Active CEP control of terahertz pulses using artificial microstructure

Despite rapid progress in metamaterials, the carrier-envelope phase (CEP) control for terahertz (THz) pulse is still challenging due to its broadband feature. Here, we demonstrate a THz CEP shifter, which consists of different stereo-metamaterial (stereo-MM) arrays. The performance of the CEP shifter is characterized by using a THz-TDS system. Simulation and experimental results show that the CEP of the THz pulse can be ideally adjusted by the proposed CEP shifter, which can be shifted as high as 2$\pi$.