Evolution of fluorine doping following the REPUSIL process for the adjustment of optical properties of silica materials

We report on the fluorine doping and codoping of powder-based silica bulk glasses fabricated using REPUSIL (Reactive Powder Sintering of Silica) technology. The maximum doping level of 1.5 mol% of SiF4 is associated with a refractive index decrease by −8 x 10−3 compared to undoped silica and an essential decrease in the transition temperature by about 200 K. Fluorine codoping is eminently suitable for the direct refractive index adjustment of actively-doped silica glass materials (e.g., Al/Yb or Al/Tm). The fluorine codoping of Al/Yb silica glass significantly reduces parasitic photodarkening processes.