OPTICAL CHARACTERIZATION OF HO3+ IONS IN LINBO3 AND IN LINBO3-MGO CRYSTALS

A detailed study of the optical absorption and emission spectra of Ho3+ ions in LiNbO3 crystals in the visible spectral region is presented. The positions of the crystal-field levels are given for the F-5(5), S-5(2) + F-5(4), F-5(3) and (5)G(6) multiplets of Ho3+ ions. The type and character of the Stark transitions have been determined by polarized absorption measurements. Optical absorption measurements and site-selective spectroscopy have shown the existence of two crystal-field sites for Ho3+ in the LiNbO3 matrix. The effect of co-doping with MgO on the optical spectre of Ho3+ ions has also been studied and a new Ho3+ Site perturbed by the presence of a neighbouring Mg2+ ion is evidenced.