Near-Field Microscopy

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Oleg Mitrofanov - One of the best experts on this subject based on the ideXlab platform.

  • Probe-Sample Interaction in Aperture-type THz Near-Field Microscopy of Complementary Resonators
    2019 44th International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2019
    Co-Authors: Lucy Hale, Igal Brener, Janine Keller, Tom Siday, Rodolfo I. Hermans, Johannes Haase, John L. Reno, Giacomo Scalari, Jérôme Faist, Oleg Mitrofanov
    Abstract:

    Subwavelength complementary metallic resonators operating in the terahertz (THz) regime are investigated with aperture Near-Field Microscopy and spectroscopy. In contrast to far-field methods, the spectra of individual isolated resonators can be retrieved. We find that we can experimentally gain spectral information without modifying the spectral properties of the resonator with the aperture-type Near-Field probe by operating it at a separation distance greater than 10 μm.

  • Resonant scattering probes for terahertz Near-Field Microscopy
    Quantum Sensing and Nano Electronics and Photonics XV, 2018
    Co-Authors: Thomas Siday, Michele Natrella, Jiang Wu, Oleg Mitrofanov
    Abstract:

    We propose and demonstrate a scattering-type Near-Field probe, designed to increase the sensitivity of high-resolution scattering probe Microscopy at terahertz (THz) frequencies. For efficient scattering of THz radiation, the probe, fabricated from indium, is designed to resonate like a dipole antenna. Efficient excitation is achieved by integrating the probe with a radially-polarized THz source. Using time-domain spectroscopy (TDS), we observe resonant enhancement of the scattered fields, and using aperture-type Near-Field Microscopy, we see high field confinement at the scattering probe apex.

  • Terahertz Near-Field Microscopy using the self-mixing effect in a quantum cascade laser
    2016 41st International Conference on Infrared Millimeter and Terahertz waves (IRMMW-THz), 2016
    Co-Authors: Paul Dean, Oleg Mitrofanov, James Keeley, Iman Kundu, Lianhe Li, Edmund H. Linfield, Giles A. Davies
    Abstract:

    We demonstrate terahertz (THz) apertureless Near-Field Microscopy exploiting the self-mixing effect in a quantum cascade laser (QCL). A THz wave is scattered by a sharp needle positioned above an object and coupled back into the QCL cavity resulting in detection of the THz Near-Field signal through the self-mixing effect. Using this technique we demonstrate two-dimensional imaging at 2.53 THz with a spatial resolution of 1 μm - the highest image resolution achieved with a THz frequency QCL to date. This method offers an experimentally simple approach to coherent, high-resolution THz imaging.

  • THz Near-Field Microscopy of graphene structures
    Proceedings of SPIE, 2013
    Co-Authors: Oleg Mitrofanov, C. Berger, Walter A. De Heer, W. Yu, Igal Brener, Robert J. Thompson, Yuxuan Jiang, Z Jiang
    Abstract:

    Properties of graphene can be tuned electrically and chemically, providing a promising system for application in terahertz (THz) devices. Graphene response can be enhanced even further by means of coupling electromagnetic waves into plasmon modes, frequency of which is controlled by geometrical parameters. To probe excitation of confined plasmon modes and surface wave excitation, epitaxial graphene and its structures are investigated using THz Near-Field Microscopy. Detected Near-Field images suggest excitation of THz surface waves occurring at graphene edges, similar to that observed at metallic edges, and excitation of confined plasmon modes. We will also discuss the impact of graphene inhomogeneity on local THz transmission properties on the sub-wavelength scale.

  • Sensing applications of THz Near-Field Microscopy
    Sensors, 2013
    Co-Authors: Oleg Mitrofanov
    Abstract:

    Terahertz Near-Field Microscopy enables THz spectroscopy analysis for a range of scientific and industrial applications. Recently developed THz Near-Field probe instrumentation and sensing applications will be discussed.

Roland Kersting - One of the best experts on this subject based on the ideXlab platform.

