Ferroelectric domain engineering of Lithium niobate

Lithium niobate (LN) has remained at the forefront of academic research and industrial applications due to its rich material properties, which include second-order nonlinear optic, electro-optic, and piezoelectric properties. A further aspect of LN’s versatility stems from the ability to engineer ferroelectric domains with micro and even nano-scale precision in LN, which provides an additional degree of freedom to design acoustic and optical devices with improved performance and is only possible in a handful of other materials. In this review paper, we provide an overview of the domain engineering techniques developed for LN, their principles, and the typical domain size and pattern uniformity they provide, which is important for devices that require high-resolution domain patterns with good reproducibility. It also highlights each technique's benefits, limitations, and adaptability for an application, along with possible improvements and future advancement prospects. Further, the review provides a brief overview of domain visualization methods, which is crucial to gain insights into domain quality/shape and explores the adaptability of the proposed domain engineering methodologies for the emerging thin-film lithium niobate on an insulator platform, which creates opportunities for developing the next generation of compact and scalable photonic integrated circuits and high frequency acoustic devices.