A strongly enhanced luminescence efficiency of zincborate glasses and glass fibers doped with trivalent europium or terbium is reported. The enhancement is attributed to a high content of direct gap ZnO nanocrystallites which operate as sensitizer for the rare‐earth ions. The glasses have a low softening point and are designed to be compatible with the silicon technology. Applications as scintillating devices integrated on silicon are suggested. ©1996 American Institute of Physics.