  • Terahertz Near-Field Microscopy
    Advances in Solid State Physics, 2020
    Co-Authors: Roland Kersting, F.f. Buersgens, Guillermo P. Acuna
    Abstract:

    We report on apertureless terahertz (THz) Microscopy and its application for semiconductor characterization. Extreme subwavelength resolutions down to 150nm are achieved with few-cycle THz pulses having a bandwidth of 3THz. The imaging mechanism is characterize by time-resolved THz techniques. We find that apertureless THz Microscopy can be well described by the electronic resonance of the scanning-tip interacting with the sample’s surface. The capacitance between tip and surface is a key parameter, which provides insight into the local high frequency permittivity of the semiconductor structure. Applying electromodulation techniques allows for imaging electronic charge distributions in microstructured semiconductors. The sensitivity of THz Microscopy suffices to detect as few as about 5000 electrons.

  • Terahertz near field Microscopy of metamaterials
    2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science, 2008
    Co-Authors: Guillermo P. Acuna, Hou-tong Chen, Roland Kersting, Florian Kuchler, Antoinette J. Taylor, Arthur C. Gossard
    Abstract:

    We apply terahertz Microscopy for studying metamaterials with resonances in the terahertz band. The data provide insight into the metamaterialpsilas local response on scales much smaller than the unit cell of the structure.

  • Apertureless terahertz Near-Field Microscopy
    Semiconductor Science and Technology, 2005
    Co-Authors: Hou-tong Chen, Simon Kraatz, Nicholas Karpowicz, Roland Kersting
    Abstract:

    Terahertz Near-Field Microscopy may serve as a novel tool to measure the high-frequency permittivity of dielectric surfaces on submicrometre semiconductor structures. We present an apertureless THz Near-Field microscope, which allows for spatial resolutions as small as 150 nm. A new model has been developed that considers the field coupling the scanning probe with a sample and reproduces the image data qualitatively and quantitatively.

  • Terahertz Near-Field Microscopy
    Nanosensing: Materials and Devices, 2004
    Co-Authors: Hou-tong Chen, Roland Kersting
    Abstract:

    We report on the development of an apertureless scanning Near-Field optical microscope for characterization of dielectric properties of nano-structures at terahertz frequencies. A spatial resolution of ≈ 150 nm is achieved, which corresponds to a sub-wavelength factor of ≈1/1000. The imaging mechanism is due to a resonant coupling between light field and the tip-surface system. This allows for image contrasts which exceed those can be expected from Mie scattering by orders of magnitude. Terahertz images of organic and inorganic structures show that the apertureless terahertz Microscopy gives insight into the dielectric properties on submicron scale.

  • Identification of a resonant imaging process in apertureless Near-Field Microscopy.
    Physical Review Letters, 2004
    Co-Authors: Hou-tong Chen, Simon Kraatz, Roland Kersting
    Abstract:

    : We report on apertureless Near-Field Microscopy in the far infrared. We identify a configurational resonance of the scanning tip-surface system to be the dominating mechanism that forms the image. Experimental data such as the high imaging contrast and its spectral properties can be well explained and make the framework of a mesoscopic resonance an alternative to conventional scattering models that are used to interpret Near-Field data. Our findings are plausibly not restricted to the far infrared and may impact on Near-Field spectroscopy in general.

Technology Delft - One of the best experts on this subject based on the ideXlab platform.

  • Towards terahertz Near-Field Microscopy
    Philosophical Transactions of the Royal Society of London Series a-Mathematical Physical and Engineering Sciences, 2004
    Co-Authors: Nick C. J. Van Der Valk, Paul C. M. Planken, Technology Delft
    Abstract:

    We have detected sub-wavelength spot sizes in the Near-Field of a metal tip, which is illuminated with terahertz (THz) pulses. The THz Near-Field is detected by using electro-optic detection in a (100) oriented GaP crystal. Contrary to conventional electro-optic detection, which uses (110) oriented detection crystals, (100) crystals only allow the detection of THz light, polarized perpendicular to our crystal surface. This component is strongly localized near the apex of the tip, which has sub-wavelength dimensions. The detection process is blind to the incident THz radiation, which is polarized parallel to the crystal surface. As a result, a sub-wavelength THz spot size with an intensity full-width half maximum (FWHM) diameter of lambda/200 is observed.

Daniel M. Mittleman - One of the best experts on this subject based on the ideXlab platform.

