We report a terahertz optical modulator consisting of randomly stacked trilayer graphene (TLG) deposited on an oxidized silicon substrate by means of THz- Time Domain Spectroscopy (THz-TDS). Here, the gate tuning of the Fermi level of the TLG provides the fundamental basis for the modulation of THz transmission. We measured a 15% change in the THz transmission of this device over a broad frequency range (0.6-1.6THz). We also observed a strong absorption >80% in the time-domain signals and a frequency independence of the conductivity. Furthermore, unlike previous studies, we find that the underlying silicon substrate, which serves as a gate electrode for the graphene, also exhibits substantial modulation of the transmitted THz radiation under applied voltage biases.
@article{arxiv.1701.08244,
title = {Broadband Terahertz Modulation in Electrostatically-doped Artificial Trilayer Graphene},
author = {Ioannis Chatzakis and Zhen Li and Alex Benderskii and Stephen B. Cronin},
journal= {arXiv preprint arXiv:1701.08244},
year = {2017}
}