Design and fabrication of near-infrared metalens

Metalens is an imaging device based on metasurfaces, which can accurately regulate the phase, polarization, and amplitude of light. It has advantages of lightweight, easy-integration and planarizartion. For miniaturization and integration of near-infrared imaging devices, a near-infrared polarized insensitive metalens based on amorphous silicon was designed and fabricated. For selecting basic structures, the focusing efficiency of metalenses designed by 8-order and 6-order primitives were compared. To improve the processing tolerance and reduce the processing difficulty, the 8-order primitive was used to design metalens, and the maximum depth-width ratio was 6. For large-span between simulation and processing of metalens, the 600 nm-thick polysilicon by chemical vapor deposition was grew. The metalens was made by electron beam etching. The measured results show that the metalens has a good appearance and the focusing efficiency is 65%.