Hexagonal boron nitride (hBN) is a natural hyperbolic material which can also accommodate highly dispersive surface phonon-polariton modes. In this paper, we examine theoretically the mid-infrared optical properties of graphene-hBN heterostructures derived from their coupled plasmon-phonon modes. We found that the graphene plasmon couples differently with the phonons of the two Reststrahlen bands, owing to their different hyperbolicity. This also leads to distinctively different interaction between an external quantum emitter and the plasmon-phonon modes in the two bands, leading to substantial modification of its spectrum. The coupling to graphene plasmons allows for additional gate tunability in the Purcell factor, and narrow dips in its emission spectra.
Nonlinear light-matter interactions in structured materials are the source of exciting properties and enable vanguard applications in photonics. However, the magnitude of nonlinear effects is generally small, thus requiring high optical intensities for their manifestation at the nanoscale. Here, we reveal a large nonlinear response of monolayer hexagonal boron nitride (hBN) in the mid-infrared phonon-polariton region, triggered by the strongly anharmonic potential associated with atomic vibrations in this material. We present robust first-principles theory predicting a threshold light field $\…
A fundamental building block in nano-photonics is the ability to directionally excite highly squeezed optical mode dynamically, particularly with an electrical bias. Such capabilities would enable the active manipulation of light propagation for information processing and transfer. However, when the optical source is built-in, it remains challenging to steer the excitation directionality in a flexible way. Here, we reveal a novel mechanism for tunable directional excitation of highly squeezed polaritons in graphene-hexagonal boron nitride (hBN) heterostructures. The effect relies on controllin…
We study the radiative heat transfer between multilayer structures made by a periodic repetition of a graphene sheet and a hexagonal boron nitride (hBN) slab. Surface plasmons in a monolayer graphene can couple with a hyperbolic phonon polaritons in a single hBN film to form hybrid polaritons that can assist photon tunneling. For periodic multilayer graphene/hBN structures, the stacked metallic/dielectric array can give rise to a further effective hyperbolic behavior, in addition to the intrinsic natural hyperbolic behavior of hBN. The effective hyperbolicity can enable more hyperbolic polarit…
This paper aims to study the reflection characteristics of optical beams in a hybrid graphene-hexagonal Boron Nitride (hBN)-graphene structure, which has been located on SiO2-Si layers. An analytical model is presented to derive the reflection characteristics by using the transfer matrix method. The upper Reststrahlen band has been chosen as the studied frequency range. It is shown that the characteristics of the reflected beam can be effectively controlled by varying the chemical potential of graphene sheets. The obtained results represent a high value of the reflected group delay (=15.3 ps) …
The hybridization of hyperbolic Polaritonics with THz Plasmonics has attracted immense attention due to its fascinating applications in this region. However, to effectively enhance the performance of these coupled modes, one way is the usage of smart materials in the heterostructures. Here, we introduce a symmetric graphene-based structure containing hexagonal Boron Nitride (hBN) layers, where two nonlinear layers have been utilized as claddings to improve the confinement of Hybrid Surface Phonon-Plasmon-Polaritons. A new analytical model is derived. A set of nonlinear equations are solved num…
In recent years, the hybridization of hyperbolic van der Waals heterostructures with plasmonic two-dimensional nano-materials is one of the interesting research areas at THz frequencies due to the coupled features of the hybrid structure. This article investigates the propagation of tunable surface phonon-plasmon polaritons in grounded hybrid graphene-hexagonal Boron Nitride (hBN) heterostructures. An analytical model is presented for the proposed structure, by applying the boundary conditions for the electromagnetic components in the various regions, to derive an exact dispersion relation. Th…
The recent discovery of natural biaxial hyperbolicity in van der Waals crystals, such as $α$-MoO$_3$, has opened up new avenues for mid-IR nanophotonics due to their deep subwavelength phonon-polaritons. However, a significant challenge is the lack of active tunability of these hyperbolic phonon polaritons. In this work, we investigate heterostructures of graphene and $α$-MoO$_3$ for actively tunable hybrid plasmon phonon polariton modes via electrostatic gating in the mid-infrared spectral region. We observe a unique propagation direction dependent hybridization of graphene plasmon polaritons…
Strong coupling between molecular vibrations and microcavity modes has been demonstrated to modify physical and chemical properties of the molecular material. Here, we study the much less explored coupling between lattice vibrations (phonons) and microcavity modes. Embedding thin layers of hexagonal boron nitride (hBN) into classical microcavities, we demonstrate the evolution from weak to ultrastrong phonon-photon coupling when the hBN thickness is increased from a few nanometers to a fully filled cavity. Remarkably, strong coupling is achieved for hBN layers as thin as 10 nm. Further, the ul…
The observation of the electrically tunable and highly confined plasmons in graphene has stimulated the exploration of interesting properties of plasmons in other two dimensional materials. Recently, hyperbolic plasmon resonance modes are observed in exfoliated WTe2 films, a type-II Weyl semimetal with layered structure, providing a platform for the assembly of plasmons with hyperbolicity and exotic topological properties. However, the plasmon modes were observed in relatively thick and small-area films, which restrict the tunability and application for plasmons. Here, large-area (~ cm) WTe2 f…
Color Centers and Hyperbolic Phonon Polaritons in Hexagonal Boron Nitride: A New Platform for Quantum Optics
ETH Zürich（苏黎世联邦理工学院）；Max Planck Institute for the Structure and Dynamics of Matter（马克斯·普朗克物质结构动力学研究所）；RWTH Aachen University（亚琛工业大学）；Institute of Quantum Electronics, ETH Zürich（苏黎世联邦理工学院量子电子学研究所）；Lyman Laboratory, Department of Physics, Harvard University（哈佛大学物理系莱曼实验室）；Harvard University（哈佛大学）；Institute for Theoretical Studies, ETH Zürich（苏黎世联邦理工学院理论研究所）；Institute for Theoretical Physics, ETH Zürich（苏黎世联邦理工学院理论物理研究所）
