The object is located in a front focal plane of the Fourier-objective. Photosensitive medium is placed in a back focal plane of the Fourier-objective, and the mirror is posed on a double focal length of the mirror from photosensitive medium. The light from input object is focused by the Fourier-objective in a volume of photosensitive medium, shaping a far field diffraction pattern of input object. This pattern is partial coherent analog of Fourier transform of input object. The light transmitted through the medium falls on the concave mirror and is reflected back, thus the mirror shapes the second copy of far field diffraction pattern of input object in the volume of photosensitive medium. Thus, these two light waves, propagating in the opposite directions, form the interference pattern in photosensitive medium, and a reflective volume Fourier hologram is recorded by monochromatic light with partial spatial coherence. The experiments on recording of these holograms and image reconstruction were realized. Patent by Russian Federation No2176099 on the device of recording of reflective volume holographic Fourier-filter in light with partial spatial coherence was taken out. Described reflective volume Fourier-holograms can be used in optical correlators as the spatial filters and spectral selectors at image recognition both in monochromatic and polychromatic light.

  7. Near-field multiple scattering effects of plasmonic nanospheres embedded into thin-film organic solar cells

    NASA Astrophysics Data System (ADS)

    Sha, Wei E. I.; Choy, Wallace C. H.; Liu, Yang G.; Cho Chew, Weng

    2011-09-01

    We investigate near-field multiple scattering effects of plasmonic nanospheres (NSPs) embedded into organic solar cells (OSCs). When NSPs are embedded into a spacer layer, the near-field scattering from the NSPs shows strong direction-dependent features, which significantly affects the optical absorption. When NSPs are embedded into an active layer, the absorption enhancement is attributed to the interplay between longitudinal and transverse modes supported by the NSP chain. The breakdown of electrostatic scaling law is confirmed by our theoretical model and should be accounted for optical designs of OSCs. The work provides the fundamental physical understanding and design guidelines for plasmonic photovoltaics.

  8. Excitonic Contribution to Near-Field Enhancements of a Carbon Nanotube Antenna

    NASA Astrophysics Data System (ADS)

    Sofka, Benjamin; Rotkin, Slava V.

    Complexes containing rare earth ions (REI) and single-walled carbon nanotubes (SWNT) show promise to be utilized for the optical sensing of biomolecules. We theoretically study the near-field electromagnetic effects in such a system using a propagating polariton model for the SWNT antenna. To be in resonance with the REI transitions that are in the NIR/optical range, excitonic transitions in the SWNT must be included in the model. We calculate measurable field enhancements in the vicinity of the SWNT antenna that lead to an increase of the REI photoluminescence. NSF ECCS-1509786.

  9. Near-field focus steering along arbitrary trajectory via multi-lined distributed nanoslits.

    PubMed

    Lee, Gun-Yeal; Lee, Seung-Yeol; Yun, Hansik; Park, Hyeonsoo; Kim, Joonsoo; Lee, Kyookeun; Lee, Byoungho

    2016-01-01

    The modulation of near-field signals has recently attracted considerable interest because of demands for the development of nano-scale optical devices that are capable of overcoming the diffraction limit of light. In this paper, we propose a new type of tuneable plasmonic lens that permits the foci of surface plasmon polariton (SPP) signals to be continuously steered by adjusting the input polarization state. The proposed structure consists of multi-lined nanoslit arrays, in which each array is tilted at a different angle to provide polarization sensitivity and the nanoslit size is adjusted to balance the relative amplitudes of the excited SPPs from each line. The nanoslits of each line are designed to focus SPPs at different positions; hence, the SPP focal length can be tuned by modifying the incident polarization state. Unlike in previously reported studies, our method enables plasmonic foci to be continuously varied with a smooth change in the incident linear polarization state. The proposed structures provide a novel degree of freedom in the multiplexing of near fields. Such characteristics are expected to enable the realization of active SPP modulation that can be applied in near-field imaging, optical tweezing systems, and integrated nano-devices. PMID:27620281

  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. Surface plasmon near-field resonance characteristics of silver shell nanocylinders arranged in triangular geometry.

    PubMed

    Jacob, Jesly; R, Ajith; Mathew, Vincent

    2011-11-20

    The optical near-field surface plasmon effects of a triangular system of silver nanoshell cylinders are numerically studied using the two-dimensional finite difference time domain method. The dependence of interparticle distance, shell thickness of the cylinder, dielectric constant of shell core as well as embedding medium, and orientation of the optical source plane on the plasmonic resonances of the nanocylinder shells is studied. The plasmonic resonances are found to have strong dependence on the interparticle distance. As the size of the particle is increased, the field intensity peak shows a redshift. The resonance condition varies with the dielectric constant of the environment as well as the core. In addition, the orientation of the incident source plane has a significant role in the near-field intensity distribution. Since the near-field intensity has the same trend as that of the scattering cross section, the results can be used in the design of various applications like sensing, antennas, and waveguides. PMID:22108888

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Ageing Characteristics Of Digital Optical Recording (DOR) Media

    NASA Astrophysics Data System (ADS)

    Huijser, A.; Jacobs, B.; Vriens, L.; Markvoort, J.; Spruijt, A.; Vromans, P.

    1983-01-01

    Accelerated ageing tests on discs with Te-alloy films for ablative digital optical recording show that these media meet the requirements for their applications in long-term data storage. In these tests, discs of the air-sandwich type with non-sealed (open) as well as sealed cavities were subjected to cyclic high temperatures (25-65°C) and high humidity (95% RH) conditions. "Open" discs incorporating pure Te as ablative material cannot with-stand such severe conditions for more than a few days whereas "open" discs applying Te-Se based alloys with 60 to 80% Te content have not reached end of life after 100 days storage under the same conditions. After such a period of accelerated ageing, hermetically sealed discs do not show any significant ageing effects at all. Ageing is defined in terms which are relevant to optical recording, such as sensitivity for writing, signal to noise ratio of written data and bit error rates and bit error distribution.

  17. Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes.

    PubMed

    Mendes, Manuel J; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2011-08-15

    This paper presents a numerical study of the light focusing properties of dielectric spheroids with sizes comparable to the illuminating wavelength. An analytical separation-of-variables method is used to determine the electric field distribution inside and in the near-field outside the particles. An optimization algorithm was implemented in the method to determine the particles' physical parameters that maximize the forward scattered light in the near-field region. It is found that such scatterers can exhibit pronounced electric intensity enhancement (above 100 times the incident intensity) in their close vicinity, or along wide focal regions extending to 10 times the wavelength. The results reveal the potential of wavelength-sized spheroids to manipulate light beyond the limitations of macroscopic geometrical optics. This can be of interest for several applications, such as light management in photovoltaics. PMID:21934983

  18. Near-field radiative heat transfer between metamaterials coated with silicon carbide thin films

    SciTech Connect

    Basu, Soumyadipta Yang, Yue; Wang, Liping

    2015-01-19

    In this letter, we study the near-field radiative heat transfer between two metamaterial substrates coated with silicon carbide (SiC) thin films. It is known that metamaterials can enhance the near-field heat transfer over ordinary materials due to excitation of magnetic plasmons associated with s polarization, while strong surface phonon polariton exists for SiC. By careful tuning of the optical properties of metamaterial, it is possible to excite electrical and magnetic resonances for the metamaterial and surface phonon polaritons for SiC at different spectral regions, resulting in the enhanced heat transfer. The effect of the SiC film thickness at different vacuum gaps is investigated. Results obtained from this study will be beneficial for application of thin film coatings for energy harvesting.

  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. Near-field imaging of interacting nano objects with metal and metamaterial superlenses

    NASA Astrophysics Data System (ADS)

    Hakkarainen, T.; Setälä, T.; Friberg, A. T.

    2012-04-01

    Employing rigorous electromagnetic theory we investigate optical the near-field imaging of two interacting dipole-like objects with metal and slightly lossy metamaterial nanoslab superlenses. Our analysis indicates that the dipole emission is suppressed by near-field interactions when the objects are close to the lens or each other. This strongly influences the image quality, in particular with objects of small size and high polarizability. The interference from two nearby objects also affects the resolution and subwavelength definition can only be obtained for objects with dipole moments predominantly orthogonal to the slab. Such an optimal imaging condition is achieved with excitation by total internal reflection. With simulations we show that in these circumstances, subwavelength resolutions of about λ/5 for silver superlens and λ/10 for metamaterial slab are reached.

  1. Optical and thermal properties of some indolenine cyanine dyes used as optical recording materials

    NASA Astrophysics Data System (ADS)

    Sun, Shuqing; Chen, Ping; Zheng, Deshui; Okasaki, Tsuneki; Hayami, Masaaki

    1998-08-01

    Compact Disc Recordable (CD-R) and Digital Versatile Disc Recordable (DVD-R) are discs where enormous mounts of digital data can be recorded. The reflection, absorption and transmission rate of laser beam in the layer of CD-R at 780 nm and DVD-R at 650 nm with no reflecting layer were numerically calculated and optical properties of a dye film was measured. The results indicate that it is preferable to use dye as the recording media with n and k value in the range of 2.0 to 2.8 and 0.02 to 0.22, respectively. Thermal properties of these dye materials were analyzed by Differential Scanning Calorie method. The decomposition temperature of dyes were varied from 200 to 300 degree(s)C resulted from different methine length, substitutes and counter anions. The optical recording mechanism of CD-R and DVD-R were also briefly discussed based on the above results.

  2. Teleseismic and near-field analysis of the Nahanni earthquakes in the Northwest Territories, Canada

    USGS Publications Warehouse

    Choy, G.L.; Boatwright, J.

    1988-01-01

    The analysis of the Nahanni earthquakes of October 5, 1985 (Ms 6.6), and December 23, 1985 (Ms 6.9), will have important implications for the assessment of seismic hazards in intraplate environments. To maximize the information available to seismic engineers, broadband data recorded teleseismically are analyzed jointly with strong-motion data recorded in the near field. The time-domain analysis of teleseismic data yields the source mechanisms, depths, and complexities of rupture of each earthquake. Both earthquakes occurred as shallow thrusts with centroid depths (6 to 7km) and shallowly dipping fault planes that correspond well with the aftershock distributions obtained from a local survey run by the Canadian Geological Survey. The shallow nodal plane for the October 5 earthquake dips 30?? to the WSW, while the shallow nodal planes of the subevents for the December 23 earthquake dip an average of 23?? to the WSW. The October 5 earthquake has an impulsive initial rupture, followed by a weak subevent of longer duration but smaller moment release. The December 23 earthquake exhibits more complexity, being comprised of three subevents of similar size. The subevent delays derived from the teleseismic analysis are used to help interpret arrivals in records of ground velocity recorded in the near field of the December 23 earthquake. The rupture geometries inferred from the joint near- and far-field analysis suggest that the rupture processes were unusually complicated and that the 2g peak that occurs late in one of the near-field records could be a localized phenomenon. -from Authors

  3. Range-gated imaging for near-field target identification

    SciTech Connect

    Yates, G.J.; Gallegos, R.A.; McDonald, T.E.

    1996-12-01

    The combination of two complementary technologies developed independently at Los Alamos National Laboratory (LANL) and Sandia National Laboratory (SNL) has demonstrated feasibility of target detection and image capture in a highly light-scattering, medium. The technique uses a compact SNL developed Photoconductive Semiconductor Switch/Laser Diode Array (PCSS/LDA) for short-range (distances of 8 to 10 m) large Field-Of-View (FOV) target illumination. Generation of a time-correlated echo signal is accomplished using a photodiode. The return image signal is recorded with a high-speed shuttered Micro-Channel-Plate Image Intensifier (MCPII), declined by LANL and manufactured by Philips Photonics. The MCPII is rated using a high-frequency impedance-matching microstrip design to produce 150 to 200 ps duration optical exposures. The ultra first shuttering producer depth resolution of a few inches along the optic axis between the MCPII and the target, producing enhanced target images effectively deconvolved from noise components from the scattering medium in the FOV. The images from the MCPII are recorded with an RS-170 Charge-Coupled-Device camera and a Big Sky, Beam Code, PC-based digitizer frame grabber and analysis package. Laser pulse data were obtained by the but jitter problems and spectral mismatches between diode spectral emission wavelength and MCPII photocathode spectral sensitivity prevented the capture of fast gating imaging with this demonstration system. Continued development of the system is underway.

  4. Achievements in scientific photography. Volume 28 - The optical image and recording media

    NASA Astrophysics Data System (ADS)

    Chibisov, K. V.

    Papers are presented on such topics as the properties of optical data recording systems, image quality, image processing, and recording media. Particular consideration is given to mathematical models for the formation of optical images; trends in the development of quality criteria for photographic systems; hybrid optoelectronic systems of image processing; and photothermoplastic recording media.

  5. Vectorial near-field imaging of a GaN based photonic crystal cavity

    SciTech Connect

    La China, F. Intonti, F.; Caselli, N.; Lotti, F.; Vinattieri, A.; Gurioli, M.; Vico Triviño, N.; Carlin, J.-F.; Butté, R.; Grandjean, N.

    2015-09-07

    We report a full optical deep sub-wavelength imaging of the vectorial components of the electric local density of states for the confined modes of a modified GaN L3 photonic crystal nanocavity. The mode mapping is obtained with a scanning near-field optical microscope operating in a resonant forward scattering configuration, allowing the vectorial characterization of optical passive samples. The optical modes of the investigated cavity emerge as Fano resonances and can be probed without the need of embedded light emitters or evanescent light coupling into the nanocavity. The experimental maps, independently measured in the two in-plane polarizations, turn out to be in excellent agreement with numerical predictions.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Physiological parameter monitoring from optical recordings with a mobile phone.

    PubMed

    Scully, Christopher G; Lee, Jinseok; Meyer, Joseph; Gorbach, Alexander M; Granquist-Fraser, Domhnull; Mendelson, Yitzhak; Chon, Ki H

    2012-02-01

    We show that a mobile phone can serve as an accurate monitor for several physiological variables, based on its ability to record and analyze the varying color signals of a fingertip placed in contact with its optical sensor. We confirm the accuracy of measurements of breathing rate, cardiac R-R intervals, and blood oxygen saturation, by comparisons to standard methods for making such measurements (respiration belts, ECGs, and pulse-oximeters, respectively). Measurement of respiratory rate uses a previously reported algorithm developed for use with a pulse-oximeter, based on amplitude and frequency modulation sequences within the light signal. We note that this technology can also be used with recently developed algorithms for detection of atrial fibrillation or blood loss. PMID:21803676

  13. 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

  14. Solomon Islands 2007 Tsunami Near-Field Modeling and Source Earthquake Deformation

    NASA Astrophysics Data System (ADS)

    Uslu, B.; Wei, Y.; Fritz, H.; Titov, V.; Chamberlin, C.

