Tellurium-doped silica fibers: spectroscopic properties and nature of active centers

Abstract

A preform and holey fibers with Te:SiO2 core composition were fabricated. Spectroscopic properties of the fibers drawn in different redox conditions were studied. Intensive absorption bands near 430, 600, 820, 1050 nm and absorption edge near 250 nm were observed. Broad luminescence bands had maxima located near 700, 910, and 1500 nm. Drawing in oxidizing conditions led to the considerable decrease of the absorption bands and to the suppression of the ∼1500 nm luminescence band. Characteristic peaks at 245 and 232 cm−1 associated with Te20 dimers were observed in the Raman spectra. Modeling of Te dimers in Te:SiO2 glass allows suggesting that a Te20 dimer can be responsible for 700 and 910 nm luminescence bands and a Te2− dimer for ∼1500 nm luminescence band.