Ultra-high numerical aperture meta-fiber for flexible optical trapping

Optical trapping represents a powerful technique to remotely control and manipulate single objects with sizes ranging from atomic to microscopic scales [1] . For usage with a single beam, commonly known as optical tweezers, high numerical apertures of at least NA > 0.8 are required, which is commonly achieved by bulky microscope objectives. Optical fibers, in contrast, represent a flexible and low-cost photonic platform to remotely deliver light to the point of interest, however, suffering from a generally low NA due to their divergent beam, which is commonly compensated by a dual fiber arrangement with counter-propagating beams [2] .