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Wei, X. (author), Urbach, H.P. (author), van der Walle, P. (author), Coene, W.M.J. (author)We present a parameter retrieval method which incorporates prior knowledge about the object into ptychography. The proposed method is applied to two applications: (1) parameter retrieval of small particles from Fourier ptychographic dark field measurements; (2) parameter retrieval of a rectangular structure with realspace ptychography. The...article 2021
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Peternella, F.G. (author), Harmsma, P.J. (author), Horsten, R.C. (author), Zuidwijk, T. (author), Urbach, H.P. (author), Adam, A.J.L. (author)A new method for fast, high resolution interrogation of an array of photonic sensors is proposed. The technique is based on the integrated Fourier transform (FT) interrogator previously introduced by the authors. Compared to other interferometric interrogators, the FT-interrogator is very compact and has an unprecedented tolerance to variations...article 2021
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Westerveld, W.J. (author), Leinders, S.M. (author), Neer, P.L.M.J. (author), Urbach, H.P. (author), de Jong, N. (author), Verweij, M.D. (author), Rottenberg, X. (author), Rochus, V. (author)Future applications of ultrasonography in (bio-)medical imaging require ultrasound sensor matrices with small sensitive elements. Promising are opto-mechanical ultrasound sensors (OMUS) based on a silicon photonic ring resonator embedded in a silicon-dioxide acoustical membrane. This work presents new OMUS modelling: acousto-mechanical non...conference paper 2019
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Peternella, F.G. (author), Esselink, T. (author), Dorsman, B. (author), Harmsma, P.J. (author), Horsten, R.C. (author), Zuidwijk, T. (author), Urbach, H.P. (author), Adam, A.L.C. (author)In this paper, the design and the characterization of a novel interrogator based on integrated Fourier transform (FT) spectroscopy is presented. To the best of our knowledge, this is the first integrated FT spectrometer used for the interrogation of photonic sensors. It consists of a planar spatial heterodyne spectrometer, which is implemented...article 2019
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Westerveld, W.J. (author), Leinders, S.M. (author), van Neer, P.L.M.J. (author), Snyder, B. (author), Urbach, H.P. (author), de Jong, N. (author), Verweij, M.D. (author), Rottenberg, X. (author), Rochus, V. (author)Future applications of ultrasonography in (bio-)medical imaging require ultrasound sensor matrices with small sensitive elements. Promising are opto-mechanical ultrasound sensors (OMUS) based on a silicon photonic ring resonator embedded in a silicondioxide acoustical membrane. This work presents new OMUS modelling: acoustomechanical non-linear...conference paper 2018
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Mann, D. (author), Voogt, S. (author), van Zandvoort, R. (author), Keul, H. (author), Möller, M. (author), Verheijen, M. (author), Nascimento-Duplat, D. (author), Xu, M. (author), Urbach, H.P. (author), Adam, A.J.L. (author), Buskens, P. (author)Protecting groups are commonly applied in multi-step molecular syntheses to protect one or multiple functional groups from reacting. After the reaction, they are removed from the molecule. In full analogy to this concept, we report the practical and scalable colloidal synthesis of Au semishells using polyphenylsiloxane protecting patches to...article 2017
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Tang, Y. (author), Xi, Z. (author), Xu, M. (author), Bäumer, S.M.B. (author), Adam, A.J.L. (author), Urbach, H.P. (author)Hyperbolic metamaterials (HMMs) are anisotropic materials with a permittivity tensor that has both positive and negative eigenvalues. Here we report that by using a type II HMM as a cladding material, a waveguide that only supports higher-order modes can be achieved, while the lower-order modes become leaky and are absorbed in the HMM cladding....article 2016
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Mann, D. (author), Nascimento-Duplat, D. (author), Keul, H. (author), Möller, M. (author), Verheijen, M. (author), Xu, M. (author), Urbach, H.P. (author), Adam, A.J.L. (author), Buskens, P.J.P. (author)Au and Ag nanoshells are of interest for a wide range of applications. The plasmon resonance of such nanoshells is the property of interest and can be tuned in a broad spectral regime, ranging from the ultraviolet to the mid-infrared. To date, a large number of manuscripts have been publishedontheopticsofsuchnanoshells.Fewofthese,however,...article 2016
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van Turnhout, M. (author), van Grol, P. (author), Bociort, F. (author), Urbach, H.P. (author)We show that in the lens design landscape saddle points exist that are closely related to local minima of simpler problems. On the basis of this new theoretical insight we develop a systematic and efficient saddlepoint method that uses a-priori knowledge for obtaining new local minima. In contrast with earlier saddle-point methods, the present...article 2015
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Tang, Y. (author), Man, X. (author), Adam, A.J.L. (author), Urbach, H.P. (author)Here we report the modeling, fabrication and measurement of a type II Hyperbolic Metamaterial (HMM) consisting of 10 pairs Ag/Al2O3 subwavelength layers to demonstrate the high pass filter property of type II HMM. The HMM is deposited on the hypotenuse side of a TiO2 prism and covered with a fluorescent dye doped PMMA layer. The excitation of...conference paper 2015
