Numerical analysis of a strip-loaded silicon rich nitride-thin film lithium niobate hybrid waveguides

Hybrid integration of silicon rich nitride and lithium niobate on insulator (SRN-LNOI) is an emerging material platform for photonic integrated circuits (PIC). In this paper, we present a systematic numerical investigation of the mode properties of a strip-loaded SRN-LNOI hybrid waveguide at 1550 nm wavelength using the full-vectorial finite difference method. Considering the anisotropic nature of the lithium niobate (LN) crystal, the effective refractive indices of the transverse electric and transverse magnetic modes of strip-loaded SRN-LN hybrid waveguides were analyzed. The single-mode condition, zero-birefringence, effective mode area, and power distribution in terms of the geometrical parameters of the strip-loaded SRN-LN hybrid waveguide are discussed in detail. Furthermore, the optical power transmission in both straight and bent waveguides, as well as the different characteristics of the optical power confinement of the fundamental modes in the SRN and LN layers were analyzed. This study provides useful information for designing high-performance photonic devices on a hybrid SRN-LNOI platform for future PIC applications.