IR-to-visible frequency upconversion in Yb3+/Tm3+ co-doped phosphate glass

- Highly efficient IR-VIS frequency upconversion in a new glass matrix.
- Intense blue and red light generation, observable at naked eye.
- Energy transfer process in Yb/Tm system is evaluated for varying Yb3+ concentration.
- Emission intensity is studied in a wide range of pump powers.
- Depletion of Tm3+ ground state caused rapid saturation above 75 mW pump.

Frequency upconversion luminescence in Yb3+/Tm3+ co-doped 60P2O5·15ZnO·5Al2O3·10BaO·10PbO glass (PZABP) excited at 980 nm is reported. Pump power dependence, lifetime measurements, and the absorption spectra of the Tm3+ ions in the visible to IR region are investigated as a function of sensitizer (Yb3+) concentration. Blue light at 475 nm and red light at 660 nm generation was observed. Intensity saturation behavior is observed for the 475 nm (1G4 - 3H6), 650-664 nm (1G4 - 3F4 and/or 3F2,3 - 3H6) and 793 nm (3H4 - 3H6) upconversion emissions, when laser power was above ∼ 75 mW (∼1.9 kW/cm2). The radiative lifetimes measured for the observed emissions were 270 μs (475 nm), 195 μs (650 nm), 177 μs (664 nm), 184 μs (793 nm) and 335 μs (1211 nm). The application of the Davis-Mott model detected a slight change of 6.6% in the value of the energy bandgap for the highest doping concentration in comparison with the undoped sample. Results indicate that the PZABP glass matrix herein reported is a promising contender as host for rare-earth doped based photonic devices.