Design of ultra-small mode area all-dielectric waveguides exploiting the vectorial nature of light

The wave nature and diffraction of light pose a significant bottleneck to the continued performance and efficiency scaling of a wide variety of integrated photonic devices, often necessitating solutions based on resonance, slow-light, or plasmonics to derive enhanced light-matter interaction. Here, we introduce all-dielectric waveguides that exploit the vectorial nature of light to achieve strong subdiffraction confinement in high index dielectrics, enabling characteristic mode dimensions below λ02/1000 without metals or plasmonics. We further show how these ultra-small mode areas may coincide or diverge from the nonlinear effective mode area. The work opens the door to new types of waveguide-based devices featuring strong near-field confinement, Purcell factors, and nonlinear effects, with broad applications spanning classical and quantum optics.