Polarization-insensitive dielectric metalenses with different numerical apertures and off-axis focusing characteristics

Optical metasurfaces with an ultra-thin, planar structure can easily adjust the phase and polarization of light waves. Based on the principle of the resonant phase, a cubic nanopillar is designed to construct the polarization-insensitive metalens in the visible light range. By simulating the phase and transmission efficiency of a cubic nanopillar with a width of 50 similar to 200 nm, the optimized height of the nanopillar is obtained. Metalenses with different numerical apertures are designed to obtain the sub-wavelength focusing effect. The focusing performance of the same metalens remains the same when the right-handed circular polarization light and the left-handed circular polarization light are incident, respectively, which proves that the designed structure is insensitive to circular polarization light. At the same time, the different off-axis focusing metalenses that can achieve flexible focusing in the desired spatial location are also designed and investigated. This research provides a reference to design polarization-insensitive photonic integrated components and flexible imaging metalenses. (C) 2020 Optical Society of America