Single color upconversion emission in Ho3+/Yb3+ and Tm3+/Yb3+ doped P2O5–MgO2–Sb2O3–MnO2–AgO glasses

The Ho3+/Yb3+ and Tm3+/Yb3+ doped P2O5–MgO2–Sb2O3–MnO2–AgO glasses were prepared by high temperature melting method. Under a 975 nm laser diode (LD) excitation, the single red and single blue upconversion (UC) emissions were observed in Ho3+/Yb3+ and Tm3+/Yb3+ doped samples, respectively. By studying the spontaneous radiative and multiphonon relaxation probabilities, we find that the multiphonon relaxation probability of 5I6 (Ho3+) state is very large (1.39 × 106 s− 1), which is helpful to the population of 5I7 state. The multiphonon relaxation probability of 3H5 and 3F2,3 (Tm3+) is also very large, which results in lots of population in 3F4 and 3H4 states. The results are that the red UC emission of Ho3+ and the blue UC emission of Tm3+ are stronger.

Research highlights
► Strong single color upconversion red and blue emissions in our sample which can be applied in color display and fluorescence labeling.
► The large multiphonon relaxation of the phosphate glass is helpful to the upconversion emissions.
► At high pump power, the red and the blue emissions begin to saturate, which shows that the upconversion emission is very strong.