A hidden advantage of van der Waals materials for overcoming limitations in photonic integrated circuitry

TL;DR

This paper reveals that the anisotropic optical properties of van der Waals materials, specifically WS2, can enhance nanophotonic device performance by expanding single-mode propagation range, offering a promising alternative to silicon.

Contribution

It demonstrates that the low refractive index perpendicular to vdW layers improves waveguide characteristics, opening new design possibilities for nanophotonics.

Findings

Low perpendicular refractive index expands single-mode range.

Anisotropic vdW materials offer new control in device design.

WS2 waveguides show promising optical properties.

Abstract

With the advance of on-chip nanophotonics, there is a high demand for high refractive index, low-loss materials. Currently, this technology is dominated by silicon, but van der Waals (vdW) materials with high refractive index can offer a very advanced alternative. Still, up to now it was not clear if the optical anisotropy perpendicular to the layers might be a hindering factor for the development of vdW nanophotonics. Here, we studied WS2-based waveguides in terms of their optical properties and, particularly, in terms of possible crosstalk distance. Surprisingly, we discovered that the low refractive index in the direction perpendicular to the atomic layers improves the characteristics of such devices, mainly due to expanding the range of parameters at which single-mode propagation can be achieved. Thus, using anisotropic materials offers new opportunities and novel control knobs when designing the nanophotonic devices.