New room temperature CW laser at 2.82 µm: U3+/LiYF4

Abstract

Recently, optical studies of U doped LiYF/sub 4/(YLF) have been made. The authors show that U/YLF is a promising IR laser because the crystal field Stark level splitting of the /sub 4/I/sub 9/2/ ground multiplet (1113cm/sup -1/) is larger than in U/sup 3+//CaF (609cm/sup -1/) which makes a four level laser possible at room temperature. However the valence state 3+ is not the most stable state for the actinide ion and the absorption spectra, as well as the pale green colour, show that usually both valence states U/sup 3+/ and U/sup 4+/ are present in the crystal. This Letter reports the first observation of CW laser emission of U/sup 3+/ in LiYF/sub 4/ at room temperature at 2.82 mu m. >