Active spatial control of terahertz plasmons in graphene

Abstract

Graphene offers a possibility for actively controlling plasmon confinement and propagation by tailoring its spatial conductivity pattern. However, implementation of this concept has been hampered because uncontrollable plasmon reflection is easily induced by inhomogeneous dielectric environment. In this work, we demonstrate full electrical control of plasmon reflection/transmission at electronic boundaries induced by a zinc-oxide-based dual gate, which is designed to minimize the dielectric modulation. Using Fourier-transform infrared spectroscopy, we show that the plasmon reflection can be varied continuously with the carrier density difference between the adjacent regions. By utilizing this functionality, we show the ability to control size, position, and frequency of plasmon cavities. Our approach can be applied to various types of plasmonic devices, paving the way for implementing a programmable plasmonic circuit.Controlling spatial patterns of plasmons constitutes a basis for a variety of applications in the fields of plasmonics, metamaterials, and transformation optics 1-3 . Of particular interest is the active control of plasmon confinement and propagation because it will enable us to develop programmable plasmonic circuits. A promising strategy achieving it is to tailor the spatial conductivity pattern in graphene. It has been proposed that plasmonic components such as waveguides, splitters, and switches can be developed in a continuous graphene sheet 4-6 . Using these components, a programmable plasmonic circuit can be configured. Experimentally, however, a platform for implementing this concept has not been developed-most of the intensive works on graphene plasmonics has focused on frequency tuning in a cavity structure with the boundary physically defined by etching 7-10 , placing metals 11 , or patterning the substrate 12 . While plasmon reflection by an electronic boundary formed at a grain boundary 13,14 , moiré-patterned graphene interface 15 , and monolayer/bilayer interface 16 , or one defined by 21. Rosolen, G. and Maes, B. Nonuniform doping of graphene for plasmon tapers, J. Opt. 17, 015002 (2015).

On Electromagnetic Turbulence

“…In stealth technology, we also may use a programmable plasmonic circuit was proposed in Ref. [27] using a transparent patterned zinc oxide gate to provide full control of plasmons in graphene. These techniques may assist in better design stealth technology [22] and Fig.…”

Synchronizing Bloch-oscillating free carriers in moiré flat bands

“…In practice the oscillator can be realized as e.g. THz photonic or plasmonic resonators [6,[32][33][34][35][36].…”

“…1, this system develops an instability towards collective oscillations at a Bloch frequency when the latter is close to the oscillator frequency. In practice, the oscillator can be realized as a THz photonic or plasmonic resonator in a 2D or a 3D architecture [6,[32][33][34][35][36]. Phase-coherent oscillations achieved in this regime represent a realization of electrically pumped THz lasing.…”

Direct Visualization of Ultrastrong Coupling between Luttinger-Liquid Plasmons and Phonon Polaritons

“… 4 − 10 Low-dimensional plasmons have the advantage of high confinement ratio and easy tunability by the dielectric environment or carrier density. 11 − 16 A particularly important phenomenon is strong coupling of quasiparticles which permits applications like induced transparency, polariton lasing, changing of the rate of chemical reactions, or enhanced sensitivity in infrared and Raman spectroscopy. 17 − 23 Strong coupling of low-dimensional plasmons was demonstrated by showing hybridization of graphene plasmons with phonon polaritons of various substrates.…”