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The glasses of the La 2 S 3 -Er 2 S 3 -Ga 2 S 3 system were synthesized from the melted samples which where quenched in to the cold 25-% solution of NaCl. Their optical absorption spectra were studied in the range of 1.2-2.9 eV at 80 K. For doped erbium glasses, there are narrow absorption bands with maxima at 2.53, 2.35, 2.27, 1.88, 1.54, 1.26 eV. With increasing of the content of La 2 S 3 (30 -40 mol. %) the bandgap width decreases (E g = 2.83 -2.73 eV) and the Urbach parameter increases (∆E = 151 -238 meV). These changes are determined by the structural disorder in the glasses.