    2008-12-01

    The earthquake of 1 April 2007 left behind momentous footages of crust rupture and tsunami impact along the coastline of Solomon Islands (Fritz and Kalligeris, 2008; Taylor et al., 2008; McAdoo et al., 2008; PARI, 2008), while the undisturbed tsunami signals were also recorded at nearby deep-ocean tsunameters and coastal tide stations. These multi-dimensional measurements provide valuable datasets to tackle the challenging aspects at the tsunami source directly by inversion from tsunameter records in real time (available in a time frame of minutes), and its relationship with the seismic source derived either from the seismometer records (available in a time frame of hours or days) or from the crust rupture measurements (available in a time frame of months or years). The tsunami measurements in the near field, including the complex vertical crust motion and tsunami runup, are particularly critical to help interpreting the tsunami source. This study develops high-resolution inundation models for the Solomon Islands to compute the near-field tsunami impact. Using these models, this research compares the tsunameter-derived tsunami source with the seismic-derived earthquake sources from comprehensive perceptions, including vertical uplift and subsidence, tsunami runup heights and their distributional pattern among the islands, deep-ocean tsunameter measurements, and near- and far-field tide gauge records. The present study stresses the significance of the tsunami magnitude, source location, bathymetry and topography in accurately modeling the generation, propagation and inundation of the tsunami waves. This study highlights the accuracy and efficiency of the tsunameter-derived tsunami source in modeling the near-field tsunami impact. As the high- resolution models developed in this study will become part of NOAA's tsunami forecast system, these results also suggest expanding the system for potential applications in tsunami hazard assessment, search and rescue operations

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Comparison and Properties of Near-Field and Far-Field Events of High Speed Jet

    NASA Astrophysics Data System (ADS)

    Kan, Pinqing; Lewalle, Jacques

    2013-11-01

    Two independent algorithms are applied to different signals to extract events that are potentially responsible for jet noise production. The data consist of 10 kHz TRPIV measurement and pressure sampling in both near- and far-field. One method uses near-field diagnostics (representatives of 2D velocity sections, e.g. velocity, vorticity, Q criterion, etc.) and near-field and far-field pressure. Applying cross-correlation and continuous wavelet to pairs of these signals, we look for the more dominant events in the time, frequency and lag domain. These are regarded as the main contributors of communication between the selected signals and are recorded as Near-Field Events. The other method only uses far-field microphones. The short time excerpts are identified as Far-Field Events that are common to three FF signals and responsible for peak energy spectrum. To compare these events, we map out their property distribution, including frequency, magnitude and time of occurrence. The individual events are also compared and a high portion is found to be common to both lists. We regard this as a verification of both algorithms. This work is supported in part by a Syracuse University Graduate Fellowship, by the Department of Mechanical and Aerospace Engineering at SU, and by Spectral Energies LLC, under an SBIR grant from AFRL.

  3. Near-field imaging of obstacles with the factorization method: fluid-solid interaction

    NASA Astrophysics Data System (ADS)

    Yin, Tao; Hu, Guanghui; Xu, Liwei; Zhang, Bo

    2016-01-01

    Consider a time-harmonic acoustic point source incident on a bounded isotropic linearly elastic body immersed in a homogeneous compressible inviscid fluid. This paper is concerned with the inverse fluid-solid interaction problem of recovering the elastic body from near-field data generated by infinitely many incident point source waves at a fixed energy. The incident point sources and the receivers for recording scattered signals are both located on a non-spherical closed surface, on which an outgoing-to-incoming operator is appropriately defined. We provide a theoretical justification of the factorization method for precisely characterizing the scatterer by utilizing the spectrum of the near-field operator. This generalizes the imaging scheme developed in (Hu et al 2014 Inverse Problems 30 095005) to the case when near-field data are measured on non-spherical surfaces. Numerical examples in 2D are demonstrated to show the validity and accuracy of the inversion algorithm, even if limited aperture data are available on one or several line segments.

  4. 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

    quantitative analysis of near-field distribution of nano-scale optical devices.

  5. Ultrafast Optical Beam Deflection in a Planar Waveguide for High Dynamic Range Recording at Picosecond Resolution

    SciTech Connect

    Sarantos, C H; Heebner, J E

    2008-07-02

    We report the latest performance of an ultrafast, all-optical beam deflector based on a prism array imprinted in a planar waveguide. The deflector enables single-shot, high dynamic range optical recording with picosecond resolution.

  6. Three-dimensional propagation in near-field tomographic X-ray phase retrieval

    PubMed Central

    Ruhlandt, Aike; Salditt, Tim

    2016-01-01

    This paper presents an extension of phase retrieval algorithms for near-field X-ray (propagation) imaging to three dimensions, enhancing the quality of the reconstruction by exploiting previously unused three-dimensional consistency constraints. The approach is based on a novel three-dimensional propagator and is derived for the case of optically weak objects. It can be easily implemented in current phase retrieval architectures, is computationally efficient and reduces the need for restrictive prior assumptions, resulting in superior reconstruction quality. PMID:26919373

  7. Nanomovement of azo polymers induced by metal tip enhanced near-field irradiation

    SciTech Connect

    Ishitobi, Hidekazu; Tanabe, Mamoru; Sekkat, Zouheir; Kawata, Satoshi

    2007-08-27

    Nanomovement of azo polymers induced by metal tip enhanced near-field illumination was studied. A protrusion with 47 nm full width at half maximum was induced with a resolution beyond the diffraction limit. At the top of the protrusion, an anisotropic movement occurs in a direction nearly parallel to the polarization of the incident light, and suggests the existence at the tip end of not only a longitudinal but also a lateral component of the electric field of light. The anisotropic photofluidity and the optical gradient force played important roles in the process of the light induced polymer movement.

  8. Detection in near-field domain of biomolecules adsorbed on a single metallic nanoparticle.

    PubMed

    Barbillon, G; Bijeon, J-L; Bouillard, J-S; Plain, J; Lamy De la Chapelle, M; Adam, P-M; Royer, P

    2008-02-01

    In this paper, we study the performances of nanosensors based on Localized Surface Plasmon Resonance in the context of biological sensing. We demonstrate the sensitivity and the selectivity of our designed nanosensors by studying the influence of the concentration of Streptavidin on the shift of Localized Surface Plasmon Resonance wavelength. In addition, to study the detection of biomolecules on a single Au nanoparticle, we used a Scanning Near-field Optical Microscope. These results represent new steps for applications in biological research and medical diagnostics. PMID:18304084

  9. Near-field diffraction of laser light by dielectric corner step

    NASA Astrophysics Data System (ADS)

    Stafeev, S.; Kotlyar, V.; Kovalev, A.

    2014-01-01

    The diffraction of a linearly polarized plane wave by a corner dielectric microstep of height equals of two incident wavelengths was studied using finite-difference time domain method and near-field scanning optical microscopy. It was shown that the corner step generates an elongated region of enhanced intensity, termed as a curved laser microjet. The curved laser microjet has a length of about DOF = 9.5λ and the smallest diameter FWHM = (1.94+/-0.15)λ at distance z = 5.5λ.

  10. Three-dimensional propagation in near-field tomographic X-ray phase retrieval.

    PubMed

    Ruhlandt, Aike; Salditt, Tim

    2016-03-01

    This paper presents an extension of phase retrieval algorithms for near-field X-ray (propagation) imaging to three dimensions, enhancing the quality of the reconstruction by exploiting previously unused three-dimensional consistency constraints. The approach is based on a novel three-dimensional propagator and is derived for the case of optically weak objects. It can be easily implemented in current phase retrieval architectures, is computationally efficient and reduces the need for restrictive prior assumptions, resulting in superior reconstruction quality. PMID:26919373

  11. Near-field analysis of a thick lens and horn combination: Theory and measurements

    NASA Astrophysics Data System (ADS)

    Tuovinen, J.; Hirvonen, T.; Raeisaenen, A.

    1991-04-01

    At millimeter waves quasi-optical systems are commonly designed based on the Gaussian beam and thin lens approximation. The accuracy of the Gaussian beam and thin lens approximation was studied in the case of a corrugated horn and lens combination at 87 giga-Hz. A special near field measurement system was constructed. Large disagreement between the measured and theoretical values were obtained with the approximative method. A more accurate theoretical model was developed based on ray tracing and use of Huygens' principle. The theoretical values obtained with the method agree well with the measurements.

  12. Near-field analysis of a thick lens and horn combination - Theory and measurements

    NASA Astrophysics Data System (ADS)

    Tuovinen, Jussi; Hirvonen, Taavi M.; Raisanen, Antti V.

    1992-06-01

    At millimeter waves quasi-optical systems are commonly designed based on the Gaussian beam and thin lens approximation. The accuracy of the Gaussian beam and thin lens approximation was studied in the case of a corrugated horn and lens combination at 87 giga-Hz. A special near field measurement system was constructed. Large disagreement between the measured and theoretical values were obtained with the approximative method. A more accurate theoretical model was developed based on ray tracing and use of Huygens' principle. The theoretical values obtained with the method agree well with the measurements.

  13. Near-field antenna testing using the Hewlett Packard 8510 automated network analyzer

    NASA Technical Reports Server (NTRS)

    Kunath, Richard R.; Garrett, Michael J.

    1990-01-01

    Near-field antenna measurements were made using a Hewlett-Packard 8510 automated network analyzer. This system features measurement sensitivity better than -90 dBm, at measurement speeds of one data point per millisecond in the fast data acquisition mode. The system was configured using external, even harmonic mixers and a fiber optic distributed local oscillator signal. Additionally, the time domain capability of the HP8510, made it possible to generate far-field diagnostic results immediately after data acquisition without the use of an external computer.

  14. Source Models and Near-Field Impact of the 1 April 2007 Solomon Islands Tsunami

    NASA Astrophysics Data System (ADS)

    Wei, Yong; Fritz, Hermann M.; Titov, Vasily V.; Uslu, Burak; Chamberlin, Chris; Kalligeris, Nikos

    2015-03-01

    Within weeks of the Solomon Islands earthquake of 1 April 2007, international tsunami survey teams discovered important biomarkers of crust rupture and tsunami heights along the islands' coastlines. Deep-ocean tsunameters recorded the tsunami waves of this event, enabling a real-time inversion of the tsunami source and model evaluation of near-field tsunami impact. The survey measurements provide valuable datasets for further confirmation of the tsunami source of the 1 April 2007 Solomon earthquake. These survey results also aided investigation of the correlation between sources determined by use of tsunameter records and those derived from seismometer records or crust-rupture measurements. In this study, to assess the near-field tsunami impact, we developed tsunami inundation models for the Solomon Islands, including tsunami waveforms, co-seismic land-level changes, and tsunami height distributions on individual islands. Compared with seismic-derived tsunami sources, modeling results based on the tsunameter-derived tsunami sources were a good match with field survey measurements. These results highlight the accuracy and efficiency of the tsunameter-derived tsunami source in modeling the near-field tsunami impact along a complex archipelago. We show that the source models, although derived by use of different methods, are all suited to initiation of inundation models developed for Solomon Islands. As these source models become available in real time or near real time, they can be implemented immediately in the inundation models to provide rapid guidance on tsunami hazard assessment, focused search and rescue operations, and post-event recovery and reconstruction.

  15. Write-once recording for multilayered optical waveguide-type holographic cards

    NASA Astrophysics Data System (ADS)

    Mitasaki, Tokinobu; Senda, Masakatsu

    2006-03-01

    We propose a write-once recording technique for multilayered optical waveguide-type holographic cards. The card medium has a construction created by adding a recording layer and a holographic grating layer to the multilayered optical waveguide composed of core and cladding layers. Individual data for each medium were recorded as an arrangement of optically transparent holes formed in the recording layer. Holograms common to all media were designed in the holographic grating layer so that diffracted lights from the holograms could pass through the holes and focus on an image sensor. We succeeded in write-once recording with a memory capacity potential of more than 128 bits.

  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. Extracting 220 Hz information from 55 Hz field data by near-field superresolution imaging

    NASA Astrophysics Data System (ADS)

    Dutta, Gaurav; AlTheyab, Abdullah; Tarhini, Ahmad; Hanafy, Sherif; Schuster, Gerard T.

    2016-08-01

    Field experiments are used to unequivocally demonstrate seismic superresolution imaging of subwavelength objects in the near-field region of the source. The field test is for a conventional hammer source striking a metal plate near subwavelength scatterers and the seismic data are recorded by vertical-component geophones in the far-field locations of the sources. Time-reversal mirrors (TRMs) are then used to refocus the scattered energy with subwavelength resolution to the position of the original source. A spatial resolution of λ/10, where λ is the dominant wavelength associated with the data, is seen in the field tests that exceeds the Abbe resolution limit of λ/2.

  18. Nonlinear spectroscopy in the near-field: time resolved spectroscopy and subwavelength resolution non-invasive imaging

    NASA Astrophysics Data System (ADS)

    Namboodiri, Mahesh; Khan, Tahirzeb; Karki, Khadga; Kazemi, Mehdi Mohammad; Bom, Sidhant; Flachenecker, Günter; Namboodiri, Vinu; Materny, Arnulf

    2014-04-01

    The combination of near-field microscopy along with nonlinear optical spectroscopic techniques is presented here. The scanning near-field imaging technique can be integrated with nonlinear spectroscopic techniques to improve spatial and axial resolution of the images. Additionally, ultrafast dynamics can be probed down to nano-scale dimension. The review shows some examples for this combination, which resulted in an exciton map and vibrational contrast images with sub-wavelength resolution. Results of two-color femtosecond time-resolved pump-probe experiments using scanning near-field optical microscopy (SNOM) on thin films of the organic semiconductor 3,4,9,10 Perylenetetracarboxylic dianhydride (PTCDA) are presented. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using SNOM. We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near-field.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Analyses of biological systems using scanning near-field infrared microscopy

    NASA Astrophysics Data System (ADS)

    Jeung, Andrew G.

    1998-12-01

    We report the construction of a Scanning Near-field Infrared Microscope (SNIM) and its successful operation towards infrared microspectroscopic analysis of biological tissue. Infrared microspectroscopy is a useful technique that can rapidly identify and localize the chemical constituents within biological tissues and cells on the basis of the vibrational spectroscopic signatures of their organic functional groups. Such analysis may be particularly useful if carried out using near-field optics so as to achieve subwavelength resolution unavailable to Fourier Transform InfraRed (FTIR) microscopy. We constructed SNIM by adapting a conventional scanning near-field microscope for use in the infrared. In particular, we employ infrared- transmitting chalcogenide fibers to serve as the fiber optic probes, and a free electron laser, a laser tunable in the mid-infrared wavelength range, is used as the illumination source. SNIM has acquired mid-infrared images of metal, semiconductor, and biological samples. We have demonstrated resolution down to 2.5 micrometers, and the device appears to be sensitive to differences in sample absorption of less than 0.1 OD. We used SNIM to examine unstained microtome sections of human atherosclerotic lesions, both by infrared imaging and by localized vibrational spectroscopy. In this way, we were able to identify and localize protein, lipid, and mineral components within the tissue. The studies of atherosclerotic tissue illustrate the usefulness of SNIM towards in situ vibrational microspectroscopic investigation of biological systems. In addition, SNIM has demonstrated the ability to perform infrared microscopic imaging in a liquid medium, and we have successfully used the device to take images of living cells in a liquid environment. We believe that SNIM provides a unique opportunity to study the cellular processes of living cells and bacteria by spectroscopic means.

