Terahertz tuning of Dirac plasmons in Bi$_2$Se$_3$ Topological Insulator

TL;DR

This paper demonstrates that high-intensity terahertz radiation can significantly tune Dirac plasmons in Bi$_2$Se$_3$ Topological Insulators, enabling the development of tunable non-linear terahertz optical devices.

Contribution

It reveals the strong renormalization and red-shift of Dirac plasmons in Bi$_2$Se$_3$ caused by high-intensity terahertz excitation, a novel insight into plasmon-light interactions in topological materials.

Findings

Dirac plasmons in Bi$_2$Se$_3$ are red-shifted by up to 60% under high-intensity terahertz radiation.

High-intensity terahertz excitation causes significant plasmon frequency renormalization.

Results suggest potential for tunable terahertz non-linear optical devices based on Topological Insulators.

Abstract

Light can be strongly confined in sub-wavelength spatial regions through the interaction with plasmons, the collective electronic modes appearing in metals and semiconductors. This confinement, which is particularly important in the terahertz spectral region, amplifies light-matter interaction and provides a powerful mechanism for efficiently generating non-linear optical phenomena. These effects are particularly relevant in Dirac materials like graphene and Topological Insulators, where massless fermions show a naturally non-linear optical behavior in the terahertz range. The strong interaction scenario has been considered so far from the point of view of light. In this paper, we investigate instead the effect of strong interaction on the plasmon itself. In particular, we will show that Dirac plasmons in Bi$_2$Se$_3$ Topological Insulator are strongly renormalized when excited by high-intensity terahertz radiation by displaying a huge red-shift down to 60% of its characteristic frequency. This opens the road towards tunable terahertz non-linear optical devices based on Topological Insulators.