Routing light with ultrathin nanostructures beyond the diffraction limit.

An open nanostructure consisting of a periodic chain of subwavelength-nanoparticles for compressing and routing light beyond the diffraction limit is proposed. The open nanostructure is ultrathin and compact, with a size much smaller than the wavelength of light. We demonstrate that our ultrathin open nanostructure provides functions that can route and manipulate light at the subwavelength scale and can also sharply bend and split light beams below the diffraction limit while exhibiting broadband, incident-angle-tolerant, and robust against disorder. A physical picture based on all-angle self-collimation is presented to understand the manipulation of light using the ultrathin open nanostructure. Experimental and numerical observations validate our findings. This approach provides great flexibility in the design of nanophotonic devices for routing and manipulating light beyond the diffraction limit.