Growth of MgO doped near stoichiometric LiNbO3 single crystals by a hanging crucible Czochralski method using a ship lockage type powder feeding system assisted by numerical simulation

Abstract

MgO doped near stoichiometric LiNbO₃ (MgOSLN) crystals have great potential for use in periodically poled structured LiNbO₃ (PPLN) for doubling frequency lasers and optical parametric oscillation infrared lasers, because of their high optical damage threshold, single domain characteristics, and very low coercive field. However, few MgOSLN crystals are commercially available in the present market because of the great difficulty in growing them. This paper describes how a hanging crucible Czochralski technique with a newly-designed ship lockage type powder feeding system assisted by numerical simulation was developed for the successful growth of high quality near stoichiometric LiNbO₃ (SLN) and MgOSLN (~1 mol%) crystals. The physical properties of the crystals were assessed by measuring their crystallinity, Curie temperature, optical properties, coercive field and thermal properties. These properties, including a coercive field of 1.4 kV mm⁻¹ and a thermal conductivity of 6.61 W (m K)⁻¹ demonstrated that the crystals meet the demands for manufacturing periodically poled crystal devices. This growth method has great potential in the mass production of SLN and other incongruently melting crystals.