Up-converted luminescence in Yb–Tm co-doped lead fluoroborate glasses

The efficient non-resonant energy transfer from Yb 3+ to Tm 3+ ions in lead fluoroborate glasses has been observed. Up-converted luminescence due to 3 H 4 – 3 H 6 transition of Tm 3+ ions has been registered under excitation of Yb 3+ ions at 975 nm. From luminescence decay analysis some parameters have been determined using Inokuti–Hirayama model. The results were compared to those recorded with singly Yb-doped samples in order to clarify the energy transfer process.