Meta-fiber optics - structuring light via 3D nano-printed meta-optics on designer multi-element fibers

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The tight focusing of light plays an essential role in many applications and is highly important for optical trapping and laser scanning microscopy. Here common microscopes show limitations such as a lack of flexibility and integrability, restricted wave front control and poor remote operating capabilities. Up to date no reliable solution exists that combines flexible, robust and remote delivery/collection of light with strong focusing.Optical fibers with single-mode (SM) cores allow for flexible and controlled transportation of light, while showing limitations regarding focusing due to the divergence of the output beam. Attempts to nano- and microstructure fiber end-faces have been undertaken which, however, have not reached numerical apertures (NAs) beyond 0.7. Meta-surfaces are ultrathin photonic devices and allow for complete wave front control. Creating meta-surfaces on fiber tips has tentatively been addressed while strong focusing at high NA was not achieved. Recently the applicants have shown that 3D nano-printed meta-lenses with NAs as high as 0.88 can be interfaced with SM fibers. The focusing capabilities have been demonstrated by trapping microbeads and bacteria with one SM fiber for the first time. These results suggest that combining nanoprinted meta-lenses with SM fibers yields a new type platform – the meta-fibers platform – for diffraction limited remote light focusing.The idea of this project is to investigate the light/matter interaction of the meta-fiber concept and demonstrate its capabilities in a series of application-relevant experiments. Specifically, the project aims for designing 3D nano-printed meta-lenses and interfacing them with optical fibers including one or more SM cores and beam expansion sections. The project includes fundamental studies of light/matter interaction in such a system taking into account the peculiarities of the fiber environment. The practical relevance of meta-fibers will be demonstrated by optical trapping (dynamic and static single- and multi-site trapping) and scanning microscopy (confocal and STED), aiming to reveal if meta-fibers allow to replace bulky optics by single compact devices. Overall this project will reveal the potential of meta-fibers and lead to a new class of integrated, flexible and compact photonic devices with unique properties regarding remote light focusing.