  • A study of background signals in terahertz apertureless Near-Field Microscopy and their use for scattering-probe imaging
    Journal of Applied Physics, 2009
    Co-Authors: Victoria Astley, Hui Zhan, Rajind Mendis, Daniel M. Mittleman
    Abstract:

    Apertureless Near-Field Microscopy is an imaging technique in which a small metal tip is held close to a surface, converting evanescent waves to propagating waves and permitting extreme subwavelength spatial resolution. This technique has recently been adapted for use in the terahertz region of the spectrum. Here, the interpretation of the measured signals and the suppression of background scattering can be complicated by the extremely broad bandwidth of the terahertz source and by the coherent (i.e., phase-sensitive) detection of the scattered radiation. We have analyzed the use of tip-sample distance modulation for the removal of background signals. We find that significant background signals, originating from scattering off the probe tip, can be observed even after modulation. These background signals result from path-length difference modulation, and thus are relevant when phase-sensitive detection is used. We use a dipole antenna model to explain the spatial variation in the scattered signal. Since t...

  • The metal-insulator transition in VO2 studied using terahertz apertureless Near-Field Microscopy
    Applied Physics Letters, 2007
    Co-Authors: Hui Zhan, Victoria Astley, Michael Hvasta, Jason A. Deibel, Daniel M. Mittleman
    Abstract:

    We have studied the metal-insulator transition in a vanadium dioxide (VO2) thin film using terahertz apertureless Near-Field optical Microscopy. We observe a variation of the terahertz amplitude due to the phase transition induced by an applied voltage across the sample. The change of the terahertz signal is related to the abrupt change of the conductivity of the VO2 film at the metal-insulator transition. The subwavelength spatial resolution of this Near-Field Microscopy makes it possible to detect signatures of micron-scale metallic domains in inhomogeneous VO2 thin films.

  • Plasmon-enhanced terahertz Near-Field Microscopy
    2007 Conference on Lasers and Electro-Optics (CLEO), 2007
    Co-Authors: Victoria Astley, Hui Zhan, Daniel M. Mittleman, Peter Nordlander
    Abstract:

    Using terahertz apertureless Near-Field Microscopy, we observe an electromagnetic field enhancement produced by a broadband plasmon resonance localized in the junction between a metal probe tip and a sub-micron-thick metallic substrate.

  • Terahertz apertureless Near-Field Microscopy of a vanadium dioxide thin film
    2007 Conference on Lasers and Electro-Optics (CLEO), 2007
    Co-Authors: Hui Zhan, Victoria Astley, Michael Hvasta, Jason A. Deibel, Daniel M. Mittleman
    Abstract:

    We report the application of terahertz apertureless Near-Field Microscopy to vanadium dioxide thin films. We observe an enhancement of the terahertz amplitude due to the metal-insulator transition induced by an applied voltage.

Paul C. M. Planken - One of the best experts on this subject based on the ideXlab platform.

  • Terahertz Near-Field Microscopy
    2005 Quantum Electronics and Laser Science Conference, 2005
    Co-Authors: Paul C. M. Planken, C.w.e.m. Van Rijmenam, N.c.j. Van Der Valk
    Abstract:

    We present results on the spatial extent and origin of the Near-Field of a metal tip and the first measurement on a crystal of CsI using THz apertureless scanning Near-Field optical Microscopy.

  • THz Near-Field Microscopy
    Optical Terahertz Science and Technology, 2005
    Co-Authors: Paul C. M. Planken, C.w.e.m. Van Rijmenam, N.c.j. Van Der Valk
    Abstract:

    We present results on the spatial extent and origin of the Near-Field of a metal tip and the first measurement of a phonon resonance in THz apertureless scanning Near-Field optical Microscopy.

  • Towards terahertz Near-Field Microscopy
    Philosophical Transactions of the Royal Society of London Series a-Mathematical Physical and Engineering Sciences, 2004
    Co-Authors: Nick C. J. Van Der Valk, Paul C. M. Planken, Technology Delft
    Abstract:

    We have detected sub-wavelength spot sizes in the Near-Field of a metal tip, which is illuminated with terahertz (THz) pulses. The THz Near-Field is detected by using electro-optic detection in a (100) oriented GaP crystal. Contrary to conventional electro-optic detection, which uses (110) oriented detection crystals, (100) crystals only allow the detection of THz light, polarized perpendicular to our crystal surface. This component is strongly localized near the apex of the tip, which has sub-wavelength dimensions. The detection process is blind to the incident THz radiation, which is polarized parallel to the crystal surface. As a result, a sub-wavelength THz spot size with an intensity full-width half maximum (FWHM) diameter of lambda/200 is observed.

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