In this work, we develop a simulation method based on supermode theory and transfer matrix formalism, and then apply it to the analysis and design of taper couplers for vertically integrated As₂S₃ and Ti: LiNbO₃ hybrid waveguides. Test structures based on taper couplers are fabricated and characterized. The experimental results confirm the validity of the modeling method, which in turn, is used to analyze the fabricated couplers.