ZnO-doped preform preparation approaches towards radioluminescent optical fibers

Zinc oxide (ZnO)-doped silica exhibits radioluminescent properties, attributed to the presence of the crystalline zinc silicate willemite (Zn2SiO4), making it a promising material for fiber-based radiation sensing. To maintain optimal waveguiding properties, a uniform ZnO distribution in the silica host material is essential. This study investigates two distinct fabrication methodologies for ZnO-doped silica preforms and their characterization of chemical and optical parameters, evaluating radial ZnO concentration and refractive index (RI) profiles. The first approach utilizes a nanoparticle-suspension doping technique via modified chemical vapor deposition (MCVD), where a porous silica layer inside a fused silica tube is infiltrated with a ZnO nanoparticle suspension. This approach results in a 1.2 mm preform core diameter with a ZnO peak concentration of 1.35 mol%, and an overall asymmetrical radial profile with an MCVD-typical central dip. The second approach uses a powder-based synthesis technique, resulting in a 14 mm preform core diameter with a nearly rectangular concentration profile at an average doping level of ~0.77 mol% ZnO. A larger, more uniform core offers the potential for enhanced radioluminescent signal output.