  10. Measurement of birefringence for optical recording disk substrates

    NASA Technical Reports Server (NTRS)

    Fu, Hong; Sugaya, S.; Erwin, J. K.; Goodman, T.; Yan, Z.; Tang, W. J.; Mansuripur, M.

    1993-01-01

    The birefringence of bare and coated substrates for magneto-optical recording is experimentally investigated using ellipsometry at the wavelengths of 632.8 nm and 780 nm. The rotation and ellipticity of the polarization state of the reflected or transmitted light is measured for different incident angles and different orientations of the incident linear polarization. The measured data is then fitted by a computer program which solves the Maxwell equations for the plane-wave propagation in a multilayer structure and minimizes the error between the measured and calculated data by adjusting the unknown parameters of the multilayer. This approach enables us to determine orientations of the three principal axes in the substrate and the corresponding refractive indices. A special feature of our ellipsometers is that a glass hemisphere is placed in contact with the substrate, which eliminates the refraction of the incident light and enables a maximum propagation angle of 70 degrees (with respect to the normal) in the substrate. This increases the sensitivity of the measurement. Certain anomalies were observed, which we believe are associated with the presence of grooves on these substrates.

  11. Aeroacoustic near-field measurements with microscale resolution

    NASA Astrophysics Data System (ADS)

    Haufe, D.; Pietzonka, S.; Schulz, A.; Bake, F.; Enghardt, L.; Czarske, J. W.; Fischer, A.

    2014-10-01

    In order to analyse aeroacoustic phenomena at near-fields, e.g. the sound-flow interaction at aircraft engine liners, measurements of the flow velocity and the acoustic particle velocity (APV) with microscale resolution are required. To this end, the APV measurement with a high spatial resolution of 10 µm was conducted by means of a laser Doppler velocity profile sensor. For validation of the APV measurements using the profile sensor in a superposed flow, a good agreement with indirect microphone measurements as a reference was achieved, up to a maximum Mach number of 0.25. Aeroacoustic measurements at a minimum distance of 350 µm to the perforation of a bias flow liner were performed using the profile sensor. As a result, acoustically induced velocity oscillations near the rim of the orifice were detected with microscale resolution. The phase-resolved oscillation field indicates vortex shedding from the perforation, which is initiated by the sound-flow interaction. Thus, it is demonstrated that the profile sensor is a valuable tool for analysing aeroacoustic phenomena at near-fields, down to the Kolmogorov scale.

  12. 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

  13. Unidirectional wireless power transfer using near-field plates

    NASA Astrophysics Data System (ADS)

    Imani, Mohammadreza F.; Grbic, Anthony

    2015-05-01

    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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Key issues influencing the performance of near-field barriers

    SciTech Connect

    Tasker, P.W.; Wisbey, S.J.; Boyle, C.B.

    1993-12-31

    In developing a national strategy for the disposal of radioactive wastes, each country will consider isolation options that are appropriate to the types of waste that are produced. The options are developed in response to specific national regulatory requirements, and thus will focus on different aspects of performance. However, there are a number of technical concerns that are common to all programmes. The major issues concerning the behavior of the chemical and physical barriers in the near field of a radioactive waste repository are discussed in this paper. The description of key issue has been divided into the following categories: barrier design, barrier evolution, scientific understanding through modelling, and validation of performance. The near-field barriers are selected and designed to provide appropriate radionuclide containment and control. Factors affecting the evolution of these barriers, such as container degradation and gas generation, determine the subsequent release of radionuclides to the human environment. Modelling repository evolution is therefore an integral feature of performance assessments, and issues such as the treatment of inhomogeneities and non-equilibrium chemistry may need to be addressed. However, the use of mathematical and computer models implies a requirement for validation. The use of demonstration experiments and natural analogues builds confidence in the predictions of repository performance models, and provides a degree of validation for otherwise inaccessible timescales.

  19. Near-field electromagnetic holography for high-resolution analysis of network interactions in neuronal tissue

    PubMed Central

    Kjeldsen, Henrik D.; Kaiser, Marcus; Whittington, Miles A.

    2015-01-01

    Background Brain function is dependent upon the concerted, dynamical interactions between a great many neurons distributed over many cortical subregions. Current methods of quantifying such interactions are limited by consideration only of single direct or indirect measures of a subsample of all neuronal population activity. New method Here we present a new derivation of the electromagnetic analogy to near-field acoustic holography allowing high-resolution, vectored estimates of interactions between sources of electromagnetic activity that significantly improves this situation. In vitro voltage potential recordings were used to estimate pseudo-electromagnetic energy flow vector fields, current and energy source densities and energy dissipation in reconstruction planes at depth into the neural tissue parallel to the recording plane of the microelectrode array. Results The properties of the reconstructed near-field estimate allowed both the utilization of super-resolution techniques to increase the imaging resolution beyond that of the microelectrode array, and facilitated a novel approach to estimating causal relationships between activity in neocortical subregions. Comparison with existing methods The holographic nature of the reconstruction method allowed significantly better estimation of the fine spatiotemporal detail of neuronal population activity, compared with interpolation alone, beyond the spatial resolution of the electrode arrays used. Pseudo-energy flow vector mapping was possible with high temporal precision, allowing a near-realtime estimate of causal interaction dynamics. Conclusions Basic near-field electromagnetic holography provides a powerful means to increase spatial resolution from electrode array data with careful choice of spatial filters and distance to reconstruction plane. More detailed approaches may provide the ability to volumetrically reconstruct activity patterns on neuronal tissue, but the ability to extract vectored data with the

  20. Feasibility of near-field odr imaging of multi-GeV electron beams at ;

    SciTech Connect

    Lumpkin, A.; Evtushenko, P.; Freyberger, A. P.; Liu, C. Y.; High Energy Physics; Thomas Jefferson Lab.

    2007-01-01

    We have evaluated the feasibility of using the optical diffraction radiation (ODR) generated as a 1- to 6-GeV CW electron beam passes nearby the edge of a single metal conducting plane as a nonintercepting (NI) relative beam size monitor for CEBAF. Previous experiments were successfully done using near-field imaging on the lower-current, 7-GeV beam at APS, and an analytical model was developed for near-field imaging. Calculations from this model indicate sufficient beam size sensitivity in the ODR profiles for beam sizes in the 30- to 50- micron regime as found in the transport lines of CEBAF before the experimental targets. With anticipated beam currents of 100 muA, the ODR signal from the charge integrated over the video field time should be -500 times larger than in the APS case. These signal strengths will allow a series of experiments to be done on beam energy dependencies, impact parameters, polarization effects, and wavelength effects that should further elucidate the working regime of this technique and test the model. Plans for the diagnostics station that will provide reference optical transition radiation (OTR) images will also be described.

  1. Feasibility of Near field ODR Imaging of Multi GeV Electron Beams at CEBAF

    SciTech Connect

    A.H. Lumpkin; P. Evtushenko; Arne P. Freyberger; C. Liu

    2007-08-01

    We have evaluated the feasibility of using the optical diffraction radiation (ODR) generated as a 1- to 6-GeV CW electron beam passes nearby the edge of a single metal conducting plane as a nonintercepting (NI) relative beam size monitor for CEBAF. Previous experiments were successfully done using near-field imaging on the lower-current, 7-GeV beam at APS, and an analytical model was developed for near-field imaging. Calculations from this model indicate sufficient beam-size sensitivity in the ODR profiles for beam sizes in the 30-50 micron regime as found in the transport lines of CEBAF before the experimental targets. With anticipated beam currents of 100 microamps, the ODR signal from the charge integrated over the video field time should be ~500 times larger than in the APS case. These signal strengths will allow a series of experiments to be done on beam energy dependencies, impact parameters, polarization effects, and wavelength effects that should further elucidate the working regime of this technique and test the model. Plans for the diagnostics station that will also provide reference optical transition radiation (OTR) images will also be described.

  2. Near-field nonuniformities in angularly multiplexed KrF fusion lasers with induced spatial incoherence

    NASA Astrophysics Data System (ADS)

    Lehmberg, Robert H.; Chan, Yung

    2005-05-01

    Induced spatial incoherence (ISI) has been proposed for KrF laser drivers to achieve the high degree of spatial beam uniformity required for direct-drive inertial confinement fusion. Although ISI provides ultrasmooth illumination at the far field of the laser, where the target is located, it can still allow the beams in the quasi-near field to develop a time-averaged spatial structure. This speckle, which arises primarily from random-phase aberration, builds up as the laser beams propagate away from the pupil plane located at the final amplifier stage; it is distinct from any structure imposed by gain nonuniformities in the amplifiers. Because of the spatial incoherence, the speckle is significantly smaller than that experienced by coherent beams. Nevertheless, it remains a damage issue, especially for the long beam delay paths required in angularly multiplexed KrF lasers. We develop a novel algorithm for calculating the time-integrated intensities; compare simulations and measurements of the near-field speckle in the Nike KrF laser; and explore options, such as aberration reduction and optical relaying, for controlling the problem in future angularly multiplexed KrF drivers. © Optical Society of America

  3. Resonant antenna probes for tip-enhanced infrared near-field microscopy.

    PubMed

    Huth, Florian; Chuvilin, Andrey; Schnell, Martin; Amenabar, Iban; Krutokhvostov, Roman; Lopatin, Sergei; Hillenbrand, Rainer

    2013-03-13

    We report the development of infrared-resonant antenna probes for tip-enhanced optical microscopy. We employ focused-ion-beam machining to fabricate high-aspect ratio gold cones, which replace the standard tip of a commercial Si-based atomic force microscopy cantilever. Calculations show large field enhancements at the tip apex due to geometrical antenna resonances in the cones, which can be precisely tuned throughout a broad spectral range from visible to terahertz frequencies by adjusting the cone length. Spectroscopic analysis of these probes by electron energy loss spectroscopy, Fourier transform infrared spectroscopy, and Fourier transform infrared near-field spectroscopy corroborates their functionality as resonant antennas and verifies the broad tunability. By employing the novel probes in a scattering-type near-field microscope and imaging a single tobacco mosaic virus (TMV), we experimentally demonstrate high-performance mid-infrared nanoimaging of molecular absorption. Our probes offer excellent perspectives for optical nanoimaging and nanospectroscopy, pushing the detection and resolution limits in many applications, including nanoscale infrared mapping of organic, molecular, and biological materials, nanocomposites, or nanodevices. PMID:23362918

  4. Characterization of nano recorded marks at different writing strategies on phase-change recording layer of optical disks

    NASA Astrophysics Data System (ADS)

    Lin, Shih Kai; Lin, I. Chun; Tsai, Din Ping

    2006-05-01

    Conductive-atomic force microscopy has been successfully used for characterizing recorded marks on commercial digital versatile disk and Blu-ray disk. Nano recorded marks beyond diffraction limit are imaged with high spatial resolution and excellent contrast of conductivity. The smallest mark size resolved is around 23.5 nm which is limited by background spots around 18.5 nm. The results of different optical power and writing strategy on the size, shape, and close packed writing process of recorded marks clearly show the opto-thermal response of phase-change recording layer.

  5. Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy.

    PubMed

    Huber, A J; Ocelic, N; Hillenbrand, R

    2008-03-01

    We demonstrate that mid-infrared surface phonon polariton excitation, propagation and interference can be studied by scattering-type near-field optical microscopy (s-SNOM). In our experiments we image surface phonon polaritons (SPPs) propagating on flat SiC crystals. They are excited by weakly focused illumination of single or closely spaced metal disks we fabricated on the SiC surface by conventional photolithography. SPP imaging is performed by pseudo-heterodyne interferometric detection of infrared light scattered by the metal tip of our s-SNOM. The pseudo-heterodyne technique simultaneously yields optical amplitude and phase images which allows us to measure the SPP wave vector--including its sign--and the propagation length and further to study SPP interference. High resolution imaging of SPPs could be applied to investigate for example SPP focusing or heat transfer by SPPs in low dimensional nanostructures. PMID:18331484

  6. Numerical calculations of ultrasonic fields I: transducer near fields

    SciTech Connect

    Johnson, J.A.

    1982-03-01

    A computer code for the calculation of linear acoustic wave propagation in homogeneous fluid and solid materials has been derived from the thermal-hydraulics code STEALTH. The code uses finite-difference techniques in a two-dimensional mesh made up of arbitrarily shaped quadrilaterals. Problems with two-dimensional plane strain or two-dimensional axial symmetries can be solved. Free, fixed, or stressed boundaries can be used. Transducers can be modeled by time dependent boundary conditions or by moving pistons. This paper gives a brief description of the method and shows the results of the calculation of the near fields of circular flat and focused transducers. These results agree with analytic theory along the axis of symmetry and with other codes that use a Huygens reconstruction technique off-axis.

  7. Numerical calculations of ultrasonic fields I: transducer near fields

    SciTech Connect

    Johnson, J.A.

    1982-04-01

    A computer code for the calculation of linear acoustic wave propagation in homogeneous fluid and solid materials has been derived from the thermal-hydraulics code STEALTH. The code uses finite-difference techniques in a two dimensional mesh made up of arbitrarily shaped quadrilaterals. Problems with two dimensional plane strain or two dimensional axial symmetries can be solved. Free, fixed or stressed boundaries can be used. Transducers can be modeled by time dependent boundary conditions or by moving pistons. A brief description of the method is given and the results of the calculation of the near fields of circular flat and focused transducers are shown. These results agree with analytic theory along the axis of symmetry and with other codes that use a Huygens' reconstruction technique off axis.

  8. Directional generation of graphene plasmons by near field interference.

    PubMed

    Wang, Lei; Cai, Wei; Zhang, Xinzheng; Xu, Jingjun; Luo, Yongsong

    2016-08-22

    The highly unidirectional excitation of graphene plasmons (GPs) through near-field interference of orthogonally polarized dipoles is investigated. The preferred excitation direction of GPs by a circularly polarized dipole can be simply understood with the angular momentum conservation law. Moreover, the propagation direction of GPs can be switched not only by changing the phase difference between dipoles, but also by placing the z-polarized dipole to its image position, whereas the handedness of the background field remains the same. The unidirectional excitation of GPs can be extended into arc graphene surface as well. Furthermore, our proposal on directional generation of GPs can be realized in a semiconductor nanowire/graphene system, where a semiconductor nanowire can mimic a circularly polarized dipole when illuminated by two orthogonally polarized plane waves. PMID:27557254

  9. Near field and exit wave computations for electron microscopy.

    PubMed

    Howie, A

    2013-11-01

    The partial wave phase shift formalism of atomic scattering is applied to compute exit wave functions for isolated Au and Si atoms under both plane wave and focused probe illumination. Connections between the far field and near field (exit) waves are clarified. This approach treats the Coulomb singularity properly though at 100 keV large numbers of phase shifts are required. In principle any form of incident wave can be handled so it may provide a means for testing traditional scattering theories used in electron microscopy. By applying the analysis to an atom embedded in a constant potential rather than free space, exit spheres of radius half the interatomic spacing can be used. PMID:23726769

  10. Study of Near Field Communication Technology in University Scenarios

    NASA Astrophysics Data System (ADS)

    Ruiz, Irene Luque; Miraz, Guillermo Matas; Gómez-Nieto, Miguel Ángel

    2009-08-01

    In this paper we present an introduction to the possibilities of NFC (Near Field Communication) technology in the University environment. NFC is the key for the development of interactive systems where "intelligent" objects interact with the user just only by touching the objects with a NFC device. We support that a University environment with active objects dispatching information and services to the users (students and teachers) can introduce an appropriate environment for the fulfillment of the new Educational European directives. Here, we briefly describe some of the possibilities of the NFC technology and we include an example of the use of NFC through a Smart Poster for a scenario where a Department directory is considered.

