Joao Rosolem, Claudio Hortencio, Claudio Floridia, Danilo Dini, Rivael Penze, Bruno Aires, Fabio Bassan, Rodrigo Morbach, Eduardo da Costa, Felipe Salgado, Rodrigo Peres, João Paulo Fracarolli, Marcus Vinícius Santana, Augusto Cezar Gregatti, Guilherme Muniz, Gerson Amadeo, Gilson Carvalho, Fernando Pertile, Luis Fernando Melegari, Heloisa Herreros, Marcelo Kurokawa, Luis de Avila
This paper presents the results of a field test of a multi-parameters' monitoring network using FBGs adapted directly in the conventional instruments of two dams which are in full operational capability. We presented the details of the design and tests of the sensor’s network, such as, the sensors adaptation, the resolution comparison between the conventional instruments and the FBGs, the network topology, the spectral occupancy distribution considering the parameters optical bandwidth and also the temperature compensation for FBGs, the number of sensors by fiber and the performance of the FBGs sensors compared with the conventional instruments used in the Dams.
In this work, we designed and recorded two-dimensional Hexagonal Photonic Crystals (2D-HPC) layers, with a linear waveguide, in erbium doped GeO2-Bi2O3-PbO-TiO2 glassy films, by combining the techniques of holographic recording and femtosecond (fs) laser micromachining. The 2D-HPC is recorded holographically in a photoresist film coated on a glass substrate by exposing the sample to the same interference pattern twice and rotating the sample of 60° between the exposures. After the development a two dimensional hexagonal array of photoresist columns remain on the glass substrate. The recording of the waveguide is made by a fs laser micromachining system focused at sample surface. The laser spot produces the ablation of the photoresist columns generating a defect line in the periodic hexagonal array. After the recording of the photoresist template, the erbium doped GeO2-Bi2O3-PbO-TiO2 film is evaporated on the photoresist and finally the photoresist template is removed using acetone. The design of the geometrical parameters of the 2D-HPC is performed by calculation of the dispersion mode curves of the photonic crystal using a 2D finite element method. The proper geometrical parameters depend on both the refractive index of the glass film and thickness. Such parameters as well as the period of the 2D-HPC have been defined in order to obtain a photonic band gap in the region of erbium luminescence band. In such condition the erbium luminescence will propagate only through the waveguide.
Holographic techniques are powerful tools to study photosensitive materials due to the high sensitivity of diffraction measurement and the ability to detect dynamic gratings. The self diffraction technique consists in to project an interference fringe pattern into the photosensitive material and to measure, in real time, the self-diffraction of the interfering beams, at the grating generated in the photosensitive material. Besides the higher sensitivity, such measurement allows to measure simultaneously and separately the phase and the amplitude grating contributions, as well as thin or thick gratings. In order to demonstrate potentiality of this technique we measured the kinetic constant of the photo-reaction in positive photoresists (AZ types) and negative SU-8 photoresist, as well as the maximum values of the refractive index and of the absorption coefficient modulations induced in these materials at different wavelengths of exposure. The same measurements were performed in SB based chalcogenide glasses in order to evaluate the potential of such materials to be used as optical data storage devices.
KEYWORDS: Optical fibers, Signal attenuation, Silica, Glasses, Dispersion, Supercontinuum generation, Fiber to the x, Fabrication, Nonlinear optics, Single mode fibers
Conventional core/clad optical fibers composed of all-solid silica material were fabricated using the "stack and draw"
technique. The optical fiber consists of Ge-doped silica glass in the core and un-doped silica glass in the clad. The optical
attenuation and the chromatic dispersion spectra of these optical fibers, with their external diameters of 212, 176, 150
and 125 μm, were characterized by using a PK2500 and a PK2800 instrument respectively. The attenuation of these
optical fibers, at 1550 nm, was approximately 5 dB/km and the zero-dispersion-wavelength range from 1350 to 1370 nm.
On the other hand, bend loss spectra of these fibers were characterized by using small bend diameter rods (bend
diameters from 2.5 to 10 mm). The bend loss spectra show that these all-solid optical fibers are almost insensitive to
bend effect. In addition we explore the nonlinear properties of these fibers to investigate the potential for supercontinuum
generation.
In this work we studied the changes of the optical constants of films in the binary system Sb2O3-Sb2S3 induced by light in
the VIS-UV. The measurements were performed before and after homogeneous irradiation of the films to a Hg lamp and
in real time during the holographic exposure of the samples (at 458nm). Changes of the absorption coefficient (amplitude
grating) and refractive index (phase grating) were measured simultaneously using the self-diffraction using the
holographic setup. Besides the films presented a strong photodarkening effect under homogeneous irradiation, the
samples holographically exposed presented only refractive index modulations. None amplitude modulation was
measured in real time for spatial frequencies of about 1000 l/mm.
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