Infrared photoluminescence of Nd3+ multicenters in KTiOPO4 crystals

Abstract The infrared photoluminiscence and optical absorption of Nd 3+ in KTP single crystals and in those co-doped with Al, Na and W have been studied. Characteristic emission band sets in 1030–1150 and 1300–1500 nm corresponding to the 4 F 3/2 → 4 I 11/2 and 4 F 3/2 → 4 I 13/2 transitions, respectively, have been observed. The excitation spectra of these bands show the splitting of the 4 F 3/2 multiplet in two sublevels. The excitation spectrum of Nd in KTP only shows the contribution of one type of Nd center, the energy difference between the 4 F 3/2 sublevels of this center is 183 cm −1 . Nd 3+ in the two slightly different titanium lattice sites is likely contributing to this spectrum. In crystals co-doped with Al the 4 F 3/2 splitting is larger, namely 202 cm −1 but still a single center is observed. The co-doping with Na or W induces the presence of additional new centers as well as new emission bands. It is inferred that Na–Nd and W–Nd pairs have been formed. W enhances the optical absorption cross section of Nd 3+ in KTP.