Tunable optical responses of a graphene-gold nanoparticle composite for visible light

Abstract

Applying Maxwell-Garnett' s effective medium model, we theoretically study the optical properties of graphene with gold nanoparticles as a function of the particle volume fraction, size of the particles, chemical potential, and temperature. To account for the visible spectrum at energies less than 3 eV, we consider up to the second order of the optical conductivity calculated using the tightbinding model. Randomly distributed gold nanoparticles have a strong influence on the optical responses of graphene, such as its absorption, reflection, and transmission, thus allowing enhanced optoelectronic properties. We find that the composite can be made to serve as a potential tunable photonic material for a reflective optical modulator by controlling the local plasmonic resonance of the nanoparticle, volume fraction, and chemical potential.