Room-Temperature Amplification of Terahertz Radiation by Grating-Gate Graphene Structures

Stephane Boubanga-Tombet,Dmytro B But,Akira Satou,Valentin Kachorovskii,Vyacheslav V Popov,Deepika Yadav,Wojciech Knap,Ilya V Gorbenko,Taiichi Otsuji

doi:10.1103/physrevx.10.031004

Abstract

We report on experimental studies of terahertz (THz) radiation transmission through grating-gate graphene-channel transistor nanostructures and demonstrate room temperature THz radiation amplification stimulated by current-driven plasmon excitations. Specifically, with increase of the direct current (dc) under periodic charge density modulation, we observe a strong red shift of the resonant THz plasmon absorption, its complete bleaching, followed by the amplification and blue shift of the resonant plasmon frequency. Our results are, to the best of our knowledge, the first experimental observation of energy transfer from dc current to plasmons leading to THz amplification. We present a simple model allowing for the phenomenological description of the observed amplification phenomena. This model shows that in the presence of dc current the radiation-induced correction to dissipation is sensitive to the phase shift between THz oscillations of carrier density and drift velocity, and with increase of the current becomes negative, leading to amplification. The experimental results of this work as all obtained at room temperature, pave the way towards the new 2D plasmons based, voltage tuneable THz radiation amplifiers.

Highlights

More than 40 years ago, active theoretical and experimental studies of plasma oscillations in two-dimensional electron systems began, and plasmonic resonances were observed [1,2,3,4,5,6,7]
We report on room-temperature THz radiation amplification stimulated by current-driven plasmon excitation
The interest in this area dramatically increased after the seminal work of Dyakonov and Shur [8], who theoretically predicted that the dc current in the channel of a submicrometer-size field-effect transistors (FETs) could become unstable, leading to the excitation of plasma oscillations, with the frequency controlled by the gate voltage, and generation of tunable terahertz (THz) radiation

Summary

Introduction

More than 40 years ago, active theoretical and experimental studies of plasma oscillations in two-dimensional electron systems began, and plasmonic resonances were observed [1,2,3,4,5,6,7]. The interest in this area dramatically increased after the seminal work of Dyakonov and Shur [8], who theoretically predicted that the dc current in the channel of a submicrometer-size field-effect transistors (FETs) could become unstable, leading to the excitation of plasma oscillations, with the frequency controlled by the gate voltage, and generation of tunable terahertz (THz) radiation. Despite tremendous efforts, neither the room-temperature resonant detection nor the currentstimulated emission or amplification of THz radiation

Results

Discussion

Conclusion