Infrared-to-visible upconversion luminescence in SrF2:Er powders upon excitation of the 4I13/2 level. Optical Materials Express. 2018. v.8. #7. p. 1863-1869

A.A. Lyapin, S.V. Gushchin, S.V. Kuznetsov, P.A. Ryabochkina, A.S. Ermakov, V.Yu. Proydakova, V.V. Voronov, P.P. Fedorov, S.A. Artemov, A.D. Yapryntsev, V.K. Ivanov. Infrared-to-visible upconversion luminescence in SrF2:Er powders upon excitation of the 4I13/2 level. Optical Materials Express. 2018. v.8. #7. p. 1863-1869.