3D Imaging of Optical Modes in Dielectric Photonic Nanocavities with Sub-wavelength Field Confinement.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41212717.
- Also identified by DOI 10.1021/acs.nanolett.5c04226 and PMC identifier 12636085.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Dielectric optical cavities are emerging as viable platforms for efficiently concentrating light within extremely small volumes of sub-wavelength dimensions. This breaks with the notion that only plasmonic nanostructures can achieve this scale of confinement and enables strong light-matter interactions without the losses typically associated with metals. Here, we directly visualize the optical modes of a topology-optimized silicon bowtie nanocavity using multi-orientation electron energy-loss spectroscopy. Tomographic reconstruction of the resulting data sets reveals the three-dimensional profiles of several polarized optical modes in close agreement with simulations. A resonance near the telecom wavelength (∼1550 nm) is shown to be tightly localized at the bowtie bridge, confirming its deep sub-wavelength mode volume. These findings establish electron beam spectroscopy as a powerful tool for mapping three-dimensional field confinement in dielectric photonic cavities with potential applications in future photonic and quantum technologies.