Rare-earth-doped silica-based glasses for photonic applications

Two different silica-based glass systems with valuable optical and spectroscopic properties in the 1.5 mm band, exploited in optical microcavities, are presented. First, we report on Er3+-activated core–shell silica spheres prepared by sol–gel process. The core consists of a silica sphere of 270 nm in diameter, while the shell is an Er2O3–SiO2 film. The second system is an Er3+-activated microcavity fabricated by rf-sputtering technique. The cavity is constituted of an Er3+-doped SiO2 layer inserted between two Bragg mirrors, fabricated by alternately stacking five TiO2 and five SiO2 thin films. Optical and spectroscopic properties were assessed, and the two systems were characterized from morphological and structural point of view.