Sub-diffractional volume-confined polaritons in the natural hyperbolic material hexagonal boron nitride

Abstract

Strongly anisotropic media, where the principal components of the dielectric tensor have opposite signs, are called hyperbolic. Such materials exhibit unique nanophotonic properties enabled by the highly directional propagation of slow-light modes localized at deeply subdiffractional length scales. While artificial hyperbolic metamaterials have been demonstrated, they suffer from high plasmonic losses and require complex nanofabrication, which in turn induces size-dependent limitations on optical confinement. The low-loss, mid-infrared, natural hyperbolic material hexagonal boron nitride is an attractive alternative. Here we report on three-dimensionally confined 'hyperbolic polaritons' in boron nitride nanocones that support four series (up to the seventh order) modes in two spectral bands. The resonant modes obey the predicted aspect ratio dependence and exhibit high-quality factors (Q up to 283) in the strong confinement regime (up to l/86). These observations assert hexagonal boron nitride as a promising platform for studying novel regimes of light-matter interactions and nanophotonic device engineering.

Laser heating of scanning probe tips for thermal near-field spectroscopy and imaging

“…3(b)). 15,16 The out-of-plane mode response at ν TO ⊥ = 780 cm 1 is not observed due to the use of a BaF 2 beam splitter with an IR bandwidth cut-off at ∼900 cm 1 . In contrast, the near-field spectrum using a KBr beam splitter of hBN on a Au substrate shows a peaked signal at the out-of-plane phonon mode resonance frequency ν TO ⊥ = 780 cm 1 , while the in-plane mode is not observed.…”

Non-linear excitation of quantum emitters in hexagonal boron nitride multiplayers

“…[1][2][3][4][5][6][7][8] For instance, studies of non-linear absorption or refraction in transition metal dichalcogenides have been promising for applications in mode locking, ultrafast photonics, and optical switching. [9][10][11][12] Hexagonal boron nitride (hBN) is another layered material 13,14 that has recently been subject to an increased research due its ability to host room-temperature quantum emitters. [15][16][17] While the origin of these emitters is still under investigation, they exhibit remarkable properties such as ultra-high brightness, full polarization, and tunable emission 18 making them very interesting for quantum sensing and optical communications.…”

Graphene-Hexagonal Boron Nitride Heterostructure as a Tunable Phonon–Plasmon Coupling System

“…The propagation characteristics can be tuned by controlling the Fermi level of graphene. Compared with the model mentioned in the previous paper [23], the effect of the sequence of excitation on the HPPP modes has been investigated in our model. Furthermore, we introduce the metal SPP in our model to further study the coupling modes' properties.…”

“…Apart from graphene, h-BN is a van der Walls crystal [18] as well as a wide bandgap (~6 eV) electrical insulator. Furthermore, h-BN also shows natural hyperbolicity [19][20][21][22][23], which means that the relative dielectric constants in-plane and out-of-plane have opposite signs. This property leads to a hyperbolic or indefinite dispersion for electromagnetic waves propagating inside such a material and results in the excitation of surface phonon-polariton mode.…”

“…These hybrid modes, regarded as an advanced version of 2D metamaterials, can absorb the virtues of both the hyperbolic dielectric h-BN and graphene by offering more freedom to manipulate infrared waves and thus create new functional optical devices. Due to exceptionally narrow resonance linewidths, up to 300 times narrower than the free-space wavelength, hybridized phonon-plasmon polaritons (HPPP) modes have been demonstrated sub-diffraction polariton propagation and sub-wavelength imaging with nanoscale resolution [19,23].…”