Abstract
Birefringence tunability is demonstrated in waveguides formed in bulk fused silica and in the core of single mode fibers, by femtosecond laser writing of stress inducing tracks that are placed with different geometries around the core of the waveguides. The femtosecond laser generated stress effect was probed by the birefringence induced spectral splitting of either Bragg grating waveguides in bulk fused silica or weakly modulated, femtosecond laser induced Bragg gratings in optical fibers. Birefringence values as low as 4 x 10(-6) and up to 2 x 10(-3) were obtained by controlling the fabrication conditions such as the laser pulse energy, the writing femtosecond laser polarization, the number of overwriting exposures, and the geometry of the induced stress tracks. Wave retarders are developed and characterized by a cross polarization technique to provide the spectral response of the stress induced birefringence, offering the convenient fabrication of short length and broadband in-line polarization devices. With this approach, millimeter length tracks provided 10 nm bandwidth polarization retarders in a single mode fiber and a 65 nm bandwidth retarders in bulk fused silica.

Abstract
The most relevant aspects related to the phase mask dithering/moving method for the fabrication of complex Bragg grating designs are reviewed. Details for experimental implementation of this technique is presented, including theoretical analysis of the calibration functions for the correct dither/displacement. Results from tailored Bragg grating structures fabricated by this method are shown. Apodized Bragg gratings with modeled spatial profiles were implemented, resulting in side mode suppression levels of more than 20 dB in gratings showing transmission filtering level higher than 30 dB. Chirped gratings with the spectral bandwidth up to 4 nm, p-shift and sampled Bragg gratings with equalized peaks equally spaced by 0.8 nm (100 GHz) were also fabricated. © 2012 The Author(s).

Abstract
Organic scintillators have been promoted and widely used in scintillating fiber-optic dosimeters (SFOD) due to their tissue-equivalent characteristics, small sensitive volume combined with high spatial resolution, and emission of visible light proportional to the absorbed electron and gamma dose rate. In this paper we will present the validation of Monte Carlo simulations of dose measurements assisted by scintillating fiber optic dosimeters operating in the visible spectral range, in the context of the development of fiber optic dosimeters targeted to Brachytherapy. The Monte Carlo simulation results are compared to measurements performed with SFOD test probes, assembled with BCF-60 (Saint Gobain) samples of 1 mm diameter and 0.35 to 1.5 cm length, coupled to PMMA optical fiber. The optical signal resulting from scintillation and Cherenkov light is transmitted through an additional optical fiber link to a remote measuring device. For SFOD probes irradiation a dedicated PMMA phantom was used. The results were validated against measurements obtained with a properly calibrated pinpoint ionization chamber (PTW). The probes were positioned in a radial arrangement, with a radioactive source at its center point. The gamma-rays source is a Nucletron Microselectron-V2 Ir-192. The dose curves are obtained according to the different positions in the phantom with the SFOD dosimeters. The system is able to use a Fiber Optic Multiplexer (FOM) controlled with Labview software.

Abstract
The present context of women physicists in Portugal is discussed, updating our report for the 2002 IUPAP International Conference on Women in Physics, in which the 30 years prior to 2000 were analyzed.

Abstract

Abstract
Polyethylene terephthalate (PET) preforms are massively produced nowadays with the purpose of producing food and beverages packaging and liquid containers. Some varieties of these preforms are produced as multilayer structures, where very thin inner film(s) act as a barrier for nutrients leakage. The knowledge of the thickness of this thin inner layer is important in the production line. The quality control of preforms production requires a fast approach and normally the thickness control is performed by destructive means out of the production line. A spectral domain optical coherence tomography (SD-OCT) method was proposed to examine the thin layers in real time. This paper describes a non-destructive approach and all required signal processing steps to characterize the thin inner layers and also to improve the imaging speed and the signal to noise ratio. The algorithm was developed by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This GPU-accelerated white light interferometry technique non-destructively assesses the samples and has high imaging speed advantage, overcoming the bottlenecks in PET performs quality control.