2025/10/01 by Wen-Zhi Mao, Hong-Yi Luan, Ren‐Min Ma · 1 voice · 1 citation
Engineering · Physics and Astronomy · #Plasmonic and Surface Plasmon Research #Photonic and Optical Devices #Photonic Crystals and Applications
paper · pdf · doi:10.1186/s43593-025-00104-x
openalex publication_date 2025/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Abstract The diffraction limit, rooted in the wave nature of light and formalized by the Heisenberg uncertainty principle, imposes a fundamental constraint on optical resolution and device miniaturization. The recent discovery of the singular dispersion equation in dielectric media provides a rigorous, lossless framework for overcoming this barrier. Here, we demonstrate that achieving such confinement necessarily involves a new class of optical eigenmodes—narwhal-shaped wavefunctions—which emerge from the singular dispersion equation and uniquely combine global Gaussian decay with local power-law enhancement. These wavefunctions enable full-space field localization beyond conventional limits. Guided by this principle, we design and experimentally realize a three-dimensional sub-diffraction-limited cavity that supports narwhal-shaped wavefunctions, achieving an ultrasmall mode volume of 5 × 10 −7 λ 3 . We term this class of systems singulonic, and define the emerging field of singulonics as a new nanophotonic paradigm—establishing a platform for confining and manipulating light at deep-subwavelength scales without dissipation, enabled by the singular dispersion equation. Building on this extreme confinement, we introduce singular field microscopy: a near-field imaging technique that employs singulonic eigenmodes as intrinsically localized, background-free light sources. This enables optical imaging at a spatial resolution of λ /1000, making atomic-scale optical microscopy possible. Our findings open new frontiers for unprecedented control over light–matter interactions at the smallest possible scales.