Near-infrared axicon lens system based on dielectric metasurfaces

Axicon is an optical device that can generate a rotating axisymmetric beam. Bottle beam is a special type of light field with a central dark spot that is completely surrounded by a light field in three-dimensional space. Due to its special light field distribution, it has high application in the micro field. Bottle beam can be generated by using axicon-lens system. Metasurface, as a type of two-dimensional planar device with sub wavelength scale, can provide a new approach to design axicon-lens due to its advantages of lightweight, planarization and flexibility. In this paper, an axicon-lens system which consist of two metasurfaces was designed and bottle beam was generated by irradiating axicon-lens system in near-infrared. The metasurface is composed of elliptical silicon nanorods. These nanorods which arrange periodically have different geometric sizes. Our proposed method has been verified based on the simulations with FDTD software. Our design provides a method for generating bottle beams with individual feature sizes that are comparable with the size of a wavelength of the near-infrared light.