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Thursday, 03 November 2011 11:08 |
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A barcode is an optical readable representation of data, that consists of parallel lines of different widths separated by blank spaces, which contains encoded information about the object it attaches. In this paper we report on the use of high refractive index optical microcavities as photonic barcode structures. The encoding platform we show here consists of porous silicon microcavities. The intrinsic luminescence of porous silicon couples strongly to the whispering gallery modes of the microcavity resulting in a unique barcode like luminescent profile associated to each single particle. Since the photoluminescence emission of porous silicon microcavities appear in the transparent region of biological tissue it may have applications for sensing in biomedicine. |
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Porous silicon microspheres: synthesis, characterization and application to photonic microcavities |
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Monday, 20 September 2010 14:25 |
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Porous silicon microspheres have been synthesized by chemical vapour deposition of disilane gas. Their spectral signatures are similar to those of electrochemically grown porous silicon, in particular they yield photoluminescence and they show an oxidation behaviour upon their exposure to the open air. The particles are highly spherical and poly-disperse in size with diameters of approximately 0.5 to 5 micrometres, and they have a very smooth surface. Because of these reasons they work as optical microcavities with well defined resonating Mie modes. These modes have been identified in the near-infrared range. They blue-shift considerably whenever the microspheres are in contact with air because of the aforementioned oxidation process. |
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Colloidal Crystal Thin Films Grown into Corrugated Surface Templates |
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Monday, 20 September 2010 14:08 |
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The influence of patterned surfaces on the formation of one- and two-dimensional colloidal crystals is analyzed. We have used the corrugated surface of a digital versatile disc (DVD) for template surface processing. When the sphere diameter is on the order of the groove width of patterned substrates, a rich variety of particle decorations appear. However, if particle size is much larger than template patterns, large domains of particle ordering are formed. |
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Diacritical study of light, electrons and sound scattering by particles and holes |
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Monday, 14 September 2009 15:11 |
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F Javier García de Abajo, Héctor Estrada and Francisco Meseguer
New Journal of Physics 11 093013 (2009)
We discuss the differences and similarities in the interaction of scalar and vector wave fields with particles and holes. Analytical results are provided for the transmission of isolated and arrayed small holes as well as surface modes in hole arrays for light, electrons and sound. In contrast to the optical case, small-hole arrays in perforated perfect screens cannot produce acoustic or electronic surface-bound states. However, unlike electrons and light, sound is transmitted through individual holes approximately in proportion to their area, regardless of their size. We discuss these issues with a systematic analysis that allows one to explore both common properties and unique behavior in wave phenomena for different material realizations.
Find this article also in IOP Select
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Influence of lattice symmetry on ultrasound transmission through plates with subwavelength aperture arrays |
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Sunday, 13 September 2009 08:43 |
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H. Estrada, P. Candelas, A. Uris, F. Belmar, F. Javier García de Abajo and F. Meseguer Applied Physics Letters, 95 051906 (2009) | We study the transmission of sound waves through aluminum plates perforated with square and triangular hole arrays. We demonstrate both theoretically and experimentally that lattice symmetry affects the position of the Wood anomalies and the width of the transmission peaks. The angle and frequency dependence of sound transmission through perforated plates are thoroughly discussed. Finally, we observe unexpected anisotropic behavior in the long-wavelength Lamb-mode bands of perforated plates. | 
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