Abstract

With the progress of Terahertz (THz) technologies in recent years, a wide range of applications have emerged including material characterization, gas sensing, biomedical imaging and communication. Fast active control over the properties of Terahertz radiation is essential for all these applications, including the controllable modulation of the phase, amplitude and polarization of Terahertz radiation. I will be discussing all electrical devices which have been successfully designed and fabricated in the THz group which can be used to actively control the polarization of transmitted THz radiation, with potential modulation speeds in the order of 100 KHz. These devices manipulate the polarization condition of transmitted radiation by combing chiral metamaterial arrays with electrically tuneable graphene for active polarization modulation. Active control of the conversion from linear polarized radiation to circular polarized radiation is demonstrated, and the rotation of linear polarized radiation by around 20 degrees is also achieved, dependant on the frequency of the incident THz radiation and the applied backgate voltage.