Photorefractive behavior of strontium barium niobate doped with trivalent rare-earths

Summary form only given. Of trivalent rare-earth dopants only Ce/sup 3+/ has been directly implicated in the photo-refractive effect in SBN (Sr/sub x/Ba/sub (1+x)/Nb/sub 2/O/sub 6/). This is expected because Ce/sup 3+/ is the most easily photoionized trivalent rare-earth. We have investigated the spectroscopy and photorefractive response of SBN doped with Ce/sup 3+/, Pr/sup 3+/ and Nd/sup 3+/. Ce/sup 3+/ shows a broad absorption extending from the band edge at about 3.2 eV (380 nm) to around 600 nm. This is assigned to a combination of 4f-5d and charge transfer absorption. In contrast, the spectrum of Pr/sup 3+/ and Nd/sup 3+/ consists of a number of sharp f-f absorption lines, together with a weak background, which may be due to other impurities or defects. In addition these ions have metastable excited state, with lifetimes of about 100 /spl mu/s.