Flatband polaritonic router in twisted bilayer van der Waals materials

Guided spiraling phonon polaritons in rolled one-dimensional MoO3 nanotubes

Polaritons in reduced-dimensional materials, such as nanowire, nanoribbon and rolled nanotube, usually provide novel avenues for manipulating electromagnetic fields at the nanoscale. Here, we theoretically propose and study hyperbolic phonon polaritons (HPhPs) with rolled one-dimensional molybdenum trioxide (MoO3) nanotube structure. We find that the HPhPs in rolled MoO3 nanotubes exhibit low propagation losses and tunable electromagnetic confinement along the rolled direction. By rolling the twisted bilayer MoO3, we successfully achieve a canalized phonon polaritons mode in the rolled nanotube, enabling their propagation in a spiraling manner along the nanotube. Our findings demonstrate the considerable potential of the rolled MoO3 nanotubes as promising platforms for various applications in light manipulation and nanophotonics circuits, including negative refraction, waveguiding and routing at the ultimate scale.