Photoluminescence increase of Er3+ in Na2O–Nb2O5–SiO2 glasses after crystallization

Photoluminescence (PL) of Er3+ doped in xNaO(0.05)-xNbO(2.5)-(100 - 2x)SiO2 (mol%) (x = 24, 27, 30, 33, 36) glasses was investigated before and after crystallization. After crystallization, Er3+ was determined to be in the glass phase. Following the precipitation of the NaNbO3 crystalline phase in these glasses, PL intensity of S-4(3/2) --> I-4(15/2) transition of Er3+ increased. A maximum of >100-fold increment in the PL intensity was observed after crystallization as compared with that of the uncrystallized glass. The mechanism of augmentation of the PL intensity is discussed in terms of the theory of PL intensity. We assume that the difference in the refractive index between the residual glass and crystallized phases was a dominant factor causing the increase of the PL intensity after crystallization. (C) 1999 Elsevier Science B.V. All rights reserved.