Process of making rare earth doped optical fibre

Abstract

The present invention discloses a process for making rare earth (RE) doped optical fibre by using RE oxide coated silica nanoparticles as the precursor materia, more particularly the method of the present invention involves preparation of stable dispersions (sol) of RE oxide coated silica nanoparticles at ambient temperature and applying a thin coating on the inner surface of silica glass tube following dip coating technique or any other conventional methods, of the said silica sol containing suitable dopants selected from Ge, Al, P, etc., the coated tubes were further processed into optical preforms by following MCVD technique and fiberised in desired configuration, the novelty lies in eliminating the step of the formation of porous soot layer at high temperature by CVD process inside a fused silica glass tube for formation of the core and also in the elimination of the incorporation of the rare earth ions into the porous soot layer following the solution doping technique or other conventional methods, the direct addition of RE oxides in the sol eliminates the formation of microcrystalites and clusters of rare earth ions and prevents change in composition including variation of RE concentration in the core which results in increase in the reproducibility and reliability of the process to a great extent, further the addition of Ge(OET)4 at ambient temperature in the silica sol reduces the quantity of GeCl4 which is required at high temperature to achieve the desired Numerical Aperture.

Description

technical field [0001] The invention relates to a method of manufacturing rare earth doped optical fiber. Background technique [0002] Optical fibers based on high-purity silica have been identified as the most efficient interconnection media for optical telecommunication networks. Such optical fibers can be used as passive transmission media to guide the long-distance transmission of optical signals. However, if rare earth (RE) ions are doped into the core of such fibers, the fibers are optically active because the rare earths are pumped at appropriate wavelengths to produce characteristic emissions. Because of the aforementioned properties, rare earth-doped fibers show great potential as active devices for photonic devices such as optical amplifiers and fiber lasers at various wavelengths. It has also been found that such fibers are expected to be used as sensors for monitoring temperature and radiation dose, among other things. [0003] Erbium-doped fiber is the activ...

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Problems solved by technology

[0024] 3. It is difficult to control the porosity of the deposited green layer because it is particularly sensitive to the deposition temperature, the speed at which the burner moves back and forth, and the flow of reaction raw materials

[0032] 11. Since the process is sensitive to parameters during various processing stages such as deposition, solution doping, drying and sintering, it is not reliable and reproducible

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