13 documents found, page 1 of 2
Waveguide features in self-patternable amine functionalized organic-inorganic h...
Ferreira, R. A. Sa; Andre, P. S.; Nogueira, R.; Vicente, C.; Macedo, A. G.; Maia, L. J. Q. [UNESP]; Carlos, L. D.; Ribeiro, S. J. L.; IEEEMade available in DSpace on 2020-12-10T16:34:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-01-01; Fundacao para a Ciencia e Tecnologia (Portuguese agency); FEDER; POCI; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); FCT; We report the use of organ...
Fabrication and optical properties of thin films with sol-gel derived di-ureasi...
Vicente, C. M. S.; Fu, L.; Andre, P. S.; de Zea Bermudez, V.; Ferreira, R. A. S.We report the fabrication and the structural and optical characterization of transparent spin coated films (average thickness values of 4.9 +/- 0.1 mu m) of organic-inorganic hybrids (di-ureasils) doped with the Disperse Red 1 (DR1) chromophore. The refractive index was measured by prism coupling and spectroscopic ellipsometry revealing that the inclusion of DR1 induces a refractive index increase of similar to...
Relative humidity sensing using micro-cavities produced by the catastrophic fus...
Alberto, N.; Tavares, C.; Domingues, M. F.; Correia, S. F. H.; Marques, C.; Antunes, P.; Pinto, J. L.; Ferreira, R. A. S.; Andre, P. S.Air humidity is a parameter with relevant interest to a wide variety of areas, both in industry or in domestic processes. Due to the growing demand on air humidity monitors, especially relative humidity, the development of sensors to assess this parameter has been increasing. Moreover, in the last years, the optical fibre based technology has been overcoming some disadvantages and limitations presented by the s...
Long range energy transfer in graphene hybrid structures
Goncalves, Hugo; Bernardo, Cesar; Moura, Cacilda; Ferreira, R. A. S.; Andre, P. S.; Stauber, Tobias; Belsley, Michael; Schellenberg, PeterIn this work we quantify the distance dependence for the extraction of energy from excited chromophores by a single layer graphene flake over a large separation range. To this end hybrid structures were prepared, consisting of a thin (2 nm) layer of a polymer matrix doped with a well chosen strongly fluorescent organic molecule, followed by an un-doped spacer layer of well-defined thicknesses made of the same p...
Flexible 90 degrees Hybrid Coupler for Coherent Optical Systems Based on Organi...
Bastos, A. R. N.; Vicente, C. M. S.; Carlos, L. D.; Lima, M.; Andre, P. S.; Ferreira, R. A. S.The next generation of optical networks requires the development of optical technology that supports high bandwidth, such as the coherent systems. The coherent detection allows the in-phase and quadrature components of a QPSK signal to be extracted as a result of the interference with a local oscillator. An integrated optics flexible 90 degrees hybrid coupler device based on a single organic-inorganic di-ureasi...
Sensing Structure Based on Surface Plasmon Resonance in Chemically Etched Singl...
Coelho, L.; de Almeida, J. M. M. M.; Santos, J. L.; Ferreira, R. A. S.; Andre, P. S.; Viegas, D.Many optical systems based on surface plasmon resonance (SPR) have been developed for working as refractometers, chemical sensors or even for measuring the thickness of metal and dielectric thin films. Sensors based on SPR present very high sensitivity to refractive index (RI) variations when compared to the traditional RI sensors. However, these kinds of systems are usually large, expensive and therefore canno...
Polarization State Control Using Thermo-Optic Effect in Organic-Inorganic Hybri...
Vicente, C. M. S.; Lima, P. P.; Bermudez, V. De Zea; Carlos, L. D.; Andre, P. S.; Ferreira, R. A. S.In this work, we report an integrated tunable wave-plate based on thermo-optic (TO) effect on a waveguide patterned by direct UV laser writing on films of organic-inorganic hybrid materials. The temperature of the waveguide was tuned inducing phase retardation between transverse electric and transverse magnetic modes. The TO coefficient of the planar waveguide is (-4.9 +/- 0.3) x10(-4) degrees C-1 at 1550 nm. A...
Fabrication of low-cost thermo-optic variable wave plate based on waveguides pa...
Vicente, C. M. S.; Lima, P. P.; de Zea Bermudez, V.; Carlos, L. D.; Andre, P. S.; Ferreira, R. A. S.An integrated variable wave plate device based on a thermo-optic (TO) effect was fabricated by patterning a waveguide channel through direct UV laser writing on the surface of sol-gel derived organic-inorganic hybrid (di-ureasil) films. The di-ureasil layer is stable up to 250 degrees C and has a high TO coefficient calculated as -(4.9 +/- 0.5) x 10(-4) degrees C-1 at 1550 nm. The waveguide temperature was tune...
Colour multiplexing of quick-response (QR) codes
Andre, P. S.; Ferreira, R. A. S.The storage capacity of a quick-response (QR) code is limited, which can inhibit several applications. A novel approach to multiplex data to improve the QR code capacity based on colour multiplexing is presented. A model was proposed to determine the recognition rate as a function of the multiplexing density and noise. Experimentally, the increase of the storage capacity by a factor of six times per unit area w...
Low-cost spectrograph based on a WebCam: a student project
Trindade, A.; Falcao, B.; Carramate, L. F. N. D.; Marques, M. I. S. F.; Ferreira, R. A. S.; Andre, P. S.This work describes the implementation of a low-cost spectrometer produced with common objects and proposed as a pedagogical students' project. This task aims to introduce the theme of image detection and to stimulate the students to develop skills in the field of optics and photonics. The performance of the developed spectrometer was tested in the characterisation of several sources such as light emitting diod...