Zone-levelling Czochralski growth of MgO-doped near-stoichiometric lithium niobate single crystals

The zone-levelling Czochralski (ZLCz) technique was used to grow MgO-doped near-stoichiometric lithium niobate (SLN) crystals for the first time. The crystal was pulled from a Li-rich solution (58-60 mol% of Li2O) having an SLN solid supplied from below in a slender platinum crucible. An inner crucible was also used to avoid bubble incorporation. With 1 mol% MgO doping, three inclusion-free SLN crystals were grown. The transmittance along the grown crystals was found satisfactory (76±1%) having an absorption edge of 303±1 nm. The small variation of the composition (Li/Nb=0.975±0.005 and Mg/Nb=1.07±0.02 mol%), refractive indices (no=2.286±0.0005 and ne=2.189±0.0007), and the Curie temperature (1209.5±1.5 °C) further confirm ZLCz as a proven method for growing SLN single crystals.