Yb2O3 doped high yttrium alumino-silicate nano-particles based D- and pentagonal (P-) shaped optical fibers having core
diameter around 30.0-35.0 μm have been obtained through the conventional modified chemical vapour deposition
(MCVD) process and solution doping (SD) technique using thin wall tubes of CSA, around 58-60 mm2, followed by
enlargement of the inner deposition surface area under suitable pressurization. The process parameters at the different
stages of preform fabrication have been optimized in order to obtain the uniform distributions of Al, Yb, and Y along the
core diameter. Nano-particles were synthesized under soaking of the porous phospho-silicate core layer in a solution of
optimum strength of ytterbium chloride, yttrium chloride, and aluminum chloride. The size of nano-particles was
maintained within 5-10 nm under doping of 0.2 mol.% of fluorine. The EDX data reveal that the nano-particles are rich
in yttria-alumino-silicate phase and dispersed uniformly. The novelty of this technique involves the direct synthesis of
rare-earth doped phase-separated nano-particles within the large core of optical fiber. The critical fabrication parameters
of the process along with the nano-structuration results and spectroscopic properties are highlighted.
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