Graphene-based silicon-on-insulator optical waveguide electro-optical modulators: pushing the boundaries of light control

Optical modulators are fundamental components in modern optical communication systems. They enable the manipulation of light intensity, a crucial function for data transmission and signal processing. Graphene, a single atomic layer of carbon atoms arranged in a honeycomb lattice, has emerged as a promising material for high-performance electro-optical modulators due to its unique electrical and optical properties. This paper uses graphene to control the light passing through a silicon-on-insulator optical waveguide to emulate an optical modulator. The electrical properties of graphene are exploited by varying the applied voltage on a graphene layer coating the Silicon-on-Insulator waveguide so the concentration of carriers is changed and, therefore, the light interaction with graphene is modified. An effective intensity modulation of light through the Silicon-on-Insulator waveguide is achieved by controlling the carrier’s concentration within the graphene layer through the applied voltage. Numerical calculations based on three-dimensional electromagnetic simulation software are performed on a small size (40 μm long, 0.6 μm width and 0.25 μm height) Silicon-on-Insulator waveguide to design and test the optical response of the proposed modulator. Silicon-on-Insulator waveguide coated with a layer of graphene and Aluminium oxide material performs well as an optical modulator for optical communication systems at 1.55 μm wavelength.