Temperature-dependent effect of modulation in graphene-supported metamaterials

Abstract

We report on a novel effect of temperature-dependent modulation in graphene-supported metamaterials. The effect was observed during the theoretical analysis of a model graphene-supported electro-optical modulator having silicon dioxide (SiO2) or hafnium dioxide (HfO2) as a buffer dielectric layer. Comparative analysis of the two materials showed that they provide approximately the same maximum values for transmission and reflection modulation depths. However, in the case of a HfO2 buffer layer, a lower chemical potential of the graphene is required to achieve the maximum value. Moreover, theoretical calculations revealed that a lower gate voltage (up to 6.4 times) is required to be applied in the case of a HfO2 layer to achieve the same graphene chemical potential. The graphene layer was found to possesses high absorption (due to the additional resonance excitation) for some values of chemical potential and this effect is extremely temperature dependent. The discovered modulation effect was demonstrated to further increase the transmission modulation depth for the simple model structure up to 2.7 times (from 18.4% to 50.1%), while for the reflection modulation depth, this enhancement was equal to 2.2 times (from 24.4% to 52.8%). The novel modulation effect could easily be adopted and applied over a wide range of metadevices which would serve as a quick booster for the development of related research areas.