Optical damage resistance and crystal quality of LiNbO3 single crystals with various [Li]/[Nb] ratios

Abstract

Lithium niobate single crystals with various [Li]/[Nb] ratios were grown by the Czochralski method from melts having compositions varying between 45.5–58 mol % Li2O. Their optical damage resistance was characterized by measurement of the photoinduced birefringence change. Their crystal quality was characterized by x-ray topography and x-ray rocking curves. The photoinduced birefringence change increased with an increase in the Li content of the crystal. The Li-poor crystals, which were richer in Nb content than the crystal with the congruent composition, showed the smallest birefringence change, in spite of the fact that the x-ray rocking curve width of these Li-poor crystals was much wider than the congruent crystal. It is concluded that the optical damage resistance of undoped LiNbO3 is increased with an increase in the Nb content of the crystal, and that the crystal quality, as represented by x-ray rocking curve peak width, has no correlation with the optical damage resistance.

Increased optical damage resistance of Zr:LiNbO3 crystals

“…The lattice parameters were calculated by the least-squares method. To measure the optical damage resistance ability of the Zr: LiNbO 3 crystals we used the Sénarmont compensation method [10]. The experimental setup for measurement of the change in optical birefringence was described by Fontana et al [11].…”

Defect structure and optical damage resistance of In:Fe:Cu:LiNbO3 crystals with various [Li]/[Nb] ratios

“…To measure the resistance to optical damage of the In:Fe:Cu:LiNbO 3 crystals, the Sénarmont method [13,18,19] was used. The experimental setup for measurement of the change in birefringence was described by Fontana et al [18].…”

“…According to the presently accepted "Li-sites vacancy model" [9,10], the composition of Nb Li 4+ is achieved by Li vacancies V Li - [11], these centers do participate in photo-induced charge transport. The dependence of photorefraction on the intrinsic defect structure was studied in crystals with different [Li]/[Nb] ratios grown by modified Czochralski techniques [12,13]. Photorefractive properties of Zn:LiNbO 3 and Mg:LiNbO 3 crystals related to the defect structure were also investigated in detail [14,15].…”

Inhomogeneity of composition in near-stoichiometric LiNbO3 single crystal grown from Li rich melt

“…Such dependence has a qualitative significance [18,19]. In order to determine the relationship between the crystal and the melt composition, differential scanning calorimetry (DSC) analyses for the raw materials s and the frozen melt were performed by a NETZSCH DSC 404. blue shifted by only about 0.15 nm from the center to the periphery.…”