Upconversion excitations in Pr3+-doped BaY2F8 crystal

We report the orange-to-blue and infrared-(IR)-to-blue wavelengths upconversion luminescence in Pr3+:BaY2F8 crystals. Mechanism of the orange light upconversion into blue P-3(0) state emission was confirmed to be energy transfer between two Pr3+ ions in the D-1(2) state. IR-to-blue upconversion has only been observed under two different color IR pumping. The first resonant step was the H-3(4) -> (1)G(4) ground state absorption transition, and the second resonant transition was the excited state absorption from the (1)G(4) to I-1(6) and P-3(J) levels. A comparison of the efficiency of the IR-to-blue upconversion in several praseodymium activated host is presented and discussed. A model of the IR pumped upconversion praseodymium blue laser is presented and the population inversion conditions are calculated.