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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
document
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
document
Ramakrishnan, G. (author), Chakkittakandy, R. (author), Planken, P.C.M. (author)
Generation of subpicosecond terahertz pulses is observed when graphite surfaces are illuminated with femtosecond near-infrared laser pulses. The nonlinear optical generation of THz pulses from graphite is unexpected since, in principle, the material possesses a centre of inversion symmetry. Experiments with highly oriented pyrolytic graphite...
journal article 2009
document
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
document
Ramakrishnan, G. (author), Planken, P.C.M. (author)
Emission of pulses of electromagnetic radiation in the terahertz range is observed when ultrathin gold films on glass are illuminated with femtosecond near-IR laser pulses. A distinct maximum is observed in the emitted terahertz amplitude from films of average thickness just above the percolation threshold. Our measurements suggest that the...
journal article 2011
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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
document
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
document
Ramakrishnan, G. (author), Kumar, N. (author), Planken, P.C.M. (author), Tanaka, D. (author), Kajikawa, K. (author)
Emission of terahertz radiation is observed when surface plasmons are excited on a thin film of gold, in the Kretschmann geometry. When a hemicyanine-terminated alkanethiol self-assembled monolayer of thickness 1.2 nm is deposited on the gold film, stronger terahertz emission is observed. Our experimental results confirm that enhanced terahertz...
journal article 2012
document
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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