Laura Kim¹, Seyoon Kim^1,2, Pankaj Jha¹, Victor Brar^1,2,3*, Harry Atwater^1,3*

1 Thomas J. Watson of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA

2 Department of Physics, University of Wisconsin-Madison, Madison, WI 53711, USA

3 Kavli Nanoscience Institute, California Institute of Technology, Pasadena, California 91125, USA

* Corresponding authors emails: vbrar@wisc.edu, haa@caltech.edu

DOI10.24435/materialscloud:sa-by [version v1]

Publication date: Jan 21, 2021

How to cite this record

Laura Kim, Seyoon Kim, Pankaj Jha, Victor Brar, Harry Atwater, Mid-infrared radiative emission from bright hot plasmons in graphene, Materials Cloud Archive 2021.13 (2021), https://doi.org/10.24435/materialscloud:sa-by

Description

The decay dynamics of excited carriers in graphene have attracted wide scientific attention, as the gapless Dirac electronic band structure opens up relaxation channels that are not allowed in conventional materials. We report Fermi-level-dependent mid-infrared emission in graphene originating from a previously unobserved decay channel: hot plasmons generated from optically excited carriers. The observed Fermi-level dependence rules out Planckian light emission mechanisms and is consistent with the calculated plasmon emission spectra in photoinverted graphene. Evidence for bright hot plasmon emission is further supported by Fermi-level-dependent and polarization-dependent resonant emission from graphene plasmonic nanoribbon arrays under pulsed laser excitation. Spontaneous plasmon emission is a bright emission process as our calculations for our experimental conditions indicate that the spectral flux of spontaneously generated plasmons is several orders of magnitude higher than blackbody emission at a temperature of several thousand Kelvin. In this work, it is shown that a large enhancement in radiation efficiency of graphene plasmons can be achieved by decorating graphene surface with gold nanodisks, which serve as out-coupling scatterers and promote localized plasmon excitation when they are resonant with the incoming excitation light. These observations set a framework for exploration of ultrafast and ultrabright mid-infrared emission processes and light sources.

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Keywords

Graphene Mid-infrared Plasmon Tunable emission