Excitation and Manipulation of In-Plane Hyperbolic Phonon Polaritons in α-MoO₃ Flakes via Plasmonic Antennas

. Maximum HPhP near-field intensity is achieved when the nanorods are aligned to optimize coupling with the anisotropic polaritonic modes, with efficiency closely linked to the resonance conditions of the plasmonic antennas. Numerical designs are corroborated well with near-field optical characterizations. Therefore, our approach establishes a platform to study interactions between plasmonic antennas and anisotropic polaritons, advancing controlled manipulation of in-plane polaritonic modes in van der Waals materials.