Nano-discs act as micro-resonators, trapping infrared photons and generating polaritons. When illuminated with infrared light, the discs concentrate light in a volume thousands of times smaller than is possible with standard optical materials. At such high concentrations, the polaritons oscillate like water sloshing in a glass, changing their oscillation depending on the frequency of the incident light.
Credit: Harvard SEAS
Paper (Science Advances – 15 Jun 2018): Ultra-confined mid-infrared resonant phonon polaritons in van der Waals nanostructures (PDF)