Doping-driven topological polaritons in graphene/α-MoO3 heterostructures

Abstract

Controlling the charge carrier density provides an efficient way to trigger phase transitions and modulate the optoelectronic properties in natural materials. This approach could be used to induce topological transitions in the optical response of photonic systems. Here, we predict a topological transition in the isofrequency dispersion contours of hybrid polaritons supported by a two-dimensional heterostructure consisting of graphene and $\alpha$-phase molybdenum trioxide ($\alpha$-MoO3). By chemically changing the doping level of graphene, we experimentally demonstrate that the contour topology of polariton isofrequency surfaces transforms from open to closed shapes as a result of doping-dependent polariton hybridization. Moreover, by changing the substrate medium for the heterostructure, the dispersion contour can be further engineered into a rather flattened shape at the topological transition, thus supporting tunable polariton canalization and providing the means to locally control the topology. We demonstrate this idea to achieve extremely subwavelength focusing by using a 1.2-$\mu$m-wide silica substrate as a negative refraction lens. Our findings open a disruptive approach toward promising on-chip applications in nanoimaging, optical sensing, and manipulation of nanoscale energy transfer.

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Cited by in corpus (15)

• Gate-tunable negative refraction of mid-infrared polaritons
• Multiple and spectrally robust photonic magic angles in reconfigurable α-MoO3 trilayers
• Roadmap for Photonics with 2D Materials
• Tunable optical topological transitions of plasmon polaritons in WTe2 van der Waals films
• Ultraconfined plasmons in atomically thin crystalline silver nanostructures
• Review on Infrared Nanospectroscopy of Natural 2D Phyllosilicates
• Toward Optimum Coupling between Free Electrons and Confined Optical Modes
• Polaritonic Quantum Matter
• Twist-angle and thickness-ratio tuning of plasmon polaritons in twisted bilayer van der Waals films
• Charge-Transfer Hyperbolic Polaritons in $\alpha$-MoO${}_3$/graphene heterostructures
• Strongly confined Mid-infrared to Terahertz Phonon Polaritons in Ultra-thin SrTiO3
• Two-dimensional talc as a natural hyperbolic material
• Manipulating Topological Polaritons in Optomechanical Ladders
• Canalized hyperbolic magnetoexciton polaritons enabled by the Shubnikov-de Haas effect in van der Waals semiconductors
• Light-induced ultrafast magnetization dynamics in van der Waals antiferromagnetic CrSBr