Abstract-Tunable terahertz reflection of graphene via ionic liquid gating

Yang Wu1,2,3, Xuepeng Qiu1, Hongwei Liu3, Jingbo Liu4, Yuanfu Chen4, Lin Ke3 and 
Hyunsoo Yang1,2

http://iopscience.iop.org/article/10.1088/1361-6528/aa57ad

We report a highly efficient tunable THz reflector in graphene. By applying a small gate voltage (up to ±3 V), the reflectance of graphene is modulated from a minimum of 0.79% to a maximum of 33.4% using graphene/ionic liquid structures at room temperature, and the reflection tuning is uniform within a wide spectral range (0.1–1.5 THz). Our observation is explained by the Drude model, which describes the THz wave-induced intraband transition in graphene. This tunable reflectance of graphene may contribute to broadband THz mirrors, deformable THz mirrors, variable THz beam splitters and other optical components.