Revealing low-loss dielectric near-field modes of hexagonal boron nitride by photoemission electron microscopy.

ABSTRACT: Low-loss dielectric modes are important features and functional bases of fundamental optical components in on-chip optical devices. However, dielectric near-field modes are challenging to reveal with high spatiotemporal resolution and fast direct imaging. Herein, we present a method to address this issue by applying time-resolved photoemission electron microscopy to a low-dimensional wide-bandgap semiconductor, hexagonal boron nitride (hBN). Taking a low-loss dielectric planar waveguide as a fundamental structure, static vector near-field vortices with different topological charges and the spatiotemporal evolution of waveguide modes are directly revealed. With the lowest-order vortex structure, strong nanofocusing in real space is realized, while near-vertical photoemission in momentum spa

SUBMITTER: Li Y 

PROVIDER: S-EPMC10415285 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature