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Planken, P.C.M. (author), van Son, P.C. (author), Hovenier, J.N. (author), Klaassen, T.O. (author), Wenckebach, W.Th. (author), Murdin, B.N. (author), Knippels, G.M.H. (author)
journal article 1995
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Pellemans, H.P.M. (author), Planken, P.C.M. (author)
journal article 1998
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Van der Valk, N.C.J. (author), Planken, P.C.M. (author)
We report on a method to obtain a subwavelength resolution in terahertz time-domain imaging. In our method, a sharp copper tip is used to locally distort and concentrate the THz electric field. The distorted electric field, present mainly in the near field of the tip, is electro-optically measured in an (100) oriented GaP crystal. By raster...
journal article 2002
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Wang, K. (author), Mittleman, D.M. (author), Van der Valk, N.C.J. (author), Planken, P.C.M. (author)
We have performed measurements on terahertz (THz) apertureless near-field microscopy that show that the temporal shape of the observed near-field signals is approximately proportional to the time-integral of the incident field. Associated with this signal change is a bandwidth reduction by approximately a factor of 3 which is observed using both...
journal article 2004
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Van der Valk, N.C.J. (author), Planken, P.C.M. (author), Buijserd, A.N. (author), Bakker, H.J. (author)
We present measurements on terahertz generation by optical rectification, in which both the thickness of the generation crystal and the wavelength of the generating optical pulse are varied. The difference between the group velocity at optical frequencies and the phase velocity at terahertz frequencies affects the time trace and spectrum of the...
journal article 2005
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Van der Valk, N.C.J. (author), Planken, P.C.M. (author)
The authors present measurements and calculations on the effect of thin dielectric coatings on the propagation of terahertz pulses along the surface of metal wires. Our measurements show that propagation over only a few centimeters of wire having a thin dielectric coating, strongly distorts the terahertz pulse, which results in a several tens of...
journal article 2005
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Van der Valk, N.C.J. (author), Van der Marel, W.A.M. (author), Planken, P.C.M. (author)
We present a new method to measure the polarization state of a terahertz pulse by using a modified electrooptic sampling setup. To illustrate the power of this method, we show two examples in which the knowledge of the polarization of the terahertz pulse is essential for interpreting the results: spectroscopy measurements on polystyrene foam and...
journal article 2005
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Lee, J.W. (author), Seo, M.A. (author), Park, D.J. (author), Kim, D.S. (author), Jeoung, S.C. (author), Lienau, C. (author), Park, Q.H. (author), Planken, P.C.M. (author)
Terahertz transmission filters have been manufactured by perforating metal films with various geometric shapes using femtosecond laser machining. Two dimensional arrays of square, circular, rectangular, cshaped, and epsilon-shaped holes all support over 99% transmission at specific frequencies determined by geometric shape, symmetry,...
journal article 2006
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Deibel, J.A. (author), Berndsen, N. (author), Wang, K. (author), Mittleman, D.M. (author), Van der Valk, N.C.J. (author), Planken, P.C.M. (author)
We report on the emission patterns from THz plasmons propagating towards the end of cylindrical metal waveguides. Such waveguides exhibit low loss and dispersion, but little is known about the dynamics of the terahertz radiation at the end of the waveguide, specifically in the near- and intermediate-field. Our experimental results and numerical...
journal article 2006
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Adam, A.J.L. (author), Van der Valk, N.C.J. (author), Planken, P.C.M. (author)
We present measurements and calculations of the terahertz (THz) electric field measured in the near field of a metal tip used in THz apertureless near-field optical microscopy (THz-ANSOM). An analytical model in which we treat the metal tip as a linear wire antenna allows us to predict almost all of the features observed in the measurements,...
journal article 2007
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Seo, M.A. (author), Adam, A.J.L. (author), Kang, J.H. (author), Lee, J.W. (author), Jeoung, S.C. (author), Park, Q.H. (author), Planken, P.C.M. (author), Kim, D.S. (author)
We present 2D measurements of the full THz electric field behind a sample consisting of multiple slits in a metal foil. Our measurements, which have a sub-wavelength spatial, and a sub-period temporal resolution, reveal electric field lines, electric field vortices and saddle points. From our measurements we are able to reconstruct the magnetic...
