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

光的紧密聚焦在许多应用中起着至关重要的作用，在光捕获和激光扫描显微镜中具有重要意义。这里常见的显微镜显示局限性，如缺乏灵活性和可集成性，限制波前控制和较差的远程操作能力。到目前为止，还没有可靠的解决方案能够将灵活、强大、远程传输/收集的光与强聚焦结合起来。具有单模（SM）芯的光纤允许灵活和受控的光传输，同时由于输出光束的发散而显示出聚焦方面的限制。已经进行了纳米和微结构纤维端面的尝试，但是没有达到超过0.7的数值孔径（NAs）。元表面是超薄光子器件，允许完全的波前控制。在高NA下的强聚焦尚未实现的情况下，在纤维尖端上创建元表面已初步解决。最近，申请者已经证明了NAs高达0.88的3D纳米打印超透镜可以与SM纤维相连接。首次用一根SM纤维捕获微珠和细菌，证明了其聚焦能力。这些结果表明，将纳米打印的元透镜与SM纤维相结合，可以产生一种新型的衍射限制远程聚焦平台-元纤维平台。该项目的想法是研究超光纤概念的光/物质相互作用，并在一系列与应用相关的实验中展示其能力。具体来说，该项目旨在设计3D纳米打印的超透镜，并将其与光纤连接，包括一个或多个SM芯和光束扩展段。该项目包括考虑到光纤环境的特殊性，在这样一个系统中光/物质相互作用的基础研究。超纤维的实际意义将通过光学捕获（动态和静态单点和多点捕获）和扫描显微镜（共聚焦和STED）来证明，旨在揭示超纤维是否允许用单一紧凑的设备取代笨重的光学器件。总的来说，这个项目将揭示超光纤的潜力，并导致一种新的集成、灵活和紧凑的光子器件，具有独特的远程光聚焦特性。

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.