Novel Light Emitting Mechanisms Originating from Graphene Plasmons Near and Far from Equilibrium

Author: Kim, Laura

Year: 2019

Degree: Dissertation (Ph.D.)

Advisor: Atwater, Harry Albert

Committee Members: Schwab, Keith C.; Atwater, Harry Albert; Johnson, William L.; Nadj-Perge, Stevan

Option: Materials Science

DOI: 10.7907/1CDC-HV37

Abstract

Graphene supports surface plasmons bound to an atomically thin layer of carbon, characterized by tunable propagation characteristics and distinctly strong spatial confinement of the electromagnetic energy. Such collective excitations in graphene enable the strong interactions of massless Dirac fermions with light. In this work, I explore fundamental properties and applications of graphene plasmons both near and far from equilibrium. I discuss the ability of graphene plasmons to interact with its local environment in various forms of mid-infrared, optically active excitations, demonstrated by tunable graphene plasmon dispersions and an emergence of a new mode via addition of a monoatomic dielectric layer. Furthermore, the viability of graphene for optics-based applications and large-scale integration is epitomized by the experimental demonstration of perfect tunable absorption in a large-area chemically grown graphene by using a noble-metal-graphene metasurfaces. Using these properties of graphene plasmons, electronically tunable thermal radiation is demonstrated. Finally, I present theoretical predictions and experimental validations of nonequilibrium graphene plasmon excitations via ultrafast optical excitation, originating from a previously unobserved decay channel: hot plasmons generated from optically excited carriers. These studies reveal novel infrared light emitting processes, both spontaneous and stimulated, and provide a platform for achieving ultrafast, ultrabright mid-infrared light sources.

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