Advancing inorganic electro-optical materials for 5 G communications: from fundamental mechanisms to future perspectives.

In the 5 G era, the demand for high-capacity and fast fiber-optic communication underscores the importance of inorganic optical materials with high electro-optical (EO) coefficients, rapid responses, and stability for efficient electro-optical modulators. The exploration of novel EO materials and their applications remains in the early stages. At present, research mainly focuses on the performance of EO materials and devices. However, the EO coefficients of different preparation methods for the same material and different materials vary significantly. Currently, a crucial gap lies in understanding the link between the EO effect and ferroelectric polarization, hindering advancements in ferroelectric material optimization. This article offers a comprehensive insight into the EO effect, initially discussing ferroelectric polarization and its relationship to the phenomenon. It then reviews standard inorganic ABO metal oxide ferroelectric ceramics and thin films, followed by an examination of emerging ferroelectrics such as HfO-based polymorph ferroelectrics and ZnO/AlN-based materials. The article concludes by addressing the challenges in investigating ferroelectric EO mechanisms and provides an outlook on the future of EO material research, including a review of the latest developments in EO effect mechanisms and their optimization for light modulation, as well as an exploration of potential areas for high-performance EO materials research.