Three-dimensional nanoconfinement of broadband optical energy in all-dielectric photonic nanostructure

We demonstrate the confinement of broadband optical energy in the visible to near-infrared regime in a three- dimensional nanoscale volume with high energy efficiency in a nanostructure consisting of multiple nanoslits in dielectric chacolgenide material. We find that a broadband optical field can be confined down to the scale of 1 nm (λ/650) with a confinement volume of λ< sup>3< /sup>/3 × 10< sup>4< /sup>. The figure of merit of the nanostructure can be up to 10 times that achieved by plasmonic lensing and nanofocusing. Our work opens a new way for truly nanoscaled photonics applicable to nanolithograpy, nanoimaging, lab-on-chip nanosensing, single-molecule detection, and nanospectroscopy.