Terahertz Metamaterial Optoelectronic Modulators with GHz Reconfiguration Speed

Abstract

All-electronic ultrafast control of terahertz radiation is demonstrated in integrated metamaterial/graphene devices. By electrostatic gating the graphene conductivity, the overall optical response of the incident terahertz E-field is modified. Depending on the configuration, amplitude, phase, and polarization of terahertz radiation could be modulated with GHz range of reconfiguration speed. An extinction ratio of >7.6 dB in amplitude is achieved at the resonant frequency of 0.75 THz. Additionally, a relative phase shift of >17.4°. is observed around a frequency of 0.68 THz. When operating as a polarization modulator, the device has reported an ellipticity change of ~40% at a frequency of 0.68 THz and a dynamic rotation of the polarization plane by >9°at resonance. The switching capability of the modulators has been investigated all electronically reporting a speed exceeding 3 GHz, only limited by the available instrumentation. Consequently, GHz-speed of modulation can be achieved for frequencies around 0.75 THz. These results represent a breakthrough for all applications where a fast, versatile and efficient modulation of THz radiation is required, such as in next-generation wireless communication, quantum electronics, and ultrafast imaging.