T 1254 (OTTO) Tellurium oxide, 99.9995% Cas 7446-07-3 - used in devices which can convert light into sound (acousto-optic material). Glasses made of tellurium oxide have high refractive indices and transmit into mid-IR region. T 1254 (OTTO) Tellurium oxide, 99.9995% Cas 7446-07-3 - used to make glasses with special properties. It is useful in optical waveguides and optical fiber amplification.