Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
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This talk will give details of the work in progress at Southampton in two areas. The first is progress on understanding how to make efficient sources of XUV using high harmonic generation. Two topics in particular will be discussed: theoretical and experimental approaches to nonlinear propagation in capillary waveguides during HHG, and the effect of gas jet structure on HHG. The second area is the use of an HHG source for scattering and imaging experiments. Scattering from self-assembled nanometre scale structures will be discussed, and initial imaging results using coherent diffractive imaging techniques (CDI)
Spectroscopy of ions in optical fibers is of particular interest for two distinct reasons. The first instance has become increasingly obvious as communications networks use active fiber elements as amplifiers in the 1.55μm band and progress toward a useful fiber amplifier in the 1.3μm band continues. These fiber amplifiers have greatly increased the scope of fiber communications, and the understanding of the detailed spectroscopy of rare-earth ions such as erbium in glass matrices has become increasingly important. Equally, the changes in optical properties of dopant ions on pulling fibers from bulk material is also important for the production of practical devices.
Yttria-alumina-silica (YAS) glasses doped with Er3+ and Tm3+ have been examined spectroscopically for their prospect as fibre amplifier gain media for optical telecommunication systems. Absorption and emission spectra, as well as emission lifetime measurements and Judd-Ofelt calculations are reported. Tm3+:YAS glass has a emission bandwidth of 122nm around 1470nm, making it promising for S+ band amplification.
Research into Tm3+-doped glasses as gain media for optical amplifiers in the telecommunications S-band has been focused on glasses with low phonon energy like tellurite and fluoride glasses, because the high phonon energy of silicate glasses precludes emission around 1470nm. Glasses in the Y2O3 - Al2O3 - SiO2 (YAS) system have, despite their silica content, a maximum phonon energy of about 950cm−1, as well as good transparency and thermal stability. We report preliminary spectroscopy on Tm3+:YAS glass which highlights their potential as S-band amplifier gain media.
Developments in the technique of Near-field Scanning Optical Microscopy (NSOM) [1] have made possible the mapping of both amplitude and phase of electric fields in photonic devices using simple interferometry. Combined with heterodyne techniques, this gives very high sensitivity within the technologically important 1.5μm wavelength regime. We describe experiments that use this capability to study one of the most important telecommunications components, the fiber Bragg grating. Interferometric SNOM allows us to measure the amplitude and phase of the optical field within the fiber Bragg gratings directly. The evanescent fields, which are usually protected by the fiber cladding, are exposed by polishing off the cladding on one side of the fiber. These fields are measured using photon scanning tunneling microscopy (PSTM), and detection is ...
The homogeneous line width of the1D2-3H4 electronic transition of Pr3+ in ZBLAN and gallium-lanthanum-sulphide (GLS) glass has been determined at 1.9 K by means of hole burning. In ZBLAN the holes show a variation in burning efficiency dependent on probe wavelength. Site-selective fluorescence results are presented to explain this effect
Fluorescence spectra of Pr3+-doped gallium lanthanum sulphide (GLS) chalcogenide glass at 300 and 1.9K are presented. Energy-selective spectroscopy is performed for the 1D2 and 3P0 levels at both temperatures, and the results show that there is strong correlation between the inhomogeneous profiles of ground and excited states, a situation which does not normally occur in rare-earth doped glasses. This is explained in terms of the relative contributions to the broadening from the nephelauxetic effect and crystal field broadening in this system. Its implication for the 1.3µm amplifier based on Pr3+ in this host is assessed.
