▎ 摘　　要

To extend the usage of the terahertz wave, we present a simple method for variable focus length terahertz wave lens based on graphene. The focus length of the graphene-based terahertz lens can be tunable by changing the applied electric field without change the configuration. To demonstrate the feasibility of the approach, numerical simulation performed with the aid of the finite element method is used to evaluate the terahertz performance of the proposed device. With an appropriate design, the focal length of the proposed device can be tuned from 7.3 mu m to 15.2 mu m. The total size of the present graphene lens is only 3.5 mu m x 13 mu m. It is believed to be applicable for future communication, imaging and sensing in terahertz range. (C) 2015 Elsevier B.V. All rights reserved.