Much more intense ultraviolet (UV) and blue upconversion fluorescence of Tm3+was observed in a new stable fluoroindate glass compared with other fluoride or oxide glasses. The intense upconversion intensity and high thermal stability of these fluoroindate glasses indicate a high possibility for the realization of a UV and blue upconversion laser. It is reported that the compositional dependence of the fluorescence intensity is largely dependent on the phonon energy of the host glass. The dependence of the phonon energy of the host glasses on contributions from multiphonon decay on the fluorescence intensity is also discussed. ©1996 American Institute of Physics.