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Roy, S. (author), Bouwens, M.A.J. (author), Wei, L. (author), Pereira, S.F. (author), Urbach, H.P. (author), van der Walle, P. (author)Optical detection of scatterers on a flat substrate, generally done using dark field microscopy technique, is challenging since it requires high power illumination to obtain sufficient SNR (Signal to Noise Ratio) to be able to detect sub-wavelength particles. We developed a bright field technique, based on Fourier scatterometry, with special...article 2015
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Leinders, S.M. (author), Westerveld, W.J. (author), Pozo Torres, J.M. (author), van Neer, P.L.M.J. (author), Snyder, B. (author), O'Brien, P. (author), Urbach, H.P. (author), de Jong, N. (author), Verweij, M.D. (author)With the increasing use of ultrasonography, especially in medical imaging, novel fabrication techniques together with novel sensor designs are needed to meet the requirements for future applications like three-dimensional intercardiac and intravascular imaging. These applications require arrays of many small elements to selectively record the...article 2015
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Livshits, I. (author), Hou, Z. (author), van Grol, P. (author), Shao, Y. (author), van Turnhout, M. (author), Urbach, H.P. (author), Bociort, F. (author)The present research is part of an effort to develop tools that make the lens design process more systematic. In typical optical design tasks, the presence of many local minima in the optical merit function landscape makes design non-trivial. With the method of Saddle Point Construction (SPC) which was developed recently ([F. Bociort and M. van...conference paper 2014
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Leinders, S.M. (author), van Dongen, K.W.A. (author), de Jong, N. (author), Verweij, M.D. (author), Westerveld, W.J. (author), Urbach, H.P. (author), van Neer, P.L.M.J. (author), Pozo Torres, J.M. (author)Several types of ultrasound sensors have been developed and are used in the field of medical imaging. Conventional transducers are made of piezo-electric material and show good practical performance. However, when the piezo-electric elements need to be small (below 100 μm × 100 μm), these transducers face challenges in fabrication as well as the...conference paper 2014
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Westerveld, W.J. (author), Pozo Torres, J.M. (author), Muilwijk, P.M. (author), Leinders, S.M. (author), Harmsma, P.J. (author), Tabak, E. (author), van den Dool, T.C. (author), van Dongen, K.W.A. (author), Yousefi, M. (author), Urbach, H.P. (author)Strain gauges are widely employed in microelectromechanical systems (MEMS) for sensing of, for example, deformation, acceleration, pressure, or sound [1]. Such gauges are typically based on electronic piezoresistivity. We propose integrated optical sensors which have particular benefits: insensitivity to electromagnetic interference, no danger...conference paper 2013
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Leinders, S.M. (author), van Dongen, K.W.A. (author), de Jong, N. (author), Verweij, M.D. (author), Westerveld, W.J. (author), Urbach, H.P. (author), van Neer, P.L.M.J. (author), Pozo Torres, J.M. (author)Ultrasound sensors such as piezoelectric transducers and CMUTs are successfully used for medical imaging. However, especially wiring of individual elements is difficult in the fabrication of small piezoelectric arrays, used in, e.g. the field of intravascular imaging. As an alternative, we designed a novel type of ultrasound receiver based on...conference paper 2013
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- Westerveld, W.J. (author), Pozo Torres, J.M. (author), Harmsma, P.J. (author), Schmits, R. (author), Tabak, E. (author), van den Dool, T.C. (author), Leinders, S.M. (author), van Dongen, K.W.A. (author), Urbach, H.P. (author), Yousefi, M. (author) article 2012
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- Westerveld, W.J. (author), Pozo Torres, J.M. (author), Muilwijk, P.J. (author), Harmsma, P.J. (author), Nieuwland, R.A. (author), van den Berg, J.H. (author), Tabak, E. (author), van den Dool, T.C. (author), Leinders, S.M. (author), van Dongen, K.W.A. (author), Yousefi, M. (author), Urbach, H.P. (author) conference paper 2012
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Westerveld, W.J. (author), Leinders, S.M. (author), van Dongen, K.W.A. (author), Urbach, H.P. (author), Yousefi, M. (author)Marcatili's famous approximate analytical description of light propagating through rectangular dielectric waveguides, published in 1969, gives accurate results for low-index-contrast waveguides. However, photonic-integrated circuit technology has advanced to high-index-contrast (HIC) waveguides. In this paper, we improve Marcatili's model by...article 2012
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Westerveld, W.J. (author), Leinders, S.M. (author), Pozo Torres, J.M. (author), van Dongen, K.W.A. (author), Yousefi, M. (author), Urbach, H.P. (author)Marcatili’s famous approximate analytical description of light propagating through rectangular dielectric waveguides, published in 1969, gives accurate results for low-indexcontrast waveguides. However, silicon-on-insulator (SOI) technology has become one of the focus platforms for integrated optics over the last decade, and the silicon...conference paper 2012
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