The 3.1 eV photoluminescence band in oxygen-deficient silica glass

Previous studies have reported the existence of a photoluminescence (PL) band near 3.1 eV in silica glass when exposed to ultraviolet (UV) light. The O3SiOOH group, the twofold coordinated silicon lone-pair center (OS̈iO) and a germanium impurity were thought to be the origin of this PL band. In this paper, we describe the characteristics of a PL band near 3.1 eV in undoped oxygen-deficient silica glass (low-OH) that has been synthesized with chemical vapor deposition (CVD) soot remelting. At room temperature, we have found two types of PL bands at approximately 3.1 eV in the low-OH glass. One band is observed at 3.08 eV (lifetime, τ∼100 μs); and the other, at 3.15 eV (τ∼10 μs).