  11. Electromagnetic Near Field Measurements of Two Critical Assemblies

    NASA Astrophysics Data System (ADS)

    Goettee, Jeffrey; Goorley, Tim; Mayo, Douglas; Myers, William; Goda, Joetta; Sage, Frank

    2015-04-01

    Preliminary measurements of the fast metal nuclear reactors at the National Criticality Experiments Research Center (NCERC) and at White Sands Missile Range (WSMR) within the past year characterize the very near field environment of these critical assemblies. Both reactors are fast, highly enriched uranium metal reactors and can be operated in a burst mode above prompt supercritical. Initial measurements of the electric and the magnetic fields within the reactor cell are consistent between the two facilities, and begin to describe the dependance on distance and polarization as might be assumed from initial Monte Carlo modelling of these facilities. The amplitude and time variation of the electric and magnetic fields are consistent with burst time scales. The polarization is consistent with the geometry of the source and with Compton scattering from fission gammas as the dominant ionization mechanism. An overview of the two fast neutron sources and the excursion dynamics, the experimental details, and summary of the modelling calculations will be provided as background.

  12. Near field properties in relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Li, Yang; Fries, Rainer; Kapusta, Joseph

    2006-04-01

    We study the properties of the soft gluon field produced in relativistic heavy ion collisions. In the spirit of McLerran-Venugopalan model, we write the field potential in a power series of the proper time τ and solve the Yang-Mills equation along with color current conservation equations simultaneously. We find that the classical gluon field at small τ, i.e., the near field, is mainly longitudinal. We also calculate the energy-momentum tensor of the field. This gluon field will decay and thermalize into a quark gluon plasma. Our results can be used as the initial conditions for the consequent relativistic hydrodynamic description of the dense parton matter.

  13. Near-field phase singularity in subwavelength metallic microstructures

    SciTech Connect

    Kang Ming; Guo Qinghua; Chen Jing; Gu Bing; Li Yongnan; Wang Huitian

    2011-10-15

    A near-field phase singularity (NFPS) depending on the spin state of the incident electromagnetic (EM) radiation is very fascinating because it can enrich the functionality of the EM radiation in metamaterials. Here we present a microscopic dipole model to describe the NFPS effect under the time-harmonic quasistatic limit. The results reveal that NFPS exists for the longitudinal components of both electric and magnetic fields as well as the transverse component of time-averaged Poynting vector. The localized surface plasmon polariton in the subwavelength metallic structure contributes to enhance the generation efficiency of NFPS by introducing the resonance of the electric dipole. This effect not only is promising for microtrapping and manipulation but also enriches the functionality of the existing metamaterials.

  14. 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.

  15. Scanning near field microwave microscopy based on an active resonator

    NASA Astrophysics Data System (ADS)

    Qureshi, Naser; Kolokoltsev, Oleg; Ordonez-Romero, Cesar Leonardo

    2014-03-01

    A large number of recent implementations of near field scanning microwave microscopy (NFSMM) have been based on the perturbation of a resonant cavity connected to a sharp scanning probe. In this work we present results from an alternative approach: the perturbation of a microwave source connected to a scanning tip. Based on a yittrium iron garnet (YIG) cavity ring resonator this scanning probe system has a quality factor greater than 106, which allows us to detect very small frequency shifts, which translates to a very high sensitivity in sample impedance measurements. Using a selection of representative semiconductor, metal and biological samples we show how this approach leads to unusually high sensitivity and spatial resolution. Work supported by a grant from PAPIIT, UNAM 104513.

  16. Theoretical and experimental examination of near-field acoustic levitation.

    PubMed

    Nomura, Hideyuki; Kamakura, Tomoo; Matsuda, Kazuhisa

    2002-04-01

    A planar object can be levitated stably close to a piston sound source by making use of acoustic radiation pressure. This phenomenon is called near-field acoustic levitation [Y. Hashimoto et al., J. Acoust. Soc. Am. 100, 2057-2061 (1996)]. In the present article, the levitation distance is predicted theoretically by numerically solving basic equations in a compressible viscous fluid subject to the appropriate initial and boundary conditions. Additionally, experiments are carried out using a 19.5-kHz piston source with a 40-mm aperture and various aluminum disks of different sizes. The measured levitation distance agrees well with the theory, which is different from a conventional theory, and the levitation distance is not inversely proportional to the square root of the surface density of the levitated disk in a strict sense. PMID:12002842

  17. Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz

    NASA Astrophysics Data System (ADS)

    Kuschewski, F.; von Ribbeck, H.-G.; Döring, J.; Winnerl, S.; Eng, L. M.; Kehr, S. C.

    2016-03-01

    Nano-spectroscopy in the terahertz frequency range remains challenging despite recent technological progress in developing both THz emitter sources and near-field optical microscopy (SNOM). Here, we combine scattering-type SNOM with a free-electron laser light source, to tune into the 1.3-8.5 THz range. A significant portion of this range, namely, the frequencies above ˜3 THz, is not covered by previously reported near-field microscopy systems. However, it constitutes an indispensable regime where many elementary processes in solids including collective lattice excitations, charge, and spin transport occur. Our approach of nano-spectroscopy and nano-imaging provides a versatile analysis of nanostructures as small as 50 nm, hence beating the optical diffraction limit by λ/4600.

  18. Manipulating quantum dot fluorescence by utilizing Brownian induced near-field interactions with plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Palombo, Nola

    Quantum dots (QDs) are semiconductor nanocrystals with size-dependent optical properties; thus making them supreme fluorophores. Plasmonic nanoparticles (PNPs), such as gold and silver nanoparticles, support localized surface plasmons on their surface. When the localized surface plasmons are excited, a highly concentrated electromagnetic field is formed near the particle. Therefore, if a QD is within the near-field of a PNP, the emission or excitation of the QD can be enhanced. However, due to Forster Resonance Energy Transfer (FRET), the QD fluorescence could instead be quenched by the proximity of PNPs. Whether enhancement or quenching occurs, is dependent upon the distance and geometry of the nanoparticles. Enhanced QD fluorescence would be helpful in biomedical sensing and imaging and solar energy conversion applications. In addition, quenched QD fluorescence caused by FRET could be applied to FRET-based sensing and imaging in medical diagnosis. This master's thesis first theoretically models the stochastic movement of QDs and PNPs in an aqueous solution. The simulation is based upon the Direct Simulation Monte Carlo method coupled with Langevin equations. Using this simulation, we were able to predict the percentage of QDs in the near-field region of PNPs. The percentage of QDs in the near-field region of GNPs for a concentration of 1 × 1013 QDs/mL and 5 × 108 GNPs/mL, is a very small percentage of 2 × 10-5%. Yet, the concentration of QDs in the near-field region of GNPs was calculated to be 1,510,000 QDs mL-1. In addition, this master's thesis experimentally explores the enhancement and quenching of QD emission for different concentrations and sizes of PNPs in aqueous solutions. The fluorescence spectra of two types of QD-PNP mixtures were measured. The first mixture was QDs and gold nanoparticles (GNPs) dispersed in distilled water, where the emission wavelength of the QDs matches the localized surface plasmon excitation wavelength of the GNPs. The second

  19. Near-Field Fluorescence Cross-Correlation Spectroscopy on Planar Membranes

    PubMed Central

    2015-01-01

    The organization and dynamics of plasma membrane components at the nanometer scale are essential for biological functions such as transmembrane signaling and endocytosis. Planarized nanoscale apertures in a metallic film are demonstrated as a means of confining the excitation light for multicolor fluorescence spectroscopy to a 55 ± 10 nm beam waist. This technique provides simultaneous two-color, subdiffraction-limited fluorescence correlation spectroscopy and fluorescence cross-correlation spectroscopy on planar membranes. The fabrication and implementation of this technique are demonstrated for both model membranes and live cells. Membrane-bound proteins were observed to cluster upon the addition of a multivalent cross-linker: On supported lipid bilayers, clusters of cholera toxin subunit B were formed upon cross-linking by an antibody specific for this protein; on living cells, immunoglobulin E bound to its receptor (FcεRI) on the plasma membranes of RBL mast cells was observed to form clusters upon exposure to a trivalent antigen. The formation of membrane clusters was quantified via fluorescence intensity vs time and changes in the temporal auto- and cross-correlations above a single nanoscale aperture. The illumination profile from a single aperture is analyzed experimentally and computationally with a rim-dominated illumination profile, yielding no change in the autocorrelation dwell time with changes in aperture diameter from 60 to 250 nm. This near-field fluorescence cross-correlation methodology provides access to nanoscale details of dynamic membrane interactions and motivates further development of near-field optical methods. PMID:25004429

  20. Nanometal Skin of Plasmonic Heterostructures for Highly Efficient Near-Field Scattering Probes

    PubMed Central

    Zito, Gianluigi; Rusciano, Giulia; Vecchione, Antonio; Pesce, Giuseppe; Di Girolamo, Rocco; Malafronte, Anna; Sasso, Antonio

    2016-01-01

    In this work, atomic force microscopy probes are functionalized by virtue of self-assembling monolayers of block copolymer (BCP) micelles loaded either with clusters of silver nanoparticles or bimetallic heterostructures consisting of mixed species of silver and gold nanoparticles. The resulting self-organized patterns allow coating the tips with a sort of nanometal skin made of geometrically confined nanoislands. This approach favors the reproducible engineering and tuning of the plasmonic properties of the resulting structured tip by varying the nanometal loading of the micelles. The newly conceived tips are applied for experiments of tip-enhanced Raman scattering (TERS) spectroscopy and scattering-type scanning near-field optical microscopy (s-SNOM). TERS and s-SNOM probe characterizations on several standard Raman analytes and patterned nanostructures demonstrate excellent enhancement factor with the possibility of fast scanning and spatial resolution <12 nm. In fact, each metal nanoisland consists of a multiscale heterostructure that favors large scattering and near-field amplification. Then, we verify the tips to allow challenging nongap-TER spectroscopy on thick biosamples. Our approach introduces a synergistic chemical functionalization of the tips for versatile inclusion and delivery of plasmonic nanoparticles at the tip apex, which may promote the tuning of the plasmonic properties, a large enhancement, and the possibility of adding new degrees of freedom for tip functionalization. PMID:27502178

  1. Mapping plasmonic near-field profiles and interferences by surface-enhanced Raman scattering

    PubMed Central

    Du, Luping; Lei, Dang Yuan; Yuan, Guanghui; Fang, Hui; Zhang, Xi; Wang, Qian; Tang, Dingyuan; Min, Changjun; Maier, Stefan A.; Yuan, Xiaocong

    2013-01-01

    Mapping near-field profiles and dynamics of surface plasmon polaritons is crucial for understanding their fundamental optical properties and designing miniaturized photonic devices. This requires a spatial resolution on the sub-wavelength scale because the effective polariton wavelength is shorter than free-space excitation wavelengths. Here by combining total internal reflection excitation with surface-enhanced Raman scattering imaging, we mapped at the sub-wavelength scale the spatial distribution of the dominant perpendicular component of surface plasmon fields in a metal nanoparticle-film system through spectrally selective and polarization-resolved excitation of the vertical gap mode. The lateral field-extension at the junction, which is determined by the gap-mode volume, is small enough to distinguish a spot size ~0.355λ0 generated by a focused radially polarized beam with high reproducibility. The same excitation and imaging schemes are also used to trace near-field nano-focusing and interferences of surface plasmon polaritons created by a variety of plasmon lenses. PMID:24165970

  2. IR near-field spectroscopy and imaging of single Li(x)FePO4 microcrystals.

    PubMed

    Lucas, I T; McLeod, A S; Syzdek, J S; Middlemiss, D S; Grey, C P; Basov, D N; Kostecki, R

    2015-01-14

    This study demonstrates the unique capability of infrared near-field nanoscopy combined with Fourier transform infrared spectroscopy to map phase distributions in microcrystals of Li(x)FePO4, a positive electrode material for Li-ion batteries. Ex situ nanoscale IR imaging provides direct evidence for the coexistence of LiFePO4 and FePO4 phases in partially delithiated single-crystal microparticles. A quantitative three-dimensional tomographic reconstruction of the phase distribution within a single microcrystal provides new insights into the phase transformation and/or relaxation mechanism, revealing a FePO4 shell surrounding a diamond-shaped LiFePO4 inner core, gradually shrinking in size and vanishing upon delithiation of the crystal. The observed phase propagation pattern supports recent functional models of LiFePO4 operation relating electrochemical performance to material design. This work demonstrates the remarkable potential of near-field optical techniques for the characterization of electrochemical materials and interfaces. PMID:25375874

  3. Analysis of biological tissues using scanning near-field infrared microspectroscopy

    NASA Astrophysics Data System (ADS)

    Jeung, Andrew G.; Erramilli, Shyamsunder; Hong, Mi K.; Huie, Phil; Smith, Todd I.

    1997-10-01

    Infrared absorption microspectroscopy is a useful technique to analyze biological tissues, as it can rapidly and non- destructively provide quantitative information about the molecular composition of tissue on a small spatial scale. At the Stanford Picosecond Free Electron Laser Center, a Scanning Near-field Infrared Microscope (SNIM) with the Free Electron Laser (FEL) as its illumination source has been used for in situ microspectroscopic characterization of constituents in human atherosclerotic tissue. The system consists of a Near-field Scanning Optical Microscope utilizing a tapered chalcogenide fiber as the scanning probe. The Stanford mid-infrared FEL provides high power infrared radiation that can be easily coupled into the chalcogenide fiber and whose wavelength is continuously tunable from 3 to 15 micrometers. With the FEL, the SNIM can acquire an image at a single wavelength of a 200 micrometer square region with 2 micrometer spatial resolution in under 30 minutes. It can also obtain infrared spectra at sub- wavelength resolution. The SNIM was used to examine unstained, frozen microtone sections of human atherosclerotic lesions. Spectra from localized regions in the sample were taken and analyzed to determine the distribution of various protein, lipid, and mineral constituents among the tissue microstructures. These findings were compared with results obtained by polarization microscopy and traditional histological staining techniques. The molecular information obtained in these studies can potentially lead to a greater understanding of atherosclerosis. Moreover, they demonstrate the usefulness of SNIM towards micrometer-scale vibrational microspectroscopy.

