LiNbO₃ is a distinguished multifunctional material where ferroelectric domain engineering is of paramount importance. This degree of freedom of the spontaneous polarization remarkably enhances the applicability of LiNbO₃, for instance, in photonics. In this work, we report the first method for all-optical domain inversion of LiNbO₃ crystals using continuous-wave visible light. While we focus mainly on iron-doped LiNbO₃, the applicability of the method is also showcased in undoped congruent LiNbO₃. The technique is simple, cheap, and readily accessible. It relies on ubiquitous elements: a light source with low/moderate intensity, basic optics, and a conductive surrounding medium, e.g., water. Light-induced domain inversion is unequivocally demonstrated and characterized by combination of several experimental techniques: selective chemical etching, surface topography profilometry, pyroelectric trapping of charged microparticles, scanning electron microscopy, and 3D Čerenkov microscopy. The influence of light intensity, exposure time, laser spot size, and surrounding medium is thoroughly studied. To explain all-optical domain inversion, we propose a novel physical mechanism based on an anomalous interplay between the bulk photovoltaic effect and external electrostatic screening. Overall, our all-optical method offers straightforward implementation of LiNbO₃ ferroelectric domain engineering, potentially sparking new research endeavors aimed at novel optoelectronic applications of photovoltaic LiNbO₃ platforms.

中文翻译：

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通过可见连续波激光照射实现 LiNbO3 晶体的全光畴反转


LiNbO ₃ 是一种杰出的多功能材料，其中铁电畴工程至关重要。这种自发极化的自由度显着增强了 LiNbO ₃ 的适用性，例如在光子学中。在这项工作中，我们报告了第一种使用连续波可见光对 LiNbO ₃ 晶体进行全光域反转的方法。虽然我们主要关注铁掺杂的 LiNbO ₃ ，但该方法的适用性也体现在未掺杂的同成分 LiNbO ₃ 中。该技术简单、廉价且容易获得。它依赖于无处不在的元素：低/中等强度的光源、基本光学器件和导电的周围介质（例如水）。光诱导磁畴反转通过多种实验技术的组合得到明确证明和表征：选择性化学蚀刻、表面形貌轮廓测量、带电微粒的热释电捕获、扫描电子显微镜和 3D Čerenkov 显微镜。深入研究了光强度、曝光时间、激光光斑尺寸和周围介质的影响。为了解释全光域反转，我们提出了一种基于体光伏效应和外部静电屏蔽之间的异常相互作用的新颖物理机制。总体而言，我们的全光学方法提供了 LiNbO ₃ 铁电域工程的直接实现，可能引发针对光伏 LiNbO ₃ 平台的新型光电应用的新研究工作。