# 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.

## Key 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.

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Source: https://tomesphere.com/paper/1701.08244