A detailed study of the spectroscopic properties of the PbF2 + GeO2 + WO3: YbF3, TmF3 glass ceramics under infrared excitation (966 nm) is performed. The absorption, emission, excitation spectra, luminescence decay times, and up-conversion efficiency are measured. The up-conversion of infrared into violet (363 nm), blue (451 and 478 nm), and red (680, 698, and 779 nm) is observed for Tm3+ ions in the sample. The up-conversion processes involve a two-photon and a three-photon absorption for the red and blue emissions (478 nm). A four-photon process happens for violet and another blue emissions (451 nm). In addition, the up-conversion emission spectra of violet, blue, and red bands of Tm3+ ions are obtained in the range of 12 to 320 K. It is found that the probability of energy transfer between Yb3+ and TM3+ ions depends on temperature. By a comparative method, absolute fluorescence efficiencies of 10(-6) and 5.86 x 10(-3) are obtained for the dominant blue (478 nm) and red (779 nm) up-conversions when the sample is excited by 966 nm light with an absorbed intensity of 16.5 mW/cm2 at room temperature.