Manipulating terahertz phonon-polariton in the ultrastrong coupling regime with bound states in the continuum.

ABSTRACT: The strong coupling between photons and phonons in polar materials gives rise to phonon-polaritons that encapsulate a wealth of physical information, offering crucial tools for the ultrafast terahertz sources and the topological engineering of terahertz light. However, it is still quite challenging to form and manipulate the terahertz phonon-polaritons under the ultrastrong coupling regime till now. In this work, we demonstrate the ultrastrong coupling between the phonon (at 0.95 THz) in a MAPbI₃ film and the metallic bound states in the continuum (BICs) in Au metasurfaces. The Rabi splitting can be continuously tuned from 28% to 48.4% of the phonon frequency by adjusting the parameters (size, shape and period) of Au metasurfaces, reaching the ultrastrong coupling regime. By int

SUBMITTER: Yang J 

PROVIDER: S-EPMC12511402 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature