Comparison of different optical models of graphene for the analysis of graphene-attached microfibers and D-shaped fibers

Abstract

We analyze the modal properties of various graphene-attached microfibers and D-shaped fibers with three optical models of graphene: the interface model, the isotropic model, and the anisotropic model, where the interface model serves as the benchmark. In the interface model, the graphene film is treated as a conductive boundary with no thickness, while, in the isotropic/anisotropic model, the graphene film is treated as an isotropic/anisotropic thin film with a finite thickness. We study, in particular, a microfiber placed on a flat graphene film, a graphene-wrapped microfiber, and a graphene-covered D-shaped fiber. Our numerical results show that the anisotropic model generates accurate results and its accuracy is relatively insensitive to the graphene thickness assumed, while the isotropic model can significantly overestimate the graphene-induced modal losses unless the graphene thickness assumed is sufficiently small. Our study clarifies the accuracies of different models for the analysis of graphene-attached fiber structures and provides an evaluation of the effect of the assumed graphene thickness on the accuracy of the widely used isotropic model. Our study also confirms that the interface model is both accurate and computationally efficient and is the preferred model for the analysis of graphene-attached fiber structures.