Gate tunable light–matter interaction in natural biaxial hyperbolic van der Waals heterostructures

Abstract

The recent discovery of natural biaxial hyperbolicity in van der Waals crystals, such as α-MoO3, 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-MoO3 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 with hyperbolic phonon polaritons for experimentally feasible values of graphene chemical potential. We further report an application to tunable valley quantum interference in this system with a broad operational bandwidth due to the formation of these hybrid modes. This work presents a lithography-free alternative for actively tunable, anisotropic spontaneous emission enhancement using a sub-wavelength thick naturally biaxial hyperbolic material.

Surface plasmons induce topological transition in graphene/α-MoO3 heterostructures

“…Final note: the authors became aware of the following relevant works by Álvarez-Pérez et al 32 ; Bapat et al 33 ; Hu et al 34 ; and Zeng et al 35 after completion of this work.…”

Perspective on Meta-Boundaries

“…Remarkably, this kind of multiple meta-boundaries can support the emergence of excitonic superfluid phase . Moreover, the out-of-plane interaction between neighboring meta-boundaries would become more complex, if there exists the interlayer twist angle, − as schematically shown in Figure e. For example, Figure f shows the multiple meta-boundaries composed of rotated multiple bilayer graphene .…”

Two-dimensional natural hyperbolic materials: from polaritons modulation to applications

“…In 2022, A. Bapat et al proposed to measure the valley quantum interference via placing a gapped Dirac system at a certain distance away from the heterostructure consisting of monolayer graphene and hyperbolic crystals of α-MoO 3 on a silicon substrate. 45 The geometrical configuration for the heterostructure is sketched in Fig. 13(a).…”

“…[31][32][33][34][35][36][37][38][39] Especially, natural HMs are endowed with many fantastic merits in comparison with traditional hyperbolic metamaterials. [40][41][42][43][44][45] For instance, they require no artificial structuring and contain no internal interfaces for the electrons to scatter off. Moreover, because of their homogeneous nature, the hyperbolic dispersion, which is in principle only limited by the atomic periodicity of the crystal lattice or effects of a non-local dielectric response, is expected to extend much further in the reciprocal space.…”

“…50,51 A comprehensive comparison of hyperbolic phonon, plasmon, exciton, and shear polaritons remains lacking. Moreover, various novel and improved applications for natural HMs (e.g., valley quantum interference and high temperature polarizers 45,52 ) have been also presented during the last two years. Thereby, it is meaningful to provide a thorough overview of these four types of hyperbolic polariton, as well as the most recent developments in the applications of 2D natural HMs.…”