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Oxide based glasses have proved to be interesting hosts due in part to their usefulness in the field of photonics. The addition of the tripositive erbium ion to the glass structure in the form of an impurity allows for the use of the glass host as a material for high power lasers and optical amplifiers. Erbium doped oxide glasses show a relatively broad emission band at approximately 1500 nm ascribed to the 4113/2 --< 4115/2 transition. This broadening of the emission band is due to the high degree of disorder inherent in all vitreous materials. Unlike in crystals where the environment of each ion is identical, individual dopant ions in a glass matrix will reside in different sites and thus, the spectra will consist of overlapping contributions from each distinct site. Furthermore, the luminescence lifetime of the 4113/2 state is long (milliseconds) and as such, these glasses are suitable for use as optical amplification devices [1]. For some applications, upconversion can prove to be deleterious and thus, any investigation into the optical properties of Er3+ glasses is not complete without studying its upconversion properties. Upconversion is a phenomenon whereby low energy photons, usually infrared, are converted into photons of higher energy. In this paper, we will present a detailed investigation of the optical properties of an erbium doped sodium phosphoniobate glass.
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