Hyperbolic phonon polaritons (HPhPs) in van der Waals materials are promising for nanophotonic applications, but they are normally limited to the mid-infrared range. Here, the authors report the observation of long-lived and highly confined HPhPs in the deep THz range in layered PbI2.
- Cristiane N. Santos
- Flávio H. Feres
- Jean-François Lampin