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 introducing wavelet transform, the mode evolution information of the terahertz phonon-polariton is successfully extracted. It indicates that the phonon radiation intensity of the MaPbI₃ film is enhanced as the coupling strength is increased. This work not only establishes a new platform for terahertz devices but also opens new avenues for exploring the intricate dynamics of terahertz phonon-polaritons.

References in corpus (8)

• Applications of Bound States in the Continuum in Photonics
• Polariton laser using single micropillar GaAs-GaAlAs semiconductor cavities
• Strong light-matter interaction with self-hybridized bound states in the continuum in monolithic van der Waals metasurfaces
• Non-Hermitian engineering of terahertz light using exceptional points in electrically tuneable collective light-matter interactions
• Microcavity phonon polaritons from weak to ultrastrong phonon-photon coupling
• Hybrid THz architectures for molecular polaritonics
• Controlling the electro-optic response of a semiconducting perovskite coupled to a phonon-resonant cavity
• Ultrafast (10 GHz) mid-IR modulator based on ultra-fast electrical switching of the light-matter coupling

Cited by in corpus (1)

• Magnetically Tunable Chiral Phonon Polaritons with Magneto-optical Bound States in the Continuum