Broadband Terahertz Modulation in Electrostatically-doped Artificial Trilayer Graphene

TL;DR

This study demonstrates a broadband terahertz modulator using electrostatically-doped trilayer graphene on silicon, achieving significant transmission modulation and revealing substrate effects on THz transmission.

Contribution

It introduces a novel THz modulator based on trilayer graphene with substrate-induced modulation effects, expanding the understanding of graphene-based THz devices.

Findings

15% THz transmission change over 0.6-1.6 THz

>80% absorption in time-domain signals

Substantial modulation of silicon substrate under voltage

Abstract

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.