  4. Nanofocusing beyond the near-field diffraction limit via plasmonic Fano resonance.

    PubMed

    Song, Maowen; Wang, Changtao; Zhao, Zeyu; Pu, Mingbo; Liu, Ling; Zhang, Wei; Yu, Honglin; Luo, Xiangang

    2016-01-21

    The past decade has witnessed a great deal of optical systems designed for exceeding the Abbe's diffraction limit. Unfortunately, a deep subwavelength spot is obtained at the price of extremely short focal length, which is indeed a near-field diffraction limit that could rarely go beyond in the nanofocusing device. One method to mitigate such a problem is to set up a rapid oscillatory electromagnetic field that converges at the prescribed focus. However, abrupt modulation of phase and amplitude within a small fraction of a wavelength seems to be the main obstacle in the visible regime, aggravated by loss and plasmonic features that come into function. In this paper, we propose a periodically repeated ring-disk complementary structure to break the near-field diffraction limit via plasmonic Fano resonance, originating from the interference between the complex hybrid plasmon resonance and the continuum of propagating waves through the silver film. This plasmonic Fano resonance introduces a π phase jump in the adjacent channels and amplitude modulation to achieve radiationless electromagnetic interference. As a result, deep subwavelength spots as small as 0.0045λ(2) at 36 nm above the silver film have been numerically demonstrated. This plate holds promise for nanolithography, subdiffraction imaging and microscopy. PMID:26691553

  5. Near-field Light Scattering Techniques for Measuring Nanoparticle-Surface Interaction Energies and Forces

    PubMed Central

    O'Dell, Dakota; Adam, Ian S.; DiPaolo, Brian; Sabharwal, Manit; Shi, Ce; Hart, Robert; Earhart, Christopher; Erickson, David

    2015-01-01

    Nanoparticles are quickly becoming commonplace in many commercial and industrial products, ranging from cosmetics to pharmaceuticals to medical diagnostics. Predicting the stability of the engineered nanoparticles within these products a priori remains an important and difficult challenge. Here we describe our techniques for measuring the mechanical interactions between nanoparticles and surfaces using near-field light scattering. Particle-surface interfacial forces are measured by optically “pushing” a particle against a reference surface and observing its motion using scattered near-field light. Unlike atomic force microscopy, this technique is not limited by thermal noise, but instead takes advantage of it. The integrated waveguide and microfluidic architecture allow for high-throughput measurements of about 1000 particles per hour. We characterize the reproducibility of and experimental uncertainty in the measurements made using the NanoTweezer surface instrument. We report surface interaction studies on gold nanoparticles with 50 nm diameters, smaller than previously reported in the literature using similar techniques. PMID:26855473

  6. Nanometal Skin of Plasmonic Heterostructures for Highly Efficient Near-Field Scattering Probes

    NASA Astrophysics Data System (ADS)

    Zito, Gianluigi; Rusciano, Giulia; Vecchione, Antonio; Pesce, Giuseppe; di Girolamo, Rocco; Malafronte, Anna; Sasso, Antonio

    2016-08-01

    In this work, atomic force microscopy probes are functionalized by virtue of self-assembling monolayers of block copolymer (BCP) micelles loaded either with clusters of silver nanoparticles or bimetallic heterostructures consisting of mixed species of silver and gold nanoparticles. The resulting self-organized patterns allow coating the tips with a sort of nanometal skin made of geometrically confined nanoislands. This approach favors the reproducible engineering and tuning of the plasmonic properties of the resulting structured tip by varying the nanometal loading of the micelles. The newly conceived tips are applied for experiments of tip-enhanced Raman scattering (TERS) spectroscopy and scattering-type scanning near-field optical microscopy (s-SNOM). TERS and s-SNOM probe characterizations on several standard Raman analytes and patterned nanostructures demonstrate excellent enhancement factor with the possibility of fast scanning and spatial resolution <12 nm. In fact, each metal nanoisland consists of a multiscale heterostructure that favors large scattering and near-field amplification. Then, we verify the tips to allow challenging nongap-TER spectroscopy on thick biosamples. Our approach introduces a synergistic chemical functionalization of the tips for versatile inclusion and delivery of plasmonic nanoparticles at the tip apex, which may promote the tuning of the plasmonic properties, a large enhancement, and the possibility of adding new degrees of freedom for tip functionalization.

  7. Design of pitch conversion component for formation of multibeam optical recording head

    NASA Astrophysics Data System (ADS)

    Sasaki, Kentaro; Kawamura, Norikazu; Tokumaru, Haruki

    2008-04-01

    We describe a design of a planar lightwave circuit for parallel information processing using visible light. The circuit serves as a pitch conversion component (PCC) that can align multiple beams close together and easily composes a compact optical system that can project optical spots at a narrow pitch on a certain small plane. From the viewpoint of its application to optical recording, a PCC is designed to have over 50 waveguides according to the fabrication of waveguides for a blue-violet beam. It is analytically confirmed that a PCC contributes to the formation of a multibeam optical recording head with numerous beams.

  8. Design of pitch conversion component for formation of multibeam optical recording head.

    PubMed

    Sasaki, Kentaro; Kawamura, Norikazu; Tokumaru, Haruki

    2008-04-10

    We describe a design of a planar lightwave circuit for parallel information processing using visible light. The circuit serves as a pitch conversion component (PCC) that can align multiple beams close together and easily composes a compact optical system that can project optical spots at a narrow pitch on a certain small plane. From the viewpoint of its application to optical recording, a PCC is designed to have over 50 waveguides according to the fabrication of waveguides for a blue-violet beam. It is analytically confirmed that a PCC contributes to the formation of a multibeam optical recording head with numerous beams. PMID:18404179

  9. A Methodology for Near-Field Tsunami Inundation Forecasting

    NASA Astrophysics Data System (ADS)

    Gusman, A. R.; Tanioka, Y.

    2014-12-01

    Here we describe a new methodology for near-field tsunami inundation forecasting. We designed an algorithm that can produce high-resolution tsunami inundation maps of near-field sites before the actual tsunami hits the shore. This algorithm relies on a database of precomputed tsunami waveforms at several near-shore points and precomputed tsunami inundation maps from various earthquake fault model scenarios. By using numerical forward model, it takes several hours to simulate tsunami inundation in each site from each fault model. After information about a tsunami source is estimated, tsunami waveforms at near-shore points can be simulated in real-time. A scenario that gives the most similar tsunami waveforms is selected as the site-specific best scenario and the tsunami inundation from that scenario is selected as the tsunami inundation forecast. To test the algorithm, tsunami inundation along the Sanriku coast is forecasted by using source models for the 2011 Tohoku earthquake estimated from GPS, W phase, or offshore tsunami waveform data. The forecasting algorithm is capable of providing a tsunami inundation forecast that is similar to that obtained by numerical forward modeling, but with remarkably smaller CPU time. The time required to forecast tsunami inundation in 15 coastal sites from the Sendai Plain to Miyako City is approximately 3 minutes after information about the tsunami source is obtained. We found that the tsunami inundation forecasts from the 5-min GPS, 10-min W phase fault models, and 35-min tsunami source model are all reliable for tsunami early warning purposes and quantitatively match the observations well, although the latter model gives tsunami forecasts with highest overall accuracy. We evaluated the effectiveness of this algorithm in the real world by carrying out a tsunami evacuation drill in Kushiro City, Hokkaido, Japan, involving the city residents. The participants found that the use of the tsunami inundation forecast map produced by

  10. Finite Element Method Simulations of the Near-Field Enhancement at the Vicinity of Fractal Rough Metallic Surfaces

    SciTech Connect

    Micic, Miodrag; Klymyshyn, Nicholas A.; Lu, H PETER.

    2004-03-04

    Near-field optical enhancement at metal surfaces and methods such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescent quenching and enhancement, and various near-field scanning microscopies (NSOM) all depend on a metals surface properties, mainly on its morphology and SPR resonant frequency. We report on simulations of the influence of different surface morphologies on electromagnetic field enhancements at the rough surfaces of noble metals and also evaluate the optimal conditions for the generation of a surface-enhanced Raman signal of absorbed species on a metallic substrate. All simulations were performed with a classical electrodynamics approach using the full set of Maxwells equations, which were solved with the three-dimensional finite element method (FEM). Two different classes of surfaces where modeled using fractals, representing diffusion limited aggregation growth dendritic structures, such as one on the surface of electrodes, and second one representing the sponge-like structure used to model surfaces of particles with high porosity, such as metal coated catalyst supports. The simulations depict the high inhomogeneity of an enhanced electromagnetic field as both a field enhancement and field attenuation near the surface. While the diffusion limited aggregation dendritical fractals enhanced the near-field electromagnetic field, the sponge fractals significantly reduced the local electromagnetic field intensity. Moreover, the fractal orders of the fractal objects did not significantly alter the total enhancement, and the distribution of a near-field enhancement was essentially invariant to the changes in the angle of an incoming laser beam.

  11. Analysing one isolated single walled carbon nanotube in the near-field domain with selective nanovolume Raman spectroscopy.

    PubMed

    Atalay, Han; Lefrant, Serge

    2004-09-01

    In this paper, we describe a new method to the selective nanovolume analysing of one isolated single walled carbon nanotube (SWNT). This concept is based on actually available imaging micro-spectrometry systems for working in near-field domain combined with a stigmatic solid immersion lens. This combination of different analytical methods, and modified and configured equipment entitles us to expand the functionality toward a three-dimensional (3D) nanovolume Raman mapping and photoluminescence intensity with a possible discrimination in polarization, as well as photoluminescence decaytime constant mapping with their unique combination. Subsequently, selective spectra can be acquired from the same location on the samples. By spectrally selecting a SWNT, we registered the spatial distribution of the emitted photons in x, y, z vectors to determine the position of a SWNT in the near-field domain. For the SWNTs that are localized with an accuracy better than 18 nm in the x, y and <1 nm in the z directions, we demonstrate an analytical sensitivity close to a single nanotube with unity throughput. This near-field capability is applied to resolve local variations unambiguously in the Raman spectrum along one single SWNT. Finally, in this paper, we report what we believe to be the first evidence of Raman mapping and 3D real optical imaging of carbon nanotubes with near-field resolution. PMID:15570957

  12. Combined Experimental and Numerical Diagnostics for Near-field Flow around a Supersonic Flight Model

    NASA Astrophysics Data System (ADS)

    Matsuda, Atsushi; Shimizu, Katsuya; Suzuki, Kakuei; Sasoh, Akihiro; Murakami, Keiichi; Aoyama, Takashi

    A system for evaluating the near-field pressure distribution around a supersonic flight model by combining experimental and numerical diagnostics has been developed. Experimental measurement is conducted using a ballistic range with four kinds of axi-symmetric flight models. Schlieren flow visualization is recorded using a high-speed framing camera and near-field pressure histories are measured using piezoelectric pressure transducers flush-mounted on the surface of flat plates in the test section. The numerical diagnostics is done using FaSTAR, a numerical simulation tool developed by the Japan Aerospace Exploration Agency (JAXA). The experimental and numerical data are compared to each other, and the numerical results well validated. Based on the numerical results, it becomes possible to estimate the accuracy of experimental conditions including the flight path and angle of attack, which cannot readily be determined only from experimental data, and to discuss the relationship between peak overpressure and aerodynamic performance. Satisfactory agreement between the experimental and numerical results at a flight Mach number of 1.66±0.02 and important insights related to rear boom strength are obtained.

  13. Broadband near-field infrared spectromicroscopy using photothermal probes and synchrotron radiation.

    PubMed

    Donaldson, Paul M; Kelley, Chris S; Frogley, Mark D; Filik, Jacob; Wehbe, Katia; Cinque, Gianfelice

    2016-02-01

    In this paper, we experimentally demonstrate the use of infrared synchrotron radiation (IR-SR) as a broadband source for photothermal near-field infrared spectroscopy. We assess two methods of signal transduction; cantilever resonant thermal expansion and scanning thermal microscopy. By means of rapid mechanical chopping (50-150 kHz), we modulate the IR-SR at rates matching the contact resonance frequencies of atomic force microscope (AFM) cantilevers, allowing us to record interferograms yielding Fourier transform infrared (FT-IR) photothermal absorption spectra of polystyrene and cyanoacrylate films. Complementary offline measurements using a mechanically chopped CW IR laser confirmed that the resonant thermal expansion IR-SR measurements were below the diffraction limit, with a spatial resolution better than 500 nm achieved at a wavelength of 6 μm, i.e. λ/12 for the samples studied. Despite achieving the highest signal to noise so far for a scanning thermal microscopy measurement under conditions approaching near-field (dictated by thermal diffusion), the IR-SR resonant photothermal expansion FT-IR spectra measured were significantly higher in signal to noise in comparison with the scanning thermal data. PMID:26906764

  14. Tailoring complex optical fields via anisotropic microstructures (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Lu, Yan-Qing; Hu, Wei; Cui, Guo-Xin

    2015-10-01

    In recent years, complex optical fields with spatially inhomogeneous phases, polarizations and optical singularities have drawn many research interests. Many novel effects have been predicted and demonstrated for light beams with these unconventional states in both linear and nonlinear optics regimes. Although local optical phase could be controlled directly or through hologram structures in isotropic materials such as glasses, optical anisotropy is still required for manipulating polarization states and wavelengths. The anisotropy could be either intrinsic such as in crystals/liquid crystals (LCs) or the induced birefringence from dielectric or metallic structures. In this talk, we will briefly review some of our attempts in tailoring complex optical fields via anisotropic microstructures. We developed a micro-photo-patterning system that could generate complex micro-images then further guides the arbitrary local LC directors. Due to the electro-optically (EO) tunable anisotropy of LC, various reconfigurable complex optical fields such as optical vortices (OVs), multiplexed OVs, OV array, Airy beams and vector beams are obtained. Different LC modes such as homogeneous alignment nematic, hybrid alignment nematic and even blue phase LCs are adopted to optimize the static and dynamic beam characteristics depending on application circumstances. We are also trying to extend our approaches to new wavelength bands, such as mid-infrared and even THz ranges. Some preliminary results are obtained. In addition, based on our recently developed local poling techniques for ferroelectric crystals, we will also discuss and demonstrate the nonlinear complex optical field conversion in Lithium Niobate wafers with patterned ferroelectric domain structures.

  15. Optical Storage Systems for Records and Information Management: Overview, Recommendations and Guidelines for Local Governments. Local Government Records Technical Information Series. Number 45.

    ERIC Educational Resources Information Center

    Schwartz, Stanley F.

    This publication discusses optical storage, a term encompassing technologies that use laser-produced light to record and store information in digital form. The booklet also discusses how optical storage systems relate to records management, in particular to the management of local government records in New York State. It describes components of…

  16. Colossal optical transmission through buried metal gratings (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Roberts, Christopher M.; Liu, Runyu; Zhao, Xiang; Yu, Lan; Li, Xiuling; Wasserman, Daniel M.; Podolskiy, Viktor A.

