Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
Search results
49 records were found.
A sensor believed to be the first truly integrated optical sensor demonstrating the detection of the liquid-solid phase transition of water is presented. The condensation, freezing, melting and evaporation of water are all detected with a planar silica Bragg grating operating in the 1.5 micron telecommunications window. Additionally, use of the sensor allows recognition of supercooled liquid at temperatures below the melting point of water.
The device is fabricated by direct UV writing with simultaneous definition of the grating, a method inherently suited to integration with other technologies. The Bragg grating is exposed and water is allowed to condense over it. Interaction with the evanescent field causes small changes in effective index (5x10) which can be detected, a sufficient sensitivity to identify the phase transitions of w...
In this paper we demonstrate that a positive change in refractive index can be induced by UV radiation in bulk Pyrex, an inexpensive, commercially available glass that is not specifically designed to be photosensitive. We describe the fabrication of channel waveguides in Pyrex by direct UV writing and show that a potassium-ion exchanged layer can be used to host single mode waveguides. The change in refractive index due to the UV writing is found to be 2x10−3.
In this paper we demonstrate that a positive change in refractive index can be induced by UV radiation in bulk Pyrex, an inexpensive, commercially available glass that is not specifically designed to be photosensitive. We describe the fabrication of channel waveguides in Pyrex by direct UV writing and show that a potassium-ion exchanged layer can be used to host single mode waveguides. The change in refractive index due to the UV writing is found to be 2x10−3.
A sensor believed to be the first truly integrated optical sensor capable of detecting the liquid-solid phase transition of water is presented. The condensation, freezing, melting and evaporation of water are all detected with a planar silica Bragg grating operating in the 1.5 μm telecommunications window. Additionally, use of the sensor allows recognition of supercooled liquid at temperatures below the melting point of water.
The device, well suited for integrated optics, is fabricated by direct UV writing with simultaneous definition of the grating. The Bragg grating is exposed and water is allowed to condense over it. Interaction with the evanescent field causes small changes in effective index (5 x 10−6) which can be detected, a sufficient sensitivity to identify the phase transitions of water clearly.
We present the first experimental demonstration of an electrically tunable, first order Bragg grating using liquid crystals. Similar devices have been modelled in the past but not experimentally realised. Using direct UV writing, a waveguide and Bragg grating are simultaneously defined in a planar silica on silicon substrate. Replacement of the overcladding with liquid crystal in the vicinity of the grating allows the electro-optic properties of the liquid crystal to be exploited. Interactions of the evanescent field with the variable refractive index of the liquid crystal allow the centre wavelength of the filter response to be tuned.
Tunability of a planar waveguide Bragg filter is achieved using a nematic liquid crystal overclad. Electrically induced changes in the liquid crystal refractive index allow a Bragg wavelength tuning range of 35 GHz.
We describe the fabrication of a waveguide laser by UV-writing in neodymium doped silica-on-silicon. The substrate is fabricated by Flame Hydrolysis Deposition and solution doping techniques. Lasing at 1048-1056nm was observed with a slope efficiency of 33% and threshold of 4mW for the transition. Lasing was also observed at 1356nm.
In this paper we demonstrate that a positive change in refractive index can be induced by UV radiation in bulk Pyrex, an inexpensive, commercially available glass that is not specifically designed to be photosensitive. We describe the fabrication of channel waveguides in Pyrex by direct UV writing and show that a potassium-ion exchanged layer can be used to host single mode waveguides. The change in refractive index due to the UV writing is found to be 2x10.
Direct UV-writing is a planar lightwave circuit fabrication technique ideal for rapid prototyping and small batch fabrication. The technique is based on the refractive index increase of a glass through exposure to a tightly focused UV beam. The translation of this beam relative to a suitable substrate allows the definition of 2-d waveguide structures such as s-bends and power couplers without the need for photolithographic or subsequent processing. Traditionally, Bragg grating structures are superimposed through UV exposure onto existing waveguides, increasing the fabrication complexity (therefore time and cost) and modifying the original properties of the channel. As an alternative to traditional techniques we have developed a Direct Grating Writing technique (DGW) retaining the advantages of Direct UV writing for channel definition b...
We demonstrate single-step writing of waveguide circuits with Bragg gratings between 1227nm and 1687nm and for the first time show that the grating bandwidth can be normalised over this large wavelength range.
