Bypassing Nonlocal Phenomena in Metals Using Phonon-Polaritons
Phonon-polaritons in hexagonal boron nitride provide a method to bypass nonlocal effects in high-confinement regimes clearing the path toward record-breaking field confinement.
We are excited to share recently published results from a long-term collaboration between POLIMA and the group of Professor Min Seok Jang at Korea Advanced Institute of Science and Technology (KAIST).
In this newly released publication, the groups use mid-infrared phonon-polaritons in hexagonal boron nitride (hBN) screened by monocrystalline gold flakes to push the limits of light confinement unobstructed by nonlocal phenomena, even when the polariton phase velocity approaches the Fermi velocities of electrons in gold.
Specifically, scattering-type scanning near-field optical microscopy allowed for direct probing of the polariton wavelength, and corresponding phase velocity, in the heterostructure. By systematically studying multiple samples with varying hBN crystal thicknesses, it was possible to demonstrate the absence of any systematic discrepancies between experiment and classical electrodynamic theory. This conclusion is further supported by theoretical modelling that explicitly accounts for potential nonlocal contributions.
Together, the results outline a pathway to bypass the impact of nonlocality in high-confinement regimes enabling future exciting experiments that push polariton confinement further than ever before.