    2015-09-01

    In Extraordinary Optical Transmission (EOT), a metallic film perforated with an array of [periodic] apertures exhibits transmission over 100% normalized to the total aperture area, at selected frequencies. EOT devices have potential applications as optical filters and as couplers in hybrid electro-optic contacts/devices. Traditional passive extraordinary optical transmission structures, typically demonstrate un-normalized transmission well below 50%, and are typically outperformed by simpler thin-film techniques. To overcome these limitations, we demonstrate a new breed of extraordinary optical transmission devices, by "burying" an extraordinary optical transmission grating in a dielectric matrix via a metal-assisted-chemical etching process. The resulting structure is an extraordinary optical transmission grating on top of a dielectric substrate with dielectric nano-pillars extruded through the grating apertures. These structures not only show significantly enhanced peak transmission when normalized to the open area of the metal film, but more importantly, peak transmission greater than that observed from the bare semiconductor surface. The structures were modeled using three-dimensional rigorous coupled wave analysis and characterized experimentally by Fourier transform infrared reflection and transmission spectroscopy, and the good agreement between the two has been demonstrated. The drastic enhancement of light transmission in our structures originates from structuring of high-index dielectric substrate, with pillars effectively guiding light through metal apertures.

  17. 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

  18. Investigation of the arcjet plume near field using electrostatic probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plum of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in) and 15 cm (5.9 in) and radial distances extending to 10 cm (3.9 in) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  19. Investigation of the Arcjet near Field Plume Using Electrostatic Probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plume of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in.) and 15 cm (5.9 in.) and radial distances extending to 10 cm (3.9 in.) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in.) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  20. Radiation and near field in resistance-inductor circuit transients

    NASA Astrophysics Data System (ADS)

    Latypov, Damir; Bulmer, John

    2012-06-01

    A full wave solution to the classical problem of a transient response in an RL circuit is analyzed. We show that when radiation effects are rigorously taken into account, the response differs from a familiar exponential decay. The circuit behaves more like an RLC circuit and can exhibit an underdamped response. As a result of a two way energy transfer between the circuit and the near field in the underdamped regime, despite the radiation losses, current decay may be slower than predicted by the standard RL circuit model. During a transient, when retardation effects become important, inductance can no longer be defined as a coefficient of proportionality between the magnetic flux through the circuit and the current in the circuit. If rate of current decay is nearly constant, one can define a time-dependent generalized inductance which turns into conventional inductance after time D/c, where D is the diameter of the current loop. Connection of this generalized inductance with the radiation damping problem is discussed. The theory developed in this paper has been used to analyze ultra wide band radiation observed during a fast laser triggered superconducting to normal transition of a superconducting switch.

  1. Near-Field Acoustical Characterization of Clustered Rocket Engines

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Vu, Bruce T.; Lindsay Halie K.

    2005-01-01

    This paper presents an approach for the prediction and characterization of the near-field acoustic levels from closely-spaced clustered rocket engines. The calculations are based on the method proposed by Eldred, wherein the flowfield from the clustered rockets is divided into two zones. Zone 1 contains the isolated nozzles which produce noise independently, and extends up to a distance where the individual flows completely mix to form an equivalent single nozzle flow. Zone 2 is occupied by the single mixed stream starting from the station where the jets merge. The acoustic fields from the two zones are computed separately on the basis of the NASA-SP method of Eldred developed for a single equivalent nozzle. A summation of the spectra for the two zones yields the total effective sound pressure level for the clustered engines. Under certain conditions of nozzle spacing and flow parameters, the combined sound pressure level spectrum for the clustered nozzles displays a double peak. Test cases are presented here to demonstrate the importance of hydrodynamic interactions responsible for the double peak in the sound spectrum in the case of clustered rocket nozzles, and the role of ground reflections in the case of non-interfering jets. A graphics interface (Rocket Acoustic Prediction Tool) has been developed to take into account the effects of clustered nozzles and ground reflections.

  2. Nanosensors: From near field to far field applications

    NASA Astrophysics Data System (ADS)

    Herrera, Gloria M.; Félix, Hilsamar; Fierro, Pedro M.; Balaguera, Marcia; Pacheco, Leonardo; Briano, Julio G.; Marquez, Francisco; Ríos, Carlos; Hernández-Rivera, Samuel P.

    2011-06-01

    The DoD Center for Chemical Sensors Development at the University of Puerto Rico-Mayagüez has worked in developing sensors for threat agents for over 8 years. Work has continued under the ALERT DHS Center of Excellence. The approaches for sensing have covered many types of threat chemicals and some types of biological simulants, including high energetic materials, homemade explosives, mixtures and formulations, chemical agents simulants, toxic industrial chemicals and spore forming microorganisms. Sensing in the far field has been based in vibrational spectroscopy: Raman and infrared. Near field detection has been mainly based on nanotechnology enabled sensing platforms for Surface Enhanced Raman Scattering. Initial use of colloidal suspensions of silver and gold nanospheres eventually evolved to metallic and metal oxide nanorods and to particle immobilization, including sample smearing on substrates and drop-on-demand thermal inkjet printing of nanoparticles. Chemical reduction of metal ions has been substituted by clean photonic physical reduction that leaves the nanoactive surface highly exposed and overcomes the physico-chemical problem of double electrical layers posed by colloidal suspensions of nanoparticles. New avenues have open wide research endeavors by using laser techniques to form nanoprisms and interference based metallic nano-images and micro-images. UV based metal reduction on top of metal oxides nanostructures promises to provide the selectivity and sensitivity expected for the last 30-40 years. Various applications and experimental setups will be discussed.

  3. 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.

  4. Research Studies on Advanced Optical Module/Head Designs for Optical Disk Recording Devices

    NASA Technical Reports Server (NTRS)

    Burke, James J.; Seery, Bernard D.

    1993-01-01

    The Annual Report of the Optical Data Storage Center of the University of Arizona is presented. Summary reports on continuing projects are presented. Research areas include: magneto-optic media, optical heads, and signal processing.

  5. Photoconductive terahertz near-field detector with a hybrid nanoantenna array cavity

    SciTech Connect

    Mitrofanov, Oleg; Brener, Igal; Luk, Ting S.; Reno, John L.

    2015-11-19

    Nanoscale structuring of optical materials leads to modification of their properties and can be used for improving efficiencies of photonic devices and for enabling new functionalities. In ultrafast optoelectronic switches for generation and detection of terahertz (THz) radiation, incorporation of nanostructures allows us to overcome inherent limitations of photoconductive materials. We propose and demonstrate a nanostructured photoconductive THz detector for sampling highly localized THz fields, down to the level of λ/150. The nanostructure that consists of an array of optical nanoantennas and a distributed Bragg reflector forms a hybrid cavity, which traps optical gate pulses within the photoconductive layer. The effect of photon trapping is observed as enhanced absorption at a designed wavelength. This optically thin photoconductive THz detector allows us to detect highly confined evanescent THz fields coupled through a deeply subwavelength aperture as small as 2 μm (λ/150 at 1 THz). As a result, by monolithically integrating the THz detector with apertures ranging from 2 to 5 μm we realize higher spatial resolution and higher sensitivity in aperture-type THz near-field microscopy and THz time-domain spectroscopy.

  6. Photoconductive terahertz near-field detector with a hybrid nanoantenna array cavity

    DOE PAGESBeta

    Mitrofanov, Oleg; Brener, Igal; Luk, Ting S.; Reno, John L.

    2015-11-19

    Nanoscale structuring of optical materials leads to modification of their properties and can be used for improving efficiencies of photonic devices and for enabling new functionalities. In ultrafast optoelectronic switches for generation and detection of terahertz (THz) radiation, incorporation of nanostructures allows us to overcome inherent limitations of photoconductive materials. We propose and demonstrate a nanostructured photoconductive THz detector for sampling highly localized THz fields, down to the level of λ/150. The nanostructure that consists of an array of optical nanoantennas and a distributed Bragg reflector forms a hybrid cavity, which traps optical gate pulses within the photoconductive layer. Themore » effect of photon trapping is observed as enhanced absorption at a designed wavelength. This optically thin photoconductive THz detector allows us to detect highly confined evanescent THz fields coupled through a deeply subwavelength aperture as small as 2 μm (λ/150 at 1 THz). As a result, by monolithically integrating the THz detector with apertures ranging from 2 to 5 μm we realize higher spatial resolution and higher sensitivity in aperture-type THz near-field microscopy and THz time-domain spectroscopy.« less

  7. Near-field evanescent waves scattered from a spatially deterministic and anisotropic medium.

    PubMed

    Li, Jia; Chang, Liping; Wu, Zhefu

    2015-06-15

    The scattering of light from an anisotropic medium, which may present either spatially random or deterministic statistics, has attracted substantial interest where the measurement of structural properties of scatterers is concerned. To date, however, no literature has studied near-zone evanescent waves scattered from a spatially deterministic and anisotropic medium. In this Letter, integral expressions are derived to represent electric fields of evanescent waves in the near-zone scattered field. In addition, the dependences of spectral densities of scattered field on the propagation distance of evanescent waves and effective radius of the scattering potential (ERSP) are also shown by numerical graphs, respectively. Potential applications of our study include the near-field optical microscopy and biomedical sensing. PMID:26076235

  8. Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field

    DOE PAGESBeta

    Piazza, L.; Lummen, T. T. A.; Quiñonez, E.; Murooka, Y.; Reed, B. W.; Barwick, B.; Carbone, F.

    2015-03-02

    Surface plasmon polaritons can confine electromagnetic fields in subwavelength spaces and are of interest for photonics, optical data storage devices and biosensing applications. In analogy to photons, they exhibit wave–particle duality, whose different aspects have recently been observed in separate tailored experiments. Here we demonstrate the ability of ultrafast transmission electron microscopy to simultaneously image both the spatial interference and the quantization of such confined plasmonic fields. Our experiments are accomplished by spatiotemporally overlapping electron and light pulses on a single nanowire suspended on a graphene film. The resulting energy exchange between single electrons and the quanta of the photoinducedmore » near-field is imaged synchronously with its spatial interference pattern. In conclusion, this methodology enables the control and visualization of plasmonic fields at the nanoscale, providing a promising tool for understanding the fundamental properties of confined electromagnetic fields and the development of advanced photonic circuits.« less

  9. Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field

    SciTech Connect

    Piazza, L.; Lummen, T. T. A.; Quiñonez, E.; Murooka, Y.; Reed, B. W.; Barwick, B.; Carbone, F.

    2015-03-02

    Surface plasmon polaritons can confine electromagnetic fields in subwavelength spaces and are of interest for photonics, optical data storage devices and biosensing applications. In analogy to photons, they exhibit wave–particle duality, whose different aspects have recently been observed in separate tailored experiments. Here we demonstrate the ability of ultrafast transmission electron microscopy to simultaneously image both the spatial interference and the quantization of such confined plasmonic fields. Our experiments are accomplished by spatiotemporally overlapping electron and light pulses on a single nanowire suspended on a graphene film. The resulting energy exchange between single electrons and the quanta of the photoinduced near-field is imaged synchronously with its spatial interference pattern. In conclusion, this methodology enables the control and visualization of plasmonic fields at the nanoscale, providing a promising tool for understanding the fundamental properties of confined electromagnetic fields and the development of advanced photonic circuits.

  10. Chirality changes in carbon nanotubes studied with near-field Raman spectroscopy.

    PubMed

    Anderson, Neil; Hartschuh, Achim; Novotny, Lukas

    2007-03-01

    We report on the direct visualization of chirality changes in carbon nanotubes by mapping local changes in resonant RBM phonon frequencies with an optical resolution of 40 nm using near-field Raman spectroscopy. We observe the transition from semiconducting-to-metal and metal-to-metal chiralities at the single nanotube level. Our experimental findings, based on detecting changes in resonant RBM frequencies, are complemented by measuring changes in the G-band frequency and line shape. In addition, we observe increased Raman scattering due to local defects associated with the structural transition. From our results, we determine the spatial extent of the transition region to be Ltrans approximately 40-100 nm. PMID:17324000

  11. Near-field resonance shifts of ferroelectric barium titanate domains upon low-temperature phase transition

    SciTech Connect

    Döring, Jonathan; Ribbeck, Hans-Georg von; Kehr, Susanne C.; Eng, Lukas M.; Fehrenbacher, Markus

    2014-08-04

    Scattering scanning near-field optical microscopy (s-SNOM) has been established as an excellent tool to probe domains in ferroelectric crystals at room temperature. Here, we apply the s-SNOM possibilities to quantify low-temperature phase transitions in barium titanate single crystals by both temperature-dependent resonance spectroscopy and domain distribution imaging. The orthorhombic-to-tetragonal structural phase transition at 263 K manifests in a change of the spatial arrangement of ferroelectric domains as probed with a tunable free-electron laser. More intriguingly, the domain distribution unravels non-favored domain configurations upon sample recovery to room temperature as explainable by increased sample disorder. Ferroelectric domains and topographic influences are clearly deconvolved even at low temperatures, since complementing our s-SNOM nano-spectroscopy with piezoresponse force microscopy and topographic imaging using one and the same atomic force microscope and tip.

  12. Plasmonic electric near-field enhancement in self-organized gold nanoparticles in macroscopic arrays

    NASA Astrophysics Data System (ADS)

    Mondes, V.; Antonsson, E.; Plenge, J.; Raschpichler, C.; Halfpap, I.; Menski, A.; Graf, C.; Kling, M. F.; Rühl, E.

    2016-06-01

    When plasmonic nanoparticles are incorporated into nanostructures and they are exposed to external optical fields, plasmonic coupling causes electric near-field enhancement which is significantly larger than that of isolated nanoparticles. We report on the plasmonic coupling in arrays of gold nanospheres (20 ± 3 and 50 ± 4 nm) prepared by colloidal chemistry and self-organization. This yields field enhancement in arrays with areas of several mm2 and provides an alternative approach to lithographic methods for preparation of nanostructures for plasmonic applications. Gold nanospheres are surface-functionalized by organic ligands, which define the interparticle distance in the array upon self-organization of the nanoparticles. The experiments are accompanied by finite-difference time-domain simulations, which quantify the dependence of the field enhancement on the interparticle distance.

  13. Volume polarization holographic recording in thick photopolymer for optical memory.

    PubMed

    Lin, Shiuan Huei; Cho, Sheng-Lung; Chou, Shin-Fu; Lin, June Hua; Lin, Chih Min; Chi, Sien; Hsu, Ken Yuh

    2014-06-16

    Based on a vector wave theory of volume holograms, dependence of holographic reconstruction on the polarization states of the writing and reading beams is discussed. It is found that under paraxial approximation the circular polarization holograms provide a better distinction of the reading beams. Characteristics of recording polarization holograms in thick phenanthrenequinone-doped poly(methyl methacrylate) (PQ/PMMA) photopolymer are experimentally investigated. It is found that the circular polarization holographic recording possesses better dynamic range and material sensitivity, and a uniform spatial frequency response over a wide range. The performance is comparable to that of the intensity holographic recording in PQ/PMMA. Based on theoretical analyses and the material properties, a polarization multiplexing holographic memory using circularly polarization recording configuration for increasing storage capacity has been designed and experimentally demonstrated. PMID:24977588

  14. Linearity in the response of photopolymers as optical recording media.

    PubMed

    Gallego, Sergi; Marquez, Andrés; Guardiola, Francisco J; Riquelme, Marina; Fernández, Roberto; Pascual, Inmaculada; Beléndez, Augusto

    2013-05-01

    Photopolymer are appealing materials for diffractive elements recording. Two of their properties when they are illuminated are useful for this goal: the relief surface changes and the refractive index modifications. To this goal the linearity in the material response is crucial to design the optimum irradiance for each element. In this paper we measured directly some parameters to know how linear is the material response, in terms of the refractive index modulation versus exposure, then we can predict the refractive index distributions during recording. We have analyzed at different recording intensities the evolution of monomer diffusion during recording for photopolymers based on PVA/Acrylamide. This model has been successfully applied to PVA/Acrylamide photopolymers to predict the transmitted diffracted orders and the agreement with experimental values has been increased. PMID:23669956

  15. Extracting 220 Hz information from 55 Hz field data by near-field superresolution imaging

    NASA Astrophysics Data System (ADS)

    Dutta, Gaurav; AlTheyab, Abdullah; Tarhini, Ahmad; Hanafy, Sherif; Schuster, Gerard T.

