UCLA

In this thesis, two models are developed to describe the optical properties of graphene from the THz to the visible spectral region. We show that the optical conductivity is mainly contributed by interband carrier transitions in the visible region and by intraband carrier scattering in the THz range. Optical properties such as refractive index and transmittance can be calculated theoretically from the model in the optical range. In the THz range, the Fermi energy and the scattering rate are two important parameters in the determination of the optical conductivity. One can use these physical quantities as fitting parameters and find their values by fitting the THz model to the experimental data. The fitted results are consistent with the data and one can predict the optical conductivity and refractive index at the frequency higher than the bandwidth of our experiments. Other physical properties such as the carrier density and the mobility can also be obtained from the fitted parameters. The resultant mobilities of monolayer graphene and bilayer graphene are consistent with the results of other groups.