Spectroscopic study and green upconversion of Pr3+/Yb3+-codoped NaY(WO4)2 crystal

The absorption spectra of Pr3+/Yb3+-codoped NaY(WO4)2 crystal has been measured at room temperature. Based on the Judd–Ofelt theory, the intensity parameters Ωt (t=2, 4, 6), spontaneous transition probabilities, integrated emission cross sections and radiative lifetimes were calculated. Upconversion (UC) emissions of the sample had been recorded under an excitation from a 975 nm laser diode, and intense green UC emissions were observed. The energy transfer mechanisms responsible for the population of 3PJ (J=0, 1, 2) level were analyzed.