Abstract

Lithium niobate (LiNbO₃) crystals have been widely used in many nonlinear optical processes such as frequency conversion by quasi-phase matching (QPM). Frequency conversion requires high intensity laser light, which may induce optical damage to the crystal resulting in the distortion of the optical beam. Adequate magnesium oxide (MgO) doping in LiNbO₃ can significantly reduced the optical damage [1]. QPM requires periodic domain inversion of the crystal’s spontaneous polarization P_s at submicron-to-few microns periods. A common method used for domain patterning of LiNbO₃ is electric field poling (EFP). While this method is an effective way to achieve domain patterning in congruent LiNbO₃, it is not always successful when applied to MgO-doped LiNbO₃, due to a pronounced sideways domain spreading [2]. In this contribution, we report on the fabrication of bulk domain structures in MgO doped LiNbO₃, which are pre-defined by a spatial modulation of the lithium (Li) concentration induced by strongly absorbed UV laser light irradiation.

© 2015 IEEE