All-optical domain inversion in LiNbO3 crystals by visible continuous-wave laser irradiation

LiNbO3 is a distinguished multifunctional materialwhere ferroelectric domain engineering is of paramount impor-tance. This degree of freedom of the spontaneous polarizationremarkably enhances the applicability of LiNbO3, for instance, inphotonics. In this work, we report the first method for all-opticaldomain inversion of LiNbO3 crystals using continuous-wave visiblelight. While we focus mainly on iron-doped LiNbO3, theapplicability of the method is also showcased in undoped congruentLiNbO3. The technique is simple, cheap, and readily accessible. Itrelies on ubiquitous elements: a light source with low/moderateintensity, basic optics, and a conductive surrounding medium, e.g.,water. Light-induced domain inversion is unequivocally demon-strated and characterized by combination of several experimentaltechniques: selective chemical etching, surface topography profilometry, pyroelectric trapping of charged microparticles, scanningelectron microscopy, and 3D Čerenkov microscopy. The influence of light intensity, exposure time, laser spot size, and surroundingmedium is thoroughly studied. To explain all-optical domain inversion, we propose a novel physical mechanism based on ananomalous interplay between the bulk photovoltaic effect and external electrostatic screening. Overall, our all-optical method offersstraightforward implementation of LiNbO3 ferroelectric domain engineering, potentially sparking new research endeavors aimed atnovel optoelectronic applications of photovoltaic LiNbO3 platformsPID2020-116192RB-I0, TED2021-129937B−I00, S2018/NMT-4291 TEC2SPAC

Using E-Z Reader to examine the concurrent development of eye-movement control and reading skill

Compared to skilled adult readers, children typically make more fixations that are longer in duration, shorter saccades, and more regressions, thus reading more slowly (Blythe & Joseph, 2011). Recent attempts to understand the reasons for these differences have discovered some similarities (e.g., children and adults target their saccades similarly; Joseph, Liversedge, Blythe, White, & Rayner, 2009) and some differences (e.g., children?s fixation durations are more affected by lexical variables; Blythe, Liversedge, Joseph, White, & Rayner, 2009) that have yet to be explained. In this article, the E-Z Reader model of eye-movement control in reading (Reichle, 2011; Reichle, Pollatsek, Fisher, & Rayner, 1998) is used to simulate various eye-movement phenomena in adults versus children in order to evaluate hypotheses about the concurrent development of reading skill and eye-movement behavior. These simulations suggest that the primary difference between children and adults is their rate of lexical processing, and that different rates of (post-lexical) language processing may also contribute to some phenomena (e.g., children?s slower detection of semantic anomalies; Joseph et al., 2008). The theoretical implications of this hypothesis are discussed, including possible alternative accounts of these developmental changes, how reading skill and eye movements change across the entire lifespan (e.g., college-aged vs. older readers), and individual differences in reading ability