On the compositional nature of bulk doped periodic poled lithium niobate crystals

The compositional nature of the Erbium, Neodymium and Yttrium bulk doped periodic poled lithium niobate crystals obtained by the off-centered Czochralski technique has been studied. It has been observed that, in all cases, the impurity concentration is constant along the periodic domain structure. Moreover, it is shown that there exists a periodical variation in the Nb concentration, which is directly related with an inversion in the Li/Nb ratio along the periodic domain structure. The magnitude of the Nb variation seems to depend on the nature of the dopant and its position in the lithium niobate lattice, together with the value of the segregation coefficient of the impurity and the shape of the solid–liquid interface during growth.