Fluorescence in Er3+-doped fluoroaluminate glass pumped at visible wavelengths

Abstract

Erbium-doped glass offers a wealth of applications. While it has already found commercial success in remotely pumped amplifiers for long-haul optical transmission, erbium-doped glass also shows promise in other emerging technologies such as eye-safe laser radar systems and three-dimensional volumetric displays.
As in other rare-earth ions, the important optical transitions in Er³⁺ result from electron transitions within the 4f shell. Shielded by the outer 5s and 5p shells, the transition energies of these electrons are not greatly affected by the host. However, the transition rates of the active ions are dependent on the host material. In oxide glasses with high phonon energies, nonradiative transitions compete with radiative transitions reducing fluorescence efficiencies. Heavy metal fluoride (HMF) glasses, such as fluoroaluminate, have lower phonon energies and exhibit more efficient fluorescence.
Upconversion, the emission at wavelengths shorter than pump wavelength, has been observed in several erbium-doped HMF glasses pumped in the near-infrared (800 nm and 980 nm). Green upconversion was the most commonly observed, but emissions were also reported at red, blue, and violet wavelengths.
This paper presents the recent results from an ongoing spectroscopic investigation of erbium-doped fluoroaluminate glass. Reported are the fluorescence spectra measured after pumping at different wavelengths in the visible region as based on previously observed absorption bands ofthe glass.