Strongly Coupled Exciton--Hyperbolic-phonon-polariton Hybridized States in hBN-encapsulated Biased Bilayer Graphene

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Main Authors: Eini, Tomer, Peres, N. M. R., Mazor, Yarden, Epstein, Itai
Format: Preprint
Published: 2025
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author Eini, Tomer
Peres, N. M. R.
Mazor, Yarden
Epstein, Itai
author_facet Eini, Tomer
Peres, N. M. R.
Mazor, Yarden
Epstein, Itai
contents Excitons in biased bilayer graphene are electrically tunable optical excitations residing in the mid-infrared (MIR) spectral range, where intrinsic optical transitions are typically scarce. Such a tunable material system with an excitonic response offer a rare platform for exploring light-matter interactions and optical hybridization of quasiparticles residing in the long wavelength spectrum. In this work, we demonstrate that when the bilayer is encapsulated in hexagonal-boron-nitride (hBN)-a material supporting optical phonons and hyperbolic-phonon-polaritons (HPhPs) in the MIR-the excitons can be tuned into resonance with the HPhP modes. We find that the overlap in energy and momentum of the two MIR quasiparticles facilitate the formation of multiple strongly coupled hybridized exciton-HPhP states. Using an electromagnetic transmission line model, we derive the dispersion relations of the hybridized states and show that they are highly affected and can be manipulated by the symmetry of the system, determining the hybridization selection rules. Our results establish a general tunable MIR platform for engineering strongly coupled quasiparticle states in biased graphene systems, opening new directions for studying and controlling light-matter interactions in the long-wavelength regime.
format Preprint
id arxiv_https___arxiv_org_abs_2506_04796
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Strongly Coupled Exciton--Hyperbolic-phonon-polariton Hybridized States in hBN-encapsulated Biased Bilayer Graphene
Eini, Tomer
Peres, N. M. R.
Mazor, Yarden
Epstein, Itai
Optics
Mesoscale and Nanoscale Physics
Excitons in biased bilayer graphene are electrically tunable optical excitations residing in the mid-infrared (MIR) spectral range, where intrinsic optical transitions are typically scarce. Such a tunable material system with an excitonic response offer a rare platform for exploring light-matter interactions and optical hybridization of quasiparticles residing in the long wavelength spectrum. In this work, we demonstrate that when the bilayer is encapsulated in hexagonal-boron-nitride (hBN)-a material supporting optical phonons and hyperbolic-phonon-polaritons (HPhPs) in the MIR-the excitons can be tuned into resonance with the HPhP modes. We find that the overlap in energy and momentum of the two MIR quasiparticles facilitate the formation of multiple strongly coupled hybridized exciton-HPhP states. Using an electromagnetic transmission line model, we derive the dispersion relations of the hybridized states and show that they are highly affected and can be manipulated by the symmetry of the system, determining the hybridization selection rules. Our results establish a general tunable MIR platform for engineering strongly coupled quasiparticle states in biased graphene systems, opening new directions for studying and controlling light-matter interactions in the long-wavelength regime.
title Strongly Coupled Exciton--Hyperbolic-phonon-polariton Hybridized States in hBN-encapsulated Biased Bilayer Graphene
topic Optics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2506.04796