Refractive-index patterning of tellurite glass surfaces by laser spot heating

A dot pattern of a refractive-index change was formed by spot heating with laser-beam irradiation on sodium tellurite glasses. The 15Na2O.85TeO2 (mol. %) glass doped with 2 mol. % of CoO was irradiated by a green light-beam spot (532 nm) approximately 800 microm in diameter from the second-harmonic generator of a Q-switched pulsed YAG laser. The map of the refractive index of the glass was determined with an He-Ne laser beam by a scanning ellipsometric technique at a resolution of 100 microm x 50 microm, indicating that the spots possessing a refractive index lower by approximately 0.05 were formed at the region irradiated by the laser beam.