A CaF_2-CeF_3 disordered crystal containing 1.06% of Er~(3+) ions was grown by the temperature gradient technique.Optical absorption and emission spectra recorded at room temperature and at 10 K, luminescence decay curve recorded at room temperature, and extended x-ray-absorption fine structure spectra were analyzed with an intention to assess the laser potential related to the ~4I_(13/2)→~4I_(15/2) transition of Er~(3+). In addition, the thermal diffusivity of the crystal was measured at room temperature. The analysis of room-temperature spectra revealed that the ~4I_(13/2) emission is long-lived with a radiative lifetime value of 5.5 ms, peak emission cross section of 0.73 × 10~(-20) cm~2, and large spectral width pointing at the tunability of the emission wavelength in the region stretching from approximately 1480 nm to 1630 nm. The energies of the crystal field components for the ground and excited multiplets determined from low-temperature absorption and emission spectra made it possible to predict successfully the spectral position and shape of the room-temperature ~4I_(13/2)→~4I_(15/2) emission band. Based on the correlation of the optical spectra and dynamics of the luminescence decay, it was concluded that in contrast to Yb~(3+) ions in heavily doped CaF_2 erbium ions in the CaF_2-CeF_3 crystal reside in numerous sites with dissimilar relaxation rates. A CaF_2-CeF_3 disordered crystal containing 1.06% of Er ~ (3+) ions was grown by the temperature gradient technique. Optical absorption and emission spectra recorded at room temperature and at 10 K, luminescence decay curve recorded at room temperature, and extended x -ray-absorption fine structure spectra were analyzed with an intention to assess the laser potential related to the ~ 4I_ (13/2) → ~ 4I_ (15/2) transition of Er ~ (3+). In addition, the thermal diffusivity of the crystal was measured at room temperature. The analysis of room-temperature spectra revealed that the ~ 4I_ (13/2) emission was long-lived with a radiative lifetime value of 5.5 ms, peak emission cross section of 0.73 × 10 ~ ( -20) cm ~ 2, and large spectral width pointing at the tunability of the emission wavelength in the region stretching from approximately 1480 nm to 1630 nm. The energies of the crystal field components for the ground and excited multiplets determined from low-temperature absorption and emission spectra made i Based on the correlation of the optical spectra and dynamics of the luminescence decay, it was possible to predict the spectral position and shape of the room-temperature ~ 4I_ (13/2) → ~ 4I_ (15/2) emission band. concluded that in contrast to Yb ~ (3+) ions in heavily doped CaF_2-erbium ions in the CaF_2-CeF_3 crystal reside in numerous sites with dissimilar dissociation rates.