Optical Induction and Erasure of Ferroelectric Domains in Tetragonal PMN-38PT Crystals

PT-relaxor ferroelectrics exhibit excellent piezoelectric and quadratic nonlinear optical properties, making them prominent candidates for realization of phononic and nonlinear photonic crystals which rely on spatially patterned ferroelectric domains. However, formation of domain patterns, especially in three dimensions, has been challenging. This paper presents the first experimental demonstration of localized ferroelectric domains and their 2D and 3D patterns inside 0.62Pb(Mg_1/3Nb_2/3)O₃-0.38PbTiO₃ (PMN-38PT) single-domain crystals engineered with focused near-infrared femtosecond laser pulses. Two types of domains are optically induced. Primary domains are formed in the focal volume of the beam, and secondary domains appearing at higher laser power, in the shape of hollow cylindrical structures, are formed around the beam. A physical mechanism of optical domain inversion involving thermoelectric and space charge fields is proposed. This study contributes to a deeper understanding of domain formation and structuring in PMN-PT relaxor-based ferroelectrics, paving the way to integrate electromechanical, acoustic, and nonlinear optical effects in a single crystal.