One color, pulsed excited-state upconversion in YAG:Tm3+

One color red laser pumping of YAG:Tm3+ crystals results in a strong upconverted near ultraviolet and blue fluorescence from the excited1D2 and1G4 multiplets. It is found that under pulsed-pumping conditions the quasi-resonant excited-state absorption from the3H4 multiplet is the responsible process. Analysis of the upconverted emission confirmed previous results on3H4 level assignments as well as on inhomogeneous line broadening in the YAG structure.