    2016-05-01

    Field experiments are used to unequivocally demonstrate seismic superresolution imaging of subwavelength objects in the near-field region of the source. The field test is for a conventional hammer source striking a metal plate near sub-wavelength scatterers and the seismic data are recorded by vertical-component geophones in the far-field locations of the sources. Time-reversal mirrors (TRMs) are then used to refocus the scattered energy with subwavelength resolution to the position of the original source. A spatial resolution of λ/10, where λ is the dominant wavelength associated with the data, is seen in the field tests that exceeds the Abbe resolution limit of λ/2.

  16. Integration of near-field probes and photonic crystal nanocavities for precise and low-loss resonance control

    NASA Astrophysics Data System (ADS)

    Chew, Xiongyeu; Zhou, Guangya; Chau, Fook Siong

    2011-03-01

    Research interest for silicon nanophotonics is a topic of heavy interest currently due to the requirements for high density communications of integrated devices with small footprints in the semiconductor industry. Silicon photonic crystals (PhC) are nanoscale subwavelength periodic structures that possess the capability to induce strong interaction between light and matter. PhC nanocavities utilizes the photonic bandgap effect to trap certain frequencies of light within a small confined region for a diverse range of applications such as enhancement and suppression of spontaneous emission, efficient and compact lasers, add/drop multiplexers, optical filters and sensing etc. In this paper, we describe a mechanically-perturbative near-field probe with a special design shape to achieve low-loss and precise resonance control of PhC nanocavities. One-dimensional (1D) PhC are chosen for our study due to the ease of integrating with low-loss SOI waveguide technology and easy integration with nanomechanical structures. Sub-micron microelectromechanical systems (MEMS/NEMS) technology is introduced as an ideal integration platform with such near-field probe designs due to its capabilities to accurately control fine displacements without the need of bulky equipment such as atomic force microscopy (AFM), scanning near field microscope (SNOM) or highly sensitive piezo-controlled micromanipulator stages. We propose that such near-field probe designs are capable of achieving large resonance spectral shift of up to few nm with high re-configurability, highly accurate actuation displacements, low power consumption, and portability. In this work, we propose an approach utilizing numerical methods to study and characterize the electromagnetic interaction between PhC nanocavities and nanomechanically displaced near-field nano-probes.

  17. Turbulence Measurements in the Near Field of a Wingtip Vortex

    NASA Technical Reports Server (NTRS)

    Chow, Jim; Zilliac, Greg; Bradshaw, Peter

    1997-01-01

    The roll-up of a wingtip vortex, at Reynolds number based on chord of 4.6 million was studied with an emphasis on suction side and near wake measurements. The research was conducted in a 32 in. x 48 in. low-speed wind tunnel. The half-wing model had a semi-span of 36 in. a chord of 48 in. and a rounded tip. Seven-hole pressure probe measurements of the velocity field surrounding the wingtip showed that a large axial velocity of up to 1.77 U(sub infinity) developed in the vortex core. This level of axial velocity has not been previously measured. Triple-wire probes have been used to measure all components of the Reynolds stress tensor. It was determined from correlation measurements that meandering of the vortex was small and did not appreciably contribute to the turbulence measurements. The flow was found to be turbulent in the near-field (as high as 24 percent RMS w - velocity on the edge of the core) and the turbulence decayed quickly with streamwise distance because of the nearly solid body rotation of the vortex core mean flow. A streamwise variation of the location of peak levels of turbulence, relative to the core centerline, was also found. Close to the trailing edge of the wing, the peak shear stress levels were found at the edge of the vortex core, whereas in the most downstream wake planes they occurred at a radius roughly equal to one-third of the vortex core radius. The Reynolds shear stresses were not aligned with the mean strain rate, indicating that an isotropic-eddy-viscosity based prediction method cannot accurately model the turbulence in the cortex. In cylindrical coordinates, with the origin at the vortex centerline, the radial normal stress was found to be larger than the circumferential.

  18. New Optical Card for Sneaker’s Network in Place of Electronic Clinical Record

    NASA Astrophysics Data System (ADS)

    Goto, Kenya; Satsukawa, Takatoshi; Chiba, Seisho; Ohmori, Takaaki

    2006-02-01

    In order to solve problems in electronic medical records, a new optical card of the digital versatile disk (DVD) type with higher capacity and lower cost than conventional compact disc recording (CD-R)-type cards has been developed, which is thinner, stronger and wearable like a credit card.

  19. A high transmittance optical recording material with long-term reliability for super-multilayer discs

    NASA Astrophysics Data System (ADS)

    Shimomai, Kenichi; Asano, Sho; Oshita, Junji; Matsuda, Isao; Kojo, Shinichi; Murai, Wakaaki; Hattori, Masashi; Shimizu, Atsuo; Fujii, Toru

    2015-09-01

    As a means of increasing data capacity, the multilayer optical disc is a promising approach. Because the recording layers in multilayer optical discs must have a high transmittance, they are commonly made of transparent oxide films. Moreover, the recording layer must have sufficient long-term reliability for data archival. In this work, a recording material with high transmittance and long-term reliability for use in super-multilayer discs was investigated. This paper clarifies the recording mechanism of GeBi oxide material and proposes a suitable material design that satisfies the abovementioned characteristics. Furthermore, experimental results of recording on super-multilayer discs based on GeBi oxide recording material are presented.

  20. On-film optical recording of camera lens settings

    NASA Technical Reports Server (NTRS)

    Thompson, R. E. (Inventor)

    1973-01-01

    An apparatus is described for recording a representation of the camera lens aperture and focus setting on the film of a camera, while the photographic image is being recorded. A data lens is provided between the camera lens and film, by means of which the aperture and focus setting may be determined. The determination is made by measuring both the location and the size of a data image provided by the data lens. The data lens apparatus requires no electrical power, is low in weight, and does not result in an increase in the external dimensions of the camera.

  1. Dynamic thermal profiling in magneto-optic recording thin films

    SciTech Connect

    Schultz, M.D.; Freedman, J.M.; Weng, R.S.; Kryder, M.K. )

    1991-04-15

    The thermal behavior of magneto-optic thin films is critical to their performance. The determination of thermal profiles which result in magneto-optic thin films when they are being written has up to now been limited to theoretical calculations occasionally matched against the thresholds for writing domains into the films. Such switching temperature'' experimental data is of limited use due to the dependence of magnetic domain shape, size, and placement on much more than just a simple isotherm location. Through the use of a high-speed (10-ns time resolution) observation system developed for examining dynamic magnetic processes in magneto-optic materials, the thermal profiles created in these films were observed as the profiles developed during the application of laser heating pulses. Images of the profiles caused by both static and scanning laser pulses are shown. Comparison of static pulse data with theoretical computations indicates that the thermal conductivity of these magneto-optic films is approximately an order of magnitude below the bulk value.

  2. Structured light-matter interactions in optical nanostructures (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Litchinitser, Natalia M.; Sun, Jingbo; Shalaev, Mikhail I.; Xu, Tianboyu; Xu, Yun; Pandey, Apra

    2015-09-01

    We show that unique optical properties of metamaterials open unlimited prospects to "engineer" light itself. For example, we demonstrate a novel way of complex light manipulation in few-mode optical fibers using metamaterials highlighting how unique properties of metamaterials, namely the ability to manipulate both electric and magnetic field components, open new degrees of freedom in engineering complex polarization states of light. We discuss several approaches to ultra-compact structured light generation, including a nanoscale beam converter based on an ultra-compact array of nano-waveguides with a circular graded distribution of channel diameters that coverts a conventional laser beam into a vortex with configurable orbital angular momentum and a novel, miniaturized astigmatic optical element based on a single biaxial hyperbolic metamaterial that enables the conversion of Hermite-Gaussian beams into vortex beams carrying an orbital angular momentum and vice versa. Such beam converters is likely to enable a new generation of on-chip or all-fiber structured light applications. We also present our initial theoretical studies predicting that vortex-based nonlinear optical processes, such as second harmonic generation or parametric amplification that rely on phase matching, will also be strongly modified in negative index materials. These studies may find applications for multidimensional information encoding, secure communications, and quantum cryptography as both spin and orbital angular momentum could be used to encode information; dispersion engineering for spontaneous parametric down-conversion; and on-chip optoelectronic signal processing.

  3. Far-field head-media optical interaction in heat-assisted magnetic recording.

    PubMed

    Yang, Ruoxi; Jones, Paul; Klemmer, Timmothy; Olson, Heidi; Zhang, Deming; Perry, Tyler; Scholz, Werner; Yin, Huaqing; Hipwell, Roger; Thiele, Jan-Ulrich; Tang, Huan; Seigler, Mike

    2016-02-20

    We have used a plane wave expansion method to theoretically study the far-field head-media optical interaction in heat-assisted magnetic recording. For the Advanced Storage Technology Consortium media stack specifically, we notice the outstanding sensitivity related to the interlayer's optical thickness for media reflection and the magnetic layer's light absorption. With 10 nm interlayer thickness change, the recording layer absorption can be changed by more than 25%. The 2D results are found to correlate well with the full 3D model and magnetic recording tests on a flyable disc with different interlayer thickness. PMID:26906574

  4. Blue laser and high-numerical-aperture optical disk system for digital video recording (DVR)

    NASA Astrophysics Data System (ADS)

    van Houten, Henk

    2001-02-01

    Based on a blue diode laser (405 nm wavelength) and a two- element objective lens with a numerical aperture of 0.85, a third generation optical recording system has been developed that is able to record 22.5 GB on a single sided 12 cm diameter disc, at a user data rate of 50 Mb/s. The system is referred to by the technical name DVR for high definition Digital Video Recording. In this paper, we review the physical and the system concept, the phase change media, the optical pick up unit, and the drive implementation.

  5. Optical Recording of Suprathreshold Neural Activity with Single-cell and Single-spike Resolution

    PubMed Central

    Ranganathan, Gayathri Nattar; Koester, Helmut J.

    2012-01-01

    Signaling of information in the vertebrate central nervous system is often carried by populations of neurons rather than individual neurons. Also propagation of suprathreshold spiking activity involves populations of neurons. Empirical studies addressing cortical function directly thus require recordings from populations of neurons with high resolution. Here we describe an optical method and a deconvolution algorithm to record neural activity from up to 100 neurons with single-cell and single-spike resolution. This method relies on detection of the transient increases in intracellular somatic calcium concentration associated with suprathreshold electrical spikes (action potentials) in cortical neurons. High temporal resolution of the optical recordings is achieved by a fast random-access scanning technique using acousto-optical deflectors (AODs)1. Two-photon excitation of the calcium-sensitive dye results in high spatial resolution in opaque brain tissue2. Reconstruction of spikes from the fluorescence calcium recordings is achieved by a maximum-likelihood method. Simultaneous electrophysiological and optical recordings indicate that our method reliably detects spikes (>97% spike detection efficiency), has a low rate of false positive spike detection (< 0.003 spikes/sec), and a high temporal precision (about 3 msec) 3. This optical method of spike detection can be used to record neural activity in vitro and in anesthetized animals in vivo3,4. PMID:22972033

  6. Toehold-mediated internal control to probe the near-field interaction between the metallic nanoparticle and the fluorophore

    NASA Astrophysics Data System (ADS)

    Ang, Y. S.; Yung, L. Y. L.

    2014-10-01

    interaction from far-field interference is established by the use of the DNA toehold concept to mediate the in situ assembly and disassembly of the MNP-fluorophore conjugate. A model gold nanoparticle (AuNP)-Cy3 system is used to investigate our proposed toehold-mediated internal control system. The maximum fluorescence enhancement is obtained for large-sized AuNP (58 nm) separated from Cy3 at an intermediate distance of 6.8 nm, while fluorescence quenching is observed for smaller-sized AuNP (11 nm and 23 nm), which is in agreement with the theoretical values reported in the literature. This work shows that the toehold-mediated internal control design can serve as a central system for evaluating the near-field interaction of other MNP-fluorophore combinations and facilitate the rational design of specific MNP-fluorophore systems for various applications. Electronic supplementary information (ESI) available: DNA sequences, size distribution analysis, photobleaching background and optical characterization. See DOI: 10.1039/c4nr03643c

  7. Nano-imaging collagen by atomic force, near-field and nonlinear microscope

    NASA Astrophysics Data System (ADS)

    Lim, Ken Choong; Tang, Jinkai; Li, Hao; Ng, Boon Ping; Kok, Shaw Wei; Wang, Qijie; Zhang, Ying

    2015-03-01

    As the most abundant protein in the human body, collagen has a very important role in vast numbers of bio-medical applications. The unique second order nonlinear properties of fibrillar collagen make it a very important index in nonlinear optical imaging based disease diagnosis of the brain, skin, liver, colon, kidney, bone, heart and other organs in the human body. The second-order nonlinear susceptibility of collagen has been explored at the macroscopic level and was explained as a volume-averaged molecular hyperpolarizability. However, details about the origin of optical second harmonic signals from collagen fibrils at the molecular level are still not clear. Such information is necessary for accurate interpolation of bio-information from nonlinear optical imaging techniques. The later has shown great potential in collagen based disease diagnosis methodologies. In this paper, we report our work using an atomic force microscope (AFM), near field (SNOM) and nonlinear laser scanning microscope (NLSM) to study the structure of collagen fibrils and other pro-collagen structures.

