Infrared-to-visible upconversion fluorescence spectroscopy in trivalent rare-earth-doped lead-magnesium-fluorophosphate glass

There has recently been a great deal of interest in searching for new vitreous materials for application as hosts in infrared-to-visible light upconverters or optical amplifiers based upon rare-earth doped systems. Some of their many applications include: color displays, high density optical recording, biomedical diagnostics, infrared laser viewers and indicators, fiber lasers and amplifiers. Fluorophosphate-based glasses have recently emerged as auspicious candidates for such photonic devices applications. These glasses are advantageous because they present low nonlinear refractive indeces, better mechanical strength, chemical durability, and thermal stability than fluoride-based glasses and are suitable for. developing low-loss, high strength, and low-cost optical fibers. It has recently been shown also that the fluorophosphate-based glass is an excellent candidate for high power lasers and broadband amplifiers in the eye-safe region around 1.5 mu m for applications in communication, medicine, and meteorology. The present work involves the investigation of optical transitions and upconversion fluorescence spectroscopy of trivalent lanthanide ions Er3+ and Tm3+ codoped with Yb3+ in P2O5-PbO-MgF2 glass, excited with near-infrared diode lasers. The dependence of the upconversion luminescence upon the Yb3+-concentration and diode laser power, and the upconversion excitation mechanisms involved are also investigated. The viability of using these glasses as host for practical applications in optical temperature sensors will also be presented.