Measuring the Complex Optical Conductivity of Graphene by Fabry-Pérot Reflectance Spectroscopy
Ghamsari, Behnood G.
Fuhrer, Michael S.
Anlage, Steven M.
Scientific Reports, 6:34166, DOI: 10.1038/srep34166
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We have experimentally studied the dispersion of optical conductivity in few-layer graphene through reflection spectroscopy at visible wavelengths. A laser scanning microscope (LSM) with a supercontinuum laser source measured the frequency dependence of the reflectance of exfoliated graphene flakes, including monolayer, bilayer and trilayer graphene, loaded on a Si/SiO2 Fabry-Pérot resonator in the 545–700 nm range. The complex refractive index of few-layer graphene, n − ik, was extracted from the reflectance contrast to the bare substrate. It was found that each few-layer graphene possesses a unique dispersionless optical index. This feature indicates that the optical conductivity does not simply scale with the number of layers, and that inter-layer electrodynamics are significant at visible energies.
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