  8. Response of marine composites subjected to near field blast loading

    NASA Astrophysics Data System (ADS)

    LiVolsi, Frank

    Experimental studies were performed to understand the explosive response of composite panels when exposed to near-field explosive loading in different environments. The panel construction under consideration was an E-glass fiber-reinforced composite laminate infused with vinyl ester resin (Derakane 8084). The panel was layered bi-axially with plain-woven fiber orientations at 0° and 90°. Panel dimensions were approximately 203 mm x 203 mm x 1 mm (8 in x 8 in x 0.04 in). Experiments were carried out with the panel fully clamped in a holding fixture, which was in turn fastened inside a water tank. The fixture was fastened in such a way as to allow for explosive loading experiments in the following environments: water submersion with water backing, water submersion with air backing, and air immersion with air backing. Experiments were performed in room temperature conditions, and additional experiments in the submerged environments were also performed at high and low water temperatures of 40°C and 0°C, respectively. A stereo Digital Image Correlation (DIC) system was employed to capture the full-field dynamic behavior of the panel during the explosive event. Results indicated that the immersion environment contributes significantly to the blast response of the material and to the specimens' appreciable damage characteristics. The water submersion with air backing environment was found to encourage the greatest panel center point deflection and the most significant damage mechanisms around the boundary. The air immersion with air backing environment was found to encourage less center point deflection and exhibited significant impact damage from the explosive capsule. The water submersion with water backing environment encouraged the least panel deflection and minimal interlaminate damage around the panel boundary and center. Water temperature was found to influence the panel center point deflection, but not damage mechanisms. Maximum positive center point

  9. Mass transport analysis in the near field of geologic repository

    NASA Astrophysics Data System (ADS)

    Lim, Doo-Hyun

    A two-dimensional model for the groundwater flow and the contaminant transport has been developed. A water-saturated, deep geologic repository for high-level radioactive wastes (HLW) is considered. The region containing a waste canister, a backfill material around the canister, and the near-field rock (NFR) surrounding the backfill is considered. Discrete-Fracture Network (DFN) is generated in the NFR based on distribution functions of the fracture geometry parameters by random sampling. Flow-bearing fracture network is identified, and is transformed into an equivalent continuous porous medium in two different ways without calculating flow rates through individual fractures. The first transformation is applied locally, generating a heterogeneous porous medium. The second transformation is applied for the entire NFR, resulting in a homogeneous porous medium. While the heterogeneous porous medium is considered to represent characteristics of water flow in DFN better than the homogeneous porous medium, the homogeneous porous medium was often used in previous performance assessment studies for its simplicity. After these transformations, the spatial distribution of groundwater flow rate is calculated by a finite element method. The numerical results for the total discharge at the outer boundary of the homogenized NFR after the second transformation are benchmarked by analytical solutions with a relative difference smaller than 0.55%. The contaminant transport is simulated by a random-walk particle-tracking method, based on the obtained flow-rate distribution. Previous study for a step equation that determines the movement of contaminant particles has been critically reviewed. Numerical results obtained by the first and second transformations have been compared. The second transformation gives smaller mean values of the residence time of particles in the NFR and greater mean values of the mass absorption rate at the outer boundary of NFR than the first one does. Thus

  10. Design of an optical fiber cable link for lightning instrumentation. [wideband pulse recording system

    NASA Technical Reports Server (NTRS)

    Grove, C. H.; Phillips, R. L.; Wojtasinski, R. J.

    1975-01-01

    A lightning instrumentation system was designed to record current magnitudes of lightning strikes that hit a launch pad service structure at NASA's Kennedy Space Center. The instrumentation system consists of a lightning ground rod with a current sensor coil, an optical transmitter, an optical fiber cable link, a detector receiver, and a recording system. The transmitter is a wideband pulse transformer driving an IR LED emitter. The transmitter operates linearly as a transducer. A low loss fiber bundle provides isolation of the recorder system from the electromagnetic field of the lightning strike. The output of an optical detector receiver module is sampled and recorded in digital format. The significant factors considered in the design were dynamic range, linearity, mechanical configuration, electromagnetic isolation, and temperature compensation.

  11. Nano-scale imaging and spectroscopy of plasmonic systems, thermal near-fields, and phase separation in complex oxides

    NASA Astrophysics Data System (ADS)

    Jones, Andrew C.

    Optical spectroscopy represents a powerful characterization technique with the ability to directly interact with the electronic, spin, and lattice excitations in matter. In addition, through implementation of ultrafast techniques, further insight into the real-time dynamics of elementary interactions can be gained. However, the resolution of far-field microscopy techniques is restricted by the diffraction limit setting a spatial resolution limit in the 100s nm to micron range for visible and IR light, respectively. This resolution is too coarse for the characterization of mesoscopic phenomena in condensed matter physics. The development of experimental techniques with nanoscale resolution and sensitivity to optical fields has been a long standing obstacle to the characterization of condensed matter systems on their natural length scales. This dissertation focuses on the fundamental near-field optical properties of surfaces and nanoscale systems as well as the utilization of nano-optical techniques, specifically apertureless scattering-type Scanning Near-field Optical Microscopy (s-SNOM), to characterize said optical properties with nanometer scale resolution. First, the s-SNOM characterization of the field enhancement associated with the localized surface plasmon resonances on metallic structures is discussed. With their ability to localize light, plasmonic nano-structures are promising candidate systems to serve as molecular sensors and nano-photonic devices; however, it is well known that particle morphology and the plasmon resonance alone do not uniquely reflect the details of the local field distribution. Here, I demonstrate the use interferometric s-SNOM for imaging of the near-fields associated with plasmonic resonances of crystalline triangular silver nano-prisms in the visible spectral range. I subsequently show the extension of the concept of a localized plasmon into the mid-IR spectral range with the characterization of near-fields of silver nano

  12. Optical information recording in biopolymer-based material

    NASA Astrophysics Data System (ADS)

    Mysliwiec, J.; Kochalska, A.; Miniewicz, A.

    2008-02-01

    In this paper we present results of possible applications of a modified DNA-dye system for dynamic processing of optical information like phase conjugation or optical correlation. The system consisted of bio-polymeric matrix made of deoxyribonucleic acid (DNA) substituted with cationic surfactant molecule cetyltrimethyl-ammonium chloride (CTMA) and doped with a photochromic Disperse Red 1 dye. Fast dynamics (a single millisecond rise and fall times) of diffraction grating formation were obtained in a typical degenerate two or four wave mixing experiments. For sample excitation we used a linearly polarized light of λ = 514.5 nm delivered by an argon ion (Ar +) laser. Complete reversibility of the signal generation with no residual light diffraction even after longer time exposures (up to few hours) was observed.

  13. Magnetic bearings for a spaceflight optical disk recorder

    NASA Technical Reports Server (NTRS)

    Hockney, Richard; Gondhalekar, Vijay; Hawkey, Timothy

    1991-01-01

    The development and testing of a magnetic bearing system for the translator of the read/write head in a magneto-optic disk drive are discussed. The asymmetrical three-pole actuators with permanent magnet bias support the optical head, and its tracking and focusing servos, through their radial excursion above the disk. The specifications for the magnetic bearing are presented, along with the configuration of the magnetic hardware. Development of a five degree of freedom collision model is examined which allowed assessment of the system response during large scale transients. Experimental findings and the results of performance testing are presented, including the roll-off of current-to-force due to eddy current loss in the magnetic materials.

  14. Near-field sea-level variability in northwest Europe and ice sheet stability during the last interglacial

    NASA Astrophysics Data System (ADS)

    Long, A. J.; Barlow, N. L. M.; Busschers, F. S.; Cohen, K. M.; Gehrels, W. R.; Wake, L. M.

    2015-10-01

    Global sea level during the Last Interglacial (LIG, Marine Isotope Sub-stage 5e) peaked between c. 5.5 and 9 m above present, implying significant melt from Greenland and Antarctica. Relative sea level (RSL) observations from several far- and intermediate-field sites suggest abrupt fluctuations or jumps in RSL during the LIG highstand that require one or more episodes of ice-sheet collapse and regrowth. Such events should be manifest as unique sea-level fingerprints, recorded in far-, intermediate- and near-field sites depending on the source(s) of ice-mass change involved. To date, though, no coherent evidence of such fluctuations has been reported from near-field RSL studies in northwest Europe. This is an important problem because RSL fluctuations during the LIG are portrayed as warning signs for how polar ice sheets may behave in a future, warmer than present, world. Here we review the evidence for RSL change during the LIG using stratigraphic data from the best resolved highstand records that exist in the near-field of northwest Europe, from a range of settings that include lagoonal, shallow marine, tidal flat, salt marsh and brackish-water fluviatile environments. Consideration of previously published stratigraphic records from two sites in the Eemian coastal-marine embayment that existed in the central Netherlands, yields no clear indications for abrupt RSL change during the attainment of the near-field highstand. Nor do we find any such indications common to other records from countries bordering the North Sea, the Baltic Sea and the White Sea. Two modelling experiments that explore the global signal of hypothetical sea-level oscillations caused by partial collapse and regrowth of either the Greenland or Antarctic LIG ice-sheet, show that the North Sea region is relatively insensitive to mass changes sourced from Greenland but should clearly register events with an Antarctic origin, especially those that occur late in the LIG. The lack of evidence for

  15. Nanofocusing beyond the near-field diffraction limit via plasmonic Fano resonance

    NASA Astrophysics Data System (ADS)

    Song, Maowen; Wang, Changtao; Zhao, Zeyu; Pu, Mingbo; Liu, Ling; Zhang, Wei; Yu, Honglin; Luo, Xiangang

    2016-01-01

    The past decade has witnessed a great deal of optical systems designed for exceeding the Abbe's diffraction limit. Unfortunately, a deep subwavelength spot is obtained at the price of extremely short focal length, which is indeed a near-field diffraction limit that could rarely go beyond in the nanofocusing device. One method to mitigate such a problem is to set up a rapid oscillatory electromagnetic field that converges at the prescribed focus. However, abrupt modulation of phase and amplitude within a small fraction of a wavelength seems to be the main obstacle in the visible regime, aggravated by loss and plasmonic features that come into function. In this paper, we propose a periodically repeated ring-disk complementary structure to break the near-field diffraction limit via plasmonic Fano resonance, originating from the interference between the complex hybrid plasmon resonance and the continuum of propagating waves through the silver film. This plasmonic Fano resonance introduces a π phase jump in the adjacent channels and amplitude modulation to achieve radiationless electromagnetic interference. As a result, deep subwavelength spots as small as 0.0045λ2 at 36 nm above the silver film have been numerically demonstrated. This plate holds promise for nanolithography, subdiffraction imaging and microscopy.The past decade has witnessed a great deal of optical systems designed for exceeding the Abbe's diffraction limit. Unfortunately, a deep subwavelength spot is obtained at the price of extremely short focal length, which is indeed a near-field diffraction limit that could rarely go beyond in the nanofocusing device. One method to mitigate such a problem is to set up a rapid oscillatory electromagnetic field that converges at the prescribed focus. However, abrupt modulation of phase and amplitude within a small fraction of a wavelength seems to be the main obstacle in the visible regime, aggravated by loss and plasmonic features that come into function. In this

  16. Holography optical memory recorded with error correcting bits

    NASA Astrophysics Data System (ADS)

    Song, J. H.; Moon, I.; Lee, Y. H.

    2014-06-01

    A novel error correction method is proposed for volume holographic memory systems. In this method the information of two adjacent binary bits is recorded in the space between the two bits, which is used to correct the errors in the data bits. The new method is compared with (15, 5) Reed—Solomon code using the same redundancy of 200% as ours. It is shown that the new method achieves the similar bit error rate as the RS code.

  17. Discrete and continuum simulations of near-field ground motion from Source Physics Experiments (SPE) (Invited)

    NASA Astrophysics Data System (ADS)

    Ezzedine, S. M.; Vorobiev, O.; Herbold, E. B.; Glenn, L. A.; Antoun, T.

    2013-12-01

    This work is focused on analysis of near-field measurements (up to 100 m from the source) recorded during Source Physics Experiments in a granitic formation. One of the main goals of these experiments is to investigate the possible mechanisms of shear wave generation in the nonlinear source region. SPE experiments revealed significant tangential motion (up to 30 % of the magnitude in the radial direction) at many locations. Furthermore, azimuthal variations in radial velocities were also observed which cannot be generated by a spherical source in isotropic materials. Understanding the nature of this non-radial motion is important for discriminating between the natural seismicity and underground explosions signatures. Possible mechanisms leading to such motion include, but not limited to, heterogeneities in the rock such as joints, faults and geologic layers as well as surface topography and vertical motion at the surface caused by material spall and gravity. We have performed a three dimensional computational studies considering all these effects. Both discrete and continuum methods have been employed to model heterogeneities. In the discrete method, the joints and faults were represented by cohesive contact elements. This enables us to examine various friction laws at the joints which include softening, dilatancy, water saturation and rate-dependent friction. Yet this approach requires the mesh to be aligned with joints, which may present technical difficulties in three dimensions when multiple non-persistent joints are present. In addition, the discrete method is more computationally expensive. The continuum approach assumes that the joints are stiff and the dilatancy and shear softening can be neglected. In this approach, the joints are modeled as weakness planes within the material, which are imbedded into and pass through many finite elements. The advantage of this approach is that it requires neither sophisticated meshing algorithms nor contact detection

  18. A compact, short-pulse laser for near-field, range-gated imaging

    SciTech Connect

    Zutavern, F.J.; Helgeson, W.D.; Loubriel, G.M.; Yates, G.J.; Gallegos, R.A.; McDonald, T.E.

    1996-12-31

    This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low impedance circuit to drive an array of lasers, which are connected electrically in series. The total optical energy produced per pulse is 10 microjoules corresponding to a total peak power of 100 kW. The entire laser system, including prime power (a nine volt battery), pulse charging, PCSS, and LDA, is the size of a small, hand-held flashlight. System lifetime, which is presently limited by the high gain PCSS, is an active area of research and development. Present limitations and potential improvements will be discussed. The complete range-gated imaging system is based on complementary technologies: high speed optical gating with intensified charge coupled devices (ICCD) developed at Los Alamos National Laboratory (LANL) and high gain, PCSS-driven LDAs developed at Sandia National Laboratories (SNL). The system is designed for use in highly scattering media such as turbid water or extremely dense fog or smoke. The short optical pulses from the laser and high speed gating of the ICCD are synchronized to eliminate the back-scattered light from outside the depth of the field of view (FOV) which may be as short as a few centimeters. A high speed photodiode can be used to trigger the intensifier gate and set the range-gated FOV precisely on the target. The ICCD and other aspects of the imaging system are discussed in a separate paper.

  19. The interaction of the near-field plasma with antennas used in magnetic fusion research

    NASA Astrophysics Data System (ADS)

    Caughman, John

    2015-09-01

    Plasma heating and current drive using antennas in the Ion Cyclotron Range of Frequencies (ICRF) are important elements for the success of magnetic fusion. The antennas must operate in a harsh environment, where local plasma densities can be >1018/m3, magnetic fields can range from 0.2-5 Tesla, and antenna operating voltages can be >40 kV. This environment creates operational issues due to the interaction of the near-field of the antenna with the local plasma. In addition to parasitic losses in this plasma region, voltage and current distributions on the antenna structure lead to the formation of high electric fields and RF plasma sheaths, which can lead to enhanced particle and energy fluxes on the antenna and on surfaces intersected by magnetic field lines connected to or passing near the antenna. These issues are being studied using a simple electrode structure and a single-strap antenna on the Prototype Materials Plasma EXperiment (Proto-MPEX) at ORNL, which is a linear plasma device that uses an electron Bernstein wave heated helicon plasma source to create a high-density plasma suitable for use in a plasma-material interaction test stand. Several diagnostics are being used to characterize the near-field interactions, including double-Langmuir probes, a retarding field energy analyzer, and optical emission spectroscopy. The RF electric field is being studied utilizing Dynamic Stark Effect spectroscopy and Doppler-Free Saturation Spectroscopy. Recent experimental results and future plans will be presented. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under Contract DE-AC-05-00OR22725.

  20. 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