Optimization of periodic poling of x-cut lithium niobate thin film

Periodic poling of lithium niobate thin film (lithium niobate on insulator, LNOI) is a critical step in nonlinear optics applications using quasi-phase matching. The electric field method is widely used to achieve periodic poling. A problem frequently encountered in congruent LNOI periodic poling is some regions which were not reversed. In this paper, repeated poling process was used to deal with the problem mentioned above. When the poling process was repeated for 6 times, the poling fidelity was nearly 100% for a periodicity of 3.8 pm. The results provide useful information for achieving high-fidelity poling in LNOI.