Ferroelectric domain engineering has wide applications in optical and electronic industries. Compared with traditional electric field poling, femtosecond laser poling has many advantages, such as higher fabrication resolution, 3D engineering applicability, and lower costs of production. In this review, the recent research progress on ferroelectric domain engineering with femtosecond laser pulses is presented. We show the latest results, including complex domain structures fabricated in various kinds of ferroelectric crystals, and discuss the influence of laser poling parameters and conditions on the morphologies of inverted domains and their physical mechanisms. The technical challenges to overcome in future are also briefly discussed.

Transverse second-harmonic generation, in which the emission angles of the second harmonic are determined by the spatial modulation of the quadratic nonlinearity, has important applications in nonlinear optical imaging, holography, and beam shaping. Here we study the role of the local duty cycle of the nonlinearity on the light intensity distribution in transverse second-harmonic generation, taking the generation of perfect vortices in periodically poled ferroelectric crystal as an example. We show, theoretically and experimentally, that spatial variations of the nonlinearity modulation must be accompanied by the corresponding changes of the width of inverted ferroelectric domains, to ensure uniformity of the light intensity distribution in the generated second harmonic. This work provides a fundamental way to achieve high-quality transverse second-harmonic generation and, hence, opens more possibilities in applications based on harmonic generation and its control.