▎ 摘　　要

In this paper, we present a triple-band line-to-circular (LTC) polarization converter based on graphene-integrated metasurface, which is composed of graphene diamond patches. Finite element method results show that there are two LTC polarizations bands with 0.36 and 0.44 THz 1 dB bandwidth, which can achieve line-to-right-circular (LTRC) conversion; there is one LTC polarization band with 2.23 THz 1 dB bandwidth, which can achieve line-to-left-circular (LTLC) conversion. We found two graphene surface plasmons (GSPs) modes were excited, which were responsible for the three LTC bands. The influences of axis lengths on the performances of LTC bands are investigated. Besides, the triple-band polarization converter can be realized when the incidence angle ranges from 0 degrees to 30 degrees and polarization angle ranges from 0 degrees to 9 degrees. Also, the frequency shifts of three LTC bands are also achieved by changing Fermi level of graphene. It is believed that our proposed polarizer can be widely used for multiband and tunable polarization conversion.