Spectroscopic properties of gallium-rich germano-gallate glasses doped with Tm3+

A series of thulium-doped gallium-rich germano-gallate glasses are fabricated and thoroughly investigated. Their synthesis under an atmosphere-controlled glove box allows for a low hydroxyl concentration estimated at 14 wt ppm. From X-Ray diffraction spectroscopy and differential scanning calorimetry, the vitreous state of such gallium-rich BGG composition is confirmed. A structural analysis performed via Raman spectroscopy supports a three-dimensional interconnected glass network of gallium and germanium tetrahedra stabilized by Ba2+ ions as a charge compensator. From steady-state and time-resolved spectroscopies, Judd-Ofelt analysis is applied to determine the radiative transition rates, both absorption and emission cross-sections along with the resonant energy transfer microparameters. Through laser excitation at 808 nm, the intense 1.8 μm trivalent thulium emission is observed, while no concentration quenching is detected. Hence, the present work demonstrates gallium rich-BGG glasses doped with Tm3+ are suitable systems for IR photonic applications, notably for the development of high-power IR lasers.