Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
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200 records were found.
Optically-pumped lasers and amplifiers can in principle benefit greatly from a guided-wave geometry in which the pump and lasing modes overlap tightly, the laser mode volume is minimized, and the product of optical intensity and interaction length is not limited by diffraction as in a bulk gain medium. This idea is most successfully embodied in the erbium-doped silica fibre amplifier, and many novel and efficient laser systems have been demonstrated in glass fibre form.
The guided-wave laser is almost as old as the laser itself. The first demonstration of laser action in glass made use of a multimode waveguide; a core rod encased in a cladding of lower refractive index so that confinement of the light would counteract the effect of the poor optical quality of the available glass, (Snitzer, 1961). However, although waveguiding has long been an essential feature of semiconductor diode lasers, in dielectric laser media by far the greatest research effort has gone into the development of bulk rods and slabs of high optical quality. Interest in the potential advantages of guided wave dielectric gain media was only quickened with the advent of high quality single mode optical waveguides, especially rare earth doped silica fibres, in which the propagation losses are so low that the benefits of optical confin...
Recently, significant power losses in ytterbium-doped fibers have been interpreted as resulting from the formation of ytterbium ion pairs [A. V. Kir’yanov et al., Opt. Express 14, 3981 (2006)]. However, there appears to be strong evidence against this model.
We review progress in the development of an unconventional type of semiconductor laser that has become the focus of much attention in recent years. The vertical-external-cavity surface-emitting laser is a diode-pumped solid-state laser with a semiconductor quantum well gain medium. It overcomes the limitation of conventional edge- and surface-emitting semiconductor lasers, which can offer either diffraction-limited beam quality, or high power, but not both in the same device. In this paper, we describe the physical principles of these lasers, emphasising those aspects that are unique to this hybrid. Optical characterisation of gain wafers is discussed, with particular attention to photoluminescence measurement; a powerful tool for the analysis of growth errors, the quantum efficiency of the active region, and the effect of multilayer i...
The idea of pulling together a Cluster of papers in celebration of the 60th birthday of Professor David Hanna FRS was inspired by his award of the European Physical Society Quantum Electronics Prize 2000 for applied aspects. The prize citation recognises David's `outstanding and numerous contributions to solid-state laser physics and non-linear optics', an evaluation warmly endorsed by those of us who have been lucky enough to work with him.
Over the years, David Hanna has made immense personal contributions to the field of quantum electronics and has inspired many students and collaborators to go on to make their own contributions. His influence can be seen in many aspects of the field and those who have worked closely with him have gone on to make significant impacts in the fields of business and academia throughout the world.
Dav...
Over the past decade, the intensive development of single-mode glass fiber as a powerful and versatile gain medium has revolutionized the technology of telecommunications and introduced us to a new kind of laser physics. The fiber geometry allows pump and laser radiation fields of high intensity to be sustained over interaction lengths of many meters with negligible propagation loss, leading to devices that operate under extreme conditions, yet in a highly compact and power-efficient form. The coupling between gain and nonlinearity in these devices leads to a range of self-adaptive behaviors that challenge both experiment and theoretical analysis in a fascinating way. In this issue, we sample some of the current preoccupations and achievements in this field.
An Yb3+-doped silica fibre laser pumped at 840nm has been used to provide the two pump wavelengths, 840nm and 1020nm, required for pumping a Pr3+-doped ZBLAN fibre upconversion laser. The performance of the upconversion laser at 491, 520 and 635nm is presented, with measurements of fibre loss at 635nm and 520nm which indicate that fibre losses are an important factor limiting the performance of the upconversion laser
