Sol-gel preparation and optical properties of SiO2-Ta2O5 glass

Ta-doped SiO2 glass was fabricated by the sol-gel process in order to obtain a glass with a high refractive index for optical use. A crack-free, clear glass rod was prepared from a low-density gel and used as the core material for fabricating optical fibers. Transmission loss in the fabricated fibers was high, in the range of 103-104 dB/km, which may be caused by coloration due to the multivalency of Ta; however, the loss was reduced by nearly one order of magnitude by heat treatment at 800 C, that is, to 75 dB/km at a wavelength of 0.8 mm. 31 refs.