Phase controllable terahertz switch in a Landau-quantized graphene nanostructure

The optical properties of a weak probe light by applying coupling fields in Landau-quantized graphene nanostructure is investigated. In this structure the electromagnetic field of terahertz-infrared radiations interfere with the electromagnetic field of the short-wavelength probe field and this effect changes the absorption and dispersion characteristics of the probe field. The linear dynamical properties of the graphene by means of perturbation theory and density matrix method are discussed. We show that the group velocity of a light pulse can be switched from superluminal to subluminal or vice versa by controlling the coupling field's intensities and relative phase of the applied fields. Therefore, this model can be used as an all-optical switch which is suitable for next generation of future all optical quantum communicational system and networks.