Room temperature photon avalanche up-conversion in Ho3+ doped fluoroindate glasses under excitation at 747 nm

Abstract The room temperature up-conversion spectrum of a fluoroindate glass doped with 2.5 mol% of Ho3+ has been detected under excitation at 747 nm. Blue, red and very intense green bands are observed. The green emission has been analysed in detail, in order to investigate the efficient up-conversion mechanism involved in this transition. The low absorption cross-section for the transition from the ground state 5I8 to 5I4, the excitation spectrum of the 5S2, 5F4 → 5I8 green emission, based on a strong excited state absorption (5I7 → 5S2, 5F4) and the temporal dynamics of the process indicate that a photon avalanche mechanism occurs.