Analysis for the Dominant Factors to Determine the Correlation Length of Silicon Waveguides on a Rough Insulator

In modern fibre-optic communications and computer optical interconnections, optical loss caused by the waveguide sidewall roughness (SWR) is one of the key restrictions that limit the adoptions and industrialization of silicon photonic integrated circuits. With the advent of the 5G era, the demand for the optical chip industry and photonic integrated circuits based on the silicon-on-insulator (SOI) waveguides is increasing. In this paper, by introducing a three-dimensional (3D) SWR and an interaction function between the optical guided mode, we re-model the Payne-Lancey (PL) theoretical model. Further, since the two key dimensionless functions in the PL model are co-determined by the waveguide structure (the width and the silicon-core index) and the waveguide structure determined correlation length, we propose an iteration strategy of the waveguide structure, the key-function and the correlation length loop, and then systematically simulate the relations among the key functions, the waveguide structures and the correlation length in the improved PL model to find the dominant factors of the correlation length of an SOI waveguide. Finally, we conduct the numerical calculations for the synchronous dependences of both the SWR caused optical propagation loss (OPL) coefficient and the correlation length of an SOI waveguide on the core refractive index. The above research results are of great significance for the design and manufacture of SOI waveguide devices.