Laser performance and spectroscopic properties of Nd3+-doped LiKYF5 and LiKGdF5 crystals

Spectroscopic and laser-pumped laser studies of Nd3+-doped LiKYF5 and LiKGdF5 are reported. The optical absorption and photoluminescence spectra art strongly polarised. the sense of polarisation of the I-4(9/2) --> F-2(5/2), H-2(9/2) absorption near 800 nm being opposite to that of the F-4(3/2) --> I-4(11/2) laser emission near 1.05 mu m. At ambient temperature (similar to 300 K) the luminescence decay times of excited Nd3+ ions are in both hosts of order 480-490 mu s, and strongly concentration dependent above 2 at.% Nd3+. Efficient laser action (similar to 25%) is observed under excitation with a long pulse Cr3+:LiSAF laser tuned to 797 nm, with low threshold energies of ca. 125 mu J.