O desenvolvimento profissional docente em discussão

This collection is the result of theoretical considerations made in the education field with emphasis on the teacher’s professional development. The diversity of authors, which came from distinctive higher education institutions located in Brazil and some arising from international context, reveals a multiplicity of relations between the themes that blend the centrality of “Rede de Aprendizado em Foco”. The studies and researches are organized around three themes: teacher’s learning in initial training and professional integration; teacher learning’s evaluations process and policies; and teacher’s professional development. The professionality’s formation in a period of deep and complex transformations in the social and educational scenarios is projected as a big challenge, especially when it is understood that a person is not born as a teacher, but it is constituted as such by processes that occur over a long period. The contact with the professional practice stands as an essential element in the context of teacher training, which in the course of professional learning experience different stages of training. The one that should be highlighted would be the learning moments that involve teaching’s practices. Thus, the main point of this work was based on the reflection of the teacher’s formative processes from the initial training to the professional development going through the teaching practice, which is considered as the beginning of the relationship between theoretical and practical knowledge in the context of educational reality and reporting formative experiences that have contributed to this training.

Acousto-optic modulation of optical reflection properties in fiber Bragg gratings and the application in fiber lasers

This thesis aims to investigate the interaction of acoustic waves and fiber Bragg gratings (FBGs) in standard and suspended-core fibers (SCFs), to evaluate the influence of the fiber, grating and modulator design on the increase of the modulation efficiency, bandwidth and frequency. Initially, the frequency response and the resonant acoustic modes of a low frequency acousto-optic modulator (f < 1.2 MHz) are numerically investigated by using the finite element method. Later, the interaction of longitudinal acoustic waves and FBGs in SCFs is also numerically investigated. The fiber geometric parameters are varied and the strain and grating properties are simulated by means of the finite element method and the transfer matrix method. The study indicates that the air holes composing the SCF cause a significant reduction of the amount of silica in the fiber cross section increasing acousto-optic interaction in the core. Experimental modulation of the reflectivity of FBGs inscribed in two distinct SCFs indicates evidences of this increased interaction. Besides, a method to acoustically induce a dynamic phase-shift in a chirped FBG employing an optimized design of modulator is shown. Afterwards, a combination of this modulator and a FBG inscribed in a three air holes SCF is applied to mode-lock an ytterbium doped fiber laser. To improve the modulator design for future applications, two other distinct devices are investigated to increase the acousto-optic interaction, bandwidth and frequency (f > 10 MHz). A high reflectivity modulation has been achieved for a modulator based on a tapered fiber. Moreover, an increased modulated bandwidth (320 pm) has been obtained for a modulator based on interaction of a radial long period grating (RLPG) and a FBG inscribed in a standard fiber. In summary, the results show a considerable reduction of the grating/fiber length and the modulator size, indicating possibilities for compact and faster acousto-optic fiber devices. Additionally, the increased interaction efficiency, modulated bandwidth and frequency can be useful to shorten the pulse width of future all-fiber mode-locked fiber lasers, as well, to other photonic devices which require the control of the light in optical fibers by electrically tunable acoustic waves.