Fluorescence enhancement of Er3+-doped sol–gel glass by aluminum codoping

Erbium-doped silica glasses prepared by the sol–gel process are desirable for applications in high-power lasers and integrated optical devices. However, its fluorescence could be quenched due to the high hydroxyl $({\mathrm{OH}}^{\mathrm{-}})$ content. Although this ${\mathrm{OH}}^{\mathrm{-}}$ content can be greatly reduced through special gas treatment [Y. Zhou, S. S. Wang, H. L. Liu, Y. L. Lam, Y. C. Chan, and C. H. Kam, EEE J. 8, 109 (1996).], the fluorescence is still considered weak for practical applications. We have used sol–gel aluminum codoping to increase the solubility of the ${\mathrm{Er}}^{\mathrm{3+}}$ ions in a silica glass host and, consequently, significantly enhanced the fluorescence intensity of ${\mathrm{Er}}^{\mathrm{3+}}$ -doped sol–gel glass to the extent suitable for practical usage.