Excited state absorption and up-conversion luminescence of Ho3+ centres in 3CaO–Ga2O3–3GeO2 glass

3CaO–Ga2O3–3GeO2 glass excited state absorption spectra-activated with Ho3+ (Ho2O3 – 0.7 wt% content) have been measured and analysed. Up-converted emission channels have been identified and the predicted up-converted emission bands have been registered under Ar ion laser (λ = 488 nm) excitation according to the excited state absorption data. A mechanism of up-converted transitions for Ho3+ centres in this prototype glass network is proposed on the basis of the obtained results.