Highly Tm Doped Silica Optical Preform by MCVD - Chelate Vapor Delivery (Soot-Dopant Stepwise Technique)

This paper presents the progress in the fabrication of highly doped thulium silica fiber. As much as 5.3 wt. % Tm alongside 7.1 wt. % Al (co-dopant) were incorporated into silica preform. The preform was fabricated using the Modified Chemical Vapor Deposition (MCVD)-chelate vapor delivery with soot-dopant stepwise technique. The preform was analyzed for several key properties such as refractive index variation along deposition length, dopants distribution profiles and UV-Vis absorption. The results showed a homogeneous dopants distribution with 4% RSD in the longitudinal refractive index along a 40 cm preform length. The UV-Vis absorption spectrum exhibited a strong absorption peak at 790 nm attributed to Tm 3H4 energy manifold