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 (OH−) content. Although this OH− 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 Er3+ ions in a silica glass host and, consequently, significantly enhanced the fluorescence intensity of Er3+-doped sol–gel glass to the extent suitable for practical usage. © 1997 American Institute of Physics.