紫外激光诱导近化学计量比钽酸锂晶体铁电畴反转

Ultraviolet Laser-Induced Ferroelectric Domain Inversion in Nearly-Stoichiometric LiTaO_3 Crystal

对紫外激光诱导近化学计量比钽酸锂晶体铁电畴反转进行了实验研究。波长为351 nm的连续紫外激光被聚焦在近化学计量比钽酸锂晶体的-z表面,同时沿与晶体自发极化相反的方向施加均匀外电场。实验证实紫外激光辐照可以有效地降低晶体畴反转所需的矫顽电场,采用数字全息干涉测量技术检测证实在激光辐照区域实现局域畴反转。研究表明采用紫外激光诱导可以实现对近化学计量比钽酸锂晶体铁电畴反转的局域控制。提出了物理机理的理论分析,认为外电场和激光辐照场的共同作用在晶体内部产生高浓度、大尺寸的缺陷结构,缺陷一定程度上降低畴体成核和畴壁运动所需要克服的退极化能和畴壁能,实现激光诱导畴反转。

Ultraviolet laser-induced ferroelectric domain inversion in nearly-stoichiometric LiTaO3 was investigated. The continuous ultraviolet laser with 351 nm wavelength was focused on the -z surface of nearlystoichiometric LiTaO3, and the homogeneous electric field which was antiparallel to the direction of spontaneous polarization was applied simultaneously. It is proved that the coercive field is effectively reduced by the laser radiation. The local domain inversion induced in the laser radiation area is confirmed by the digital holographic interferometry. The investigation proves that the ferroelectric domain inversion can be locally controlled by the ultraviolet laser irradiation. It is regarded that the defect structure with jumbo size and high density in the crystal lattice is generated by the complex coaction of incident irradiation field and external electric field. The defect dominates the nucleation by reducing depolarization energy and domain-wall energy required for domain-nucleus growth and domain wall movement, and the laser-induced domain inversion is realized.