Active and Smart Terahertz Electro-Optic Modulator Based on VO2 Structure

thin film, the transmission, reflection, absorption, and phase of THz waves can be modulated efficiently. In particular, the antireflection condition can be actively achieved and the modulation depth reaches 99.9%, accompanied by a 180° phase switching. Repeated and current scanning experiments confirm the high stability and multibit modulation of this electro-optic modulation. Most strikingly, by utilizing a feedback loop of "THz-electro-THz" geometry, a smart electro-optic THz control is realized. For instance, the antireflection condition can be stabilized precisely no matter what the initial condition is and how the external environment changes. The proposed electro-optic THz modulation method, taking advantage of strongly correlated electron material, opens up avenues for the realization of THz smart devices.