Light-induced enhancement of alternating current poling quality and mechanical quality factor in ferroelectric single crystals

Alternating current poling (ACP) and light fields have been studied as domain engineering methods for regulating the domain structures and improving the physical properties of ferroelectric crystals because of their convenience, effectiveness, and economic advantages. In this study, we propose a LACP method (ACP under above-bandgap light illumination), by which the transparency and electro-optic properties of Mn- and Fe-doped KTa_1−xNb_xO₃ single crystals were improved compared with only ACP. Furthermore, the mechanical quality factor (Q_m = 538) of the sample poled using the LACP method increased significantly by 206% in contrast to that of the sample poled by the conventional high-temperature direct current poling method. The results reveal that the light-induced reorientation of defect dipoles is responsible for the enhancement of the ACP quality and Q_m. This study provides an efficient and fast poling approach to the material design for multifunctional devices.