It has been known for a long time that silica optical fibers containing parts per million (ppm) level of 3d transition elements exhibit high transmission losses. The optical absorption of these transition elements in vitreous silica has been fully investigated [1]. We used these undesirable elements to silica optical fibers developers to our advantage by incorporating them into the fiber core in order to make high attenuating fibers. Such High Attenuation Fibers (HAF) can be tailored to produce a controlled level of attenuation with high degree of wavelength uniformity. This is accomplished with the selection of the material used as dopants, the dopants concentrations, the cross-section fiber geometry, and the length of the attenuating fiber.
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