▎ 摘　　要

Ultrafast signal processing in the time domain with high resolution and reconfigurability is a challenging task. This paper, for the first time to our knowledge, introduces a time-varying metasurface consisting of a graphene micro-ribbon array for implementing a time lens in the terahertz domain. Given that the surface conductivity of graphene is proportional to the Fermi energy level in the terahertz regime, it is possible to change the phase property of the incident electromagnetic pulse by changing the Fermi level while the Fermi level itself is a function of voltage. Upon this fact, a quadratic temporal phase modulator, namely, a time lens, has been realized. This phase modulation is applied to the impinging signal in the time domain. The terahertz time lens is a key element for processing of ultrafast temporal pulses. Using this time lens, a temporal filter in the terahertz regime is designed and simulated, which could have applications in terahertz communication and spectroscopy. (C) 2018 Optical Society of America