New insight into two-step near-infrared quantum cutting in Pr3+ singly doped oxyfluoride glass-ceramics

Efficient near-infrared (NIR) quantum cutting (QC) in RE3+/Yb3+ requires the UV-blue photon excited RE3+ donor has intermediate energy level to separate the energy gaps (similar to 10000 cm(-1)) resonant to Yb3+ absorption. Thus the unique Pr3+/Yb3+ resonant QC at low Yb3+ content (room temperature) essentially requires Pr3+-doping features distinctive NIR radiative transitions: in our prepared Pr3+-doped oxyfluoride glass-ceramics containing CaF2 nanocrystals, a two-photon NIR-QC from blue-photon excited P-3(j) (j = 0, 1, 2) states takes place efficiently with (1)G(4) acting as an intermediate level. The underlying energy transfer mechanisms involving the two-step sequential transitions of P-3(0)->(1)G(4) similar to 915 nm and (1)G(4)-> H-3(4) similar to 990 nm (crucial resonant routes for the further 1Pr(3+)-> 2Yb(3+)), as well as the D-1(2)-> F-3(2) similar to 873 nm and D-1(2)-> F-3(3,4) similar to 1040 nm, are rationally distinguished by means of photoemission, excitation, and time-resolved fluorescence spectra. (C)2015 Optical Society of America