Multilayer all-polymer metasurface stacked on optical fiber via sequential micro-punching process

Metasurface technology is revolutionizing the field of optics and pursuing expanded functions via technical developments, such as the integration of multiple metasurfaces with optical fibers. Despite several attempts to realize metasurface-on-fiber platforms, negligible fiber-facet areas pose a serious obstacle to efficient and precise fabrication. Herein, we demonstrate a novel sequential micro-punching process that enables rapid and precise stacking of multiple polymer metasurfaces on the end face of a single-mode optical fiber. Mesh-type nanohole metasurfaces are fabricated on a 1.8-μm-thick polymethyl methacrylate (PMMA) layer via e-beam lithography, and the PMMA layer is separated from the substrate and prepared in the form of a membrane using the external frame. Furthermore, the PMMA metasurfaces are sequentially punched through the fiber and stacked on top. Employing a micro-punching process, we demonstrate highly efficient all-polymer metalenses and orbital angular momentum (OAM) metasurfaces coupled with single-mode fibers operating in the telecommunication band. A 1550 nm laser beam passing through three metalens layers stacked on the fiber is focused at a distance of 135 μm with 83% efficiency. In addition, the 1550 nm beam passing through three OAM metasurfaces on the fiber is converted into a perfect vortex beam with a topological charge of 3. We believe that our proposed micro-punching process will cause a breakthrough in the fabrication of metasurface-integrated optical fibers that will be utilized in a wide range of applications.