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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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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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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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Zimmerling, J.T. (author), Wei, L. (author), Urbach, H.P. (author), Remis, R.F. (author)We present a Krylov model-order reduction approach to efficiently compute the spontaneous decay (SD) rate of arbitrarily shaped 3D nanosized resonators. We exploit the symmetry of Maxwell’s equations to efficiently construct so-called reduced-order models that approximate the SD rate of a quantum emitter embedded in a resonating nanostructure....journal article 2016
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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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El Gawhary, O. (author), Pereira, S.F. (author), Urbach, H.P. (author)Providing a femtosecond optical pulse with a proper transverse spatial profile represents a fast and relatively simple method to force a quantum system to follow a prescribed temporal evolution. In the present work, we show that the quantum system presents a surprisingly high sensitivity with respect to the spatial shape of the pulse. We discuss...journal article 2011
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Roy, S. (author), Assafrao, A.C. (author), Pereira, S.F. (author), Urbach, H.P. (author)Inspection tools for nano-particle contamination on a planar substrate surface is a critical problem in micro-electronics. The present solutions are either expensive and slow or inexpensive and fast but have low sensitivity because of limitations due to diffraction. Most of them are also substrate specific. In this article we report how Coherent...journal article 2014
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Westerveld, W.J. (author), Pozo, J. (author), Leinders, S.M. (author), Yousefi, M. (author), Urbach, H.P. (author)We investigate directional couplers in silicon-on-insulator photonic technology. We theoretically and experimentally demonstrate a large coupling-induced phase delay that occurs when nearly all light is coupled from one waveguide to the other, i.e., when the coupler operates as a cross-coupler. We show that even a tiny asymmetry in the two...journal article 2013
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El Gawhary, O. (author), Kumar, N. (author), Pereira, S.F. (author), Coene, W.M.J. (author), Urbach, H.P. (author)Scatterometry is a well established technique currently utilized in research, as well as in industrial applications, to retrieve the properties of a given scatterer (the target) by looking at how the light coming from a certain source is diffracted in the far field. Currently the light source is often a discharge lamp that, after wavelength...journal article 2011
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Roy, S. (author), Ushakova, K. (author), Van den Berg, Q. (author), Pereira, S.F. (author), Urbach, H.P. (author)A fast noninvasive method based on scattering from a focused radially polarized light to detect and localize subwavelength nanoparticles on a substrate is presented. The technique relies on polarization matching in the far field between scattered and spurious reflected fields. Results show a localization uncertainty of ?10?4?2 is possible for a...journal article 2015
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El Gawhary, O. (author), Wiegmann, A. (author), Kumar, N. (author), Pereira, S.F. (author), Urbach, H.P. (author)Through-focus phase retrieval methods aim to retrieve the phase of an optical field from its intensity distribution measured at different planes in the focal region. By using the concept of spatial correlation for propagating fields, for both the complex amplitude and the intensity of a field, we can infer which planes are suitable to retrieve...journal article 2013
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Reyes Reyes, A. (author), Hou, Z. (author), Van Mastrigt, E. (author), Horsten, R.C. (author), De Jongste, J.C. (author), Pijnenburg, M.W. (author), Urbach, H.P. (author), Bhattacharya, N. (author)We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm?1. Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present in a complex gas mixture without any pre...journal article 2014
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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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Assafrao, A.C. (author), Wachters, A.J.H. (author), Verheijen, M. (author), Nugrowati, A.M. (author), Pereira, S.F. (author), Urbach, H.P. (author), Armand, M.F. (author), Olivier, S. (author)Under appropriate laser exposure, a thin film of InSb exhibits a sub-wavelength thermally modified area that can be used to focus light beyond the diffraction limit. This technique, called Super-Resolution Near-Field Structure, is a potential candidate for ultrahigh density optical data storage and many other high-resolution applications. We...journal article 2012
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Ushakova, K. (author), Van den Berg, Q.Y. (author), Pereira, S.F. (author), Urbach, H.P. (author)Spot size reduction is demonstrated by printing focused spots from amplitude-modulated radially polarized light at the wavelength ? = 405 nm on a photoresist. Amplitude modulation is realized by ring illumination and by application of an optimized amplitude distribution function. Amplitude modulation is implemented via spatial light modulator,...journal article 2015
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Kim, M.S. (author), Scharf, T. (author), Da Costa Assafrao, A. (author), Rockstuhl, C. (author), Pereira, S.F. (author), Urbach, H.P. (author), Herzig, H.P. (author)Bessel-Gauss beams are known as non-diffracting beams. They can be obtained by focusing an annularly shaped collimated laser beam. Here, we report for the first time on the direct measurement of the phase evolution of such beams by relying on longitudinal-differential interferometry. We found that the characteristics of Bessel-Gauss beams cause...journal article 2012
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Westerveld, W.J. (author), Urbach, H.P. (author), Yousefi, M. (author)We present an accurate and fast 3D simulation scheme for out-of-plane grating couplers, based on two dimensional rigorous (finite difference time domain) grating simulations, the effective index method (EIM), and the Rayleigh-Sommerfeld diffraction formula. In comparison with full 3D FDTD simulations, the rms difference in electric field is...journal article 2011
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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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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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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