OPTICAL BANDS OF CR-3+ INDUCED BY MG-2+ IONS IN LINBO3, CR,MG

In this paper, the role of Mg ions in the optical properties of Cr3+ (absorption, luminescence, and lifetime) in doubly doped LiNbO3 single crystals is analyzed. Additional R lines (denoted as R1" and R2"), associated with Cr3+ ions perturbed by nearby Mg2+ ions, were observed. Divalent magnesium ions affect also the 4T1 and 4T2 excited-state levels of Cr3+ ions, producing a red shift in the 4A2 --> 4T1 and 4A2 --> 4T2 absorption bands. This red shift explains the change observed in the color of Mg-doped samples. The crystal-field parameters and Racah parameters of this Cr3+ defect site are reported and compared with those corresponding to singly doped crystals.