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Brusche, J.H. (author), Segal, A. (author), Urbach, H.P. (author)The finite-element method is applied to model phase-change recording in a grooved recording stack. A rigorous model for the scattering of a three-dimensional focused spot by a one-dimensional periodic grating is used to determine the absorbed light in a three-dimensional region inside the phase-change layer. The optical model is combined with a...journal article 2005
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Xu, M. (author), Urbach, H.P. (author), De Boer, D.K.G. (author), Cornelissen, H.J. (author)The application of wire grid polarizers as efficient polarizing beam splitters for visible light is studied. The large differences between the transmissivity for different polarizations are explained qualitatively by using the theory of metallic wave guides. The results of rigorous calculations obtained by using the finite element method are...journal article 2005
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Brok, J.M. (author), Urbach, H.P. (author)We discuss a mode expansion technique to rigorously model the diffraction from three-dimensional pits and holes in a perfectly conducting layer with finite thickness. On the basis of our simulations we predict extraordinary transmission through a single hole, caused by the Fabry-Perot effect inside the hole. Furthermore, we study the fundamental...journal article 2006
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De Boer, D.K.G. (author), Urbach, H.P. (author), Xu, M. (author)Poster presentation Optics Research Group TU Delft in cooperation with Philips and STWjournal article 2006
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Janssen, O.T.A. (author), Urbach, H.P. (author), 't Hooft, G.W. (author)The excitation of surface plasmons by subwavelength slits in metal films is studied using a rigorous diffraction model. It is shown that the plasmon is launched by a slit in antiphase with the incident magnetic field. This is true independent of slit width and of the metal used. Using this phase information, maxima and minima in transmission are...journal article 2006
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- Janssen, O.T.A. (author), Urbach, H.P. (author), 't Hooft, G.W. (author) journal article 2007
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Wei, X. (author), Wachters, A.J.H. (author), Urbach, H.P. (author)We present a three-dimensional model based on the finite-element method for solving the time harmonic Maxwell equation in optics. It applies to isotropic or anisotropic dielectrics and metals and to many configurations such as an isolated scatterer in a multilayer, bi-gratings, and crystals. We discuss the application of the model to near-field...journal article 2007
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Xu, M. (author), Urbach, H.P. (author), De Boer, D.K.G. (author)A color and polarization separating backlight can be obtained by using a surface-relief grating made of birefringent material as an outcoupling structure on top of the lightguide. A rigorous finite element diffraction model was applied to study the polarization effect of such a grating. The diffraction of plane waves by the anisotropic grating...journal article 2007
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Urbach, H.P. (author), Pereira, S.F. (author)Closed formulas are presented for the field in the lens pupil for which the longitudinal electric component at the focal point is larger than any other focused field with the same power. The fullwidth-at-half-maximum of the squared amplitude of the maximum longitudinal component is 15% to 30% less than that of the classical Airy spot.journal article 2008
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Xu, M. (author), De Sio, L. (author), Caputo, R. (author), Umeton, C.P. (author), Wachters, A.J.H. (author), De Boer, D.K.G. (author), Urbach, H.P. (author)Recently, a novel holographic diffraction grating made of polymer slices alternated to homogeneous films of nematic liquid crystal (POLICRYPS) was realized. We study the optical performance of the POLICRYPS gratings by both numerical simulations and experiments. Characterization of the grating at normal and conical reading mount are performed....journal article 2008
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Sluijter, M. (author), De Boer, D.K.G. (author), Urbach, H.P. (author)We present simulations of a novel liquid-crystal-based electro-optical device that enables a switching effect owing to a backreflection phenomenon. In the simulations, we exploit the optical properties of a liquid-crystal layer with a Freédericksz alignment in an unconventional way. The resulting switching effect of the proposed optical design...journal article 2008
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Sluijter, M. (author), De Boer, D.K.G. (author), Urbach, H.P. (author)Firm evidence of the biaxial nematic phase in liquid crystals, not induced by a magnetic or electric field, has been established only recently. The discovery of these biaxially anisotropic liquid crystals has opened up new areas of both fundamental and applied research. The advances in biaxial liquid crystal-related topics call for a good...journal article 2009
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Urbach, H.P. (author), Pereira, S.F. (author)Closed formulas are derived for the field in the focal region of a diffraction limited lens, such that the electric field component in a given direction at the focal point is larger than that of all other focused fields with the same power in the entrance pupil of the lens. Furthermore, closed formulas are derived for the corresponding optimum...journal article 2009
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Cui, M. (author), Zeitouny, M.G. (author), Bhattacharya, N. (author), Van den Berg, S.A. (author), Urbach, H.P. (author), Braat, J.J.M. (author)We experimentally demonstrate that a femtosecond frequency comb laser can be applied as a tool for longdistance measurement in air. Our method is based on the measurement of cross correlation between individual pulses in a Michelson interferometer. From the position of the correlation functions, distances of up to 50 m have been measured. We...journal article 2009
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Sluijter, M. (author), Herzog, A. (author), De Boer, D.K.G. (author), Krijn, M.P.C.M. (author), Urbach, P.H. (author)For the first time, to our knowledge, we report ray-tracing simulations of an advanced liquid-crystal gradientindex lens structure for application in switchable two-dimensional/three-dimensional (3D) autostereoscopic displays. We present ray-tracing simulations of the angular-dependent lens action. From the results we conclude that the lens...journal article 2009
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Sluijter, M. (author), Xu, M. (author), Urbach, H.P. (author), De Boer, D.K.G. (author)We study the applicability of geometrical optics to inhomogeneous dielectric nongyrotropic optically anisotropic media typically found in in-plane liquid-crystal configurations with refractive indices no=1.5 and ne=1.7. To this end, we compare the results of advanced ray- and wave-optics simulations of the propagation of an incident plane wave...journal article 2010
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Vuong, L.T. (author), Adam, A.J.L. (author), Brok, J.M. (author), Planken, P.C.M. (author), Urbach, H.P. (author)Circularly polarized electric fields incident on subwavelength apertures produce near-field phase singularities with phase vorticity ±1 depending on the polarization handedness. These near-field phase singularities combine with those associated with orbital angular momentum and result in polarization-dependent transmission. We produce arbitrary...journal article 2010
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Xu, M. (author), De Boer, D.K.G. (author), Van Heesch, C.M. (author), Wachters, A.J.H. (author), Urbach, H.P. (author)Polarization gratings can be realized by polarization holographic recording in photoanisotropic materials. In this paper, we study two types of polarization gratings. One is recorded with two orthogonally circularly (OC) polarized beams and the other one with two orthogonally linearly (OL) polarized beams. The interference of both cases is...journal article 2010
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Zeitouny, M.G. (author), Cui, M. (author), Bhattacharya, N. (author), Urbach, H.P. (author), Van den Berg, S.A. (author), Janssen, A.J.E.M. (author)We have investigated correlation patterns generated by a frequency-comb laser in a dispersive unbalanced Michelson interferometer and apply the developed formalism to the case of distance metrology. Due to group velocity dispersion, the position of the brightest fringe of the correlation pattern, which is used for distance determination, cannot...journal article 2010
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Janssen, O.T.A. (author), Wachters, A.J.H. (author), Urbach, H.P. (author)The incoherent emission of periodically structured Light Emitting Diodes (LEDs) can be computed at relatively low computational cost by applying the reciprocity method. We show that by another application of the reciprocity principle, the structure of the LED can be optimized to obtain a high emission. We demonstrate the method by optimizing one...journal article 2010