In‐Plane Anisotropic Phonon‐Polaritonic Resonances with α‐MoO3 microdisks

Phonon polaritons (PhPs) in two‐dimensional van der Waals (vdW) crystals exhibit strong spatial confinement and long polariton lifetimes, making them promising for developing novel nanophotonic devices at mid‐infrared frequencies. Here, using α‐phase molybdenum trioxide (α‐MoO3) microdisks, we have demonstrated in‐plane anisotropic PhP resonances with degree of polarization (DoP) of almost 100% from far field observation. Such in‐plane polarization‐dependent PhP resonances, originating from the anisotropic crystal structure of α‐MoO3, are readily tuned by the disk length and fits well to numerical simulations. Our findings show new possibility for engineering in‐plane polarizers based on vdW crystals and may promote the development of functional polarization‐sensitive optoelectronic devices at mid‐infrared frequencies.This article is protected by copyright. All rights reserved.