Optical absorption in graphene integrated on silicon waveguides

摘要

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