Divalent copper as the possible active center for solid-state NIR lasers

We were able to observe an intense, broadband photoluminescence in different crystal hosts, doped with $\mathrm {C u}^{2+}$. These matrices include corundum (alpha-Al
2
O
3
), different spinels: $\mathrm {M g A l}_{2} \mathrm{O}_{4}, \mathrm{MgGa}_{2} \mathrm{O}_{4}, \mathrm{ZnAl}_{2} \mathrm{O}_{4}, \mathrm{ZnGa}_{2} \mathrm{O}_{4}$, spinel-like compounds $\mathrm{LiAl}_{5} \mathrm{O}_{8}, \mathrm{LiGa}_{5} \mathrm{O}_{8}$, perovskites $\mathrm{LaAlO}_{3}, \mathrm{GdAlO}_{3}$. The main common feature of these materials is the large magnitude of the crystal field, which contributes to the appearance of photoluminescence. Otherwise, the strong electron-phonon coupling in the ground state due to the manifestation of the Jahn-Teller effect can lead to photoluminescence quenching due to the high rate of non-radiative relaxation. It has also been demonstrated that codoping with divalent ions dramatically enhances the photoluminescence of copper in corundum and perovskites.