Negative refraction in hyperbolic hetero-bicrystals

Abstract

We visualized negative refraction of phonon polaritons, which occurs at the interface between two natural crystals. The polaritons - hybrids of infrared photons and lattice vibrations - form collimated rays that display negative refraction when passing through a planar interface between the two hyperbolic van der Waals materials: molybdenum oxide ($Mo{O}_3$) and isotopically pure hexagonal boron nitride ($h^{11}BN$). At a special frequency ${\omega }_0$, these rays can circulate along closed diamond-shaped trajectories. We have shown that polariton eigenmodes display regions of both positive and negative dispersion interrupted by multiple gaps that result from polaritonic level repulsion and strong coupling.

References in corpus (5)

• Observation of topological polaritons and photonic magic angles in twisted van der Waals bi-layers
• Subdiffractional focusing and guiding of polaritonic rays in a natural hyperbolic material
• Configure polaritons in twisted $\alpha$-MoO3
• Overcoming losses with gain in a negative refractive index metamaterial
• Femtosecond photo-switching of interface polaritons in black phosphorus heterostructures

Cited by in corpus (11)

• Roadmap for Photonics with 2D Materials
• Unidirectional Ray Polaritons in Twisted Asymmetric Stacks
• Phonon transition across an isotopic interface
• Ultraconfined plasmons in atomically thin crystalline silver nanostructures
• Polaritonic Quantum Matter
• Directional strong coupling at the nanoscale between hyperbolic polaritons and organic molecules
• Electron-optics using negative refraction in two-dimensional inverted-band $pn$ junctions
• Retrieving optical parameters of emerging van der Waals flakes
• Two-dimensional talc as a natural hyperbolic material
• A negative index metamaterial driven by phonons on a ZnO platform
• Negative Refraction of Terahertz Phonons via Interfacial Momentum Compensation