Broadband near infrared photoluminescence of Cu 2+ ‐doped corundum (α‐Al 2 O 3 )

Abstract Copper‐doped corundum (α‐Al 2 O 3 ) possesses an intense broadband photoluminescence in the near infrared. This photoluminescence is originated from Cu 2+ ions, which substitute for Al 3+ ions in corundum lattice. Co‐doping with Ge is necessary to obtain the luminescent material. It seems, that simultaneous introduction of Ge is needed to provide the charge compensation for heterovalent Cu 2+ → Al 3+ substitution, in such a way that the whole process (Cu 2+ , Ge 4+ ) → 2Al 3+ is charge‐balanced. The broad photoluminescence spectrum matches well with transparency window of silica optical fibers and the quantum yield seems to be satisfactory, so copper‐doped corundum can become demanded as a new active media for solid state lasers and amplifiers. This is the first example of photoluminescence from octahedrally coordinated Cu 2+ ion in oxide materials.