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- Title
Revealing low-loss dielectric near-field modes of hexagonal boron nitride by photoemission electron microscopy.
- Authors
Li, Yaolong; Jiang, Pengzuo; Lyu, Xiaying; Li, Xiaofang; Qi, Huixin; Tang, Jinglin; Xue, Zhaohang; Yang, Hong; Lu, Guowei; Sun, Quan; Hu, Xiaoyong; Gao, Yunan; Gong, Qihuang
- 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 space and narrow spread in energy space are simultaneously observed due to the atomically flat surface of hBN and the small photoemission horizon set by the limited photon energies. Our approach provides a strategy for the realization of flat photoemission emitters. The application of time-resolved photoemission electron microscopy (TR-PEEM) to non-conducting materials is challenging. Here, the authors report the TR-PEEM characterization of near-field dielectric modes and photoemission properties of insulating hexagonal boron nitride structures on indium tin oxide/glass substrates.
- Subjects
PHOTOEMISSION; ELECTRON microscopy; BORON nitride; DIELECTRICS; WIDE gap semiconductors; MOMENTUM space; DIELECTRIC waveguides
- Publication
Nature Communications, 2023, Vol 14, Issue 1, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-023-40603-4