Paulo S. André

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In this paper, we propose an efficient and accurate method that combines the Genetic Algorithm (GA) with the Nelder-Mead method in order to obtain the gain optimization of distributed Raman amplifiers. By using these two methods together, the advantages of both are combined: the convergence of the GA and the high accuracy of the Nelder-Mead. To enhance the(More)
In this work we proposed a relative humidity (RH) sensor based on a Bragg grating written in an optical fiber, associated with a coating of organo-silica hybrid material prepared by the sol-gel method. The organo-silica-based coating has a strong adhesion to the optical fiber and its expansion is reversibly affected by the change in the RH values(More)
The applicably of multi-objective optimization to ellipsometric data analysis is presented and a method to handle complex ellipsometric problems such as multi sample or multi angle analysis using multi-objective optimization is described. The performance of a multi-objective genetic algorithm (MOGA) is tested against a single objective common genetic(More)
In this paper we summarize the research activities at the Instituto de Telecomunicações--Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical(More)
All-optical flip-flops are key elements in photonics switching techniques, which justify the continuous interest to develop new solutions for high-speed and low-power one-bit memories. In this paper, a novel scheme for all-optical clocked D flip-flop based on a single Mach-Zehnder interferometer, with semiconductor optical amplifiers in both arms (SOA-MZI),(More)
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 °C and has a high TO coefficient calculated as -(4.9 ± 0.5) × 10(-4) °C(-1) at(More)
Optical cross-connects (OXC) introduce crosstalk and intersymbolic interference due to filtering in the optical signal. We show experimentally and by simulation that higher optical signal-to-noise ratio (OSNR) penalties are obtained for the combined effect of both impairments compared to the sum of the penalties taken independently. Furthermore, the(More)
This paper presents results about the refractivity tuning in IR emitting organic layers, achieved via photo-patterning. Results are used to design a channel waveguide. Optical field distribution shows a single mode profile at the end facet of the waveguide.