Broad-band excitation mechanism for photoluminescence in Er-doped Ge25Ga1.7As8.3S65 glasses

Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy have been carried out at both room temperature and at 5 K on a series of Er -doped GeGaAsS glasses with varying doping concentrations, ranging from 200 to 7400 ppm Er. It is found that increased Er doping concentration results in an increase in the strength of the broad band excitation of the Er3+ at oms. In addition, at low temperatures, a direct link between the broad band excitation process and the host glass luminescence is observed. The increa sed strength of the broad band excitation of the Er3+ dopants corresponds w ith a decrease in the intensity of the host glass luminescence in the more heavily doped samples. This is interpreted as a quenching of the host glass luminescence through an increase in the non-radiative transfer of energy f rom defect states in the glass to the Er dopants. This supports a previous hypothesis that the same native defect states in the glass are involved in both the host glass PL and the broad band PLE of the rare earth dopants. Th e implications of the current results for the understanding of luminescence properties in undoped chalcogenide glasses are discussed briefly. (C) 1999 Elsevier Science B.V. All rights reserved.