journal article 2007
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Ahn, K.J. (author), Lee, K.G. (author), Kihm, H.W. (author), Seo, M.A. (author), Adam, A.J.L. (author), Planken, P.C.M. (author), Kim, D.S. (author)
journal article 2008
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Adam, A.J.L. (author), Brok, J.M. (author), Seo, M.A. (author), Ahn, K.J. (author), Kim, D.S. (author), Kang, J.H. (author), Park, Q.H. (author), Nagel, M. (author), Planken, P.C.M. (author)
Using terahertz-light excitation, we have measured with sub-wavelength spatial, and sub-cycle temporal resolution the time- and frequency-dependent electric-field and surface-charge density in the vicinity of small metallic holes. In addition to a singularity like concentration of the electric field near the hole edges, we observe, that holes...
journal article 2008
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Chakkittakandy, R. (author), Corver, J.A.W.M. (author), Planken, P.C.M. (author)
We describe a simple terahertz (THz) time domain spectrometer with a bandwidth extending up to 7.5 THz. We show that by keeping the generation and detection crystals close to each other a high signal-to-noise ratio (SNR) can be achieved without using lock-in detection and dry nitrogen flushing. The observed spectra show very good agreement with...
journal article 2008
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Kihm, H.W. (author), Lee, K.G. (author), Seo, M.A. (author), Ahn, K.J. (author), Adam, A.J.L. (author), Kang, J.H. (author), Park, Q.H. (author), Planken, P.C.M. (author), Kim, D.S. (author)
We study the dielectric constant dependent diffraction phenomena of single slit apertures, both theoretically and experimentally. We experimentally simulate perfect metal and real metal cases by investigating subwavelength diffraction by a single slit, both in nano-optical and in terahertz regimes, keeping the slit-width/wavelength ratio...
conference paper 2008
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Planken, L. (author), De Weerdt, M.M. (author), Van der Krogt, R.P.J. (author)
The Simple Temporal Problem (STP) is a sub-problem of almost any planning or scheduling problem involving time constraints. An existing efficient method to solve the STP, called ?STP, is based on partial path consistency and starts from a chordal constraint graph. In this paper, we analyse this algorithm and show that there exist instances for...
conference paper 2008
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Seo, M.A. (author), Adam, A.J.L. (author), Kang, J.H. (author), Lee, J.W. (author), Ahn, K.J. (author), Park, Q.H. (author), Planken, P.C.M. (author), Kim, D.S. (author)
We performed terahertz near-field experiments on single rectangular holes with various lengths grown on an electro-optic crystal substrate with ?/100 resolution. We find that the near-field amplitude becomes proportionally larger as the rectangle becomes narrower, strongly suggesting that a constant energy passes through even for a very narrow...
journal article 2008
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Adam, A.J.L. (author), Brok, J.M. (author), Seo, M.A. (author), Ahn, K.J. (author), Kim, D.S. (author), Kang, J.H. (author), Park, Q.H. (author), Nagel, M. (author), Planken, P.C.M. (author)
An erratum is presented to correct an error in the discussion section of [Opt. Express. 16, 7407-7417 (2008)] and to add a relevant reference on earlier work.
journal article 2008
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Adam, A.J.L. (author), Planken, P.C.M. (author), Meloni, S. (author), Dik, J. (author)
We show terahertz reflection images of hidden paint layers in a painting on canvas and compare the results with X-ray Radiography and Infrared Reflectography. Our terahertz measurements show strong reflections from both the canvas/paint interface and from the raw umber/lead white interface, indicating sufficient refractive-index contrast. Our...
journal article 2009
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Nielsen, K. (author), Rasmussen, H.K. (author), Adam, A.J.L. (author), Planken, P.C.M. (author), Bang, O. (author), Jepsen, P.U. (author)
We report on a new class of polymer photonic crystal fibers for low-loss guidance of THz radiation. The use of the cyclic olefin copolymer Topas, in combination with advanced fabrication technology, results in bendable THz fibers with unprecedented low loss and low material dispersion in the THz regime.We demonstrate experimentally how the...
journal article 2009
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