Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
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286 records were found.
The technology of Bragg gratings has matured significantly over the past years, now to the extend where significant fibre-optic companies are being formed with main emphasis based on and around Bragg grating technology. With the recent advances in the manufacturing capabilities of Bragg gratings there obviously also will develop a demand for filters of even higher complexity to perform very specific filtering tasks. Currently it is the imagination that often sets the limits for what can be achieved experimentally. A superstructured Bragg grating refers to a Bragg gratings where a slowly varying apodisation-envelope is imposed on top of the fast underlying Bragg grating pitch. Such an envelope, performed in real-space, will result in a specific response in frequency space often uniquely defined by the superstructure profile. In this tut...
With the evolution of transmission-systems from point-to-point links to dynamically reconfigurable networks there has developed a need for tunable devices with accurate setting capabilities and stability. When signals are redirected different dispersion accumulates due to the differences in transmission-paths. Furthermore, with the ever increasing bit-rates, differences in signal launch powers and hence the potential for non-linear effects to begin to play their part will have to be considered, and therefore tunability is of increasing importance to either fine tune these dispersion-values or even compensate for some of the non-linear effects. To accommodate these tasks a number of approaches to tune dispersion using Bragg gratings have been demonstrated. Some of these have covered both strain- and temperature- tuning techniques using ...
Single fibre Bragg gratings designed to compensate pure 3rd-order dispersion are demonstrated for the first time. The shown devices exhibits dispersion-profiles of ~20ps/nm2, ~40ps/nm2 and ~225ps/nm2 over bandwidths of 4.5nm, 6nm and 3nm respectively, they have peak reflectivities of ~75% and are only 8mm, 23mm and 40mm long.
Introduction
Advances in internet traffic and a steadily increasing demand for bandwidth and better bandwidth utilisation have started to pull systems providers towards higher bit-rate systems to achieve reduced channel and component count. Increasing the channel bit-rate can impose penalties to the dispersion performance of the system though and therefore close attention has to be paid to the dispersion slope generated in this. A number of approaches have been proposed previously to accommodate this. These i...
A double (2 x π/2) phase-shifted Er/Yb fibre DFB laser shows a 50% reduction of the shift in lasing wavelength and a 10% reduction of the linewidth, compared to standard single phase-shifted fibre DFB designs.
We develop a simple tuning scheme for dispersion slope compensation with fiber Bragg gratings. A dispersion slope tuning range between -12ps/nm2 and -3ps/nm2 is demonstrated within a bandwidth of ~3nm.
Accumulated dispersion can limit the number of grating filters in a network. We derive a simple analytical equation for the out-of-band dispersion of any filter, and conclude on the resulting node-limitation of an optical network.
Variations in the diameter along the length of an optical fibre limits the quality of a grating written into the waveguide. We discuss how fibre design plays an important role in minimising these imperfections
We show that p phase-shifted Distributed Feedback (DFB) Raman fibre lasers of 30cm length are resilient against phase and amplitude errors up to ~5%, with negligible deterioration of the threshold and slope-efficiency of the lasers.
An experimental and theoretical investigation of how the polarization mode competition and beat frequency of Er-doped fiber distributed-feedback lasers depend on perturbations such as localized transverse forces, back reflections, or changes in pump polarization is reported. Good agreement between the experiments and a comprehensive theoretical model is obtained. Use of a dual-polarization laser as a transverse force sensor with a resolution on the order of 1-100 nN/√Hz above 20 Hz is also discussed.
