Optical absorption in graphene integrated on silicon waveguides

TL;DR

This paper demonstrates the integration of graphene on silicon photonic circuits and measures its optical absorption coefficient with high precision, providing insights for designing graphene-based optoelectronic devices.

Contribution

It introduces a precise measurement method for graphene's optical absorption in integrated photonic structures and validates it with theoretical modeling.

Findings

Maximum absorption coefficient of 0.2 dB/μm on graphene/waveguide hybrid

Measurement method based on Mach-Zehnder interferometry

Results align with theoretical models using graphene's universal ac conductivity

Abstract

To fully utilize graphene's remarkable optical properties for optoelectronic applications, it needs to be integrated in planar photonic systems. Here, we demonstrate integration of graphene on silicon photonic circuits and precise measurement of the optical absorption coefficient in a graphene/waveguide hybrid structure. A method based on Mach-Zehnder interferometry is employed to achieve high measurement precision and consistency, yielding a maximal value of absorption coefficient of 0.2 dB/{\mu}m when graphene is located directly on top of the waveguide. The results agree with theoretical model utilizing the universal ac conductivity in graphene. Our work provides an important guide for the design and optimization of integrated graphene optoelectronic devices.