Effect of subgrain boundaries on domain-inverted structure in periodically poled near-stoichiometric LiTaO3 crystal

We investigated the effect of subgrain boundaries on periodic domain-inverted structures with a period of ∼30 μm in near-stoichiometric LiTaO3 (SLT) crystals and found that they negligibly affected the structures. Using SLT crystals having subgrain boundaries and a quasi-phase matching technique, we fabricated a 2-mm-thick, 60-mm-long periodically poled SLT frequency converter with a domain-inverted structure with a 30.5-μm period and demonstrated optical parametric oscillation.