Linear optical characterization of graphene structure

Abstract

Graphene as a newly developed 2D material has attracted a lot of attention for its promising applications in optoelectronic fields. To pursue a profound understanding of its optical properties, this thesis presents the optical refractive index in response to the infrared incidents, and its modulations under external electric field. We tested the optical reflection response of monolayer graphene on an SiO2/Si substrate at 1550nm laser incident. The derived value of the graphene optical refractive index was: 2.75-1.56i at 1550nm, which made up for the deficiency of graphene optical properties in the infrared region. We also compared the results for the current work with studies in the visible spectrum, and we provide a value range for graphene RI, which can be used to estimate the monolayer graphene optical response to different incidents and substrates. Finally, we checked the graphene optical reflection changes in response to an external electric field using a top-gated graphene samples at 1064nm incident. We found that the tunability of complex refractive index of graphene verified according to gate voltage. Additionally, through comparison with other experimental work, we have found the optical refractive index trends are similar in infrared range.