Designing MMI structured beam-splitter in LiNbO 3 crystal based on a combination of ion implantation and femtosecond laser ablation

In this work, the design and numerical study of a MMI-based LiNbO3 beam splitter were presented, with a combination of ion implantation and femtosecond laser ablation as a fabricating strategy. The designed splitters show advantages such as good fabrication tolerance, low insertion loss, compactness, and simple fabrication processes. We also demonstrated that the self-imaging principle could be applied to design low-loss MMI beam splitters for multi-mode input with mode number m = 1 and n>1 by carefully choosing the geometry parameters. The presented fabrication strategy provides an alternative choice for the fabrication of power splitters also with other MMI-based devices in various optical monocrystal chips.