Graphene based THz modulators are promising due to the conical band structure and high carrier mobility of graphene. Here, we tune the Fermi level of graphene via electrical gating with the help of ionic liquid to control the THz transmittance. It is found that, in the THz range, both the absorbance and reflectance of the device increase proportionately to the available density of states due to intraband transitions. Compact, stable, and repeatable THz transmittance modulation up to 93% (or 99%) for a single (or stacked) device has been demonstrated in a broad frequency range from 0.1 to 2.5 THz, with an applied voltage of only 3 V at room temperature.
@article{arxiv.1506.02363,
title = {Graphene terahertz modulators by ionic liquid gating},
author = {Yang Wu and Chan La-o-vorakiat and Xuepeng Qiu and Jingbo Liu and Praveen Deorani and Karan Banerjee and Jaesung Son and Yuanfu Chen and Elbert E. M. Chia and Hyunsoo Yang},
journal= {arXiv preprint arXiv:1506.02363},
year = {2015}
}