Ultracompact metalens-based beam-focusing fiber-optic device with a large numerical aperture

Conventional optical fibers have good light conduction and transmission properties, and have been widely used in the fields of long-distance fiber-optic communication and sens-ing. However, due to the dielectric properties of the fiber core and cladding materials, the spot size of the transmitted light is dispersive, which greatly limits the application areas of optical fiber. The emergence of metalenses based on arti-ficial periodic micro-nanostructures is opening the door to a variety of fiber innovations. We demonstrate an ultracom-pact beam-focusing fiber-optic device based on a composite structure of a single-mode fiber (SMF), a multimode fiber (MMF), and a metalens consisting of periodic micro-nano silicon column structures. Convergent beams with numeri-cal apertures (NAs) of up to 0.64@air and a focal length of 63.6 mu m are produced by the metalens on the MMF end face. The metalens-based fiber-optic beam-focusing device could find new applications in optical imaging, particle capture and manipulation, sensing, and fiber lasers. (c) 2023 Optica Publishing Group

Automated summary

Conventional optical fibers have been widely used in long-distance fiber-optic communication and sensing, but the dispersive spot size limits their applications. Metalenses with artificial micro-nanostructures are introducing new possibilities for fiber innovations.