On the optical absorption and photoluminescence of Er-doped Ge–S–Ga glasses

Abstract We have studied the absorption and photoluminescence (PL) of (GeS 2 ) 80 (Ga 2 S 3 ) 20 glasses doped with 0.17, 0.35 and 1.05 at.% Er. The sharp bands centered at around 660, 810, 980 and 1540 nm in the absorption spectra can be associated with intra 4f-shell transitions in Er 3+ ions from 4 I 15/2 level to 4 F 9/2 , 4 I 9/2 , 4 I 11/2 and 4 I 13/2 levels, respectively. It has been observed that the absorption edge shifts towards lower energies with increasing Er concentration. A decrease in the absorption coefficient in the range of weak absorption, as well as the host luminescence in more heavily doped samples has been established, which may be associated with less native defects in the glassy structure. The role of excitation wavelength ( λ ex ) on the PL emission band at 1540 nm using different Er 3+ -doping level has been evaluated. It has been found that the total PL band remains almost the same under direct excitation of Er 3+ ions (at λ ex = 644, 770 and 982 nm), while it becomes narrower under the host excitation (at λ ex = 532 nm).