Millimeter-wave metalens with extended depth of focal on the short focal length

Abstract

Millimeter wave (mm-wave) metalens has shown significant progress in recent years. However, the existing works in the literature on the extended depth of focal (EDOF) metalens present limitations for mm-waves. More specifically, the good performance of the EDOF requires a focal length larger than the radius of the metalens, which limits its miniaturization applications. In this work, mm-wave metalens with EDOF on the short focal length was proposed. The focus distribution was equally divided and the spin Hall effect was employed to guarantee the uniform focus intensity. From our analysis, it was demonstrated that the designed metalens can work at mm-wave frequencies and also achieve extended focal depth at half the metalens’ radius. The proposed metalens has the unique characteristics of short focal length (The focal diameter ratio is 0.36) with EDOF. Moreover, it can be used in the mm-wave field for short-distance imaging and detection, also the development of high-power metalens applications may be facilitated.