Identifying an object, be it of dielectric or plasmonic or chiral nature, by only using light beam is familiarized as optical sorting. As far as is known, a single optical setup is not reported so far, where these three different kinds of Mie sized particles can exhibit completely distinct behaviors. Chemical-based sorting of these various types of particles is still considered as a notable industrial problem due to the use of very expensive chemicals. This work presents a novel all-optical technique to distinguish classes of nanoscale Mie objects by separately placing them over a metasurface consisting of double-lined gold nanostructures. The proposed setup promotes an effective on-chip material-based optical sorting of silica (a dielectric object), gold (a plasmonic object), and chiral nanospheres by generating a dual surface plasmon polariton (SPP) energized plasmonic complex field, which induces fully different behaviors in Mie scatterers having dissimilar material properties. For instance, when simple plane wave is imposed underneath the metasurface, plasmonic object experiences the counterintuitive optical pulling force, dielectric object experiences pushing force, whereas the chiral object experiences optical lateral force. The proposed optical setup may introduce a new method of all-optical sorting without using chemicals or costly materials.

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Due to their sub-millimeter spatial resolution, ink-based additive manufacturing tools are typically considered less attractive than nanophotonics. Among these tools, precision micro-dispensers with sub-nanoliter volumetric control offer the finest spatial resolution: down to 50 µm. Within a sub-second, a flawless, surface-tension-driven spherical shape of the dielectric dot is formed as a self-assembled µlens. When combined with dispersive nanophotonic structures defined on a silicon-on-insulator substrate, we show that the dispensed dielectric µlenses [numerical aperture (NA) = 0.36] engineer the angular field distribution of vertically coupled nanostructures. The µlenses improve the angular tolerance for the input and reduces the angular spread of the output beam in the far field. The micro-dispenser is fast, scalable, and back-end-of-line compatible, allowing geometric-offset-caused efficiency reductions and center wavelength drift to be easily fixed. The design concept is experimentally verified by comparing several exemplary grating couplers with and without a µlens on top. A difference of less than 1 dB between incident angles of 7° and 14° is observed in the index-matched µlens, while the reference grating coupler shows around 5 dB contrast.